Rattling sound from 3k -3.5k rpm. Any ideas?

[A_A_G]

My 1998 Montero Sport with the 3.0 v6 145k miles is making a fairly loud metallic tapping/rattling noise. It is especially bad between 3-3.5k rpm. Below or above that and its much more quiet.

I did the timing belt and water pump a couple of months ago. I also did an oil change about 2 weeks ago. Could an oil filter cause this?

 

[Falken]

Maybe you are off by 1 tooth on the timing belt change?

Maybe hook it up to a scanner at Autozone?

Is the check engine light on?

Have someone rev the engine to 3.5k rpm, and listen carefully with the hood up. Put a deposit on a mechanics stethoscope and scope for noises.

I doubt it is your oil filter.

 

[suspiciousmind]

I'd suspect a heat shield rattle....exhaust manifold or cat maybe?

 

[dishdude]

Are you sure it's not detonation?

I also second the loose heat shield or broken up cat.

 

[sasha]

Originally Posted By: Falken
Maybe you are off by 1 tooth on the timing belt change?

Maybe hook it up to a scanner at Autozone?

Is the check engine light on?

Have someone rev the engine to 3.5k rpm, and listen carefully with the hood up. Put a deposit on a mechanics stethoscope and scope for noises.

I doubt it is your oil filter.


with the timing off the CEL would have triggered for cyl1,3,5, or 2,4,6 missfire. plus the valves would have been bent.

 

[SteveSRT8]

Originally Posted By: A_A_G
My 1998 Montero Sport with the 3.0 v6 145k miles is making a fairly loud metallic tapping/rattling noise. It is especially bad between 3-3.5k rpm. Below or above that and its much more quiet.

I did the timing belt and water pump a couple of months ago. I also did an oil change about 2 weeks ago. Could an oil filter cause this?


I would be most suspicious of the parts recently replaced.

Also: Belt Tensioner, idler, alternator, AC compressor, it can be a LOT of things.

And note that one tooth off on the timing won't cause a misfire in most cars.

 

[A_A_G]

The truck runs fine, just like before I did the work on it. I tried pinpointing the noise and it seems to be coming from the top of the engine bay.

 

[A_A_G]

Originally Posted By: dishdude
Are you sure it's not detonation?

I also second the loose heat shield or broken up cat.


I use to have a ranger that pinged like [censored] but I dont think this sound is similar. I added 89 octane and mmo to see if it is detonation.

 

[MrQuackers]

Yep, maybe serpentine belt tensioner.

 

[Falken]

The belt tensioner would make noise at idle too.

I am guessing that as the PCM adjusts to ADVANCE timing around 3500 RPM, if he is a tooth off in ADVANCE maybe it would cause the knocking / tapping.

Everything else would be easy to diagnose with a person holding the engine at 3-4k RPM and listening with the hood up.

If nothing else is apparent I'd just double check that the timing is ok.

You don't get valve clash or bent valves from hitting the piston by only being off 1 tooth.

I am ONLY guessing BTW, the car isn't in front of me.

Just, it is odd right after you changed your timing belt.