so my truck caught on fire

[Guilty-by-Design]

like every Wednesday at 4:00pm i was cruizing down 8th street on my way to work, when suddenly my truck seams to stall out. I come to a stop and i am promptly greeted by a huge plume of white smoke from under the hood that quickly becomes black smoke... at this point i throw it in park and slam the e-break on and yank the hood release. by the time i get around front the pop the hood an older gentleman meets me, fire extinguisher in hand. A few well aimed blasts and the fire is out. I thank the man for helping and he is gone just as fast as he had arrived. a quick under the hood inspection reviles a well done wire bundle against the passenger firewall and a melted hard plastic vac line or two. i thought to myself that would explain the black smoke but what about the white??? as it turns out im standing in what appears to be the better part a quart of tranny fluid... By this time the cops and fire department are there asking the normal question. The cop then informed me of the huge trail of tranny fluid i left, two car lengths worth.

My question to you is what would cause that much tranny fluid to leak into the engine compartment.

What i know:
-It was localized on the passenger side
-Transmission lines to the radiator are fine
-It was tranny fluid not oil
-Only apparent source is top of fill tube

any help would be greatly appreciated

[N2TRUX]

Originally Posted by Guilty-by-Design

.....-Transmission lines to the radiator are fine....

This would be my guess for the source. Inspect them carefully.

[Jonboy]

If the transmission overheats, the fluid will expand, and it WILL come out the dipstick tube. The Catalytic converter is right in the area where the fluid drops to. There was a bulletin from GM about this in the early 90's, and that is also why the dipstick and tube was redesigned, to incorporate a boot seal and a locking cap. I found this out the hard way, and got to watch my Suburban burn to the ground on the side of the highway about 3 AM one morning.

[Keith Seymore]

Originally Posted by Jonboy

If the transmission overheats, the fluid will expand, and it WILL come out the dipstick tube. The Catalytic converter is right in the area where the fluid drops to. There was a bulletin from GM about this in the early 90's, and that is also why the dipstick and tube was redesigned, to incorporate a boot seal and a locking cap.

Yep. This is absolutely true.

K

[STOCKISH]

I saw a couple of the Suburbans come through the dealer burnt to a crisp because the transmission overheated and dumped trans fluid on the cat causing a fire. Hope yours isnt too bad off.

[86swb]

Man, you are lucky that guy was there. I always carry a fire extinguisher in the cab at all times just in case.

[locab36]

I know that towing in Overdrive will overheat a 700R4 and make it puke fluid and catch fire. Saw a couple of those. The only other reason for a tranny to overheat would be brake drag or radiator/pump problems. How often did you use your E-brake? Up here in Michigan you don't want to use the E-brake unless its used regularly due to cable sticking leaving the brake still engaged. Most manual trans will be fine but autos I don't use them. Of course I would attempt to use in an actual emergency.

John

[cableguy0]

Tranny fluid definately burns a thick bright white. I think the other guys covered reasons for the tranny to leak. The black smoke would have been from the plastic burning.

[68 TT]

I have had a flare crack on a tranny cooler line and spray fluid everywhere. It looked intact when the car was not running but under pressure it sprayed all over the place. Check the condition of the flares at the ends of the tranny cooler lines.

[nechevy]

What type of trans setup. Since I've also seen the vacuum lines suck up trans fluid and spit it on the exhaust. If it a th350

[Guilty-by-Design]

thank you all for the comments... i have more thoroughly inspected my truck and found that the tranny cooler lines are in good condition, no leaks that i could see, this was tested while in gear at varied rpm.

@ locab36: i use my e-break every day... it has been a habit to apply it every time i exit a vehicle.

@ nechevy: it is a th350

[Tony_SS]

How come trans fluid on the cat causes a fire? Is it the cat or the trans fluid thats getting ignited?

And this is why I always carry an extenguisher under my seat too. But hearing these stories makes me nervous to drive my kids in the truck.

[68 TT]

The cat is hot enough to start trans fluid on fire, so is a header for that matter.

[68 TT]

It is a risk for anything with transmission cooler lines running near the exhaust system not just our trucks. That's why it is best to keep your cooler lines all metal. They are less likely to burst and cause a fire.