Guess that engine noise! (video)

S

stephenspann27

NAXJA Forum User
Location
College Station, Tx
http://www.youtube.com/watch?v=dCZAuFcKbmo

I know it isn't likely many of you will be able to give me any answers from this short video. The noise actually gets quite a bit louder if I get the engine hot enough. I plan to buy a stethoscope tomorrow and try to narrow it down. It seems to be coming from front of the engine. When I had the pan off to replace the rod bearings (thought they were the source of the noise) I checked the timing chain tension. It had probably 1/2 slack in it..which is service limit. I read somewhere that the timing chain can slap the cover and make this kind of noise. Also... heard about the torque converter bolts getting loose.. but this noise seems to be at the front of the engine.
 
I thought about that.. but usually piston slap is worse when an engine is cold.. then once the piston heats up and expands the slap goes away. The temp thing also puts a hole in the timing chain theory.. I might pull the belt tomorrow just to rule out he accessories.
 
yeah its hard to hear anything obvious from that video. exhaust leak maybe? noisy valvetrain? could be the idler pulley as well.
 
stephenspann27 said:
http://www.youtube.com/watch?v=dCZAuFcKbmo

I know it isn't likely many of you will be able to give me any answers from this short video. The noise actually gets quite a bit louder if I get the engine hot enough. I plan to buy a stethoscope tomorrow and try to narrow it down. It seems to be coming from front of the engine. When I had the pan off to replace the rod bearings (thought they were the source of the noise) I checked the timing chain tension. It had probably 1/2 slack in it..which is service limit. I read somewhere that the timing chain can slap the cover and make this kind of noise. Also... heard about the torque converter bolts getting loose.. but this noise seems to be at the front of the engine.
Click to expand...

Sounds exactly like what I had, and did two years ago. Did rod bearing and a new oil pump to see if I could keep her going until I had time to build up another motor, still had the same noise. Well, fast forward to now, the rebuild has been in for a year and a half, and I just got around to pulling apart the old motor. The first thing I found was the timing chain dampener was hard as a rock and had deep grooves worn into it. Easy to think the noise was just the chain slopping around, and made me think I wasted a lot of time and money on a rebuild...

Nope! Got a little deeper into it and found the two front main bearings had spun so bad the block is wasted now! The thing is, oil pressure was not that bad, even before the pump was changed. I know I could have/should have checked the mains while I was in there back then, but with the wear this thing had, I would still have had to build another motor either way. As far as the stethescope, it was still difficult to pinpoint the noise with one because the sound was resonating throughout the entire block. Sorry if your motor is going the same way as mine, but it is something to think about. Good luck, keep us updated!
 
stephenspann27 said:
Hopefully mine is just the timing set. I wish I had taken all my main caps off and looked at the bearings. I took the rear most one off to replace the RMS, and the bearing looked great.
Click to expand...

You know what, you just reminded me, I also did the rear mail seal while I was in there, and that bearing looked fine. That's probably why I didn't check the rest of them back then...
 
Last edited:
Check your torque convertor to flywheel bolts.. They are loose....

Good Luck

Nick
 
So I finally got around to taking the belt off today.. and it purred like a kitten.. ran out of time.. tonight.. but tomorrow I'll put the belt back on and try to narrow down which accessory it is.. if that is in fact the issue. So far the A/C compressor, and Alternator are very suspect. The shaft on the water pump seems to be bent, it's a new pump, old pulley, put on by the previous owner.. but I don't know if a water pump could be making that much noise..
 
I'm now 99% sure it is a belt driver accessory. I got the motor warm, and making the noise fairly loud, took the belt off and it was totally gone. I"m not ruling out the dampener though, the rubber looks pretty bad in it.. and I think it may be hitting the timing cover when the belt is on it.
 
Finally located the culprit. I've been narrowing down the accessories. I have convinced myself it is the alternator because I put a hammer handle on the alternator with the motor running and the vibrations coming through the handle were perfectly in sync with the noise. I got no vibration on any of the other accessories.
 
You mentioned a stethoscope earlier, but a trick we use in the mechanics world is a very long screw driver (about 3 feet) with plastic handle. Put the screwdriver end on wherever you think the noise is, and you ear on the handle end. You should be able to pin point it that way.

~James
 
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