Moe Greene Posted March 11, 2020 Share Posted March 11, 2020 Hello, I recently purchased a 1990 Comanche 4.0 5spd The knock originates around the lower rear end of the engine block and bell housing, I can't tell for certain if its the engine block or bell housing. The knocking sound starts pretty much as soon at the engine starts, even on cold starts. Oil pressure when cold hovers a bit above 40 and as the engine warms up it lowers below 40 (around 30). The knocking seems to quite down a bit when warmed up but with that said it doesn't go away. The knock has a direct correlation to engine RPM, that seems to mellow at higher rpm. Please advise :) I have disconnected each injector one at a time while engine is running, this did not make the sound go away. Year: 1990 Engine: 4.0 Oil: 10w40 synthetic Engine Oil filter: Wix Transmission: AX-15 5 speed manual with internal slave cylinder Link to comment Share on other sites More sharing options...
Pete M Posted March 11, 2020 Share Posted March 11, 2020 popped the inspection cover to look at the flywheel? Link to comment Share on other sites More sharing options...
Moe Greene Posted March 11, 2020 Author Share Posted March 11, 2020 Just now, Pete M said: popped the inspection cover to look at the flywheel? Hi Pete, I have not removed the inspection cover yet, can you please let me know what I should keep my eye on when looking at the flywheel. Link to comment Share on other sites More sharing options...
87Chief Posted March 11, 2020 Share Posted March 11, 2020 Look for cracks in the flywheel, or to see if it is hitting something. Link to comment Share on other sites More sharing options...
Pete M Posted March 11, 2020 Share Posted March 11, 2020 yeah, have someone rotate the crank by hand while you look closely for flaws or warping or anything that's not normal. Link to comment Share on other sites More sharing options...
JMO413 Posted March 12, 2020 Share Posted March 12, 2020 I'm guessing yours sounds like mine they way you describe it. I've never found the cause. I will be following to see what you find. Link to comment Share on other sites More sharing options...
Moe Greene Posted March 12, 2020 Author Share Posted March 12, 2020 Hey all, Not sure if I’m missing something but I don’t see the inspection cover, seems like a massive dust cover, please advise. Link to comment Share on other sites More sharing options...
JMO413 Posted March 12, 2020 Share Posted March 12, 2020 1 minute ago, Moe Greene said: Hey all, Not sure if I’m missing something but I don’t see the inspection cover, seems like a massive dust cover, please advise. Mine is a massive cover it doesnt come out unless the tranny comes out. Link to comment Share on other sites More sharing options...
Warren Mohler Posted March 12, 2020 Share Posted March 12, 2020 How does the clutch work? Link to comment Share on other sites More sharing options...
Moe Greene Posted March 12, 2020 Author Share Posted March 12, 2020 4 minutes ago, JMO413 said: Mine is a massive cover it doesnt come out unless the tranny comes out. I believe mine is the same exact way. I may take out the starter and see if I can find anything. BTW how many miles has it been since the sound started for you? Link to comment Share on other sites More sharing options...
JMO413 Posted March 12, 2020 Share Posted March 12, 2020 2 minutes ago, Moe Greene said: I believe mine is the same exact way. I may take out the starter and see if I can find anything. BTW how many miles has it been since the sound started for you? I bought it that way. Owned it almost two years and a little over 4k miles. Nose is not really any better or worse. Link to comment Share on other sites More sharing options...
Moe Greene Posted March 12, 2020 Author Share Posted March 12, 2020 Hey all, I think I figured out where to look. So to backtrack a bit. I purchased the truck from a complete idiot who didn’t take care of any maintenance on the car... he was selling at with a “bad Slave cylinder” and deemed it ”not able to drive” I towed it home and saw that the master cylinder had a gash in the boot and was 100% empty. I replaced the master cylinder today, and as soon as I push the clutch pedal the knock goes completely away! So my next task is drop the tranny and see what’s going on. Anyone think it’s the throughout bearing? Link to comment Share on other sites More sharing options...
Warren Mohler Posted March 12, 2020 Share Posted March 12, 2020 Have someone work the clutch while running and watch harmonic balancer to see if it moves forward Link to comment Share on other sites More sharing options...
Moe Greene Posted March 12, 2020 Author Share Posted March 12, 2020 46 minutes ago, Warren Mohler said: Have someone work the clutch while running and watch harmonic balancer to see if it moves forward Hi Warren, Thanks for the tip, I'm definitely going to do this before moving over to the transmission. Just for clarification, I'm looking to see if the harmonic balancer moves forward when clutch is pushed down? Should there be any play in the harmonic balancer when car is idling? Link to comment Share on other sites More sharing options...
Warren Mohler Posted March 12, 2020 Share Posted March 12, 2020 No, do this BEFORE removing trans, any movement would indicate thrust bearing wear Link to comment Share on other sites More sharing options...
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