1997 5.7 Vortec Engine Knock/Tap

PlayingWithTBI · Apr 3, 2022

Years ago I had a 70 Buick Skylark with a 350 which had a knocking noise when I bought it. A mechanic told me it was piston slap, turned out to be the torque converter, replaced it and drove it another 2 years.

97Suburban · Apr 4, 2022

AuroraGirl said:
try reducing spark plug gap if you are at the factory gap by .010 if it fixes it then it was some light knocking or chuggle and possibly unrelated noise etc

Reduced the gap and did not have a change in noise.

Jeff Janssen said:
Is this what a cracked flywheel sounds like? (Given his comment above about unloading the flywheel by moving the Trans between P & R)

I've heard the flex plate could be an issue and the noise seems to be coming from the bottom of the engine.

Pinger said:
Is it a trick of the light or are there 'bits' flying from behind the radiator when it's revved?

There is some leaves that were flying around, the truck has been sitting for a while.

I'm gonna check the starter next to see if its stuck engaging and hitting the flex plate.

97Suburban · Apr 11, 2022

No luck on the starter, next step is to remove the engine and see what's wrong. Does anybody know the best (most detailed) step by step guide to remove the engine?
Thanks.

Jeff Janssen · Apr 12, 2022

97Suburban said:
No luck on the starter, next step is to remove the engine and see what's wrong. Does anybody know the best (most detailed) step by step guide to remove the engine?
Thanks.

I'd look into the flex plate first... I believe somebody said it was possible to unbolt the torque converter from the flex plate, slide the TC back to the rear of the trans (with a prybar, all you need is about 1/8 of an inch clearance) and then you should be able to start the engine and see if the noise shows up or not. I'm sure somebody will chime in pretty quick if that's not a good idea...

AuroraGirl · Apr 12, 2022

Jeff Janssen said:
I'd look into the flex plate first... I believe somebody said it was possible to unbolt the torque converter from the flex plate, slide the TC back to the rear of the trans (with a prybar, all you need is about 1/8 of an inch clearance) and then you should be able to start the engine and see if the noise shows up or not. I'm sure somebody will chime in pretty quick if that's not a good idea...

GM had said that as a diagnostic thing in the past and now says do not do that whatsoever

I have a feeling that the procedure is safe, the crayon eaters were ending up toasting good torque converters and parts that GM had to then shell out or at least spend time investigating since crayon eating doesnt understand how to tighten bolts back down and do it all right.

Theory tho, idk

1997 5.7 Vortec Engine Knock/Tap

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