850 tdi engine rattle

[john123456]

Has anyone ever known a d5252t to rattle from 1500rpm to 2000rpm? Under slight load or full load she rattles but backing off the throttle eliminates the rattle.

It doesn't do it any higher then 2000rpm and I have changed every pulley and belt and also the dual mass flywheel and clutch.

I think it sounds like a tensioner or belt slack but I cant remember if it was the same before I changed the belts

[john123456]

Could it be the vacuum pump? I don't get any noise at idle and when I pump the brakes there is minimal difference in engine tone. I've just read so much about people changing them.

[Juular]

The vacuum pump does produce a toe curling rattle when it's on its way out. You could always disconnect it to rule it out.

[john123456]

I managed to change the vacuum pump a couple of days ago. The brakes are much better but the rattle is exactly the same lol.

Also changed the turbo as that was on its way out.

Worn out catalytic converter maybe rattling? Before I start opening up the engine

[Luxobarge]

Originally Posted by john123456

Worn out catalytic converter maybe rattling? Before I start opening up the engine

I'm not familiar with the diesel models, but I thought they didn't have a cat?

[brickman]

Does have a cat, should be fairly easy to lower it down from turbo and look inside, can see the insides and check.

Simple thing, engine cover? or the bolts that hold it down? Mine has a alloy piece that's riveted on the back of the cover, thing rattles every few years, drill out rivets and put new ones on. Rattle is small but annoying. Check for bolts, diesels rattle everything loose eventually.
These ones go quite heavy on their engine mounts, and even worn it sags down at gearbox end touching the sub frame making a sound and vibration strong enough to make you think bottom end has gone lol*


*bottom end on these are strong unless you go really big on nozzles and turbo