: Oil low pressure on 1996 4.5L Northstar



hwelchwa
11-25-04, 05:53 PM
My 1996 4.5L Northstar has a problem. When climbing a long hill the water temperature will rise from the normal 205 to above 230. At this temperature the oil light comes on when the engine is at idle. We have changed the oil and the oil pressure sensor. This occurs without fail at temps above 230. Once the engine returns to normal operating temp the problem is cured.

mcowden
11-25-04, 10:21 PM
Are you absolutely sure it's the oil light and not the temperature light? The oil light looks like an oil can with a drop of oil coming out of the tip. The temperature light can be hard to distinguish. On some cars it looks like a radiator, and on others it looks like something sticking up out of a pool of water. I can't think of any reasonable explanation for why the oil light would come on when the temperature gets to a certain point, but maybe one of the experts can lend some thoughts here.

Have you had the cooling system serviced lately? What is the coolant level? What color is it? On a '96 4.6L Northstar, it came from the factory with a 50/50 mix of distilled water and the orange "DexCool" coolant in it, which needs to be changed every 5 years or 100,000 miles. If it hasn't been done yet on your car, it's overdue. When it's changed, the supplement needs to be added to prevent leaks.

If the coolant level is low, that could cause the temperature increase and the temperature light to come on, which to me seems like the more likely scenario.

Good luck...

Michael :welcome:

Spyder
11-26-04, 01:43 AM
Mine does the same when the temp gets really hot, the hot oil is thinner than when it is cooler, which causes lower pressure...are you running 10W-30 or 5W-30? I've seen before where people have found that running 5W-30 will cause that to happen. Also, on a 96, does it say "STOP ENGINE -- LOW OIL PRESSURE" or is there a light? My 94 makes a noise, and flashes that message on the screen...I went through the same thing, replaced the oil pressure sensor, which is a real bastard to get to without the right socket...we used vice grips :) ...and finally put the right oil in and it has never happened again.

Rob Benham
11-26-04, 03:11 AM
From what I have learned on this site, the fans should be running at full speed at this temp. Are you able to get out quickly enough to check that they are functioning? Make sure you're a/c is off for the test.

If the fans are not running, look for code ACP AO11 hi side temp

The rise does seem excessive. I have a 94 SLS N* and down in "the valley" everything is so flat...and hot, and the temp sticks at 203 with the A/C on and 199 with it off. However, when I'm in the hill country the temp does rise on a climb, but only to 207 ish.

I'm only a newcomer to Cadillac, but I do feel that you need to contain that temp rise as the main issue, and hope that the oil pressure is ok when the temp problem is solved. RB

growe3
11-26-04, 04:11 PM
I drive California valley and foothills daily; normal engine temperature range is 199 F to 228 F.

Temperatures up to 234 F in summer are normal for the Northstar. Temperatures can exceed 234 F during hot weather and high engine demands for short times without damage to the engine. If the engine gets to hot it will go into "limp mode" to get you to a safe location.

Make sure you are using a good quality 10-30 engine oil, and always replace the oil filter at each oil change.

-George

hwelchwa
11-29-04, 02:14 PM
It is definitely the oil light. If I do not accelerate to above idle RPM the "Low Oil Pressure" warning message illuminates and eventually I get the Stop Engine message. The cooling system was serviced last year. Thanks for your reply. Harry


Are you absolutely sure it's the oil light and not the temperature light? The oil light looks like an oil can with a drop of oil coming out of the tip. The temperature light can be hard to distinguish. On some cars it looks like a radiator, and on others it looks like something sticking up out of a pool of water. I can't think of any reasonable explanation for why the oil light would come on when the temperature gets to a certain point, but maybe one of the experts can lend some thoughts here.

Have you had the cooling system serviced lately? What is the coolant level? What color is it? On a '96 4.6L Northstar, it came from the factory with a 50/50 mix of distilled water and the orange "DexCool" coolant in it, which needs to be changed every 5 years or 100,000 miles. If it hasn't been done yet on your car, it's overdue. When it's changed, the supplement needs to be added to prevent leaks.

If the coolant level is low, that could cause the temperature increase and the temperature light to come on, which to me seems like the more likely scenario.

Good luck...

Michael :welcome:

hwelchwa
11-29-04, 02:21 PM
I use 10W-30 as Cadillac recommends. I tried an additive but that did not help so I changed the oil and filter again. No change. I tried adding 12 quarts of oil and reving the engine to 3500 rpm about 20 times to clean out the primer pump for the oil pump and then changed oil again. No change. I am getting a lot of oil burn (out the tailpipe) when I come down a long grade in second gear and then accelerate at the bottom. I don't know how the two could be related. Thanks for your reply, Harry


Mine does the same when the temp gets really hot, the hot oil is thinner than when it is cooler, which causes lower pressure...are you running 10W-30 or 5W-30? I've seen before where people have found that running 5W-30 will cause that to happen. Also, on a 96, does it say "STOP ENGINE -- LOW OIL PRESSURE" or is there a light? My 94 makes a noise, and flashes that message on the screen...I went through the same thing, replaced the oil pressure sensor, which is a real bastard to get to without the right socket...we used vice grips :) ...and finally put the right oil in and it has never happened again.

BeelzeBob
11-29-04, 02:32 PM
Are you positive that the oil pressure sending switch is the correct one??? If a generic aftermarket switch is installed it will often trigger false low oil pressure alarms due to the generic setpoint of the aftermarket switches. The OEM switch is set to a very low pressure (about 4 psi I believe) to avoid this. The Northstar runs very low oil pressure at idle anyway which is normal and when the oil and engine is on the hot side the oil pressure will often drop down to the 5 or 6 psi range at idle so the OEM switch MUST be used to avoid false warnings of low oil pressure.

The oil overfill is just for when the relief valve sticks and the oil pump will not prime at all and there is zero oil pressure. You'll know if you have zero oil pressure. Otherwise, in your case, that procedure was pointless.

If the OEM oil pressure switch is in place then I would consider going to a slightly heavier oil if you are getting the engine hot frequently and do not worry about cold cranking speeds (like as in -40 cold cranking speeds). Try one of the heavy duty diesel oils like Delvac/Delo/Rotella that are usually available in gallon jugs in discount stores in 15W40 weight. That would be good compromise for hotter weather use and the heavy duty oil is an excellent product...probably the best oil on the market currently available.

peteski
11-30-04, 12:33 AM
Try one of the heavy duty diesel oils like Delvac/Delo/Rotella that are usually available in gallon jugs in discount stores in 15W40 weight. That would be good compromise for hotter weather use and the heavy duty oil is an excellent product...probably the best oil on the market currently available.

Even better than Synthetics?! :lildevil:

Just kidding Bbob, just kidding... :halo:

Before everybody starts a mad war here - let's not... there are so many Dino vs. Synth. threads on this forum already!

I WAS JUST KIDDING - HONEST! :bonkers:

Peteski

dkozloski
11-30-04, 01:39 AM
Both the Dino and the synthetic guys are on the wrong track anyway. A couple of lubrication engineers that worked for Shell oil company on a synthetic aircraft oil project with some of my engine customers said that the very toughest lubricating film they had ever encountered was from vegetable castor oil. They said the only way to removed a castor oil film was to grind it off. In fact castor oil was the oil of choice for many years in race cars and boats. The only down side is that it gets gummy if you let it sit around for the air to get at it. Where do you suppose the trademark Castrol comes from.

hwelchwa
12-10-04, 03:32 PM
I checked with my mechanic and he says the sensor was OEM from Cadillac.

I need a little hand holding on the oil weight change. I live in Hawaii so cold starting is not a problem. Would it help to go to 30W or 10-40W. I have a problem with using Delo in the Cad. The manual is so hung up on 10-30W and only 10-30W.

Thanks for the help, Harry

BeelzeBob
12-10-04, 03:42 PM
My 1996 4.5L Northstar has a problem. When climbing a long hill the water temperature will rise from the normal 205 to above 230. At this temperature the oil light comes on when the engine is at idle. We have changed the oil and the oil pressure sensor. This occurs without fail at temps above 230. Once the engine returns to normal operating temp the problem is cured.


BTW....no such thing as a 4.5 Northstar. It is a 4.6. The 4.5 engine was a pushrod engine...but it was not produced in 1996 so I'm sure you have a Northstar.


Use the 15W40 Delo or Delvac or Rotella oil. It will be fine in the hotter climate you are in. The owners manual specifies the correct oil considering that the car might be shipped anywhere from Fairbanks , Alaska to Saudia Arabia....or Hawaii. The owners manaul oil also has to comply with the oils approved for certification and the fuel economy label testing....which on your car meant a GF-3 oil. The Delo/Delvac/Rotella oils are not GF-3/GF-4 oils since they do not have the fuel economy enhancing friction modifiers in the oil...so they technically are not GF-3/GF-4 oils despite their high quality...and they legally cannot be listed in the owners manual since only GF-3/GF-4 oils are "legal" for certification and fuel economy testing reasons.

Use the 15W40 HD oils. They are better for the engine than the GF-3/GF-4 conventional oils and even better than the synthetics that are GF-3/GF-4 since they have more antiwear additives in them. The slightly extra viscosity will help the low oil pressure at hot idle somewhat and is actually good for the engine in the hotter climates you are in. The 15W40 oils are also not shown in the owners manual (besides the legalities of the slight fuel economy penalty) because of cold starting issues at -30 and -40. Unless you are parking overnight at the top of the mountains there you are not likely to see those temps....LOL.


No to belabor it....but ask your "mechanic" what sender he changed and where is it located. There is an "oil sending unit" in the side of the oil pan that is easy to access....but that is the oil LEVEL sending unit and has no affect whatsoever on the oil pressure warning. There is a separate oil pressure warning switch screwed into the oil filter adapter on the side of the block just above the oil filter. That is the switch that needs to be replaced for the low oil pressure warning with the OEM switch... He should destinctly remember this as the correct low oil pressure switch on the oil filter adapter is MUCH harder to get to and replace.

BeelzeBob
12-10-04, 03:58 PM
Both the Dino and the synthetic guys are on the wrong track anyway. A couple of lubrication engineers that worked for Shell oil company on a synthetic aircraft oil project with some of my engine customers said that the very toughest lubricating film they had ever encountered was from vegetable castor oil. They said the only way to removed a castor oil film was to grind it off. In fact castor oil was the oil of choice for many years in race cars and boats. The only down side is that it gets gummy if you let it sit around for the air to get at it. Where do you suppose the trademark Castrol comes from.


Castor oil has good lubrication properties and it does "cling" to parts (you can wash it off with solvent, however. Grinding is a bit extreme) but it has little or no high temperature capability. That is why it is not commonly used. It is an excellent product for certain applications (like some racing two strokes and in nitromethane for small model airplane engines) but it is not very well adapted or adaptable to automotive applications. Castor oil has very good properties when diluted with gasoline or fuel like in twostrokes....but if you've ever worked on a two stroke that ran with castor oil you know it can be washed off easily with solvent.

I would suspect that the oil development engineers for the oil companies and the additive companies like Paramins "know" about castor oil.....LOL.

dkozloski
12-10-04, 06:24 PM
bbobynski, have a look at this URL. http://www.plasma.kth.se/~olsson/castor.html It explains how the temperature instability of castor oil is a good thing.

eldorado1
12-10-04, 09:24 PM
bbobynski, have a look at this URL.

Ow my eyes! :disappoin

BeelzeBob
12-10-04, 11:33 PM
bbobynski, have a look at this URL. http://www.plasma.kth.se/~olsson/castor.html It explains how the temperature instability of castor oil is a good thing.


It may be a "good thing" for some situations (such as in a two stroke) but for the crankcase oil in a 4 stroke that is not a good thing. You cannot put a lubricant into the crankcase that changes constantly with temp, especially high temp. You would never know what was in there....LOL. That is the advantage of the synthetic at very high temps (above 300 degrees F)...it does NOT change and remains very stabile.

Rob Benham
12-11-04, 12:23 AM
Ah, happy memories. Trailing behind my pal’s bike in a cloud of Castrol “R” smoke. Smelt like burnt cabbage. :cycle:

Spyder
12-11-04, 12:57 AM
mmm ... burnt cabbage... ...I'm hungry

hwelchwa
12-11-04, 07:17 PM
You are correct about the engine, it is 4.6L. Thanks for the info on the oils. I will check with my mech on Monday regarding the sensor. Harry

Inspector
01-11-05, 12:49 AM
Well folks I have been experiencing a tappet noise that comes and goes. This morning my wife was on her way to work and the "LOW OIL PRESSRE STOP ENGINE" msg came on. She did as she was supposed to and shut her down.:thumbsup: Becuase of the lifter noise (I know it is not a pushrod engine):drinker I have elected to replace the oil pump which as it turns out is not that bad a job. The pump is expensive but when you own a Cad isn't everything. The engine has 150 thou on it but has been babied all its life. I may have a relief valve problem but as long as I am there what the heck I'll just change the pump. The pump has had some upgrades over the years so will probably be a good idea to do. I'll let everyone know how it works out.
The car is a 94 Concourse Deville with the Y engine.

Denny:annoyed:

BeelzeBob
01-11-05, 01:43 AM
Well folks I have been experiencing a tappet noise that comes and goes. This morning my wife was on her way to work and the "LOW OIL PRESSRE STOP ENGINE" msg came on. She did as she was supposed to and shut her down.:thumbsup: Becuase of the lifter noise (I know it is not a pushrod engine):drinker I have elected to replace the oil pump which as it turns out is not that bad a job. The pump is expensive but when you own a Cad isn't everything. The engine has 150 thou on it but has been babied all its life. I may have a relief valve problem but as long as I am there what the heck I'll just change the pump. The pump has had some upgrades over the years so will probably be a good idea to do. I'll let everyone know how it works out.
The car is a 94 Concourse Deville with the Y engine.

Denny:annoyed:


Was the oil pressure really low?? Sure it wasn't the oil pressure switch on the oil filter adapter?? That is the usual cause for the low oil pressure warning.

My bet is that if you pull the pump off it will look brand new. The oil pumps on the Northstars are pretty bulletproof and it is extremely rare to hear of a problem with one other than an occasional stuck relief vavle on some of the early engines. That would result in absolutely no oil pressure on startup...but is easily cured by overfilling the crank case with an extra 8 quarts of oil to force the pump to prime and blow the tiny piece of debris out of the pump.

If you do take it apart be very carefull with the damper and the damper bolt. There is a high press on the damper onto the crank snout and it is difficult to pull off. Do NOT use the production bolt to pull the damper on as it will damage the first few threads on the bolt and cause the bolt to then jam in the crank snout. Use a puller to pull the damper on until it is seated and then install the damper bolt. There is a pretty high torque required to tension the damper bolt. It will take about 300 ft.lb. to achieve the proper torque and angle. That is necessary as the only drive mechanism for the oil pump drive sleeve is the tension of the damper squeezing the drive sleeve against the front of the crank.

I would do a little more diagnosis on the oil pressure before replacing the pump.....It is likely a waste of time.

The oil pump or pressure will not cause noise with the tappets.... Likely you have a bit of debris in one of the tappets that is causing the high pressure chamber to leak down causing the noise. The tappets need very very little oil pressure to operate as all the oil pressure does is to supply oil to the low pressure chamber.. The functional part of the lifter is self pressurizing so the actual delivery oil pressure is irrelevant.

BeelzeBob
01-11-05, 01:55 AM
Well folks I have been experiencing a tappet noise that comes and goes. This morning my wife was on her way to work and the "LOW OIL PRESSRE STOP ENGINE" msg came on. She did as she was supposed to and shut her down.:thumbsup: Becuase of the lifter noise (I know it is not a pushrod engine):drinker I have elected to replace the oil pump which as it turns out is not that bad a job. The pump is expensive but when you own a Cad isn't everything. The engine has 150 thou on it but has been babied all its life. I may have a relief valve problem but as long as I am there what the heck I'll just change the pump. The pump has had some upgrades over the years so will probably be a good idea to do. I'll let everyone know how it works out.
The car is a 94 Concourse Deville with the Y engine.

Denny:annoyed:


Replacing the oil pump is likely a waste of time and money. The pumps are very robust and will look like brand new after thousands of miles. The gerotor style pumps just do not wear like the spur gear pumps of old did.

Are you sure it wasn't the low oil pressure switch on the oil filter adapter?? That is the usual cause for low oil pressure warnings.

About the only failure mode of the oil pump on the earlier year Northstars was the relief valve sticking but there is a very simple solution for that problem. Overfill the sump with an extra 8 quarts of oil so as to submerge the pump and force it to prime. Start the engine, rev it to 4000 or so to force the relief valve to open and the debris will be dislodged. Shut down, drain the oil to the correct level and drive another 150K.

If you do end up taking the front end apart be sure and be careful with the damper. The damper will be hard to pull as there is a high press load onto the crank snout. Do NOT attempt to pull the damper onto the crank with the production damper bolt. The initial threads on the bolt can be distorted doing that and the bolt will then crossthread and jam in the crank. Use a proper puller and seat the damper firmly and then install the bolt. The bolt will require about 300 ft lb to properly tension to the correct torque and angle. This is important as the only drive for the oil pump is the compression of the oil pump drive sleeve by the tension of the damper bolt trapping the oil pump drive against the front of the crank.

I would check the oil pressure first to make sure you do not have oil pressure and then use the over fill technique to make sure it is not a stuck relief valve.

There is likely no correlation between the random noisy lifter and oil pressure. The direct acting hydraulic tappets in the Northstar require very very little oil pressure to operate correctly. If they are making noise randomly then it is more likely a bit of debris unseating the check ball in the high pressure oil chamber or a worn check ball. The lifter is functionally self pressurizing so all the oil pressure does is supply oil to the low pressure chamber. That takes very little so as long as there is some oil pressure the lifters are usually perfectly happy.

Inspector
01-11-05, 06:12 AM
bbob:

The crank pulley bolt came loose allfully easily. I'm wondering if it had lost the torque.
When I did a restart after the wife shut it down I could hear more valve train noise like all were making slight ticking sounds. It just occured to me that it was low or no oil pressure.
When it is cold there is no noise at all, except for now and as it warms it may or may not make a tappet noise.

When torqueing the crank pulley, how do you hang on to it to keep it from turning while putting on the final 120 degrees to the tight? I may do a retorque before tearing the cover off.
Denny

BeelzeBob
01-11-05, 02:00 PM
bbob:

The crank pulley bolt came loose allfully easily. I'm wondering if it had lost the torque.
When I did a restart after the wife shut it down I could hear more valve train noise like all were making slight ticking sounds. It just occured to me that it was low or no oil pressure.
When it is cold there is no noise at all, except for now and as it warms it may or may not make a tappet noise.

When torqueing the crank pulley, how do you hang on to it to keep it from turning while putting on the final 120 degrees to the tight? I may do a retorque before tearing the cover off.
Denny

I have never heard of that bolt coming loose "on it's own" but if someone ever worked on it and did not tension it correctly (which is easy to happen as tightening it correctly is difficult) it could certainly come loose later on. I have seen it happen several times. The oil pump will stop turning and the engine will have no oil pressure if that happens for sure. Retightenting the bolt will correct the problem generally. The engine is pretty robust to temporary oil pressure loss so likely it will not have hurt anything.

I would certainly just retighten the bolt correctly and see how it works. If it came loose that easily then it could not have been tightened correctly at some point.

There is a tool that is a flat disc of thick material with a long handle and three prongs that will engage the three spokes of the damper. In the center of the metal disc is a hole large enough to put the socket thru to turn the bolt. Using that "grunt tool" is the recommended procedure.

You can get under the car, take the torque converter dust cover off and lock the flex plate with a tool of some sort. You can generall hold it with one person using a large screwdriver in the teeth of the flexplate locked up against one edge of the block.

The other way that is probably the easiest in the field is to use a large air impact. Pretorque the bolt to the torque setting (I forget what it is but I think something like 80 nM or so....) and then mark it with a paint dot to track the rotation. Slide a substantial socket over the bolt and mark the OD of the socket to track the rotation. Liberal use of the impact will turn the bolt slowly to the desired angle against the inertia of the cranktrain. This is OK to do if the damper is fully seated and the bolt is all the way in and pretorqued. You are just using the impact to turn the bolt to the correct angle to stetch it to the desired tension. That bolt is pretty robust so it will handle the impact loads with no problem as long as it is screwed in all the way before touching it with the impact.

Where people screw up is they put the damper on until it reaches the press load, start the bolt (only a few threads will engage) and then hit it with an impact to pull the damper on. The extremely high loads and the impact action on the bolt will distort the first few threads (due to the partial engagement) and then the bolt will slowly seize up as it screws into the deep threads in the crank and eventually just stop turning or snap off. In either case it usually scraps the crank as it is impossible to get the welded in bolt out of the crank.

I wouldn't hesitate to use the impact procedure to tension the bolt as long as you keep track of the rotation with paint marks relative to the damper spokes.

Inspector
01-11-05, 04:32 PM
Okay here is what I did. I retorqued the bolt and overfilled the crankcase. Started the engine, no oil pressure till I reved it a couple of times. I do now have oil pressure how much I don't know. Without the assys and drive belt there is a noise coming from the oil pump area. Similar to a worn bearing in a power steering pump. A cavitation of sorts. I still have one lifter (tappet racket) making some noise. I have now removed the pulley and will replace the pump as I think it has gone bad.:banghead:
To reinstall the pulley, have you any ideas that may save me from scewing up the replacement?
Denny

BeelzeBob
01-11-05, 11:31 PM
Okay here is what I did. I retorqued the bolt and overfilled the crankcase. Started the engine, no oil pressure till I reved it a couple of times. I do now have oil pressure how much I don't know. Without the assys and drive belt there is a noise coming from the oil pump area. Similar to a worn bearing in a power steering pump. A cavitation of sorts. I still have one lifter (tappet racket) making some noise. I have now removed the pulley and will replace the pump as I think it has gone bad.:banghead:
To reinstall the pulley, have you any ideas that may save me from scewing up the replacement?
Denny

interesting to see what has happened in there.....

I suspect that everything is fine. The pump will make some hydraulic noise as it is a pretty high capacity unit. You would not normaly hear the noise standing above with the accessory belt running but down directly in front of the engine with no accessories it sounds loud. It is fine.

I would have told you to take it out and drive it for awhile as it can often take 20 to 30 minutes to fully purge the air out of the direct acting hydraulic tappets. Since the hydraulic element in the tappet is "upside downwards" the air purging characteristics of the DOHC lifter is not the best. It can take quite awhile to quite down if the tappet has been run with no oil pressure and it has injested air.

Put the damper back on, put the accessories together and drive it. It is fine. Honestly, I have never seen an oil pump fail or wear out on a Northstar...it just does not happen.

If you really must replace the pump....As stated above....make sure to pull the damper on with a puller not the bolt. Lube the crank with a very tiny bit of antiseize or assembly oil before trying to pull the damper on.

When you put the oil pump on realize that the bolts that mount the pump are special and have a special thread pitch. Be sure to clean the bolts up and apply loctite to them before tensioning. Make positively sure to hold the pump firmly against the block before running the bolts down. The pump can slip off the drive sleeve and catch on the end of the drive sleeve as the bolts pull it up thus cracking the cover....if you make sure it is seated correctly and hold it there as you run the bolts in this cannot happen.

Inspector
01-12-05, 12:16 AM
BBob:

Its all back together. I put the new pump in and the noise is gone. The tappet noise is also gone. I went out and drove it on the freeway and all is now quiet. The only thing that is bugging me now is the seal protector that was on the back of the crank pulley.:hmm: It came loose and is now making a racket. I will get in there and cut it off tomorrow of the next day. I feel confident that the oil pressure problems are now a thing of the past. :2thumbs: This car has had an oil change every 4000 miles since it was a pup. Can't understand why all this happened. Ofcourse the pulley bolt was not up to torque and that may have been the start. I do feel that the pump or relief valve has a problem. I am going to take it to work tonight and take it apart to see if the valve is defective or if there is any wear in the G rotor.
Thanks for all your help in this little project. :) I will keep in touch.
brad1454@msn.com
Denny:lildevil:

BeelzeBob
01-13-05, 12:25 AM
Cool. Glad it worked out good. Just make sure you got that darned damper bolt tight enough so it doesn't happen again.!!

Inspector
01-13-05, 03:45 PM
Bbob:

This morning I attemped to adjust the ISC. As instructed I retracted the plunger and disconnected the connector. The engine stalled. Is there a basic idle speed adjustment of is this all controlled by the PCM? I will look at the control more to see if there is a screw hidden out of sight.
As for the oil problem there seems to be no problems with that. No noise at all from the valve train.
Denny:worship:

Inspector
01-13-05, 09:01 PM
Bbob:
E mail me would ya. I'll give you my phone number.
Denny
brad1454@msn.com

BeelzeBob
01-14-05, 02:16 AM
Bbob:

This morning I attemped to adjust the ISC. As instructed I retracted the plunger and disconnected the connector. The engine stalled. Is there a basic idle speed adjustment of is this all controlled by the PCM? I will look at the control more to see if there is a screw hidden out of sight.
As for the oil problem there seems to be no problems with that. No noise at all from the valve train.
Denny:worship:


Sounds like you need to clean the throttle body bore. If the throttle body is clean and the AC is off and engine warmed up in park the engine should (barely) idle at 450-500 with the ISC plunger retracted and the throttle closed. If you are sure that the EGR is closing correctly and such and the engine will still not idle at the min air point (throttle closed with gap to ISC motor plunger) then there is a small, hidden set screw on the other side of the throttle body to adjust the min air idle....but that seldom to never needs adjusting so I would look for other problems first.

Inspector
01-14-05, 02:49 AM
The throttle bore is clean. As far as I can tell everything is in working order. I did find a stop screw on the lever side of the throttle body but you would have to remove the TB to get at it. It is standing bottom up to keep the throttle valve from closing all the way. I assume that it needs to be run in just a thread or two to keep the engine running. As for the TPS side I could't find an adjustment screw. On the DIC when selected the idle RPM shows 650. When I start the engine it will rev fairly high (1500 to 2000) maybe but settle down to 650 shortly.

Denny:mad:

BeelzeBob
01-14-05, 03:03 PM
The throttle bore is clean. As far as I can tell everything is in working order. I did find a stop screw on the lever side of the throttle body but you would have to remove the TB to get at it. It is standing bottom up to keep the throttle valve from closing all the way. I assume that it needs to be run in just a thread or two to keep the engine running. As for the TPS side I could't find an adjustment screw. On the DIC when selected the idle RPM shows 650. When I start the engine it will rev fairly high (1500 to 2000) maybe but settle down to 650 shortly.

Denny:mad:

That all sounds like it is working fine. Why do you think you need to adjust the idle or change it...???

Did you get the e-mail I sent you??

Inspector
01-14-05, 11:35 PM
I did not get your E mail.

The reason that I thought that it should be adjusted is that it didn't act the way that you describe it. As I read it I thought that with the plunger fully retracted and unpluged that the idle should be in the range that you suggested. Because the engine stalled I thought that the basic idle should have been adjusted to give me that 450 to 500 rpm then adjust the plunger to get a 030 clearance to the lever. Did I misunderstand?

brad1454@msn.com or jetinspector@hotmail.com or Dennis.L.Bradford@Delta.air.com

Denny

BeelzeBob
01-15-05, 12:42 AM
I did not get your E mail.

The reason that I thought that it should be adjusted is that it didn't act the way that you describe it. As I read it I thought that with the plunger fully retracted and unpluged that the idle should be in the range that you suggested. Because the engine stalled I thought that the basic idle should have been adjusted to give me that 450 to 500 rpm then adjust the plunger to get a 030 clearance to the lever. Did I misunderstand?

brad1454@msn.com or jetinspector@hotmail.com or Dennis.L.Bradford@Delta.air.com

Denny


Well...it should idle at 450-500 when the idle speed motor is retracted...but..retract it and make sure that there is clearance between the plunger and the lever. The RPM reference part of the procedure is to make sure the plunger is retracted and that the throttle lever is going closed far enough. If the cruise link or something is misadjusted then the idle will not go to 450 at closed bore so that will screw up the idle speed control. If it stalls that is probably OK because it means that the throttle lever is closing sufficiently. Was the AC off and the engine thoroughly warmed up??

What I meant with the question was....what prompted you to go thru the idle procedure?? General interest or was there some sort of stalling or idle problem that you were trying to investigate/fix by checking the idle speed control motor plunger adjustment...???

Check your hotmail box....

Inspector
01-17-05, 11:25 PM
BBob:

Never got any of the E mails that you sent. Try the Delta one.
Denny

BeelzeBob
01-18-05, 01:27 AM
BBob:

Never got any of the E mails that you sent. Try the Delta one.
Denny


Did you check the hotmail box...??? I tried the Delta addressa and it was returned as undeliverable. Is there a typo there...???

Eldyfig
01-25-05, 02:17 PM
I am also having this problem. It happened when I ventured downtown into the city traffic. After a little stop and go, I was stopped at a light. I received a Stop Engine warning in the OBD I. Then it displayed Low Oil Pressure. Unlike hwelchwa, My temp started rising slowly. It runs normally around 203 for this weather. After the warning, it reached 223. As soon as I starting moving, the warning went away. The temp starting coming down. I did a couple more stop and goes, then the same thing happened again.

After that last warning, I made it to the expressway. When I got up to speed on the expressway, my temp went lower than usual. It fell to 190. That is lower than a blast of cool air from open road would get it. My guess is that the cooler oil from the pan finally got through the engine.

I didn't notice any unusual engine noise during the low pressure period. What should I do, besides stay away from downtown?

When changing the oil pressure sensor, will oil come out of the port?

BeelzeBob
01-25-05, 03:29 PM
I am also having this problem. It happened when I ventured downtown into the city traffic. After a little stop and go, I was stopped at a light. I received a Stop Engine warning in the OBD I. Then it displayed Low Oil Pressure. Unlike hwelchwa, My temp started rising slowly. It runs normally around 203 for this weather. After the warning, it reached 223. As soon as I starting moving, the warning went away. The temp starting coming down. I did a couple more stop and goes, then the same thing happened again.

After that last warning, I made it to the expressway. When I got up to speed on the expressway, my temp went lower than usual. It fell to 190. That is lower than a blast of cool air from open road would get it. My guess is that the cooler oil from the pan finally got through the engine.

I didn't notice any unusual engine noise during the low pressure period. What should I do, besides stay away from downtown?

When changing the oil pressure sensor, will oil come out of the port?


If the AC was off the engine cooling fans will not even turn on until 225. If you normally use the AC and were in ECON or OFF and/or the temp was 42 or cooler then AC was disabled and the coolant temp alone would activate the cooling fans. Perfectly normal. If the coolant temp crept up it might have thinned the oil sufficiently to cause the low oil pressure warning to trip.

It is more than likely an aging oil pressure warning switch. Look above the oil filter on the oil filter adapter. Get the correct OEM part from a Cadillac dealer as it has specific setpoints for your engine and a generic switch from an autoparts store will likely cause the false warnings also.

If you unscrew the switch from the filter adapter to change it some drips of oil will come out but not more than a few drops....it won't spew out or drain the sump or anything....unless you take it out with the engine running....LOL

What weight oil are you using?? A 10W30 oil is recommended and a thinner oil could also trip the oil pressure warning when the engine is hot.

Eldyfig
01-25-05, 03:53 PM
Thank you. I regularly use 10W30 Valvoline. I have 114k miles on the car now. I will get with the caddy dealer nearby and arrange to spend some of that tax refund. I have seen the switch before when I have done oil changes, but never looked hard enough to see what it takes to get it off. I will be soon though.

BeelzeBob
01-25-05, 03:59 PM
Take the splash panel off under the car that is between the rad support and the engine cradle. You can reach up and over the cradle crossmember that way and it is much easier to access.