knfeparty

I replaced engine mounts with Meyle ones and also replaced exhaust hangers. I had been experiencing a strange vibration that I thought was my engine mounts, part of the weird sound was due to my exhaust manifold nuts backing off (I since replaced them with new ones).
I now have a new and much more aggravating sound with the new stuff installed. It is especially noticeable during engine braking or even with the clutch pressed in during certain RPMs. It was unbearable with the aftermarket exhaust, which was also contacting the transaxle, so I put my stock catback in. This made the noise much quieter but it is still there.

So what is my RPM-related noise? Doesn't matter if the clutch is in or out.
Suggestions I've received:
Heat shield around the cat
the stuff inside the cat has broken and is rattling around
passenger side engine mount heat shield is contacting the exhaust manifold

What types of sounds do collapsed lifters/broken valve springs make?

Engine has been otherwise running fine and even got 26+ mpg on a 120 mile trip!

Yabo

balance shafts out of alignment?

knfeparty

but the balance shafts have been good for awhile now...can they skip a tooth?

gregeast

When I replaced the mounts I had a similar vibration. Turns out that I had over tightened the top nut on one of the mounts. The spec is something like 16lbs/ft (don't quote me on that), which is not much more than finger tight. Loosened it up to the correct torque and all was well, and smooooth, in the world.

Anaheim944

When I bought my car I replaced my mounts because of a vibration problem. It got a little better but It went completely away after a routine rotation. I also had an issue with the muffler rattling when I didnt make the smoothest shift in the world at low rpm's. It ended up being the muffler mounts little off from where theyre supposed to be. Good Luck

hidsolutions

I once found out by purchasing some Meyle trans mounts is they only offered their "HD" version. The rubber on the OEM Replacement from Meyle was SUPER hard. Almost urethane or delrin it felt. If this is the same case on your mount replacement it is probably now transmitting the vibration to another part of the car and something that wasn't there before is now vibrating more and causing a noise.

Will have to get under there and see if you can find it. Since you say it is worst on engine braking have a friend run next to the car and engine brake in first and see if you can isolate the noise a little better. May even be able to hear it while the car is up on jackstands.

FRporscheman

My BS belt skipped 180 degrees on the lower shaft, spontaneously, JUST when I changed my flywheel. I was convinced the vibrations were from the flywheel, and it took me a long time and a bunch of money to figure out it was the BS.

And I had even checked it once. But I only checked the top one.... which was fine......... But that's just my experience.

knfeparty

At idle the car is smooth, and it's really not so much that there is really bad vibration, it's just that the vibration is causing contact somewhere that makes a lot of noise.

If it was BS belts, would it be at all RPMs, moreso at low or high, or what?

Also I'm getting a lot of vibration in the shifter, even with the clutch in (which is really odd to me). How do you tell if transmission mounts have gone bad, and how hard are they to replace?

FRporscheman

Your '89 would have only one tranny mount. I'm not sure how to tell if it's bad but I'd think if it vibrates more during accel or decel.

BS out of alignment will cause more vibrations at lower rpms.

Is it actually a vibration, or just a noise?

knfeparty

both but the noise (new) worries me; the vibration does not.