Need help with some troubleshooting...

[Na5.0HO]

Ok, the stang has been "running" great... but does it while making a funny sound which concerns me.

Stock 302 block with Performer 5.0 Intake, 1.6 SVO R.R., underdrive pulleys and AC / Smog deletes.

It's a chattering sound, which sounds like a marble rolling around inside my block, but it only does it when the car is hot.

Can't pinpoint the sound, however, sounds like it's definately coming from the engine, but is not the exhaust (I've had plenty of exhaust leaks in the past and this is NOT air.

The rockers are all tight and I turned the crank by hand to listen to the rest of the valvetrain and nothing was clicking.

No excessive oil loss/burning and spark plugs all came out ok, so I'm ruling out piston rings. Figure this includes pistons and rods.

If people can suggest other things that could be causing this to help me troubleshoot I will be greatly appreciative. This is keeping me from driving it out of fear of unknown.

Thanx in advance and let em' rip...
Jason

 

[Na5.0HO]

Anyone have any clues??

 

[FiveO]

get one of those things doctors use when they listen to your heart and lungs...forget what those dang things are called...stethescope?... but we used them in autoshop to listen to the engine.

 

[Na5.0HO]

Thanx for the advice... I tried that technique using a 12'' socket extension which didn't help, but I bet a stethescope would help better.

 

[FiveO]

i would check your rockers and pushrods...i had a buddy that hard a similar sound cause he had some problems with his rockers and pushrods.

 

[Na5.0HO]

Thanx, they all seemed tight, but I'll have to roll my pushrods to make sure they're all straight...

 

[jrichker]

If you hear the noise only when the engine is above idle & under load, then you have preignition. Turn down the spark advance a few degrees and see if it lightens up or quits.

 

[Na5.0HO]

If you hear the noise only when the engine is above idle & under load, then you have preignition. Turn down the spark advance a few degrees and see if it lightens up or quits.

Thanx for the input... I'm going to check that out tonight and hope it fixes it.

 

[Na5.0HO]

The problem continues after turning the timing down to 10* (orig 14*) and the sound can be heard when the car is in neutral (under no load) So, I am thinking the timing and ignition is not the problem.

I appreciate the help so far, but does anyone else have any ideas...

 

[Michael Yount]

If it's a manual tranny and you can hear it in neutral at idle, perhaps throwout bearing? Based on the marbles in a can description, my guess would've been detonation too - but not in neutral at idle.

 

[Na5.0HO]

If it's a manual tranny and you can hear it in neutral at idle, perhaps throwout bearing? Based on the marbles in a can description, my guess would've been detonation too - but not in neutral at idle.

You can hear it while in gear or in neutral (clutch in or clutch out) as long as the engine is above the 1,300 rpm area (possibly where it's just loudest). And the throwout bearing has been squeaking for a while, yet, the clutch grabs strong. If this helps, I have also noticed that the sound speeds up with the engine (goes faster when I rev it fast or slow)

Thanx... still baffled ... anyone else??

 

[FiveO]

You can hear it while in gear or in neutral (clutch in or clutch out) as long as the engine is above the 1,300 rpm area (possibly where it's just loudest). And the throwout bearing has been squeaking for a while, yet, the clutch grabs strong. If this helps, I have also noticed that the sound speeds up with the engine (goes faster when I rev it fast or slow)

Thanx... still baffled ... anyone else??

it speeds up with the engine.... that should tell you a lot right there. i know i said this but i still think it could be pushrods or rockers.