Euro 1994 E36 M3 - White smoke mystery

[mlambert]

Hi guys,

Right a couple of weeks back I was cruising my car (not pushing as she was cold) when the power cut out (not engine) for a few seconds, then when she kicked back in she was down on power and lots of white smoke. I called out the rac (uk recovery company) and we swapped around the coil packs, but she wouldn't start and idle for long.

Anyway, back home I messed with the coil packs/sparks and they seem fine. She now starts and idles fine (strong smell of fuel though) and she drives, but with a loss of power at low revs (not loads, but noticeable). As she warms up, the smoke returns and the car starts 'popping' on the overrun. The smoke starts of stinking of fuel, then turns to a sweet burning smell.

Now I've got a Peake research tool and it's showing no codes, the MAF is a few months old (bosch new), she has passed an emissions test (despite filling the guy's garage with smoke) and she has also passed a compression test. There's no coolant loss at all (it looks and smells fine), no brake fluid loss, and bar the 'popping' on the overrun and the smoke, she is starting and running fine (never overheated, still isn't).

Any ideas? I've been told it could well be bad fuel (I use high grade '97-'99), a rare fuel pump issue (where it might be pushing too much out under certain circumstances) or the start of a head gasket problem. However none of these quite fit.

All ideas welcome!

Thanks,

Marc.

[JhwShark]

Interesting issue...
You had a compression check - what was the state of the each plug and its associated comp?
A SMOG test what were the numbers??
In the morning before you try and start - Is there any sludge on the inside of the radiator cap or a line of sludge in the overflow tank? Is there any sludge on the inside of the oil fill cap?

Seems it could be the head gasket due to white smoke or crack in the head's water jacket (they can get fine/small cracks from certain running conditions).

Rich conditions usually show as brown smoke and soot in the tail pipe: what does the pipe show when you stick your finger in it rub the inner edges and pull out??

Jon

[mlambert]

Originally Posted by JhwShark

Interesting issue...
You had a compression check - what was the state of the each plug and its associated comp?

The plugs were a little sooty on the ends, but that may be because since this problem she's been revved up on idle more than run.

A SMOG test what were the numbers??

I didn't get the exact figures because the guy said she was bang on all round.

In the morning before you try and start - Is there any sludge on the inside of the radiator cap or a line of sludge in the overflow tank? Is there any sludge on the inside of the oil fill cap?

Nope, no sludge and nothing seems wrong with the coolant (levels and smell)

Seems it could be the head gasket due to white smoke or crack in the head's water jacket (they can get fine/small cracks from certain running conditions).

Interesting, I've not heard of the water jackets. Are they replaceable? Is it worth some k-seal to try and see if it temporarily fixes it (then I know it's a problem)

K-Seal, K-Tek, QuikSteel, QuikTape, Just-For-Copper

Rich conditions usually show as brown smoke and soot in the tail pipe: what does the pipe show when you stick your finger in it rub the inner edges and pull out??

Jon

Well the smoke isn't pure white, but not brown. There's plenty of soot in the tail pipe, but again that may be because she hasn't been given a good run for a while.

This is definitely a mystery like I say, nothing really seems to fit the problem! Thanks for your input, it's much appreciated!

Marc.

[JhwShark]

The water jacket is a reference to the channels in the engine/head that provide coolant to cool...

You really need to find the true oil pressure before doing much else!

I believe your block is steel and head is aluminum, if you go the selant route (assuming you can not find anything else wrong) as a stop gap make sure that you use a sealant that is compatible with the metals in your car...
Jon

[mlambert]

Originally Posted by JhwShark

You really need to find the true oil pressure before doing much else!

I'll look into the best way of doing it.

I believe your block is steel and head is aluminum, if you go the selant route (assuming you can not find anything else wrong) as a stop gap make sure that you use a sealant that is compatible with the metals in your car...
Jon

K-seal apparently is, but I'm loathe to use a bodge just yet



Cheers!

[darkhorrus]

I'm going to say that it's the head gasket or a cracked block. Next time you do an oil change look to see if your oil is a chocolate milk brown. if you put some of the oil on water it will separate and the coolant will form little pools inside the oil....

Also, when your engine is cool, dip your finger inside the coolant and rub it between your fingers- my coolant feels slightly oily- about as oily as sweat(my 328is needs a head gasket)