Smokey start....what's about to go?

Fri Jun 22, 2007 2:00 pm

Firstly I've a 91 316i, M40 engine.

When I start it first thing in the morning it appears to have no power, unless I rev it slightly (to about 2500rpm) after this it drives completely fine. It feels as though there is a blockage somewhere and it's cleared with a few revs.

If I try to drive it without doing this it kind of jerks along in a completely undriveable state.

I'd noticed it to smoke slightly during this process, this morning I noticed that this smoke was a distinct blue colour. It had originally looked black so I'd put these issues down to the choke/ it flooding on startup.

The car doesn't appear to be burning any oil, I've done 2500 miles since changing the oil, and it has moved down on the stick slightly, but not a crazy ammount.

The car smells strongly of petrol sometimes when it's started, I don't know if this is related, it's another thing I'm looking into.

Sorry about the long post, does anyone know what's going on/had something similar happen to them?

Thanking you in advance,

Peter

Fri Jun 22, 2007 2:14 pm

Could be fuel related as overfueling usually cases slightly black smoke, is the tail pipe quite sooty?

Usually a bit of blue smoke on start up is worn valve stem oil seals as the oil in the top of the head seaps down then stem of the valves and drops into the cumbustion chamber/ on top of the piston, so when you start up you burn that bit of oil off.

Fri Jun 22, 2007 2:25 pm

Thanks for that E30BeemerLad, is there anything I can do about the valve stems/will they be alright for long?

The exhaust is slightly sooty, nothing crazy though. And my fuel consumption isn't rediculous, it's in the high 30's.

Fri Jun 22, 2007 6:05 pm

Stem oil seals will be OK, I mean they need doing, but nothing terribly urgent. I believe they can be done without taking the head off, just a fiddly job.

You can buy additives to put in your oil that are supposed to help tired engine oil seals, whether they are any use or not is another thing

High 30's MPG, oh lordy, I don't think I've had that experience for quite some time

Fri Jun 22, 2007 10:36 pm

To be honest I was shocked at the high 30's, I was getting about that from a 1.3 golf.

There are some pluses to having a 316 (not many), and I don't have the lightest foot in the world!

Fri Jun 22, 2007 10:41 pm

Your petrol smell is probably caused by the pipes under the inlet manifold leaking.

Fri Jun 22, 2007 10:45 pm

smithy318i wrote:Your petrol smell is probably caused by the pipes under the inlet manifold leaking.

I tried checking these the other day, followed some pictures I found on another thread, couldn't really see them that well.

The picture on the other thread had the manifold removed, should it be possible to check them properly without taking it off? The pipes I could see looked alright.

Sat Jun 23, 2007 12:43 am

Get the blue engine temp sensor changed! Good fun on an M40!! (start hunting about half way along under the inlet manifold).

Sat Jun 23, 2007 9:28 am

Brianmoooore wrote:Get the blue engine temp sensor changed! Good fun on an M40!! (start hunting about half way along under the inlet manifold).

I'll get in there and have a look.

Thanks everyone for all the help!