SMOKING 2.7

[turners]

WHEN I START THE CAR ITS FINE, NO SMOKE. HOWEVER, WHEN I WIND THE CAR UPTO ABOUT 5500-6000 RPM AND CHANGE GEAR IT KICKS OUT A LARGE CLOUD OF BLUE SMOKE. WHEN THE ENGINE WAS BUILT APROX 3000 MILES AGO, THE HEAD WAS RE-MACHINED ON THE VALVE STEM OIL SEALS. THE PROBLEM HAS BEEN THERE EVER SINCE THE ENGINE WAS PUT BACK TOGETHER. ANY IDEAS ON THE CAUSE OF THE BLUE SMOKE?

[kam-325i]

Blue smoke is caused by the combustion/burning of oil in the chamber.

So oil is getting in to the chamber at high revs, when the oil is at a higher pressure, could be leaky head gasket, worn rings, bad valve stem oil seal thingys...

[turners]

SHOULD HAVE SAID THE ENGINE IS IN A 1989 3251SE. THE ENGINE HAS AN ETA 2.7 BOTTOM END, 323I HEAD, 284 SHRICK CAM AND ZONE CHIP. THE HEAD WAS RE-MACHINED AS IT WAS BURNING OIL PREVIOUSLY BEFORE EVERY COMPONENT IN THE HEAD WAS REPLACED.

THE CAR MAYBE OVER-FUELLING, NOT SURE IF THIS WILL AFFECT IT OR ADD TO THE SMOKE. CAR HASNT BEEN SET UP ON A ROLLING ROAD YET.

[kam-325i]

Overfueling will not cause blue smoke, burning oil does. its that simple.

If all of the head has been checked out to be ok, the start looking at oil coming from either the head gasket or past the pistons.

[turners]

HAS HAD A NEW HEAD GASKET, VALVE STEM OIL SEALS ETC ALL DONE WHEN HEAD WAS MACHINED. COULD IT NEED RE-MACHINING IF NOT DONE CORRECTLY IN THE FIRST PLACE OR MAYBE EVEN THE BOTTOM END IS THE PROBLEM?

[E30BeemerLad]

Piston rings most likely in my opinion given the new components and work done to the head, but I may be wrong

[kam-325i]

Well, if you know that the top end is good, the it should only leave the bottom end.

What was machined on the head ?

[turners]

ONLY THE VAVLE STEM OIL SEALS WERE MACHINED, AS FAR AS IM AWARE NOTHING ELSE WAS DONE TO THE HEAD.

[Martinaston]

How do you machine a valve stem oil seal ? There rubber.

[turners]

I WAS TOLD THEY WERE MACHINED WIDER AND THEN LARGER SEALS FITTED.

[Jimbob]

For god's sake turn the CAPS LOCK off.

[Martinaston]

I think you mean the valve guides, If you had the valve guides drilled then you should have new valves with larger stem's, the oil seal sits on top and if not put on carefully you can tear the inner sleeve on the top of the valve leading to oil loss and another head off job.
But if thats the problem it normally shows when you start the car after it's stood for a while.

Are you sure it's not just got too much oil in it and is burning off through the breather pipe at high rev's ?

[turners]

I dont think it has got too much oil, especially because i have topped it up quite considerably twice in only 3000 miles. If i was to remove the head would it be pretty obvious that the oil was coming past the seals. would the burning oil also lead to a reduction in bhp?

[Martinaston]

If you're loosing power as well it sounds more like the piston rings are worn or broke, Do a compression test on all the cylinders.

As for topping up the oil are you sure the dipstick pipe is pushed in as far as it goes into the block ?
If it's not it will look like the oil level is low because the dipstick is sitting too high.

When the lump was put together what work was done on the bottom end and how many miles had it done ?

[turners]

The bottom end had only just over 80,000 when it was removed from the 5 series. Im sure the oil levels when i checked them were correct. the engine pulls stronger than my other 325i but im not convinced its as quick as it should be.

[Martinaston]

Cheapest option for now would be just a compression test rather than pulling the head off. You can see the valve stem seals with the rocker cover removed but all you can check is if they have gone brittle by gently poking them. To see if they let oil past you have to remove either the inlet or exhaust manifold and look down the ports to see if you can see oil running down the valve stem. But as i mentioned that normally shows as a puff of blue smoke when you start the car.

If the block was put straight in without any work done, due to the higher rev's play in the bearings and gudgeon pins might allow for play in the pistons that can cause the rings to hit the lip at the top of the cylinder's and crack a ring.
But that would only normally be on a high mile'er, did you see the car it came out of ?

[sheldo]

hi m8 have had the exact same problem with my 2.7. Had a compression test done and it was only holding about 70%ish so i was told. Having it rebuilt as we speak.

did u have the bottom end rebuilt when you done the conversion? Mine didn't and thats the cause of the problem. Having it rebored and new pistons and rings and bearings. Also my headgasket had only done a couple of thousand miles but was leaking down the side of the block but didn't show the usual signs of mayo in the filler cap.

Not nice thing to happen that blue smoke cloud. i simpathise with ya!

[turners]

The bottom end was not touched when it was put together. The person who built the engine said that the bottom end was new and didnt need any work. I didnt actually see the car the the engine came out of. It sounds like it may be the bottom end, as the head was like new when fitted. alsothere is no smoke when the engine is started, only when revved beyond 5000 rpm.

[Martinaston]

Oh dear.
Anyway welcome to the Zone.

[Jimbob]

It's a bit worrying that it happens after 5000 revs, the poor old bottom end never revved passed 4200 or something along those lines when it was in the 5 series.

[Jhonno]

sounds like pistons rings to me if the head is rebuilt properly...