Heavy White Smoke Only On Startup

[NightRunner]

Hey guys, had a quick question I wanted to post. I've been experiencing a pretty heavy white smoke cloud appear when I start my truck 80 percent of the time (both cold starts and restarts), and some white smoke when going from a stop very seldomly as well. The oil was recently changed and shows no sign of a blown head gasket from what I could tell, so I'm pushing that back on the list of possibilities. I'm assuming it's either the intake gaskets which to my knowledge have never been replaced, the "modulator" on my 700R4 leaking or something else.

Reason I'm asking however, is that I did read that something from the brake setup (I believe it was the brake booster?) can leak into the engine and cause this white smoke to appear. While servicing my brakes a couple days ago, I noticed my brake fluid reservoir was dangerously low. I'm starting to connect 2 and 2 here and need some insight. Is anyone aware of what hoses, lines, etc. to check for this known leak? I'd like to make sure it's not the brake system or modulator on the transmission leaking before I tear into replacing the intake gaskets.

Any advice is appreciated, thanks all!

 

[Jay33089]

Not to be a downer, but I had the exact same problem with my 98. Ended up being a cracked head. Ran fine no skips or burps.

 

[NightRunner]

Honestly even if it is a cracked head, it's not a downer. Just another reason to do a Vortec top end swap and ditch this dreaded TBI setup. Lol

 

[someotherguy]

Have to assume the 1991 C1500 since you said 700R4 but did not mention which vehicle from several in your sig.

There's no vacuum modulator on a 700R4, so it cannot introduce trans fluid into your engine's vacuum system.

For the brake booster to be leaking fluid into the vacuum system, your master cylinder would have to be bad and leaking out of the rear seal into the booster. This would also usually include visible fluid leaking down the booster, which would also eat the paint off it.

Keep in mind as your brake pads and shoes wear, the fluid level in the reservoir will drop, this happens in a normally functioning brake system with zero leaks. As long as the fluid level doesn't dip to below minimum, you do not need to add fluid - doing so will just cause an overflow condition at your next brake job when you compress the caliper pistons to install the new pads.

Just helping knock some suspects out of the running.

Richard

 

[NightRunner]

Sorry about that. Yeah, it's my 1991 C1500 in question. The fluid itself definitely looked below minimum as the front part going into the booster was completely empty exposing the hole that goes into the booster, and the reservoir behind it was way below the notch between the two sections, almost completely empty. The brake pads and shoes are in passable condition, but I'll get them changed and have the brake system bled and 100 percent again to see if the fluid returns or if it is malfunctioning.

 

[Jay33089]

Sorry about that. Yeah, it's my 1991 C1500 in question. The fluid itself definitely looked below minimum as the front part going into the booster was completely empty exposing the hole that goes into the booster, and the reservoir behind it was way below the notch between the two sections, almost completely empty. The brake pads and shoes are in passable condition, but I'll get them changed and have the brake system bled and 100 percent again to see if the fluid returns or if it is malfunctioning.

That sounds like a leaky wheel cylinder!

 

[NightRunner]

That sounds like a leaky wheel cylinder!

Well maybe I need to get into the rear drums sooner rather than later and see if one of the wheel cylinders truly is leaking. Thanks for the guidance!

 

[skylark]

Disconnect and plug the brake booster vacuum line to eliminate that is the source of the issue. I'm not suggesting that you drive it like this just that you check it on Startup.

 

[someotherguy]

Well maybe I need to get into the rear drums sooner rather than later and see if one of the wheel cylinders truly is leaking. Thanks for the guidance!

You'll see it wet on the lower part of your backing plates and drums.

Richard

 

[someotherguy]

Disconnect and plug the brake booster vacuum line to eliminate that is the source of the issue. I'm not suggesting that you drive it like this just that you check it on Startup.

May take a couple starts to clear any remaining fluid in the line, if this is in fact the cause of the smoke. Excellent advice though.

Richard