Intermittent Squeal - Replace Lifters or Throwout Bearing??

[TexasPettey]

I've recently started to hear a very intermittent squeal from the rear of my Gen1 engine. It's very difficult to replicate. It's not there on startup. If I run the engine for a while at temp & rev it, I can get it to happen, but it disappears after a short while.

It's definitely at the rear of the motor with a sound similar to a belt squeal. I haven't detected any excessive valve noise, even using a mechanics stethoscope. However a search found one or two instances of lifter failure with similar characteristics. I also thought that it might be a throwout bearing making noise. I've got both stock lifters and a stock clutch on the car. Neither have been replaced since the car was new.

The sound doesn't change when I depress the clutch. It has some small change with RPM, but not much. I'm cautious about driving it much to diagnose, since little problems can get big quick when driven.

Any ideas beyond lifters and throwout bearing as to the cause? Any way to tell if the lifters might be bad? If it is the lifters, can they be replaced without removing the heads?

 

[1TONY1]

If it is the lifters, can they be replaced without removing the heads?

No, you would have to pull the head/s.

 

[coupe]

Pilot bearing possibly? Had a friend that would get a "squealing" noise at random times...pilot bearing replaced and sound was gone.

 

[TexasPettey]

Pilot bearing possibly? Had a friend that would get a "squealing" noise at random times...pilot bearing replaced and sound was gone.

Thanks. Can this be replaced with the crank in place when the tranny is out?

 

[coupe]

Yes it can.

 

[Tom F&L GoR]

I had a roller lifter fail. A few oil changes prior I found a teeny part of a teeny washer, which turned out to the the thrust washer keeping the needles of the roller in place.

When the roller finally stopped rolling (after 1/3 of the needles fell out) the squeal was that of a slipping belt, except it was constant and surprising not really tied to RPM. That may make sense, since the cam is only turning half speed. When it happened, I took off the belt and started the engine for a moment - since the noise didn't go away I knew it was internal. Unlike yours, once it started making noise, it did not go away. Ever.

I actually drove it home about 4 miles because it was loud, but not so that I'd worry it wouldn't make it. Heads do have to come off, getting the cam out means loosening the trans mount so you can angle the block up enough to clear the frame member in front of the engine to get the cam out.

While one lifter made the noise, several others were sliding a little. There were sharp edges on the lobes where the roller had worn a path down the middle. The OEM replacement lifter is same as from the Chrysler V-6, and not the American V-6.

Anyway, I attribute part of the reason because this engine had 1.7 rockers for the previous 60,000 or more miles (I bought it that way) and had been drag raced by the previous owner and AX and track time by me. It wasn't cheap to repair, but in hindsight, perhaps not a surprise either.

If it is a roller lifter that is sliding, a used oil wear metal analysis should show elevated iron levels. Obviously a squealing throwout bearing would not...

 

[Jack B]

I had a roller lifter fail. A few oil changes prior I found a teeny part of a teeny washer, which turned out to the the thrust washer keeping the needles of the roller in place.

When the roller finally stopped rolling (after 1/3 of the needles fell out) the squeal was that of a slipping belt, except it was constant and surprising not really tied to RPM. That may make sense, since the cam is only turning half speed. When it happened, I took off the belt and started the engine for a moment - since the noise didn't go away I knew it was internal. Unlike yours, once it started making noise, it did not go away. Ever.

I actually drove it home about 4 miles because it was loud, but not so that I'd worry it wouldn't make it. Heads do have to come off, getting the cam out means loosening the trans mount so you can angle the block up enough to clear the frame member in front of the engine to get the cam out.

While one lifter made the noise, several others were sliding a little. There were sharp edges on the lobes where the roller had worn a path down the middle. The OEM replacement lifter is same as from the Chrysler V-6, and not the American V-6.

Anyway, I attribute part of the reason because this engine had 1.7 rockers for the previous 60,000 or more miles (I bought it that way) and had been drag raced by the previous owner and AX and track time by me. It wasn't cheap to repair, but in hindsight, perhaps not a surprise either.

If it is a roller lifter that is sliding, a used oil wear metal analysis should show elevated iron levels. Obviously a squealing throwout bearing would not...

Tom:

which brand?

 

[Felisol]

how to change only the throwout bearing on my 2001 Viper ACR ?

Thank you

 

[Tagoo]

See if the sound changes when you push the clutch in or let it out. If so, I think it would indicate a throw-out bearing.

 

[dave6666]

how to change only the throwout bearing on my 2001 Viper ACR ?

Thank you

I've got a DIY with pics at V.A. and T.V.G. that covers that. Just look for my threads.

__________________________________________________

Please note the complaint-free content. Dave, contemporary mod-rice Viper/Ricer owner, and I approve this message.

 

[AZTVR]

how to change only the throwout bearing on my 2001 Viper ACR ?

Unless you've recently done a clutch job and changed the clutch disc and pressure plate, pilot bearing, and clutch slave cylinder, I would suggest that you might as well replace them all and not just the throwout bearing. You really don't want to do this job again any time soon unless you enjoy extracting transmissions.. Dave's write-up makes it so that you will know EXACTLY how to do it, so there aren't the usual blind alleys that a first timer usually encounters in a job like this. But, it still is a hassle if you don't do this kind of thing often.

 

[-FROG-]

Unless you've recently done a clutch job and changed the clutch disc and pressure plate, pilot bearing, and clutch slave cylinder, I would suggest that you might as well replace them all and not just the throwout bearing. You really don't want to do this job again any time soon unless you enjoy extracting transmissions.. Dave's write-up makes it so that you will know EXACTLY how to do it, so there aren't the usual blind alleys that a first timer usually encounters in a job like this. But, it still is a hassle if you don't do this kind of thing often.

I somewhat agree. Depending on the miles on your car, the clutch may be good still, might can tell by looking at it. BUT, I have replaced the Slave cylinder in both my Vipers and I always recommend for people to go ahead and replace the slave cylinder if you are going to have the tranny out. ALSO, you get a pilot bearing when you buy a slave cylinder. AND.... usually when you replace the slave, you typically want to replace the master cylinder too. The Master is a pretty easy install and not too expensive. If you are going to go through all the trouble of taking the trannie out, just replace them to avoid having to do it later.

 

[GTS Dean]

My vote would be pilot bearing. When one of the balls begins to gall, it forms a hot spot and quits rolling. This dragging ball stresses the cage and loosens it, causing the remaining balls to vibrate loose. This is probably the squeal you are hearing.