Grinding and squeaking from timing belt area

Post Sun Dec 29, 2013 10:52 am

Hi Zoners,

My 325i Sport has developed a subtle grinding noise from the front of the engine which has now been joined by a slight chirping.

It only happens when hot and there is no untoward play on the fan/water pump pulley. The fan viscous coupling is relatively new. After rebuilding the front end and doing an engine swap in the last 18 months I can't actually remember how new the pump and timing belt tensioner are!

Having checked with a stethoscope, I am happy that it is not the alternator. I have no PAS.

My real problem is that I am due to thrash the car round Bruntingthorpe all day tomorrow!

Most likely culprit to my ears is the tensioner pulley. There is nothing to suggest that the belt is rubbing against the cover. I am trying to decide how long till the pulley fails.

Any ideas?

Post Sun Dec 29, 2013 11:03 am

I wouldn't be driving it anywhere, until its been diagnosed, you can't muck about where Timing Belts/Tensioners involved.

Post Sun Dec 29, 2013 11:06 am

I'd take the front timing cover off and check the tension and belt condition before even starting it again.

Post Sun Dec 29, 2013 11:17 am

Thats a good start, check the water pump bearings as well.

Post Sun Dec 29, 2013 7:51 pm

There is a large irregularly shaped rubber plug that fills a cap between the rear of the belt cover and the block that is positioned behind the diagnostic socket. If you remove this plug, you can at least get a finger inside and get some idea of the state of the belt. If there appears to be loads of rubber dust around, then the spindle of the tensioner bearing has come loose, which pushes the belt against the front cover. The edge of the belt gets worn away, until it's less than half its original width, at which point it's likely to break.
Part #6 is the rubber plug: http://2009.bmwfans.info/parts/catalog/ ... pper_part/

Post Sun Dec 29, 2013 9:22 pm

Thanks for the comments.

Actually, with regard to the rubber plug, by shining a torch downwards past the thermostat I can see the tensioner and belt through a gap and that there does NOT appear to be fragmented belt around.

For lack of time in daylight hours today and various other reasons, I shall be taking the car as is. I take the risk as an informed adult and hold no-one responsible but myself.

Might be asking how to get a valve out of a piston this time tomorrow!

Post Mon Dec 30, 2013 10:44 pm

100 miles there, perhaps 50 full on laps, 100 miles back.

The car took everything I threw at it and the grinding noise is now slightly louder - front end strip down tomorrow!

Amusing to drive the car back to back with an E92 M3 with the ridiculously clever DCT box - guess which I preferred?

Post Mon Dec 30, 2013 10:51 pm

You were brave! And potentially lucky!

Post Sun Jan 26, 2014 11:59 am

Only just got round to the front end strip down. Annoyingly I have not found anything obviously wrong!

Water pump has very slight play, but turns without undue noise.

Intermediate shaft is perfect.

Nothing visibly wrong with the distributor cap.

Crank turns without noise.

Alternator pulley has very slight play but again turns smoothly (anyway, noise was definitely not from there).

Tensioner pulley has some play but nothing that I would describe as untoward and again, turns smoothly enough.

Belt looks new.

New tensioner, water pump and belt?

Eurocarparts or Dealer?

Opinions greatly appreciated.

Post Sun Jan 26, 2014 1:08 pm

ContiTech belt/tensioner kit from ECP is good enough.

My water pump is AirTex, got it from GSF.

The ones on ECP are Circoli and I've read some dodgy things about it, so decided to go with AirTex, as they seem to be OEM supplier for Ford.

Possibly, GSF could be selling a different make now, as I bought mine in 2012, so better double check with them.