Possible knock

sts70004

Registered User
I've developed a noise that sounds almost like a knock in my engine. I've got around 168k miles, and its changes with RPMs, but you don't hear it when you rev, you hear it when you let off the revs. It also seems to be louder and more of a thud when you listen with a stethoscope to the valve covers. I can hear it against the supercharger too, but it didn't sound that loud on the timing cover. Any ideas? I just changed the balancer to that $100 one that AutoPartsNew4U.com sells. Its been sitting 3 months before this, and the noise only appeared after about a days worth of driving. Oil pressure appears to be good (I did the swap to the mustang sensor, so it doesn't give me a number, but at least it sweeps and isn't a dummy light) or at least registers in the normal range for my SC. Oil isn't milky or anything and I didn't see any metal in it. I can take a video if that might be helpful.
 
could also be the coupler in the supercharger. They're known for goin bad and making all kinds of racket... A solid coupler to replace it can be had on ebay for 20 bucks or less. Best way to see if it's that is to take your S/C or jackshaft belt off and see if the noise goes away. If it does, you know it's not the motor. If you search supercharger coupler on here you should find threads with more detailed info.
 
could also be the coupler in the supercharger. They're known for goin bad and making all kinds of racket... A solid coupler to replace it can be had on ebay for 20 bucks or less. Best way to see if it's that is to take your S/C or jackshaft belt off and see if the noise goes away. If it does, you know it's not the motor. If you search supercharger coupler on here you should find threads with more detailed info.

Ah should've specified in original thread, this is with all the belts off. It sounds like its exactly on time and in beat with my exhaust pulses. Does that help? It sounds too high in my opinion (just me hoping really lol) so I don't think its a rod bearing or main bearing. But it does sound a lot louder towards behind the supercharger. Is it at all possible its a sudden detonation, since I don't really hear it at idle, its only when warm and its exactly as you let off the throttle. Possible problem due to a faulty injector caused from sitting for the 4 months it was?
 
well then it sounds like it could be in the valve train bent push rod or valve did you use any kind of starting spray on the motor at anytime?
 
Definitely a rod knock. Do not run the engine anymore or you will risk a spun bearing and ruined crankshaft or worse. If you pull the engine now you might get lucky and just have to replace bearings.
 
Definitely a rod knock. Do not run the engine anymore or you will risk a spun bearing and ruined crankshaft or worse. If you pull the engine now you might get lucky and just have to replace bearings.

Alrighty thats what I was afraid of... :( Its so quiet right now I think I can probably just slip new bearings in it right now. I don't have access to a shop, is it a big hassle pulling the k-member to do this from the bottom?
 
Well I just got a hold of a buddy who has an engine lift, so that takes care of that for me. I'll just slip a new set of bearings in, and while the engine is out, I think I'll give it a good cleaning, port the blower and exhaust, paint it, and then also build some subframe connectors to stiffen up the chassis a little bit. Hopefully in three weeks time I'll be back on here with pictures.
 
Definitely a rod knock. Do not run the engine anymore or you will risk a spun bearing and ruined crankshaft or worse. If you pull the engine now you might get lucky and just have to replace bearings.

Hey I tried to send you a message but your PM box is full. Do you sell sets of bearings for the engine?
 
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