My car is blowing a good cloud of white smoke at startup (sometimes), it isn't smoking noticeably after warming up. I did a search here on the board and know it's most likely coolant, oil, or brake fluid. I checked last night and the overflow tank and radiator were low so I refilled them. I also noticed that the brake fluid is about 1/2 full which I thought was strange as I just filled it about 3 weeks ago. The car is a 95 SE with approx. 120k miles.

I haven't tried all the tests suggested in other posts (need to get air compressor), but I did try a few things... 1st the smoke didn't have a antifreeze smell, maybe oil or brake fluid. 2nd didn't see any bubbles in the radiator neck. 3rd oil was changed 3 weeks ago and still looks clean, not milky.

What's the easiest way to tell if the brake booster is leaking without doing a tear down. Can I check the vacuum hose going to the booster?

 

If white smoke is coming out of your exhaust it's oil. Unless you poured brake fluid into your engine.

 

this is incorrect

white=coolant
black=fuel
blue=oil

 

I'm not sure what's the weather like in Missouri but the cloud of smoke could be as simple as condensation in the exhaust system being evaporated by the heat. Its more apparent in cold weather. It looks like coolant-type smoke but its more "misty" and doesn't look as thick. It goes away after the car is running at normal operating temp. I'm basing my opinion on you stating that the smoke doesn't smell like coolant and the oil isnt milky etc .

If your brake fluid level is dropping at a rapid rate you might want to check the calipers. Take them off the caliper mounting brackets and look at the dust seals to see if they're wet with brake fluid. The brake fluid "circuit" has nothing to do with the engine so you're not going to experience brake fluid-derived clouds coming out of the exhaust pipe.

To check the brake booster airtightness simply turn off your motor and pump the brakes. The pedal should travel less and less after each successive stroke.

 

Thanks guys. I know that normally brake fluid does not enter the combustion chamber, but after read some posts with simular problems I found some interesting references to burning brake fluid. It sounds like a long shot, but I can't find any leaks for the fluid.

Here's a post by DBM about a simular issue: http://forums.maxima.org/showthread....ht=white+smoke

DBM's post to the thread:

Several possibilities come to mind: the smoke might be from ...
- engine oil
- coolant
- brake fluid

Engine oil.
This is more often noticed as blue smoke.

Coolant.
This is usually noticed as constant white smoke. Coolant may find its way into the combustion chamber as the result of a blown head gasket or a cracked casting. If possible, stand behind the vehicle and sniff this white smoke. Water vapor is odorless but antifreeze has a characteristic sweet aroma.

Brake fluid.
This is a rarity, but I cite it here in the interest of completeness. The master cylinder may leak at its rear seal, and the leaked fluid pools in the power brake booster. Sooner or later the booster diaphragm develops a leak and the pooled brake fluid is sucked into the intake manifold and burned in the combustion chamber.

Keep an eye on all three fluids.

 

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Bump..
i'd like to know what the white smoke is from and it wasn't answered in this post. how do you check the brake booster? the smoke is not from condensation in the exhaust system being evaporated by the heat, that looks like a mist not smoke.

 

Brake fluid going into the booster never crossed my mind because I never heard of anyone with a master cylinder's rear seal (primary piston cup) leaking.

Since brake fluid is glycol-based, it should come out of the tailpipe as a white cloud like coolant. It could be either two.

 

I haven't found the cause yet, too many other projects going on. I've been keeping a eye on the fluids and there have been no noticeable losses. Oil looks good, no bubbles in radiator, and brake fluid seems to be holding steady. The smoke has a burned petroleum smell - maybe oil. My engine has had a noticeable tick for the last 6k or so miles. I'm wondering now if I have a bad valve guide or at least a bad valve seal. Probably both as I don't think a valve seal would cause a ticking noise.

 

Sounds like you can rule out coolant then, that has a very sweet smell.