Bad rod bearings or false alarm?

[Randall]

Hey everybody,
I was just wondering if any of you have had experience with faulty or worn out rod bearings. Here comes my long description.....
For the last few weeks I have been hearing a rattling noise especially around 2000 RPMs when in gear that seems to be getting louder. There has been a rattling noise ever since I got my clutch redone in January, but it was only audible when you would take your foot off of the clutch pedal while the car was idling, and as soon as the clutch was pressed in, walla, the noise disappeared. That seems to be the same cure for the newer noise, as when I push in the clutch pedal and keep RPMs at 2000 while coasting down the road the noise goes away. I ran the codes, and got nothing at all, and I did a cylinder balance test and it passed and the noise never came on while the cylinders were being dropped. Also, there is no abnormal noise when the engine is cold upon start ups. I am scarred the Rod Bearings are bad and just need some guidance with this issue, or testing procedures to rule that out. I have a suspicion it could be an exhaust leak, but upon having the system checked and a few holes re-welded, the noise is as loud as ever. It sounds like a metallic rattling, that seems to match engine speed to an extent. Thanks for any advice!
-Randall

 

[93superSHO]

Check the torque limiter mounting plate on the tranny. behind dvr tire side of the case up high you will feel/see 2 bolts, make sure they are tight and that plate isn't loose. Is the transaxle to engine mounting bolts loose(were they torqed?) I highly doubt it is rod bearings from what you are describing, they will give a lower "knocking" type sound either at idle, de-accellerating, or about 2800-3400rpms from the 5-6 I have personally encountered. If you are worried about the rod bearings tho it might not be a bad time to consider them if they have not been done for awhile or at all before.
oh, did you check the y-pipe hanger at the oil pan for that being loose. It sounds(from what you describe) as though something is not tightened down all the way. I would go thru and check all the things that are tampered with when replacing a clutch.

 

[SASHO91]

sounds like its clutch related....

I know my A-Z clutch disc made noise at idle...


However, Rod Bearings are well worth the effort. If you do not know the previous records on the car, IMO i would jump under there and do them asap. Considering the car has 120k on it. They are a very very good preventive maintanance item(s)

On the noise though... i would check the tranny roll dampner(the "shock" looking thing on the driver side strut tower) and make sure everything is tight.
If all is well there, i think that the "problem" is somewhere in the clutch area.. if its not causing shift problems, then its not a problem per se, just an annoyance(sp?)

EDIT: being that there is no oil pressure at startup, worn bearings may knock until oil pressure compensates for the worn-ness... like i said, RB's are extremely important.

 

[Randall]

Awesome info guys!!!
Thanks for the ideas, and yes I just crawled under there and to my surprise, the bottom two bolts that tie the engine and transaxle together are completely missing!! Would that make this type of noise? So much for trusting a shop with the job. I will check for the other things you guys mentioned tomorrow. Thanks again! By the way, the noise also disappears during decceloration, hopefully a loose part is the noise maker!

 

[Randall]

well, upon checking the underside of my SHO, I was surprised to see that the bottom two tranny to motor bolts were missing entirely and the tranny was a half inch lower than the engine with the engine plate looking a bit off too. I took it immediately back to the shop and without hesitation they fixed the problem, but to my disgust, the noise seems the same or even slightly louder. I have noticed it completely goes away upon decceloration, and that it's noise range is really noticeabe on slow acceloration from 2000 RPM to about 3400 or a little more when it seems to go away. I have not yet checked the Roll Damper, so I will do that too, and as far as the y-pipe, I have the catless SHOShop piece, which seems to be a very tight, but clean fit. Thanks for any further advice. There also is no noticeable abormal noise upon start up, and upon fast acceloration the noise almost isn't audible. Thanks again!

 

[projectSHO89]

Since it started when the clutch job was done, I'd suggest focusing on the throw-out bearing.

Steve

Hey everybody,
I was just wondering if any of you have had experience with faulty or worn out rod bearings. Here comes my long description.....
For the last few weeks I have been hearing a rattling noise especially around 2000 RPMs when in gear that seems to be getting louder. There has been a rattling noise ever since I got my clutch redone in January, but it was only audible when you would take your foot off of the clutch pedal while the car was idling, and as soon as the clutch was pressed in, walla, the noise disappeared. That seems to be the same cure for the newer noise, as when I push in the clutch pedal and keep RPMs at 2000 while coasting down the road the noise goes away. I ran the codes, and got nothing at all, and I did a cylinder balance test and it passed and the noise never came on while the cylinders were being dropped. Also, there is no abnormal noise when the engine is cold upon start ups. I am scarred the Rod Bearings are bad and just need some guidance with this issue, or testing procedures to rule that out. I have a suspicion it could be an exhaust leak, but upon having the system checked and a few holes re-welded, the noise is as loud as ever. It sounds like a metallic rattling, that seems to match engine speed to an extent. Thanks for any advice!
-Randall

 

[Randall]

Thanks for the tip Steve, and I did follow it, but the shop says that the TOBs in SHOs are a part of the non adjustable system and therefore are always in contact with the clutch assembly, but they said when the clutch is pressed in when the noise goes away that it indicates that the problem is not the TOB. I don't know if I am being fed a line or what, what do you guys think? I just want this noise to go away! Thanks for the help so far too! I might pay the exhaust shop a visit again to see what he thinks about the noise.

 

[Minnesho]

what kind of clutch did you have put in? was it a SPEC clutch?

 

[Randall]

I know it was a stock replacement clutch, and I believe it was by LUK. It came in a clutch kit, but I never saw it as the shop performed the operation in 3 and a half hours and I thought it was a joke when I showed up to get info on what parts were going to be involved when they said it was done. Anyway, they didn't give me any trouble when I went back and pointed out the misaligned tranny and engine, and they fixed it right then. But, the noise is still there. It does seem to go away when the secondaries open, but then again, I have a catless Y-pipe and it is possible, though unlikely, the noise just is getting drowned out. I am not sure what to look for now but I was wondering if timing belt tensioners make noise when they are bad, as it seems to be an engine noise, although when I am driving between 2000 and 3500 hundred RPMs and the noise occurs, simply pressing the clutch in makes the noise stop, and even when I rev the engine back up to where it was and hold it there with the clutch pressed in, the noise doesn't come back, 95% of the time. Any other ideas guys?

 

[Wht91+]

I know it was a stock replacement clutch, and I believe it was by LUK. It came in a clutch kit, but I never saw it as the shop performed the operation in 3 and a half hours and I thought it was a joke when I showed up to get info on what parts were going to be involved when they said it was done. Anyway, they didn't give me any trouble when I went back and pointed out the misaligned tranny and engine, and they fixed it right then. But, the noise is still there. It does seem to go away when the secondaries open, but then again, I have a catless Y-pipe and it is possible, though unlikely, the noise just is getting drowned out. I am not sure what to look for now but I was wondering if timing belt tensioners make noise when they are bad, as it seems to be an engine noise, although when I am driving between 2000 and 3500 hundred RPMs and the noise occurs, simply pressing the clutch in makes the noise stop, and even when I rev the engine back up to where it was and hold it there with the clutch pressed in, the noise doesn't come back, 95% of the time. Any other ideas guys?

TOB possibly was that also replaced with the clutch??

 

[Randall]

Well, I never saw it, but yes, they said there was a new TOB included in the kit. I am wondering, is there is a way to verify that the TOB is bad without removing the transmission?

 

[SASHO91]

I would take the car back to the shop that changed the clutch at. And have them listen to the noise at idle, and show them that it goes away when you press the clutch in.

It still sounds like the clutch disc is making the noise. If the TOB is bad you wouldnt be able to get into gears while the car is running.
Im betting that its the clutch disc thats making the noise.

 

[Randall]

Well, I did take the car back, twice now for them to hear the noise, or at least the one that occurs while the car is idling, and they insist that it has nothing to do with the clutch but instead is a "worn out bearing inside the tranny or gear rattle". I never heard the noise before though, and the noise that occurs while driving, between 2000 and 3500 or so RPMs seems to be the same noise, just louder. I still would like to know if it could be a timing belt tensioner or valve noise or even something else. If anyone knows how to rule these things out, I will make a donation to the forum in your honor!
-Randall

 

[Off Road SHO]

well, upon checking the underside of my SHO, I was surprised to see that the bottom two tranny to motor bolts were missing entirely and the tranny was a half inch lower than the engine with the engine plate looking a bit off too!

If that is true, and you drove it like that, you are going to have more problems than that noise. Just having the two bottom bolts missing wouldn't allow ANY gap in the engine to tranny contact area. But, if in addition they didn't have the rest of the bolts tightened up, you could end up with a gap like that at the bottom.

That is a serious misalignment issue and more than likely did some damage to the disk and the pressure plate.

That engine plate is only .025" inches thick and the gap that it goes into is about .028" wide. It's a tight fit because they are using the pan for rigidity and therefore can't have any slop.

I'm afraid you might have some damage.

Tom

 

[SASHO91]

This could be the cause of my hypothesis... the disc being the culprit. Well the actuall spline "hub" on the disc to be exact... the tranny might not have got tighten down properly, creating too much slop. and putting too much strain on the disc "hub" from the input shaft on the tranny.

 

[Randall]

You guys sound right, but how do you diagnose that? Does the inspection plate allow visual access to the clutch assembly? I spent some time driving the car over the weekend and I noted a few more things:
The noise doesn't occur the first 1/4 to 1/2 mile driven after sitting overnight
The noise can now be heard with the windows up coming from the driver's side firewall and/or floor
The noise NEVER occurs upon decceloration or when coasting, even in gear
The car's performance seems untouched
So, if you guys can help me solve this I would be grateful, but either way I will probably donate to the forum in your honor for the help. Thanks again!
-Randall

 

[Randall]

Well, the source of the noise revealed itself, a picture says a thousand words, right?


The noise had actually gone away the past couple days, then in a 5 second time frame while coming down the freeway it suddenly sounded like marbles being thrown into a ***, and bang! The tow truck driver said I should go after the tranny shop because we talked about how the tranny was a 1/2 inch below the engine with the missing bolts, and he said that the non-centered force of the input shaft caused premature wear on the bearings..... it sounded good to me, but right now I am so depressed with the loss of my SHO that I don't know what to do. What do you guys think? Anyone know where to find a good running engine in California?

 

[Randall]

..........bump.........

 

[Calypso]

OUCH

Yeah, go after the shop...

-Matt

 

[Randall]

It is a good thing I have gone down to the shop a few times in the past month to have them verify my complaints, so that they can't say anything against me. I also found that there is a missing plate or bracket that used to sit on the front side of the transaxle, because dirt and grease outline something that used to be there. I take back all the good things I said about "clutchworks" and strongly urge no one to go there! This was the only job I haven't done myself on the SHO, and man it turned out bad! I will post some pics in a few days when I yank the broken 3.0 out, but does anyone have any great tips they can offer to make the removal of the motor easier? From now on, whenever I hear any type of metallic noise I am replacing the rod bearings the same day!