Clouds and clouds of white smoke about 10 seconds after starting

Hello Everyone,

I’ve got a 1994 Daimler XJ40 that is probably only really good as a parts car and I’m about to list it for sale so that someone can make use of it. I’d like to satisfy myself before I list it that there’s nothing wrong with the engine because recently, about 5 to 10 seconds after starting, it’s producing clouds and clouds of acrid white smoke.

I’ve read that this is possibly brake fluid leaking from the master cylinder in to the inlet manifold, but I can’t find a post here that deals specifically with this problem. It seems fairly likely as the problem occurs as the brake system gets pressurised. Short of pulling the fuse for the brake pump, is there a reliable test I can do to verify that this is the problem?

The car doesn’t seem to be losing coolant and it seems to be smoke rather than steam that I’m getting. However, I don’t see that the brake fluid level going down either - I’m working on the theory that a little oil in the combustion chamber creates a lot of smoke.

It’s a bit of a mystery to be honest.

Many thanks for taking the time to read :slight_smile:

How would you describe the odor of the clouds?

Hi Rog - thanks for your question! It’s difficult to describe exactly, except to say that it smells smoky rather than steamy. It’s kind of acrid - like something’s on fire, lodges in the back of the throat a bit.

Sorry - I know that’s probably not very helpful!

That does help.

Anti freeze “smoke” might have a sweetness to its smell. Your description doesn’t seem to line up with that. And, you stated the coolant level holds steady.

I don’t see how brake fluid could get into a combustion chamber.

The smoke from oil getting past a valve seal or piston rings could be considered to have an acrid odor. Cars I’ve had that burned oil emitted clouds that had kind of a very light bueish gray hue. Is the car very high mileage? And does you oil level decrease over time?

I agree that getting BF into the combustion chamber on a non vacuum brake system is a non starter, assuming this car still has its original brake booster system.

Thanks gents - ah, so it’s a different brake system that causes BF to get into the fuel mixture. Looks like I can rule that out.

The smoke definitely doesn’t smell sweet either.

I don’t see any blueness to the smoke to suggest it’s engine oil - I know what that looks like.

If anything, its appearance is most Iike over-fuelling, but I’ve never seen fuel smoke in such copious amounts

Thinking about it (I’ll verify this) the check engine light may be on, on the dash, too.

I’m going to start and move the car in the next little while so I’ll get a pic or video of it. I must admit that the last few times I’ve run the engine, I’ve done so in the dark because the smoke quickly fills my driveway and then goes over the fence to smoke-screen next-door’s garden, too!

White smoke normally Brake fluid
White steam, coolant
Blue smoke oil.
Black smoke petrol

Overfueling is light grey to black, if unburned it smells like fuel so another dead end I‘m afraid.
It’s not loads and loads of condensation in the exhaust boiling off from the smoke screen description.

Thanks again folks - yeah, I’d not thought of the fuel smell with over-fuelling - that’s rules out then.

To be honest, I guess it could be condensation in the exhaust system, that would account for the volume of ‘smoke’, and the fact that none of the car’s fluids seem to be going down.

Who knows what steam that’s been forced through an exhaust system would smell like - possibly a bit acrid and burnt.

So far I’ve not had the courage to just run the engine and see if it goes away. Maybe I’ll wait until next door go out before I start it up again.

I’ll keep you posted with more information when possible!

You need to idle it for quite a bit if you think it could be lots of water in the exhaust. I was thinking of that because you said it’s a parts car.

If it smells like fireworks or sulfur your catalyst could be burning lots of fuel.
I remember a 7 series that had a horrible smell to it but emissions etc. were all in order. Maybe that adds to it.

When i first went looking for an XJ40, I test drove one that started right up but had been sitting for some time -months, maybe. This car filled the entire cul-de-sac of the owner’s neighborhood with smoke and opaque god knows what for several minutes, but eventually cleared up and then it seemed fine.
I took it for about an hour’s worth of driving and the smoke issue didn’t return other than the puff of oil smoke they all do.

Have you given the car a good hot run and then checked the startup condition? Could just be a load of built up crap in the exhaust system.