**update on engine knock**

[FOMOCOTOSHO]

Ok Everyone,

I replaced the rod bearings as everyone told me to do and I still have an engine knock. When I first start the motor up it's perfectly quiet, but as soon as I put it in gear & put load on it it starts knocking, and doesn't stop knocking when you put it back out of gear until you turn it off again & restart.

My technician thought it must be coming from the transmission (tranny knocK?) so I called my tranny guy and he's never heard of a knock coming from the transmission but says it's not impossible. He thinks it's the bearings.

The bearings definitely had some wear but they weren't that bad.

What do you think? I had to wait for 2 weeks for the bearings to start and now I don't know what to do!??! Everyone said it wouldn't be the main bearings.

 

[Kens1992mtxSHO]

Have you been able to figure out where it's coming from? It could be anything from spark plug wires to cam chain tensioners.

 

[ycode90]

"Knock" or "rattle"?

 

[FOMOCOTOSHO]

"Knock" or "rattle"?

I can't really tell the difference but if I would guess I'd say more of a rattle sound. I had both of my technicians listening to it from top side & below it on the hoist with their stethoscopes and neither of them believe it's an engine knock.
I took it to the tranny guy and he listened and said he didn't think it would be from the tranny, however it could be a flywheel? My techs thought it might be a flywheel also.

Anyone else had any flywheel issues? Any way you can tell without tearing it apart? I'm worried about driving it further until I know but I don't have any other transportation and the car has been down already for 2 weeks doing the rod bearings.

The engine was completely redone with all new parts (minus bearings & piston rings) only about 500 miles ago (kens1992mtx) and I don't believe the ATX have timing belt tensioners do they?

 

[SHOspazz92]

It's rare to see ATX's spin rod bearings, Altho it certainly does happen. I might be talking out of my ass hear (and I assure you, I generally do), But you said the car only does it when you put it in gear, So maybe it's somthing that is ran off vacume, I.E. - The butterflies, Or somthing of the sort that get's more Vacume pressure when the car is actually put in to gear.


Edit - Yes, The ATX's do have timing belt tensionsors. Put your hand on the top timimg belt cover. If you can feel somthing slapping against it with the engine running, Then your Timing belt is loose. Also, On the front valve cover on the right side there is a disctinct **** - The Timing chain runs under here - Put your hand on there as well to see if you feel anything hitting the valve cover - This would mean your timing chain tensionor is worn and the chain is slapping around in there. At the very least, If you figure out it's coming from the Front (Left side looking from the front) or Rear (Right side) of the engine, That can narrow it down.

-Sam

 

[FOMOCOTOSHO]

It's rare to see ATX's spin rod bearings, Altho it certainly does happen. I might be talking out of my ass hear (and I assure you, I generally do), But you said the car only does it when you put it in gear, So maybe it's somthing that is ran off vacume, I.E. - The butterflies, Or somthing of the sort that get's more Vacume pressure when the car is actually put in to gear.


Edit - Yes, The ATX's do have timing belt tensionsors. Put your hand on the top timimg belt cover. If you can feel somthing slapping against it with the engine running, Then your Timing belt is loose. Also, On the front valve cover on the right side there is a disctinct **** - The Timing chain runs under here - Put your hand on there as well to see if you feel anything hitting the valve cover - This would mean your timing chain tensionor is worn and the chain is slapping around in there. At the very least, If you figure out it's coming from the Front (Left side looking from the front) or Rear (Right side) of the engine, That can narrow it down.

-Sam

Nothing coming from the front of the motor with the timing gear, etc, or the top valve train. It's coming from down low or the tranny end. Definitely sounds more like a "rattle" than a knock the more I listen.

Thoughts? Possibly could be a cracked fly wheel or something?

 

[SHOspazz92]

Is it a high pitched Metallic rattling noise? Is there a possibility that it is the covers to your Catalytic converters? My fathers's SHO just had this issue and it was taken care of for 5 dollars at a exhaust shop.

-Sam

 

[FOMOCOTOSHO]

Is it a high pitched Metallic rattling noise? Is there a possibility that it is the covers to your Catalytic converters? My fathers's SHO just had this issue and it was taken care of for 5 dollars at a exhaust shop.

-Sam

All the exhaust is new & tight/secure.

 

[blownsho94]

Flywheel? You bet, I did a clutch job recently and did not tighten the flywheel down to spec and when I fired it up, sounded like the engine was blown. Also, I've found a SPEC clutch kit needs some shaving off of the pressure plate bolts or, they will hit the bellhousing causing a slight knock.

-- Kevin

 

[BlackonBlack89]

I think it something with the tranny. As u say it happens when u put it in gear. I knoq diddly squat bout the auto's though.

When u first start it... can u rev it, hold revs, do whatever and the noise does not appear?? but as soon as it goes into gear it does make it. I think that would be a good chance it not the engine.

 

[FOMOCOTOSHO]

I think it something with the tranny. As u say it happens when u put it in gear. I knoq diddly squat bout the auto's though.

When u first start it... can u rev it, hold revs, do whatever and the noise does not appear?? but as soon as it goes into gear it does make it. I think that would be a good chance it not the engine.

yes when I first start I can rev it up & do anything and it will not appear. The instant it goes in gear it appears, however it doesn't disappear again until you turn it off, even if u put it back in park or neutral. If it is the flywheel maybe it's not fully disengaging because it's cracked, bent, or loose and so that's why it doesn't go away?

 

[SHO1]

If it's coming from the tranny, It Very well may be the diff. pin broken/loose and allowing spider gears to rattle around and grind away inside the diff housing, if so it may eventually blow thru the whole tranny. Need to check and see what the tranny fluid looks like asap. If it's the diff, that's all you may need now, but if it blows, you will need an entire tranny.

 

[whiteman_01]

I dont think atx's have diff probs, do they?

 

[SHO1]

Don't think so, atleast not as often as mtx's.
Thanks, I Missed that part, I didn't realized it was an atx, seeing clutch mentioned in there somewhere didn't help and the last descrip. of the probs, sounds and symptoms sounded exactly like an mtx and my 1st SHO back in '96.

 

[FOMOCOTOSHO]

Would it help you guys if I recorded a video of the noise w/ my camera & uploaded to youtube for you to listen to?

 

[SHO1]

It might, depends on how good a quality it comes thru.

 

[FOMOCOTOSHO]

**FINAL UPDATE**
Hey everyone, well I found my other noise. I was planning on having the transmission rebuilt eventually but because of this new noise & decided to move up the plans since I suspected it might be something with that. Well Friday night driving home from work the tranny completely let go so I towed it into my tranny shop. Today they tore into it and called me--the found the noise

So I guess it was the flex plate after all! Anyone else ever have this happen to them? I guess it's kind of a relief to know it wasn't anything else with the motor at least!

 

[AREA 91]

I did that in my 67 Impala with a 327ci engine. The 30 year old flex plate has been replaced with a SFI approved version.

 

[hawkeye18]

holy shit. That is amazing. i have never seen a flexplate core out like that. That reminds me of that one corvette with powdercoated wheels...

 

[Phoenix]

holy crap , never saw that happening....