Backstory. So since i got my M3 its had this annoying noise at about 1800rpm when accelerating under load. It only happened when the oil temp was over 90c, and only when under load. It wasn’t vanos, because it persisted after i rebuilt that. The car also made a similar noise occasionally on cold start.
After some further reading i read some reports of the original 3.0 timing chain tensioner being rubbish and losing tension. The other week i had a good look at my tensioner. I noted that it looked a lot like the original tensioner, and it was weeping oil.
A common upgrade is to use the timing chain tensioner of the new 3.2 Evo engine, which is a completely new design and more reliable.
This is the old one,
The tensioner is pretty easy to replace really. I read heaps of write ups, but i was still a bit nervous as it’s a REALLY crucial part.
You need to move the washer bottle (disconnect the two electrical connections), and remove the RH wing from the radiator shroud (little push pin at the top). In my case i also needed to remove the exhaust cam sensor to reduce any risk of me damaging it.
A 32mm spanner will be required to remove the tensioner. With the space created the spanner will just fit.
My tensioner leaked a bit of oil when removed, but otherwise removing it was straight forward.
It was pretty obvious when removed that the old tensioner was original, and it’s clearly very worn.
Old vs New
Clear signs of heavy wear on the piston. This is the same on both sides.
The contact point wasnt too bad considering.
I put a little fresh oil on the contact point of the new tensioner and gently installed into the hole. I aligned the contact point and wound the tensioner backwards a few times before winding it in by hand. It wound in by hand till a couple of turns, and a quick spin of the spanner had it seated and sealed correctly.
Started up, silent. So far so good. Decided to take it for a spin and almost immediately noticed the throttle response was smoother and quicker when backing out of the driveway. During the drive, after i got it up to temp the car felt good. The engine is quieter, and its probably a placebo, but feels like it pulls stronger, especially down low.
Once the oil temp was up, at around 90-95c i decided to give it the worst combination of conditions i could think of, where previously it would have rattled its nuts off. Heavy load, low RPM. Silent. Not even a peep.
Great success. For anyone still running an original tensioner, get rid of it.
The PN for the tensioner and gasket i used were, 11311405081 and 07119963418