View Full Version : Faint white smoke under hood

02-22-2012, 07:58 AM
This has been annoying me lately. I have already replaced the valve cover gaskets. First time noticing it was at a stop light at a busy intersection by my house. Faint white smoke coming up between the hood and windshield (driver side). Baby it home for another mile or so. Wasn't there when I looked as soon as I got home. Hasn't happened for a good month, but last night after work, the same thing happened, but I noticed it coming out of the front of the hood too. Very faint, no distinguishable smell other than slightly burnt. Car still pulls real hard. No smoke out of the exhaust. It's just so occasional and so faint it's hard for me to pinpoint the problem.... Ideas?

02-22-2012, 08:47 AM
White smoke suggests water or antifreeze burning off. Is it accompanied by a sweet smell? If its only occasioal it sounds like a slow leak. Get underneath the car and see if you can locate any coolant colored residue

02-22-2012, 08:49 AM
Water pump weephole getting coolant on the exhaust?

02-22-2012, 09:12 AM
I'll have time this weekend to get under the car and take a better look. All my gaskets are just a year old since my motor was built last spring

02-22-2012, 01:36 PM
Might be leaking coolant somewhere. Just pop the hood and let the car idle and see if you notice anything. See where the smoke is coming from as it may be a really small leak so it may evaporate once the coolant is hitting something hot (exhaust) to make it smoke.

02-25-2012, 09:16 PM
I drove the car today and let it idle while I checked around the engine bay today. Still didn't see any smoke/steam coming from anywhere. Typical... only happens when I am unable to inspect/diagnose it. I looked under the car too, but did not notice anything. I have zero puddles developing under the car while parked after being driven. I'm stumped.... It's my DD and I have to get to work, so I'll just keep driving it.

What are some other things that could cause white smoke from the engine bay?...

02-25-2012, 11:54 PM
Check around the radiator cap. My brother's car would do that every so often and it was steam leaking from the cap (totally different car but same principle applies). Eventually the seal on the cap went bad enough that it actually burped some coolant and got the radiator wet around it. He replaced the cap and all was good.

02-28-2012, 05:24 PM
Ok, so I changed my oil and inspected underneath for possible coolant leaks but could not find any. The only thing I did notice was that my power steering rack was very gunked up. The very first and most significant occurrence of the white smoke came from the general area of where the power steering pump is (at least that's where it appeared to come from as I was sitting at a stop light). Since then, I have noticed some black residue under my hood. What are the odds the current faint white smoke is coming from my power steering fluid? I'm not leaving puddles on the ground though.

It is always dark by the time I get home from work, so I have to wait for the weekends to mess with the car, but I wanted to get input on here until then.

Edit: During the oil change I notice metal shavings on the magnetic drain plug. I posted about that here:

Evidently it's normal for newly built engines, but I am still concerned that these two issues may be related. Or... they may not. The smoke is fairly recent compared to the engine being built a year ago.

02-28-2012, 10:52 PM
I've had this happen before, it was a small weeping from the valvecover gasket that would burn off tiny bits of oil on the exhaust manifold. I know you said you replaced the gaskets, but maybe something isn't torqued down enough, or a gasket is pinched/damaged. Or maybe a PCV line is damaged/broken/loose and is weeping oil residue down to the manifolds.

Power steering seems doubtful, because the fluid would have to somehow be reaching a surface hot enough to cause it to burn.

02-29-2012, 10:36 AM
it'd be hard for the power steering fluid to be leaking anywhere that would burn it off, but still possible. the best thing you can do is check any hoses, water hoses, pcv hoses, heater hose's, TB heater hoses, etc. then i'd take some good degreaser and thoroughly clean the engine bay. get all that gunk off and it will be much easier to find a leak. you can't see fluid's leaking on top of grease and grime, but you can see them leaking on a clean surface.

02-29-2012, 11:00 AM
Good points. I'll be cleaning this weekend then!

03-26-2012, 02:10 AM
Update: I cleaned up the underside of the engine bay, but have yet to see anything noticeable since then. I have, however, noticed a whistling sound almost as if I am driving a remote control RC car that gets louder with the rpm's. It isn't too loud, but I am positive this did not used to happen. Would there be any connection to the whistling sound and the faint white smoke under the hood? Again, I can only see it at night and it smells more burnt than sweet.

03-26-2012, 03:24 AM
Did you check those PCV lines? And also the fresh air line from the TB to the valve cover (passenger side)?