325ISE - Burning Smell from engine bay

[Razza]

As above since yesterday i've noticed a burning smell coming from the engine bay. Its a dry acrid burning smell, no smoke and no indication on the dash that anythings wrong (temp guage is fine).

Seems to be coming from the radiator area but I can't see anything wrong. The radiator was replaced about 4 years ago.

Its driving ok but was a but chuggy today and I could hear a slight grinding as I pulled into my driveway.

Could it be the radiator or another theory I initially had was a siezed caliper but surely that would be obvious when driving.

Any ideas or common faults. Its got 150k on the clock and has had timing belt, water pump etc replaced about a year ago.

Should also say that I was on holiday and when I started it up the first time there was a slight "whump" noise which I have never heard before or since - i then drove 60 miles to work and it was only when I parked I noticed it.

Cheers

[Speedtouch]

I would check the alternator first, then the wiring to the starter motor, etc. Also check the engine-to-body earth strap.

And, carry a fire extinguisher with you, just in case!

[Brianmoooore]

Check the wires that go to the oil level sensor for heat damage. There's a very poor bit of design in this area in that the oil level sensor is earthed via its metal case and also by a wire, via the engine loom, to the earthing point on top of the RH suspension turret.
This means that it is in parallel with the main engine to body earthing lead, so if that develops a poor connection, (a not infrequent occurence), the poor little sensor wire attempts to carry the starter motor current - it fails miserably.

[Topblag]

+1 for the fire extinguisher. Grinding sounds in any context are not good, don't drive it unless you have to.

[Speedtouch]

Just a thought; maybe your car has a charcoal canister or some similar emissions control device fitted.

These sometimes overfill and 'burp' which would explain your 'whump' noise.

[Razza]

Thanks for the help, I'm talking it to the garage tomorrow.

Would a clutch on the way out emit a burning smell? - I've had about every problem under the sun with E30's but never had a clutch go.

It is however driving ok and the clutch pedal doesn't seem any stiffer or otherwise than normal.

If it is the clutch I'm looking at about £800 at a garage arn't I

[Speedtouch]

Yes, a badly worn slipping clutch will give off a burning smell.

It's easy enough to test for; drive up a hill in a high gear and accelerate hard - if it then slips, you'll be able to feel, hear and probably smell it.

Cost of getting a garage to replace the clutch will vary widely - shop around.

Alternatively, hire an engine crane and do it yourself; these old Beemers are usually fairly straightforward to work on...

But, first check to see if you have one of those carbon canisters fitted:

(Extract from E30 Zone Wiki)
"To meet increasingly stringent emissions regulations, later engines were fitted with a Carbon Canister. This small brown container sits in the engine bay and is bolted to the inner wing. It captures fumes from the fuel tank venting system, filtering them through a self-contained carbon filter and releases them into the throttle body. The carbon canister was controlled by a small electric valve. If you find an unused plug on the loom underneath the throttle body, it is for this valve.

Utterly redundant, the Carbon Canister system causes more problems that it solves in older cars, and is recommended to be removed if found, or at least disabled.

Removal is simple. When disconnecting, the end of the rubber hose to the canister from the back of the car MUST be left open, and should be tucked inside the reinforcement for the suspension turret. The hose from the valve that goes towards the inlet manifold MUST be blocked off and airtight, either by a plug in the end of the hose, or a cap on the metal stub pipe into the manifold.

For cars not fitted with the Carbon Canister, it is this blanking plug on the intake that is a major cause of air leaks."