Greetings all. I am trying to narrow down an engine knock. And really hoping its not a bearing. Ok here are some details I have been able to narrow down so far. It sounds like it is coming from the bottom side of the engine. i know a good sign it could be bearing. I got a auto stethescope and poked around, but cannot find it directly. I put it on the oil pan and cause of all the oil its not really too loud there. I put it on the torque converter cover and its prolly the loudest there than anywhere else I have found. It knock speeds up with the engine speed, and slows with the engine. Its there and most prominent under idle. and when gliding before a stop sign it is really noticeable. I was trying to get more symtoms last night, and i noticed that it really doesnt seem to be there under a load. such as lightly brake torquing the car. just giving it a little gas the noise does not seem to be there. but soon as i go back to idle it returns. Any help here would be great.. Thanks
Chris
ok Chris,
I am not an expert and am pretty new to the TR thing, however, I have heard of bad torque converters making the noise you describe. I have also seen engine knocks that only show themselves at idle. I would go under the car, unbolt the torque converter, pull it away from the flex plate and start the car to see if the knock is still there. Since the knock is most noticable at idle, you should have no trouble doing this. If the knock is still there you have eliminated the transmission/torque converter from the equation. If the knock goes away, then you know it is either the trans or torque converter (my money would be on the torque converter at that point). I hope this has been some help. I am not a guru or anything but hope this helps.
Dan
Well ... Knock is never a good thing however,.. I would bet a dollar that says your converter bolts are just loose,... just had this problem with my brothers car a few weeks ago,.. there are only three of them. all you need to do is pull the flywheel cover of stick a screwdriver between the teeth and the starter housing and use a 15 mm wrench to tighten up the bolts. the only pain in the but is turning the engine over by hand, I recomend alot of patience and a good ol rag, and its best to just grab a hold of the flywheel and turn,...best of luck to ya!
yea, the bolts were lose when i started looking through this site and seeing that come up alot. I tightened them all up at that time, and soon as i started it the knock was still there. I am liking the idea of "disconnecting" the converter and see if the problem goes away like Daniel said. I have yet to do this, so it will be a learning experience yet again. cant be too hard to just pull that apart and run the engine and see if the noice goes away. any suggestions would be great hehe. thanks Chris
well i pulled off the converter, and knock was still there. tried the gm top engine clean again as well, no luck that easy. did notice a few more things though. when i put it in drive it gets alot less noticable, drive or reverse, and "load" i guess. I got down there again while in park and listened with the stethescope, and still sounds loudest on the touque converter cover, and even the tranny, but since all that was disconnected, it dont make since. I spose it could be a noise coming from the crank transferring through to the tranny. I am trying to see if there is anything else to try before i go pulling off the oil pan and checking bearings. thanks for any thoughts.
Something else to maybe try before going under it, take the belt off the engine and start it up and see if the noise changes. If it is a bearing though, about the only good thing I can say is you can actually pull the pan off with the motor in, I was surprised by that, definitely can't do that on my other cars. Mine ended up being #5 I think. I tried to put in a new bearing, maybe slightly oversized, it worked for about 5 minutes, then the knock came back. Good luck.
What kind of car are you working on.
This is an 87 Grand national. It was sitting for 3 years before i got to buy it. WHen i got it i replaced the coil pack that was bad and that was bout it to get it running, then soon as it started i noticed this knock. underside of the engine, can really hear it on the converter cover. i have disconnected the converter and same thing. all bolts are tight on that part too. i would just like something to verify that it is a bearing before i pull that oil pan off again. thanks
If I am not mistaken a rod knock would make noise under a load, but a wrist pin would be more on deceleration. Sounds like it could also be a timing chain maybe? I have also read on this site that a cracked exhaust manifold can make a similar sound. I personally had a knock in my 79 but turned out to be the mechanical fuel pump but I know you don’t have that. That is one of those thing you almost have to hear to help.This may not help much but maybe it will give you something more to look at.
Have you checked for a cracked flywheel?
no i have not looked that in depth at the flywheel, is that a common occurrence.
I say pull the pan and have a look..it's not that hard to do with the motor in the car, and you'll save obtaining more potential damge while running the car and guessing what it is. If it's back by the convertor..concentrate back there - including bearings and rods. Make sure you have good oil pressure at idle, and the oil level is right, too. Throw in some motor honey and see if that helps..it may tell you if it's engine related. If it quiets down, you got bad news on your hands, and flushing the motor honey is the least of your probs. :\ If not - concentrate on crank to flywheel/convertor area again. As posted before - its just a guessing game if we can't hear what you're hearing. A .wav or .mp3 of the noise would be sweet.
