: Started to hear an intermittent grinding noise

04-02-09, 02:07 AM
from the front of the motor on my 1994 STS Seville. Yesterday I was having a problem with my alternator or so I thought, turned out it was the battery cable. I take my daughter to school this morning ( 2 miles ) and when I get home I hear a grinding noise coming from under the hood. I listen by the front of the motor, passenger side where the balancer is located, I'm calling that the front. The noise would be there for about 1 or 2 seconds and then go away for a few seconds. It sounds like a metal line is touching a pulley while the car is running, push the line into the pulley and pull it away, that's what it sounds like.

I'm listening trying to figure where it's coming from, the tensioner pulley looks and feels okay, the idler pulley the same so I rev the engine. While the RPM's are increasing the grinding would stay constant, when the thrust is reversed and the RPM's are coming down the grinding would go away. Are there timing chains for the cams, are they gear drive, what could be in the front of the motor to cause this noise? It's not real loud but just noticeable with the hood closed.

Now the good part, while I'm revving the engine I finally give it a few good blasts ( maybe 4-5k RPM's ) and the noise quit, gone! It almost sounde lke a small pebble may have been stuck next to one of the pulleys, maybe a nut, screw, who knows and when I revved it good, it spit it out. I have no idea how the cams are driven, I assume chains and would also assume there is a chain tensioner, maybe the chain tensioner was sticking if that's possible. That is what is really sounded like, a loose timing chain scraping the inside of the cover when the thrust is almost neutral.

Someone may ask, if it's gone, why are you asking these questions?
1. I've owned and worked on cars long enough to know that if you have a noise, or say a knock, a tick and it goes away, it's coming back. You can bet it's coming back sooner or later, probably sooner. So, that being the case, I want to be somewhat prepared when it does come back. The only way it doesn't is if it was an object of some sort that was "laying" up against either the power steering pulley or crankshaft balancer pulley and it was dislodged when I revved the engine real high.

I know I can find an illustration of the inside of a 1994 Northstar engine but it won't tell me what others may have experienced or what an expert mecahanic believes the problem could be or have been!

Any comments would be most appreciated!

04-02-09, 12:01 PM
Can't help much on what or where the noise was, but the cams are chain driven. Open the oil fill cap and look in with a flashlight and you'll see one. There are nylon tensioners on them and they will last the life of the engine.

04-03-09, 02:55 AM
Thanks Ranger, I'll look inside tomorrow and go from there. So far the noice hasn't returned so maybe it was a piece of trash that had gotten up against one of the pulleys.

As far as the cam's being driven by chain with a nylon tensioner, I'll take your word that they will last the lifetime of the engine. I'm assuming lifetime is in the 200k range, at least I beleive my engine will go that far, easy. I have about 108 or 109k and it's like brand new, still pulls very hard and doesn't burn 1 speck of oil.

04-03-09, 12:04 PM
We have had people here with over 350K. There is a thread somewhere entitle "Who Can Beat Me".

04-03-09, 01:38 PM
A/C compressor clutch? I have had this problem before but on a 98 monte carlo. When the defroster is on the A/C cycles on and off because it is used for removing moisture in the cabin. Well when it would turn off the clutch would make this horrible metal grinding noise.

Like you said it stayed constant when you rev the engine. One day it went away and never came back.

04-28-09, 05:33 PM
The grinding noise that I first mentioned has never come back. What I have now is a whining noise, same area, the front of the motor. I've checked everything that turns with the belt and am quite sure that the whining has nothing to do with any of those parts. It's coming from the front of the motor and is quite noticeable when the motor is cold. When it wamrs up the whining noise almost goes away.

It's not the power steering but sounds a lot like a bad power steering pump! What is in or near the front of the motor that could casue that whine. It's a 1994 STS that I'm talking about, around 110k miles.

04-28-09, 08:19 PM
The water pump is on the rear of the motor and is belt driven off of the left bank intake cam. Check the belt tensioner.

04-28-09, 10:33 PM
Ranger, That seems like a reach but I'll certainly give it a try. The whining doesn't sound like a typical pulley bearing going out. Any bearing be it the alternator, belt tensioner, a/c comp, all create more of a grinding or squeeling noise, most of the time! It wouldn't surprise me that it's something I haven't experienced before. When you think you've seen or heard it all, a new noise will show up.

This noise sounds more like a gear drive for a cam or a transmission with a clogged filter. There is a local transmission shop that said they would diagnose the problem for no charge and felt certain they could locate the problem. I believe it's a young mechanic that's a little over exhuberant and have my coubts about their ability to locate the problem without removing parts one at a time.

In the morning I'll chekc that tensioner and would be tickled if that was making the whining noise.

I'll check back and keep you updated.

04-29-09, 08:11 AM
rodman, I just posted an opinion in a similar thread next to this one - by restoman.

04-29-09, 11:02 AM
Submariner, I read your post from the other thread and although that's not what I want to hear, I'm starting to believe that the problem is internal to the front of the motor and waht you've described with the timing chain slipper, that could very well be the problem. It's nearly time for an oil change so I'll get a good look at the oil and filter for plastic deposits. I guess if the plastic is worn away then the chain would be rubbing against a metal part thus making the whining sound that I'm hearing.

I'm pretty sure without asking but I'll ask anyway, it's probably a big job getting at the slipper for replacement?

Ranger, I did look at the water pump tnesioner and in fact, removed the belt, the whine was still present. I left that belt off and removed the serpentine belt and still the whine was present.

I may try and post a little video clip with sound so ya'll can hear the noise even though I believe the problem has been narrowed down. It would be more for future reference and aslo to see if I can do it.

Thanks, I will keep ya'll posted......

04-29-09, 11:50 AM
Is there any chance this "whine" is a vacuum leak whistle from the manifold over pressurization valve?

04-29-09, 03:57 PM
Ranger, I guess it could be that valve your talking about and what makes me think that is the whine went away a few minutes ago on the highway. When I got off the highway, the whine was gone. WHen I accelerated, it was not present until I pushed harder on the accelerator, about half way down with the pedal, it started again. I caould make it go away with light pressure on the accelerator and make it come back with more throttle.

Where exactly is that valve on a 1994 STS? I stopped at a garage on the way home and the mechanic listened and pointed to where I hear the noise, the front of the back bank of cylinders next to the firewall. It would be where the camshaft sprocket would be if the cover wasn't there. He thought it was a camshaft tensioner which I was beginning to think myself.

If it was a tensioner, how could it go away and then come back? Seems a mechanical problem would be constant where as a valve could be opening, sticking, staying closed, and therefore the noise would come and go.

I have to run but I'll check back shortly.

04-29-09, 07:48 PM
The cam chains have hydraulic tensioners which ride on the engine oil pressure. It's possible that you could alter or alleviate the problem with an oil/filter change. If that doesn't do it, then you're possibly looking at going into the front of the engine timing cover (chaincase). Not fun.

04-29-09, 09:16 PM
The over pressure relief valve is exactly opposite the TB. It's tucked back in a hole behind the P/S pump. If you hear it at idle you can listen in there with a stethoscope or rubber hose or reach in with a stick or long screwdriver and press on the valve (flapper door) to add tension and see if that quiets it down.

04-29-09, 10:04 PM
What you describe really sounds like the a/c clutch to me. Try turning the a/c off and see if the sound becomes constant. If so, there's your culprit.

04-29-09, 10:39 PM
Turning off the A/C might not do it. My wife's '96 Bonneville started making a scraping noise (A/C off) and I determined it was the clutch. I assumed the pulley bearing was bad, though I noticed that there was no clearance between the clutch plate and the pulley and they where making contact. When I got the clutch off the bearing seemed to be fine. I reinstalled the clutch plate with the proper clearance this time and all is well. This was just a couple of days ago and the wounds are just beginning to heal.

04-29-09, 11:58 PM
Krashed989, I maybe should've started a new thread because the scraping noise or grinding noise is gone. It did sound like a a/c clutch going bad which I've had before, the grinding noise just quit several days ago and has been replaced with a whining noise, similar to a bad power steering pump but somewhat quieter.

Appreciate the reponse though....

04-30-09, 12:09 AM
The cam chains have hydraulic tensioners which ride on the engine oil pressure. It's possible that you could alter or alleviate the problem with an oil/filter change. If that doesn't do it, then you're possibly looking at going into the front of the engine timing cover (chaincase). Not fun.

Submariner, Thanks for the info, I understand that to work on the timing chain tensioner the engine has to be removed, is that accurate? Of course before I get to involved, I'll keep looking and trying something much easier and cost effective, like changing the oil and filter.

04-30-09, 12:13 AM
Ranger, apparantly there was little to no room to work on your wifes a/c, therefore the wounds you mentioned. It appears that to work on the timing chain in my STS would be similar if not impossible with the motor in the car. I haven't given up on the problem being smething other than the tining chains. In the morning I will look at the over pressure manifold valve, will keep you posted.

Thanks and have a good night.........

04-30-09, 04:10 AM
I'm pretty sure you can work on the chains/tensioners with the engine in the car through the passenger-side wheel well. The hard part will be keeping the cam gears from jumping teeth, then you would have to go through the trouble of removing the valve covers and retiming the engine. You would have to have a puller for both the harmonic balancer, and the waterpump drive pulley (if you're removing the valve covers). If you remove the valve covers you would also probably want to buy new valve cover gaskets, a new cam seal, and rtv sealant to get the gaskets to stay in the valve cover during installation. The old valve cover gaskets may absorb oil and become too big to reuse. However, the timing cover gasket looks reusable. I would replace it anyway since you're digging that far in there though.

05-01-09, 01:47 AM
I'm pretty sure you can work on the chains/tensioners with the engine in the car through the passenger-side wheel well. The hard part will be keeping the cam gears from jumping teeth, then you would have to go through the trouble of removing the valve covers and retiming the engine. You would have to have a puller for both the harmonic balancer, and the waterpump drive pulley (if you're removing the valve covers). If you remove the valve covers you would also probably want to buy new valve cover gaskets, a new cam seal, and rtv sealant to get the gaskets to stay in the valve cover during installation. The old valve cover gaskets may absorb oil and become too big to reuse. However, the timing cover gasket looks reusable. I would replace it anyway since you're digging that far in there though.

Krashed989, your saying that you believe it is possible to get at the timing chain tensioner(s) through the wheel well and that you can get the cover ( timing I assume ) off the front of the motor without having to remove many other components.

If I get involved myself, I would probably purchase a field service manual but to be honest, I don't think I have it in me anymore to take on such a job. I've built race motors, race cars, rebuilt street motors, removed and replaced motors, transmissions, rear ends, all in the distant past. I've built so many GM big blocks and small blocks that I could do them in my sleep. All of the torque spec's, tightneing sequences, bearing clearances, were all etched in my memory, no service manual needed. I just don't have the flexibility anymore and what I do I have is a lot of aching joints.

One thing I can still do though is stomp on that accelerator pedal, no problem there, don't need a field service manual for that either!

Appreciate all the help!

05-01-09, 03:00 AM
Yeah, it might be difficult to make the job comfortable in the wheel well there. I'm pretty sure it can be done though.... If I was in the mainland I'd offer to do it for you, but I'm probably too far away for that to be feasible. I always like hanging out with experienced gear heads. There's just so much to learn that it's crazy :p

05-02-09, 02:07 AM
Krashed989, thanks for the reply and offer. I'm quite tired right now, been a long day but I'll get back with everyone tomorrow, strangs as this may sound, the whine seems to be quite a bit better today.

I'll update this weekend...

05-04-09, 01:59 AM
The over pressure relief valve is exactly opposite the TB. It's tucked back in a hole behind the P/S pump. If you hear it at idle you can listen in there with a stethoscope or rubber hose or reach in with a stick or long screwdriver and press on the valve (flapper door) to add tension and see if that quiets it down.

Ranger, this may sound a but far fetched but this is what I'm thinking may be happening. Over the last couple of days, the whining seems better or not as loud. It also seems like I can lessen the whine with less throttle or, I can increase the sound of the whine by increasing the throttle. If I apply enough throttle so that the RPM's will exceed 3k prior to a shift, the whine will increase in sound and when the tach hits 3000, it sounds like someone flipped on a switch and the whine gets even louder.

I used a few different devices to listen for the noise like you suggested earlier. The hose seemed to be the best as I could hear the bearings quite clear on the alternator, a/c comp, power steering pump and on and on. The valve covers produced a noise like you would expect from a cam turning inside of a bushing and a chain running across a sprocket, nothing unusual and NO whine that I could detect. There's not a lot of room but I was able to shove the hose ( 1/2" rubber hose ) behind the power steering pump and then I detected a whine, quiet at idle and a little louder when revving the engine.

I don't believe the noise is form air blowing throught he hole but rather the hole being opened enough for an internal engine whine to escape out through that hole/valve. I went back several times to all the components and heard the same noises that you would expect to hear. When I went behind the power steering pump, I could hear the whine. I was able to push the hose from the front, I believe the positive battery cable goes through the same area but the result is the hose being positioned near the front/side corner of the intake with the front being the front of the car. I'm thinking with more throttle, the manifold vaccum/pressure is increasing/decreasing and thus allowing that over pressure valve to open and the whine is a noise that is always present internally in all N* motors but never heard unless slightly because it is an internal noise.

You mentioned to put pressure on the flapper door of the valve but I can't even see the valve on my engine. I have no idea if I was next to the valve but from listening behind the power steering pump starting from the left side closest to the firewall and going to the right towards the front of the car, I would suspect that the valve is closer to the front of the car or to the far right of the power steering pump ( behind it of course ).

If the blower fan inside the car is running because I have the a/c on, I cannot hear the whine. The radio being on very low, I cannot hear the whine. I'm going to drive the car as is and certainly, I'll keep my eyes and ears open in the event there is a change in the whine or something obvious rears it's ulgy head.

I'm thinking of removing the beauty cover to get a look at that valve. Would I be able to see that valve with the beauty cover off? If I can, I may just plug the valve and start the car to see if the whine is reduced to what one would expect to be normal. Maybe the battery cable is somehow involved with this problem, apparantly it must pass through the side of the intake!

Any and all opinions would be very much appreciated.....:hmm:

05-04-09, 09:11 AM
With the cover off, you might be able to see far enough into the manifold recess to see an edge of the overpressure valve, but won't have any way to "seal" it (don't do that, anyway). BUT, remove the cover and do your listening check again.......at least this time you'll know where the tip of the ear hose is......Another possibility is that the end of the PCV vacuum hose, which runs from the front passenger side of the rear cam cover to the nipple next to the overpressure valve is either cracked or loose. That hose system is under constantly varying vacuum during engine operation. A leak there could be a slight hiss or as loud as a train whistle.

Take a look at the line drawing - the mechanic's hand is in the recess where the overpressure valve is located. Your manifold may be a bit different, but the location is the same.......

(Don't forget that the overpressure valve relieves excess manifold pressure from a backfire only, so it blows OUT to the atmosphere, not IN. If you push on it with a long screwdriver, you are closing it.)

05-19-09, 01:19 AM
I still have the whining noise, no change, no louder and no quieter. I did stop at a transmission repair shop recenty which had said they would dignose the noise/problem for no charge. The fella could hardly get my hood open and the tells me the noise is coming from the front of the engine somewhere. I told, that's what I told you before we opened the hood, that I had loosened the belt to stop everything from turning, a/c comp, alternator, tnsioner, etc. and that the noise was still present. He says, well you'll have to leave it for a day or two which I wasn't to enthused about.

Other than the noise, everything is fine although I see there is a code for the ride control. Could there be some sort of little motor or comp. near the front of the engine related to the ride control?

Kind of quit looking for awhile, getting frustrated and it doesn't seaem to be hurting anything. I'll keep you posted when I find out what it may be.

If there are any suggestion, they would be much appreciated!

I have not checked the over pressure valve in the fron to the manifold yet.

05-31-09, 01:07 AM
The grinding noise has been resolved, the idler pulley broke yesterday, gave no warning. I had started the car and turned the a/c on while I put a few things in the trunk. When I got in the car and put the car in gear, I couldn't turn the steering wheel, looked down and saw a no charge message. Shut the car off, looked under the hood and the idler pulley was sitting sideways.

I replaced the pulley and now the initial intermittent grinding noise is gone, infact it's pretty quiet now. I still have the whining noise but it's not very loud, barely noticeable if I'm easy on the throttle. I think what was happening is that there was 2 problems, each problem creating it's own significant noise. The noise from both of those problems combined made a 3rd noise which I thought was a another problem creeping up. When I replaced the idler pulley, the intermittent grinding noise went away along with that 3rd noise and now I only have the whining noise.

I also think that the grinding noise had become constant at a low level and I must've been gotten used to hearing it so it didn't raise a red flag. The grinding would still come and go at a very noticeable decible level and that's probably why I didn't notice or pay attention lately to the lower decible constant grinding noise.

It's a completely different car, like a normal car again. It surprises me that not to long ago, I had loosened the belt and spun everything I could get my hands on, the idler pulley, the alternator, and the tensioner pulley. They all felt and spun okay. I started the car with the belt loose and it seemed like most if not all of the noises were still present.

I'm quite happy in that a problem has been corrected and for a small amount of money to boot.

I will keep everyone posted about the whining noise if I ever find out what it is. It's not very loud right now and doesn't seem to be affecting the performance of the car, fuel mileage pretty much the same as always. Even though it doesn't seem to be posing any problems I still want it gone so sooner or later I'll have an answer.

Thanks to everyone who was willing to share their knowledge and took the time to reply!

05-31-09, 03:46 AM
I'm glad you got your problem resolved, and you didn't have to completely dismantle your car to fix it either! :thumbsup:

05-31-09, 09:11 PM
I'm glad you got your problem resolved, and you didn't have to completely dismantle your car to fix it either! :thumbsup:

I will admit that an idler pulley is a lot easier to change than a timing chain/tensioner. Hoping that the whine is not coming from the timing chain assembly, like I said, it's not that loud but still present. I can live with it the way it is but obviously the whine is sginaling that there is something not quite right.


06-11-09, 08:23 PM
Here we go again, today I noticed that the whine seemed to have diminished so I turned everything off and to my surprise, the whine is gone. I can go WOT and no noise, ran it up to almost 6k and no noise. I'm happy that the whine is gone so I'm thinking what did I do if anything. I did take a hardened rubber hose and stuck it down behind the power steering reservoir and poked around. If the whine was coming form the over pressure valve, maybe I closed a partialy open valve, who know's.

I get home and am so surprised that the whine is gone that I sit in the driveway listening to the engine. The next thing I know, I here what sounds like alifter, about 5-6 clicks and then it goes away. I started to listen and for about 10 seconds, nothing, then the click comes in weak at first getting alittle louder for about 6 clicks, maybe 2 seconds worth and then it's quiet. I listened for several minutes and it keeps repeating itself, quiet for about 10 seconds and then 2-3 seconds worth of what sounds like lifter noise, 1 lifter would be my guess.

Any thoughts on what this could be, quiet for about 10 seconds and then about 2 seconds of lifter noise, click, click, click about 5-6 times and then quiet.

Comments would be appreciated!

06-11-09, 09:36 PM
...Any thoughts on what this could be...

Well here's your problem, your radio is not loud enough and it's causing you to hear too many things! :p

Hmmmm.... Well it is a fairly old car. Maybe there's too much bearing clearance causing there to not be quite enough oil pressure up top in the heads. In that case, it might time to raise the viscosity of the oil you use. Or it could be that one of your flat tappet hydraulic lifters is getting cupped and wearing down a cam lobe, however I would think that would be a constant tapping. I've heard stranger stories though. You would have to pull valve covers to see if that's the problem. Sadly, it's fairly common with these engines...

06-12-09, 01:11 AM
Krashed, are you saying that lifter problems are quite common or cam/lifters are common problem areas? I don't believe it's a lifter getting cupped/ground down or a problem with a lobe. From my experience with race motors years ago, it's quite clear when you've losing a lobe on your cam, especially an exhaust lobe, it'll pop back through the carb, throttle body, what ever your induction system is.

I appreciate the response and your right, it is getting a little old but is in great shape, 110k miles which isn't really that bad. It's just such a starnge noise, I'm 99% certain that it's a lifter. Sounds like a lifter when an engine gets low on oil and a lifter starts to tap, add a little oil, give it a rev and it's quiet. My engine taps maybe 6 taps and then it's quiet for 10 maybe even 15 seconds, then like clock work, here coems the tick for about 6 ticks and then it's gone again.

It sounds like a lifter pumping up and then pumping down, over and over.
It is time for an oil change so I'll try that and look at the filter real close like Submariner or Ranger mentioned awhile back.

I just can't believe I have another noise and your right, I've been listening to the radio to low lately, need to keep it turned up!

I have a sneaking suspicion that the whine which went away and this intermittent tap are related, they almost have to be. The whine goes away and this tap shows up at about the same time. I mention this because someone who knows what everything looks like underneath these valve covers might put two and two together!

Thanks again and I'll let you know what I find. It's not terminal, of course I'll knock on wood after saying that but it's probably more of a nuisance than anything............

06-12-09, 09:26 AM
Cam lobes and, in your case, hydraulic cam followers are ground a few thousandths off center so the lifter rotates in its bore as the valve train operates. This evens out wear and (hopefully) prevents the cam from wearing a rectangular groove into the top of the follower. What you are hearing is one or two followers rotating in and out of a slight wear spot, minutely changing the cam/follower and/or the follower/valve stem clearance. At hot idle there may not be just enough oil flow/pressure to quickly take up the clearance, so you get an idle "tick". Actually quite common in older hydraulic cammed engines. Eventually that tick will go right on up into the 2000 - 3000 rpm range, and then you're in for cams and followers.

The whine is (was) from something either leaking vacuum or rotating a lot faster than a cam at idle - the lifter tick has nothing to do with the whine.

Change to a "fleet" 10W-30 oil and a WIX filter for your 1994 engine. The fleet oils carry a much higher additive package than oils designated "for gasoine engine use" (the starburst symbol) because they are also rated for diesel service and that engine's much higher scuff wear problems. Chevron, Shell, Pennzoil all make fleet and marine oils. Perfectly satisfactory, and your tick will disappear.

06-12-09, 11:12 AM
Submariner, I do appreciate the advice on the oil, what surprises myself is that the lifter noise/tick which just started, will go away for about 10 seconds and then tick about 5-6 times, maybe 2 seconds worth and then another 10 seconds of quietness. It's like clock work, my experience with lifter noise is that it's either present or it's not. I failed to explain that after the 10 seconds of quietness, the tick starts and is barely audible and then gets louder each tick for about 5-6 ticks and then it just stops, it'll be quiet for another 10 seconds.

I know that if I change the oil and it goes away, then it's a mute point. I guess I have an engineers mind and I'm trying to envision what is going inside that engine. I'm always trying to understand how something works so this ticking going away and then coming back just seems a little odd.

I'll let you know how this turns out, I suspect it'll go away by changing the oil.

06-12-09, 11:27 AM
Yep........the tick and 10 seconds of quiet is the time it takes the cam follower to rotate about 360 degrees in its bore.

An engine has one or two methods of evening out valve stem and lifter wear: some have a rig on the valve keeper referred to as a "valve rotator", a sort of coil spring thingy, part of the valve retainer, that slowly turns the valve itself as the engine runs, evening out stem tip and seat wear. Also, as I posted, the cam lobes are ground off-center by a few thousandths of an inch which rotates the lifter/follower in its bore.

I'll bet you're hearing the effect of a cam follower rotating in and out of a wear pattern. Common. Got boxes of worn Olds 455 lifters and rotators.

Get to one of AJ's engine/head pics in his build posts. Take a hard look at the circular wear pattern in the top of a follower - that's the indication that the follower itself rotates in its bore. The worst wear case is that the follower is actually worn into a dished shape by the cam lobe - the lobe eventually eats through the surface hardened follower face, and both begin to wear rapidly.

06-12-09, 12:10 PM
Submariner, now that makes sense, it's taking about 10 seconds for the follower to rotate, at that point it's getting into a wear pattern that's allowing it to make the tick or whenever the follower is in that particular point of the wear pattern, there's either a little to much clearance or not enough oil/pressure to take up that extra clearance.

I did notice that the tick is not present while the engine is still cold, in fact it doesn't start until the engine is over 200 degrees.

Will be changing the oil today, soon, I'll let you know how it turns out,


06-12-09, 06:29 PM
I changed the oil and filter, unfortunately it made no difference. I started to listen closer for the noise and it's coming from the same area that the whining was coming from, right in behind the power steering reservoir/pump where the over pressure valve is located.

I listened with a hose on top of the valve covers, the beauty covers, the front of the engine and everything sounds okay, the turning of well lubricated bearings/cams/chains etc. I can't seem to pick up on the tick, tick, tick, unless I get behind the power steering.

I guess I'll have to take it apart and get a look in there or take it to a garage. The engine runs fine, even when the tick starts for those souple of seconds the engine doesn't miss beat.

So it goes.......

06-12-09, 10:12 PM
Maybe it has something to do with the P/S pump?

06-12-09, 11:47 PM
Ranger, at this point it wouldn't surprise me, i keep going to the back of the pump, somewhere in behind it is where this new noise is coming from. What Submariner was saying about the cam follower rotating in the bore seemed to fit my noise/problem to the tee!

I changed the oil/filter and no change what so ever. After the oil and filter change, I started to listen with a rubber hose again and I keep ending up behind the power steering pump/reservoir. I listened all over across the valve covers, front and back, the noise I heard was a like a perfect bearing noise, you can hear everything turning just smooth as silk. The tap tap tap is a little more pronounced on the top of the beauty cover towards the front of the engine but still doesn't seem like that's where it's coming from. When I try and get behind the power steering pump and listen with the hose the tap tap tap is quite loud and pronounced.

What is so odd is that it goes away after about 5 taps and it's quiet for about 10 seconds, then it repeats itself all over again. I can let the car idle and you could set an alarm clock with the way this noise comes and goes. I watched and listened to the engine very close while letting it idle after the oil change. When the tap tap tap starts, at first I expected to see a change in the idle performance of the engine but it doesn't seem to affect the way the engine runs at all. I bumped the RPM's up to about a steady 2000 RPM's and the tap tap tap stays pretty constant, it doesn't come and go at that RPM range, it's constant.

I don't think it's in the engine at least not anything that could potentially damage the engine, of course I would hate to be wrong.

I don't know of anything to do anymore other than take it somewhere and have them start taking the engine apart.

One more thing, when I had the car up on the ramps to change the oil, I decided to start the engine with the belt removed prior to changing the oil. I figured it would be a good time to try this again prior to draining the oil. I loosened the serpentine belt and took it off the power steering pulley. I then went to start the engine and it would barely turn over, it seemed to really be straining. I thought, maybe the belt got twisted up on a pulley and is holding the engine from turning over. When I first looked at the belt it looked like it was twisted around one of the pulleys which would in turn hold the enginefrom turning over freely. When I grabbed the belt, it was loose, it wasn't wrapped around the pulley like it had appeared. At that point I wanted no part of what I may have been getting into so I out the belt back on, tried to start the engine and it started like always, spun like a top! What was that all about?

lastly, assuming I have a little minor engine work that will require some of the engine to be taken apart, I'll probably have the oil pan gasket and half block gaskets changed to stop any oil leaks. What ever may be leaking will be fixed. My question asking for advice is this, if the engine was out of the car to replace gaskets/o-rings, what other work would you do if it was your car/engine? The mileage is 110k, it doesn't burn a drop of oil and it deosn't use any antifreeze.

There is a plastic box that covers the a/c fan motor and other associated items, it's located on the firewall, that will also be changed. I've been told that the engine has to be removed to change that box so this would be the time.

Of course I would change the radiator and heater hoses, belts, any and all accessories!

If I have to have the motor opened I may as well somewhat restore the entire under the hood components, bad idea, good idea?

Comments and advice would be most appreciated!

06-13-09, 12:15 AM
Theres no chance I would drop a 94 N* and not stud it while it was out.

I've got an 01, and I'd probably have to do it if I had to drop the motor.

06-14-09, 01:46 AM
At the moment my car is driveable althought the tap tap tap that just started is quite annoying and could lead to bigger and more costly problems.

I timed it and at idle, the engine is quiet for about 6 seconds and then it starts out with a pretty quiet tap with each tap getting a bit louder for about 10 taps, maybe 1.5 to 2 seconds worth of tapping, then it stops for another 6 seconds. I first thought it was about 10 seconds but it's closer to 6. If it is alifter and Submariner seems to have hit the nail in the head, how big of a job is it to replace a lifter. I've repalced many rocker arms, pushrods, lifters and so on in a conventional engine back in the 70's and 80's, not a very big job.

If in fact my tick or tap is a lifter, I'm certain that I would be able to identify the problem lifter when I get a good look at everything.

What bothers me is that this problem didn't start with a barely audible tik tik tik, and then get progressively worse. It just appeared the other day so i was wondering if it was possible for a follower or some other mechanical part to fail, partially brake, bend, anything that would increase the gap so that the hydraulic component is unable to make up the dfference. If so, would it be noticeable with the valve/cam covers off.

I'm not big on additives and have never been but of course I would add something to the oil if I thought it had a chance to clear up the tap. Has anyone had a similar experience with a quiet engine for 6 seconds and then a tap for a couple of seconds, if so, what corrected the problem?

The oil and filter was changed yesterday, made no difference at all. The engine is quiet until it warms up to around 208-210 degrees, then the cycle of tapping begins.

Any and all comments are appreciated..........

06-14-09, 09:07 AM
When was the last time you did a couple of really healthy WOT's ?

06-14-09, 01:20 PM
Submariner, I really haven't done any WOT's lately, it's been a couple of months I guess. I've stomped on it a few times but have been backing off just over 3k. In the back of my mind I was thinking about going out and run it hard to see what happens. The way it suddenly came on I'm thinking there's a piece of dirt, something that may be plugging the lifter from pumping up or staying pumped up and that some RPM's may be needed to dislodge it.

It seems like if it was wear which I'm sure there is some where, that you would get a little light tic, tic, tic, when yo first got to the point of to much clearance, this is a pretty healthy tap by about the 4th or 5th tap.

Okay, you've convinced me, I'll go and beat on it, get the RPM's up aorund 6500-7000 and see what happens.

06-14-09, 03:04 PM
Submariner, is this similar to my 94 N*, I didn't look real hard but I couldn't find any pictures that AJ may have posted. Looking at that picture, it's seems doubtful that a rockerarm or follower could have bent or broken to cause a few thousands of extra clearance. Now, something could break but I would suspect that the valve wouldn't open at all and you would certainly notice it as a serious problem. It looks as though the only potential problem relating to clearance would be the lifter. Looking at this picture I guess there'a an oil passage that runs throught he head passing from lifter to lifter.

Attached Thumbnailshttp://www.cadillacforums.com/forums/attachments/northstar-performance-technical-discussion/50436d1244663510t-hydraulic-valve-lash-adjustor-evaluation-2000-roller-valve-actuator.jpg (http://www.cadillacforums.com/forums/attachments/northstar-performance-technical-discussion/50436d1244663510-hydraulic-valve-lash-adjustor-evaluation-2000-roller-valve-actuator.jpg)

06-14-09, 04:17 PM
Well, I went out and went throught the gerars 1 time, ran as hard as ever, turnbed the tires when it hit second gear, hit third around 80 MPH and approx. 6500 RPMS. When I slowed down I could hear the tap constantly. I was only about 1 mile from home, drove home and now it's tap, tap ,tap all the time, hitting pretty hard.

I listened all over with a hose and when I go from end of the valve covers to the other all I hear is a shishshsshshsh like you would expect. It's only when I get to the front of the engine behind the power steering pump/reservoir do I hear a tap.

I'm sure it's loud enough now that I'll try and get a sample with my phone so others can hear the tap but it looks like it's tear down time. I'm starting to think that something is breaking, if a cam lobe was grounding down that fast I would notice a change in perfomance by now but the motor is running fine.

No codes, no oil pressure indicator coming on, don't have any idea what it could be now. I'll keep you posted when I find out what it is. I'll probably take my car to Southwest Cadillac, I have a lot of faith ithat James can diagnose and repair pretty much anything on any cadillac.


06-14-09, 04:32 PM
The cam setup picture(s) are for the 2000-+ Northstars. You should have direct-acting followers, with the cam lobe bearing directly on the follower itself - sort of like pushing the bottom of a beer cup placed directly over the valve stem.

Start the car - tap, tap, tap ?? Listen carefully and have an assistant turn the steering wheel full left/right. Any change ??

06-15-09, 02:07 AM
This is a picture of when I was working on my dads 99 eldo, but the 94 is the same setup I think. His engine was ticking like mad and the follower was very cupped.


06-15-09, 03:11 AM
Krashed, If you don't mind me asking, what did you replace or what type work did you do on your dad's eldo? If you changed lifters or a cam, was it a very hard job?

Looking at the picture you posted I assume that's what I woul dbe looking at if removed the valve cover which should be simple enough. Apparantly I need to remove the valve cover to where I believe the noise is ocming from and have a look. I'm failry certain that if it is a lifter, it's only one. I guess it could've just got to the point where the clearance can't be made up by the lifter anymore therefore it's tapping. As suddenly as it came on I would think that soemthing broke or bent but it's probably just wear like Submariner mentioned.

Thanks for the picture and reply...

06-15-09, 05:18 PM
That was a discovery that was made while I was doing the headgaskets. You can see the oil is yellow, like mustard. That's because dex-cool mixed with it. I just sent the heads to a machine shop and let them deal with it. They rebuilt the heads and replaced the cam and followers. It runs better than new now.