Need Help Identifying Sound in Motor

[DSM_23]

Hey, ok Ive been trying to figure out this sound on my car for about 3 1/2 years, alot of times I've blown it off but sometimes it really bothers me that I dont really know what it is. It sounds very close to the car in the clip in the link. I figured that if it was a rod it would be getting worse over time or would have blown by now since its been nearly 4 years since it started this noise. I used to think it was a balance shaft bearing, but they were taken out. Im completely stumped on what it is, I was thinking it was a timing belt tensioner but everything was changed out down there while the motor was out. Any ideas people so I can solve this mystery???

justin

Link to clip with car with similar sound..

http://video.yahoo.com/video/play?p...od+knock&toggle=1&cop=&ei=UTF-8&vback=Results

 

[andymoraitis]

Justin,

This is a long thread so I didn't re-read it, but have you checked for a cracked or separating crank pulley. I know you looked at everything when you checked the timing assembly, but it might not be a bad a back idea to check again just in case you overlooked it.

Hang in there and let us know what you find,

A.

 

[DSM_23]

yes i have checked the crank pully it is perfectly fine. What else could it possibly be?

 

[DSM_23]

someone has to have more suggestions to what it could be

 

[DSM_23]

Ok I finally made a video of MY car making the sound, it sounds worse on video I dont know if the speaker is more sensative or what. But it almost is making a rattling sound while blimping the throttle around 2.5-3k. I hope this helps someone.

http://media.putfile.com/Talon-Motor-Sound

justin.

 

[92awddsm]

Do you still have the support bracket that goes from the back of the im to the block? I had one come loose and made a similar noise.

Also, were the pistons replaced when the engine was rebuilt? If not, have any of them hit valves before? If so, it is possible that when it hit a valve, it could have been enough force to collapse a piston skirt. It wouldnt be visible damage, but it could be found if all the pistons were miced when they were out. That would also cause a similar sound.

 

[DSM_23]

The support bracket im not sure about but the noise is coming from the crank pulley ish area it sounds like. So I dont think it would be that but I'll check in case. The pistons were not replaced because they were in great shape and had 164-160 psi compression. Also, the valves have not hit the pistons. Im to the point where Im so annoyed by this sound I dont even want to drive it. Its tripping my knock sensor off I, so I dont have anywhere near the power I should and its really starting to make me parnoid that something is going to blow up even if its done it for so long.

 

[fallenauthority]

This has got me way stumped. The sound is no where near as severe as a rod knock, and with it going on for so long I highly doubt rod knock anyway without you having a new window in your block. Sounds like it may be piston slap though, either way it definitely sounds like an internal problem. Sorry to say but I think the only way to figure it out is to remove the motor and drop a new one in, and tear down the old one.

 

[DSM_23]

Yea it has me just as stumped. But with piston slap it appears as if compression is very low in that cylinder right? Plus how is it possible to get it on the stock pistons/bore?

 

[dsmboy51]

well, i thought i was the only one with that same noise... i find that if it does it just turn the car off and start her back up and it stops....... But they are dsm's and they all have attitudes

oh and i have a freshly rebuilt motor

 

[DSM_23]

This noise doesnt dissapear after restart.

 

[DSM_23]

While driving today I was testing out to see if it was strickly rpm dependent or throttle dependent. I can bring the rpms up and never here the sound or if I just barely use any throttle it makes it noticably, same goes for while driving. If Im just barley hitting the throttle I can hear it but anymore than that and it dissapears. At idle the motor is dead silent and sounds great you just hear the lope of the cams. If im in first gear and start very slowly accelerating I can hear it the best it almost sounds like something is rattling in the motor. What else can I check for/test that I may be forgetting? Thanks

justin

 

[rockNro11]

It sounds like a wrist pin noise. If you can't get the plug boots off then unplug all your injectors and take the retainers off soz you can plug/unplug the injectors quickly and easily. Start the engine and unplug the injectors one atta time. If disabling one makes the noise almost disappear then its probably a wrist pin problem.

 

[DSM_23]

Well I just went out and did the spark plug pull test and..................it still makes the exact same sound while blimpin the throttle well maybe thats a good sign , Not sure. Keep the suggestions coming, thanks

justin

 

[DSM_23]

Well........yesterday we dropped the pan and well............I'll upload pics of the bearings soon, but cylinder 1's rod bearing was pretty f-ed up . The others showed some dark marks but nothing to outrageous, Im curious if the crank made it or not, I dont believe the bearing spun out, the bearing guide looks as if it was fatigue/load wear, as in it was basically begining to flake up and was cracked, upon taking the rod cap off the bearing just fell out and broke in 4 peices . I have absolutly NO idea how It was so smooth/quiet and it lasted 4 years Any ideas ? Also im not looking to go crazy so im pretty sure it would be wise to get new pistons/rings, bearings, and do you think I'll be able to recondition the rods? Also I may need a crank if someone has one.

justin

 

[DSM_23]

here are a couple pics, tell me what you think

 

[andymoraitis]

I'd recommend pulling the crank, having it micropolished, and also checking the rods to make sure nothing's out of round. Might as well re-ring it while it's apart. You could rebuild to stock specs if you really don't want to make big power. What surprises me is that it went for 4 years like that. When mine spun number one, it sounded awful right away and would have punted through the block pretty quickly if I kept driving it.

 

[DSM_23]

Do you think the crank could be ok since it didnt actually eat the entire bearing completly up? And wouldnt it be wise to just buy new rods/pistons as well? I wouldnt think that its ok to reuse rods/pistons and how they fatigue over time, im only looking to make around 400whp eventually so I think I probably wont get anything to extreme. So what does it look like the cause of that bearing failure was to you?

justin