D90: possible trans brake rattle

[dsreiter]

My D90 is rattling (similar to valve chatter, but louder), sounds like it's coming from the transmission brake, but the sound disappears over 2,800 RPMs. Could the brake be binding?

 

[joey]

Does it rattle just when moving? If so, I would put it on a lift and check it.

Not sure about the brake binding, but it is possible.

 

[dsreiter]

It only rattles when moving and only under about 2,800 RPMs. At first I thought it was valve noise from the engine over-labouring, but it is definitely coming from the transmission brake/drive shaft area.

 

[joey]

Okay is it load based as well? i.e. does it sound worse going up hill? Is it speed based, or just RPM?

 

[dsreiter]

It seems to only be RPM-based, totally disappears over 2,800 RPMs regardless of gear, speed or load.

I think my oil cooler line blew last night. Smoke started pouring out, I pulled over right away, there was oil everywhere, almost nothing left in the sump. At least the engine didn't seize.

 

[joey]

If it is completely RPM based, it is an engine thing. Maybe a loose bolt on the flywheel.

 

[dsreiter]

I was playing around with that rattle on some hills and as it turns out, it does get worse under load, but then disappears after 2,800 RPMs. It sounds the worst up to 2,500 RPMs going uphill, under load.

It sounds a bit like the noise that my Series III made with a bad universal joint between trans brake and drive shaft. What do you think?

 

[joey]

If it is a U-joint, I would change it before it comes apart. Since they are cheap I would start there.