gLomeli

I have a 1990 ZR1 with a little over 17000 miles. It has a knocking noise around flywheel area. My mechanic thinks it may be the crankshaft thrust bearing. What are the symptoms or signs of this problems and can you advise of price range re: repairs. With this low mileage it is difficult for me to accept this diagnosis. Please advise....Thanks

wfot

The transmissions in the zr1 make a lot of noise when idling and warm. If the noise stops when yu push the clutch pedal in, everything is good. Also the noise will o ly be at idle, rev it up over 1000 and the noise will go away if everything else is in good order.
the cars have a dual mass flywheel to keep things quite as well, if the flywheel is in poor condition, you will get a lot of noise as well.
if it is just the normal trans noise, you can try a top grade oil as well. Redl8ne high shook works well and keeps shifts smooth too.
J

ghlkal

To add to what wfot wrote, the dual-mass flywheel can make strange noises if your LT5 isn't idling well.

Do you know if the injectors have been changed? Even with only 17K miles, the 1990 injectors do not like ethanol in fuel. We've all had to change them. When my injectors started failing, the rattling from the flywheel was obvious. Once I replaced the injectors and the idle smoothed out, the knocking noise went away.

I'd check the injectors first.

ccmano

Injectors....! It only takes one injector to fail and the dual mass flywheel will make this noise. First time I experienced it I thought it was rod knock.
Most mechanics are clueless about these cars.
H

biggiefl

Mine at 24k had the #3 injector fail and everyone thought it was a rod or trans knock. When I pulled the plugs to do a compression test I noticed one plug was dry(#3). 16 new injectors and 4hours of labor I am all set.

Paul Workman

The dealer replaced the injectors on my 90 before I bought it. But! They used NOS and in 3 years alcohol had already trashed them.
I replaced them myself with Accel 150821s from Summit 8 years ago and she idles sweetly still.
About that time i switched to the Fidanza Aluminum flywheel. It still idles fine (stock cams) but I installed a sprung hub disc & bumped the idle rpm to 850 to keep the ZF6 (black tag) from rattling.

Photoguy000

Replace the injectors. I had to do this last year, sent videos to a few people with a similar scary rattle and shake Of the car and everyone (including Marc haibeck) and they all suggested that.

Used accel injectors car runs crazy good now. ��