I can't figure this one out. Its a fast tinny knocking sound, it doesn't do it in park or neutral at any RPM. It only happends under load, and only under light load. If I floor it, it usually makes the noise for a sec then stops. If I am going a constant speed regardless of RPM's it doesn't make it. Only if I'm going a constant speed and touch the gas a bit to accelerate it knocks/rattles like crazy, but stops if I ease up and level the rpms. It usually does it above 3000 rpm's. It also makes this sound after I lift from accelerating hard. It seems to be worse when its cold, but it still does it warm just not as loud. I figure it can't be in the engine since it doesn't do it in park or neutral, and something like a rod or a wrist pin would knock continuosly and follow RPMs I would imagine. Any ideas? It's not detonation, its way to loud for that and I've tried many timing settings with no change in the noise. I'm thinking cracked flexplate or a crapped out torque converter. The motor has 4000 miles on it, and makes good oil pressure. Its been doing this for a while, it started out only doing it when I lifted after accelerating hard, now it does it under the above circumstances. The torque converter bolts are tight, and I've looked everywhere for anything that could vibrate. My passenger side header is only an 1/8" from the frame, maybe thats causing it, no idea.

 

Hmm. I'm curious too. My Ford does this. I was told it may be play in the drivetrain/u-joints taking up slack, ie transition from the engine pulling the drivetrain, to the rear wheels pushing the drivetrain. It seems to do it when accelerating slightly, and is very noticeable when lifting quickly.

 

Actually, I noticed today it does it in neutral/park as well. When I blip the throttle when the engines still cool, it will breifly rattle up around 2800-3200 RPM's. But it sounds like more of a vibrating knock, I'm stumped. This friggen sound is bugging me. I just hope its nothing like a wrist pin or anything.

 

Could it be an exhaust leak....like maybe around of headers gasket?????

Just a simple thought.....

Valves adjusted???

tony

:confused:

 

I was going to say detonation all the way, until you said you ruled that out. Can't be ujoints, because they wouldn't typically make noise under load. They like to make noise when you take off, apply the brakes, or let off the gas. Not under load.

Since I'm not an auto guy, can't comment on the bad converter. Could there be something interfering with your flexplate? Starter, inspection shield, etc.?

Let us know.

 

i had a similar problem in a bmw...turns out it was a bad convertor

 

I am leaning towards a bad converter, when I put the motor and tranny together I stupidly didn't have the converter seated all the way (it's tough to tell). When we torqued everything down it seemed tight but I just figured the locator pins were a little snug, until I heard a crack and realized the flexplate was bent towards the engine block. I removed the trans, checked the flexplate, and inspected the case and pump before reassembling. I'm thinking something must have broken at this point. Since it doesn't do it all through all RPMS I'm pretty sure its not in the motor, even though it latley started doing it in neutral/park as well. I have no idea, I'm probably going to tear the motor apart over the winter for inspection and more mods, I just hate thinking theres a problem with this essentially new motor. I intend on buying a high stall converter so if the converters bad then no problem. I checked for exhaust leaks and found nothing substantial, I went over the motor with a long prybar held to my ear and the only noises I hear are a slight ticking out of both valve covers (probably from guideplates) and the mechanical fuel pump makes noise (which is going to be changed out for an electric pump when I swap the TPI on). Now this is only at idle that I listened, and the noise in question only occurs at 2800 rpm or above, but I would imagine that internal engine problems would be audible at idle as well. No idea, I can't figure it out. :cry