98 Z24 Chain rattle - Very Frustrated!!!

Hello.

I have a frustrating problem that I am having trouble solving (as are my mechanic and my local GM dealership) on my '98 Z24 (about 150,00 kms).

I recently had my water pump replaced (for the second time). About 2 weeks after the replacement, a fairly loud rattle began in the area of the water pump/timing chain. The noise only occurs once the engine is warm (i.e. not at startup).

My mechanic tried replacing the chain tensioners, tensioner shoe, and finally the chain itself (thinking it was possible stretched), but to no avail. He has checked engine oil pressure and that was fine.

They can't understand why the noise is still occurring. After his difficulties, I took it to my GM dealer and the mechanic there believes that the engine is out of time ("by one or two teeth"). He also noted that exhaust gases were found in the engine housing when they opened the oil filler cap to check for that.

My regular mechanic disagrees with GM, saying that the car would be running like crap if it was out of time (it runs fine, with no noticeable lack of power, even when the noise is present), and that 'some' exhaust-type gases coming the oil filler cap is not unusual.

The noise does seem to be getting louder, and my wife (the regular driver of the car) has indicated that the temperature gauge doesn't read as high an engine temperature as before (the thermostat was replaced at the same time as the water pump).

I have noticed that when the steering wheel is turned slightly when at idle, the noise goes away almost completely (my mechanic first noticed that, and he lubed some connection with the power steering pump, but it didn't help them diagnose the problem).

This is driving me nuts. I can't continue to spend $$ having people look at it only to give me possible wrong advice (timing off with car running fine???).

Has anyone else had this problem or a similar one??!!!!

I want to figure this out and then seriously consider getting rid of this POS cavalier. Nothing but problems for me (brake rotors warped/machined/replaced, tie rods replaced, onto my third water pumps, struts replaced, etc. etc. etc.)

Thanks,
Corey

Anyone have any ideas?

well, I agree with your regular mechanic, the car ISN'T out of time. It would run like shit, if it ran at all. I would have to say, just going by your description, that it would have to be power steering related. There's no other reason why it would go away when the steering wheel is turned. The bearings on the pump may be bad?? It's hard to say.

the powersteering pump on that engine does not run off a belt or is not any where near wear the noise would be coming from if it were timing chain rattling. (it runs off one of the cams,on other side of head). just a ?, but does the car only do it at idle,or does it do it even at higher rpms(after warm-up). because when you turn the wheel you have a change in idle. did the car do this w/the first water pump change?you said they changed the chain sliders/shoes,but these cars are actually known that the chain tensioner does not fully engage some times,which will cause a noise"loose chain".some times also, people put the chain in wrong,they leave the wrong side tight& wrong side of chain slacked,which could cause it to jump a tooth or so out of time,but being out of time shouldnt cause a noise but putting chain in wrong will. the only part of your problem that really puzzles me is that it doesnt make noise at cold start-up, except thicker/colder oil!?!?:confused:

I dont know about the chain jumping teeth but I do agree if you beleive it is ciming from the timing chain it could be the Tensioner itself (not shoes). I had a simular problem when I changed my waterpump I re-installed the tensioner (hydraulic) with the piston upside down. This was very loud and noticable, so I removed the tensioner and figured out the problem, but when I reinstalled the tensioner a bur on the tensioner piston wall caused the piston to "hang up". It would run ok sometimes with no noise but then it would "chatter" like the chain was loose. I went to the local junk yard and found a replacement. It worked good. I had a simular noise occure about a month later, I took it apart again to find a piece of gasket sealer had made its way through the oil system from the oil pan and lodged itself in the Tenioner piston sleeve, blocking oil flow, preventing the tensioner from working properly. Damn I hate working on this car!

yeah,i know what you mean about you hate working that car,but working on our own cars sure does eliminate the hassle of trying to tell your dumbass mechanic what to look for (such as , the probs that you found) ,we just tear it back down and find the damn problem and fix it

I think you have an imporperly installed or defective hydraulic timing tensioner. If VERY specific installation instructions aren't followed to a TEE, the tensioner will not function properly, causing the rattle you describe.

in my experience you can follow those instrurtions to the last TEE and still have problems with these monstrositys

thats for sure :banghead:

the powersteering pump on that engine does not run off a belt or is not any where near wear the noise would be coming from if it were timing chain rattling. (it runs off one of the cams,on other side of head). just a ?, but does the car only do it at idle,or does it do it even at higher rpms(after warm-up). because when you turn the wheel you have a change in idle. did the car do this w/the first water pump change?you said they changed the chain sliders/shoes,but these cars are actually known that the chain tensioner does not fully engage some times,which will cause a noise"loose chain".some times also, people put the chain in wrong,they leave the wrong side tight& wrong side of chain slacked,which could cause it to jump a tooth or so out of time,but being out of time shouldnt cause a noise but putting chain in wrong will. the only part of your problem that really puzzles me is that it doesnt make noise at cold start-up, except thicker/colder oil!?!?:confused:

Hi godenm, thanks for the reply.

The noise is most present at idle when the engine is warm. I believe it is still present while driving, but it is hard to tell with the engine/road noise (it seems to have been getting louder recently; originally i couldn't hear it while driving). Also, it is still present when I turn the steering wheel at idle (doesn't go away completely as I originally thought - it's just louder now so I can stil hear it although it does quiet down).

No, it didn't do after the first water pump change. And it didnt start immediately after the most recent one (it start a week or two later).

Nope, no noise on cold startup.

You mention that "being out of time shouldnt cause a noise but putting chain in wrong will." It was my understanding from the mechanic at the GM dealership that the car being 'out of time' was caused by the timing chain being put in wrong ('one or two teeth off'). Is this not the case?

Thanks,
Corey

I think you have an imporperly installed or defective hydraulic timing tensioner. If VERY specific installation instructions aren't followed to a TEE, the tensioner will not function properly, causing the rattle you describe.

Hi richtazz, thanks for the post.

After the car started to make the noise, my mechanic's original though was that the tensioner was not put back in correctly. He even methioned that there was a specific way to re-install it, and that if it wasn't followed exactly that some slack in the chain could result (creating the noise).

Since he told me that right off the bat (he wasn't afraid to admit that their shop might have screwed-up), I figure that they probably installed it correctly (at least after I had brought it back for them to cure the noise). With how much was done (replaced the tensioner/shoe/chain) I'm wondering if it could be something else. It sure sounds like a loose chain noise to me though.

Thanks again,
Corey

in my experience you can follow those instrurtions to the last TEE and still have problems with these monstrositys

Hi mborutski,

I'm wondering how you have been able to correct this in the past? Just trying several tensioners until you found one that worked well when installed properly?

Thanks,
Corey