292 sounds like a diesel

[DoubleL]

Hello all! I was wondering if some of you might have some insight. My 292 is "rattling" pretty bad. It is worse under load and very light idling. My timing is dead on. It increases a little when I push the throttle but a lot when I throttle it and it is actually under load. I was wondering if you guys hsd some ideas?

[old cruiser]

Is it valve clearance rattle? , 292 prone to go out of adjustment I've replaced many adjusting nuts over the years on 292s , they loose there ability to stay tight.
Just a thought

[jtrichard]

how many miles on it? what is the oil pressure like at idle? if its not valve train then I would say it rods and/or mains another thing could be is torque converter bolts or flywheel bolts are lose ... I bought a 396 once that the yard said it had a rod/main problem(knock) and would have to be rebuilt all that was wrong was the torque converter was falling off

[DoubleL]

Originally Posted by old cruiser

Is it valve clearance rattle? , 292 prone to go out of adjustment I've replaced many adjusting nuts over the years on 292s , they loose there ability to stay tight.
Just a thought

I think I'll start by adjusting the valves. Just got ot figure the best way to do it.

Originally Posted by jtrichard

how many miles on it? what is the oil pressure like at idle? if its not valve train then I would say it rods and/or mains another thing could be is torque converter bolts or flywheel bolts are lose ... I bought a 396 once that the yard said it had a rod/main problem(knock) and would have to be rebuilt all that was wrong was the torque converter was falling off

No oil pressure gauge but I have one I can hook up and see.

[factorystock]

Could the noise be coming from the exhaust manifold? Its not uncommon for these long straight 6's to develop exhaust manifold leaks. Try a new gasket and check to see manifold is not warped.

[lmdangerous]

A 292 with a lot of miles is known to have wrist pin rattle- look at the pistons they are huge - very heavy. What is your oil pressure?? Also as stated check the flywheel bolts, and the harmonic balancer will rattle also if its loose or coming apart.
If its rods or wrist pins - while idling - pull a plug wire at a time - and the knock /rattle will get louder- if not - look at the other spots.

[Wrenchbender Ret]

Most of the 292 engines have forged pistons for heavy duty. They are fitted a little loose when new because they expand more then the cast pistons. When they get worn or scuffed they rattle a lot. Like Im says the wrist pins can knock also. It is a sound like a diesel makes. They will run for years like that but it is annoying.

[C10 - C90 Bill]

Boy did this topic get my attention. Back in the 80's my '64 292 started making funny noises and after a while it sounded just like a Diesel. I checked just about everything and just could not determined what it was. Till a Chevrolet mechanic friend of mine discovered it. It was a bad Timing Gear. The Key-way waddled out and was probably 2 or 3 times wider than it should have been and was rocking back and forth.

Turns out, whoever re-built the engine did not install the Gear properly. We could tell that he hammered it on instead of pressing it on.

Not saying that this is exactly your problem, but it is worth checking into.

Bill

[Irishbleueyes]

Wrist pins will knock under load, not usually at idle. Loose rod will knock mostly on immediate decel. Could be valve train but as loud as a diesel? Timing gear would show huge fluctuation on timing light if it was loose. My guess, wrist pins are bangin...

[C10 - C90 Bill]

Originally Posted by Irishbleueyes

Timing gear would show huge fluctuation on timing light if it was loose.

Best I can remember is the Timing looked normal or pretty much normal at idle, but once I revved it up some, it would jump around erratically. That info is what might have lead my mechanic friend to locate the problem at the Timing Gear. This was actually my first engine with Timing Gears. All my others had Chains.

Bill

[Irishbleueyes]

Originally Posted by C10 - C90 Bill

Best I can remember is the Timing looked normal or pretty much normal at idle, but once I revved it up some, it would jump around erratically. That info is what might have lead my mechanic friend to locate the problem at the Timing Gear. This was actually my first engine with Timing Gears. All my others had Chains.

Bill

6 cyl are bad ass.. I hate timing lights, they can fluctuate from different type plug wires even, can't live with em - can't live without em...