: Lifter, Cam, Valve Issue? (Sounds like Chubby Ranger)



wachuku
04-20-08, 01:25 AM
Sorry in advance for a long post.

My vehicle seems to share similarities with issues described in several other threads about "lifter noises".

http://www.cadillacforums.com/forums/cadillac-seville-cadillac-eldorado-forum/131216-99-sts-n-lifter-noise-advice.html
http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/129385-front-valvetrain-clacking.html
http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/129524-northstar-valvetrain-clatter.html

Much of what I've read appears to be discussions among people more knowledgeable than me, and I have trouble piecing everything together. Hence this post.

My car sounds much like the audio previously provided by ChubbyRanger:

http://members.cox.net/chubbyranger/clatter.wav

There is a clacking noise that seems to occur at half RPM.

The noise is subtle when listening from the engine however. The noise is most prominent when standing by the side of the car -- as if the clacking was coming through the exhaust and reflecting off the pavement below the car. The clacking is also audible in the cabin in a muffled form.

My A/C is out -- a topic for another thread -- and before I spend time and money on the A/C -- among several other improvements I'd like to make to the car -- I'd like to know whether the engine might be facing it's last days.

I run wide open throttle (WOT) several times a week, and this yields no change in the noise. So if it's the often mentioned "carbon slap", it's got to be a tough case of it. (Also wouldn't "carbon slap" be at RPM?)

I've released the belt tensioner, which doesn't change the noise.

I've opened the oil cap and listened -- the clacking is not audible via that path.

I've poked around listening with a screwdriver, and I can't find the clacking at all (although whether I listened at the right spots is a big question).

If I had to guess I'd say the clacking originates from the rear bank near the PCV -- but as I've said the clacking is subtle when listening form the engine and prominent when listening from the side of the car (or even from the cabin).

I had the car at the dealer in July 2007 and here's the record:
"customer states loud ticking in engine. Slight lifter noise and slight generator bearing noise".

I had the car in 3/31/2008 to check for A/C leak after "low refrigerant" message (leak found coming from compressor). At that time I also requested a check on the "lifter noise", and the result was no noise detected.

I had the car in again on 4/18/2008 to evacuate the A/C (over half the refrigerant had escaped), and I was able to talk to two mechanics simultaneously with the car running. They say they know lifter/cam noise and I that my car doesn't have it, but the noise is way less in the garage -- perhaps because their floors are "rubber" (softer than concrete), I don't know -- the whole place seems "sound-subdued".

Maybe I should drop it, but I'm telling you the clack is loud and like the audio by ChubbyRanger. On the other hand it's been around for a year now, so how bad could it be?

Is their a way to understand this noise better? I don't want to spend a lot of time and money on the car if the engine is going bad. Fixing the A/C compressor is just the start of what I'd like to do. The rest is related to sound deadening and audio equipment, perhaps for SQ comps. Other than the "clack" and the A/C the car seems real nice.

I am willing to spend time trying to figure out this prominent clack.

dkozloski
04-20-08, 02:18 AM
There are an awful lot of moving parts in a Northstar V8. Some are bound to make some noise. If the engine doesn't sound like something inside is trying to get out you're probably OK.

chubbyranger
04-20-08, 05:15 AM
I haven't posted the finals on my threads yet because the story isn't complete but the diagnosis on my noise is not one, but two, bad exhaust cams. Most of the lifters are junk or future junk. As a bonus I had 3 headbolts that would not hold torque so its headgasket time too. :banghead: Using the screwdriver stethoscope was most effective for me when I removed the intake sight cover (a.k.a "beauty cover") and listened around the camshaft cover and head area where they meet. Mine was most pronounced around cylinder #5. Taking the cam covers off is a nasty job because you have to lower the cradle to remove them from the engine bay - not easy without a lift.

How many miles on your car? I'm at 101,000 (and holding...)

foos
04-20-08, 05:18 AM
My 99 always makes a little ticking/slapping sort of sound at idle but goes away when I rev it up.. It sounds more like a sound a diesel would make when it's idling.. It's been there for years and years and it never changes.. I was going to try and do the ring cleaning TSB one of these days because I still burn a lot of oil..
Does the noise happen when you rev the engine higher than idle?
Can you 'feel' the noise?

If you can't feel it and it goes away when you rev up a little then I wouldn't worry about it right now. If it gets worse over the next several months, then worry about it :)

chubbyranger
04-20-08, 06:05 AM
Mine also had the symptom where the noise was louder outside the car with the hood down and most pronounced in the garage -> enclosed space with concrete floor makes for the best sound reflection. Mine never got to the point I could hear it in the car unless the windows were down and even then I needed something to reflect the sound. That was how I caught it in the first place - driving into work I closely parallel a jersey barrier with my window down and I noticed the ticking noise on a few successive days. Started chasing it and you've probably read the rest...

wachuku
04-20-08, 12:29 PM
Hey fellas thanks for the responses and the questions. I’ll respond and add some follow-up questions.

dkozloski the engine doesn’t sound like something inside is trying to get out.

chubbyranger are your two bad exhaust cams associated with the same cylinder? Otherwise if both were making noises wouldn’t they be “off-rhythm” per cam rotation? The clack I’m hearing appears to be once per cam rotation – although today I’ll check to be sure the clack is on the cam cycle and not the crankshaft cycle. As for headgaskets, mine were done around 75,000 miles by a cadi dealer prior to my purchasing the car and I think they’re legit. Mileage now is 118,000.

chubbyranger can you elaborate a little on the “screwdriver stethoscope” method you used. I’m not 100% clear on the anatomy. I removed the plastic silver cover and listened around with a screwdriver, but where is the “camshaft cover and head area where they meet”? If I remember correctly the middle area comprises black tube-like looking structures and then to the front and back of the tubes there are silver blocks that I assume the pistons are under. Do I listen at the junction of the black and silver? And with the cam cover on, could I still here something?

foos thanks for your observations. My car sounds like a diesel when idling. That’s a great description. When I rev the engine, the clack is still there, but it becomes relatively quieter because other sounds tend to overwhelm the clack. I’ve looked at those ring cleaning posts that go beyond WOT. Maybe one is worth a try. Shortly after I purchased the car I ran WOT and got plumes of black smoke that I assume were carbon. Perhaps one head is so bad that all the WOTs can’t clean it. The engine does burn quite a bit of oil. (I don’t track oil consumption but I’d guess it’s towards the quart per 500 mile range). I can’t feel the clack but it seems like the clack in front manifests as a vibration-like distortion sound at the tailpipe.

The clack has been prominent for at least a year / 10,000 miles, and probably longer. During that time I haven’t been bashful about redlining the car, sometimes through two gear shifts.

Why would one typically worry about lifter issues anyway? What are the typical ramifications? Having had the clack for a year with no changes suggests that it may be benign – unless I’ve just been unusually lucky so far.

chubbyranger
04-20-08, 02:24 PM
Listen on both the black cam cover and the silver part underneath and work your way from left to right. You should be behind the "black tube structures" (aka the fuel rail) to listen to the rear bank. My sound was the most pronounced around #5 in the back. It was the tech that found the front, although I really didn't check there. Both the front and rear bank exhaust cams had rounded over to cause the noise, I assume on #5 in the rear. The shop is saving the junk parts for me so possibly I can post some pics but it will be at least a week. The problem with a bad lifer or cam is that you can be tossing metal fragments into the engine. If you want to get an idea of what you're dealing with you can get an oil analysis done and that will give you some insight as to whether you're facing an internal mechanical wear problem. From what I've read here (and now live) cam and lifter problems don't seem to be unusual for these cars. If you want a reference for my audio recording, it was made using a camcorder held about a foot over the intake manifold and pointed toward the rear bank.