Need assistanced diagnosing engine noise
Yep, Im asking for opinions. Im pretty sure I know what the problem is, but I figured I'd do a little desktop diagnosis for conversation.
The problem: Engine noise (sounds like little monkeys with a hammers beating on the top end) that comes and goes based on rpm, load, and engine temp. Sounds to me like a wrist pin problem or piston slap. The Cobra engine is supercharged, its a 96. Mileage is 64k. Its not bottom end noise, and is coming from the back passenger side cylinder. Before I got there and looked at it I was hoping for a broken rocker arm or something in the head. I really can't see a top end head noise varying with load. Any takers? I would just tear it down but I'm not gonna be able to work on it for at least a few weeks, I have two other engine jobs ahead of it in my garage. |
RE: Need assistanced diagnosing engine noise
its definitally monekys you better get in there and get that f**ker. lol. nah i couldnt tell yah what its is. hope its not abig deal. your wife was braggin about killin your GT in that thing lol. dont make it to fast. good luck
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RE: Need assistanced diagnosing engine noise
Windsor plant motors equipped in many of Ford's Trucks/SUV's & Mustangs experienced nasty piston slap at start-up and would eventually go away when engine temperatures came up. Very few people experienced anymore slap after warm-up. I'm pretty sure those older Cobra motors were hand built by SVT..
Piston slap usually sound erratic (spelling) It isn't always creating noise in a rhythm, sounds like it's just kinda floating around in there hitting whatever the hell it wants. BUT, before the motor died in my 88 Iroc-z, I had some nasty piston slap occuring, if I eased into the throttle and eventually went WOT I heard nothing. If I downshifted and put it to the floor, it sounded like she was ready to violate my oil pan. I also had a nasty case of piston slap in my 02 GT that required a replacement short block... ****ty luck eh? The idea of a wrist pin getting ready to let go is scary. It can make a mess of that block real quick, although when we had a failure in our small block modified, it sounded like it was a top end problem, until we stuck a steth to the block and oil pan. If it's not causing any driveability problems or lack of power, I'm gonna say you hit this one right on the head!!! |
RE: Need assistanced diagnosing engine noise
Correct, there is no drivability problems or power loss - other than from running rich and retarted since it has a blower tune and the blower is in the trunk, courtesy of the former owner who thought the problem was a knocking blower unit. I'm planning on removing the valve cover on that side when I get a chance, and if I find nothing there then out comes the engine.
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RE: Need assistanced diagnosing engine noise
Md, im only 19 and you can take this advise if you' like. But i wanna whack the donkey with a stick too. :D I'd take a stethoscope and put it to youre head. Valves more so. Ford put out a TSB on this issue i can email you the info if you'd like. Its a TSB on all 32 valve DOHC motors to date. Its especially noisy at idle. And it comes from the passengers side rear of the head. Just my 2 cents. I hope it helped.
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