Gosh darn dang rattle from 2500 to 3000 RPMs

[ecgreen]

OK, I have a rattle in my 2.9 only from 2500 to 3000 RPMs. The rattle does not get faster with acceleration as far as I can tell. Also, if I use a heavy throttle, I don't hear the rattle. Compression is good, all new fuel system, new vacuum lines, fresh gaskets all around. I am inclined to think its not an engine sound, but I dunno at this point. BUt then again I have checked heat shields and muffler systems and nothing seems loose.

Anyone ever have an RPM specific rattle?

 

[RonD]

Does it do in a driveway test or only when moving, i.e. wind or road speed rattle?

 

[rusty ol ranger]

Im inclined to say its lifter noise

 

[ecgreen]

Im inclined to say its lifter noise

You could be right, the valve train is a little noisy as well. Two questions:

1. Could this cause damage if left unfixed? I have had this engine apart so many times, the thought of doing it again...ugh
2. Anyway to test if its lifters?

Sean

 

[Uncle Gump]

What Ron D said... will it rattle free rev or does it have to be underload?

 

[ecgreen]

What Ron D said... will it rattle free rev or does it have to be underload?

Free rev rattle as well as under load. But like I said, rattle is not bad or absent when I floor it.

Thanks so much for the help BTW guys. I have no idea what I'd do without this forum.

 

[Uncle Gump]

Take the fan belt off on a cold engine... see if the noise is still there. Don't run it to long... the water pump won't be turning. If it doesn't rattle... look to the belt driven accessories.

 

[ecgreen]

Take the fan belt off on a cold engine... see if the noise is still there. Don't run it to long... the water pump won't be turning. If it doesn't rattle... look to the belt driven accessories.

Solid direction...I can do that.

 

[Nez'sRanger]

I got that rattle too... Drives me nuts! But I've accepted it at this point. I've tried rocker arm lash adjusting, new oil pump, roller rockers, all new fuel system (except for the actual tank and lines), new everything.
At this point (which is a guessing game, really), I'm guessing something in the bottom end is fouled up, and I won't mess with it until I rebuild my spare engine.

 

[ecgreen]

I got that rattle too... Drives me nuts! But I've accepted it at this point. I've tried rocker arm lash adjusting, new oil pump, roller rockers, all new fuel system (except for the actual tank and lines), new everything.
At this point (which is a guessing game, really), I'm guessing something in the bottom end is fouled up, and I won't mess with it until I rebuild my spare engine.

I suppose it could be pistons slapping at certain RPMs. Anyhow I have a back up block in the barn. I should start the process...

 

[rusty ol ranger]

I suppose it could be pistons slapping at certain RPMs. Anyhow I have a back up block in the barn. I should start the process...

Next oil change replace a qt of oil with a qt of lucas and see if it gets quieter or stops. Then youll know if its internal engine.

In my 20ish years on TRS i only remember a very small few 2.9s dying from bottom end issues, unless it had coolant in the oil from a cracked head.

2.9s are pretty stout. Ill about bet its beginning of lifter noise.

 

[bcschief]

This sounds more like a pinging issue> Consider checking the ignition timing with the spout connector unplugged. The timing spec should be under your hood or on the core support on the emission's label.

 

[rusty ol ranger]

timing spec is 10* BTDC

 

[Uncle Gump]

I thought it might have been a spark knock issue myself when I first read this... but after saying it will rattle on a free rev too... I didn't think it was on top of the list as a cause.

 

[ecgreen]

I will update on this, but I am a few jobs away from getting to tackling this one.