knock fixed!

[wfoote]

When I first got my 91SS it came with what ultimately turned out to be a broken piston ring land. After changing the piston there was a slight knock. I figured it was a skirt knock as it came and went.

Recently on a cold start the thing was really knocking loud and I expected it was the beginning of the end. So I got the car home which is about 35 miles away from civilization. (I like my privacy)

I tried pulling the injector plugs off one at a time and couldn't get the knock to change so in my mind that ruled out a main bearing or rod bearing.

The knock seemed to be coming from the front of the engine so how to pinpoint the knock.. I live in a state that believes the 2nd amendment favors individual rights to keep and bear arms and I noticed a long rifle cleaning rod. These things make awesome stethescopes all you need to do is get your ear near the handle. I started listening to various parts of the engine and I placed the end of the cleaning rod on the water pump outlet by the thermostat and wow, the knocking hurt my ear.

I am now thinking wow, water pumps knock??? So the next morning, I restart the car and of course the knock is now very faint. Since I do live so far away from town I can't risk a breakdown so I take the accessory belts off and the timing belt covers off. Nothing looks amiss so I restart the engine and probe things again. Of course it isn't knocking at all now.

I decide to take the timing belt off and check the pulleys. Guess what, when I removed the bolts on the tensioner one of the bolts came out with the threads!!!! I found a longer bolt which torqued nicely and voila, knock gone.

I had been fretting over this for several months now, to celebrate I de-snorked the car. Gotta love the rumble and the smooth quiet idle.

[Aerotech]

Wow, nice find. Add that one to the fault isolation manual... I'll bet more than a few people would have yanked the engine or sold the car.

[93forestpearl]

Nice work.

I had one of those moments with my beater wagon. I had pulled the motor for a clutch, timing belt, oil pump reseal, etc. Put it back together to hear a horrid knock from the front of the motor when I was burping the cooling system. I went as far as to pull the timing covers off only to backtrack and find the AC tensioner pulley bearing bad bad, and hitting the timing cover. Then there was a big *whew*

[BXSS]

My parent's old MPV had a crazy knock @ 1 time that would go away @ certain RPMS so I thought idler pulley.
A local mechanic who happens to own a machine shop said the motor was dead, & would need to be pulled, torndown, inspected, & rebuilt.

We changed the timing belt + idler pulleys & the knock was gone!