details on the jeep, 1991 xj, 4.0 ho, 5 speed 4x4. pretty much stock other then minor trimming on the front fenders 30" bfg's and no exhaust behind the cat.

So, heres what happened. me and my buddy decided to take my jeep and his tracker down a trail that has about a foot or so of snow on it. No problem, the xj wasnt having any issues but had to pull the tracker out 3 times on the way in. We made it to the end of the trail and started to head back, again no problems. As soon as I get to the head of the trail, I go to stop so I dont drive out into traffic. Soon as I press on the clutch, it goes to the floor without any resistance! I slam on the brakes and it comes to a stop, killing the engine.

I pop the hood to have a look, at that time I then notice a bunch of smoke coming from under the hood. I open it up, and the exhaust manifold area is up in flames! Me and my buddy start throwing snow on it, and have the fire out within a minute. I have not had a chance to have an indepth look to the see what all was burnt due to it being dark out, but from the looks of things it isnt that bad at all.


My first theory is the hose to the master cyl. for the clutch was broke/ripped or pulled off, and when I stepped on the clutch peddel it shot brake fluid onto the exhaust manifold, causing it to ignite.. But then I was thinking, I beleave the fluid takes like 400-450f to ignite. would the exhaust manifold be hot enough to ignite it?


My next theory is the intake manifold may have been leaking, and dripped fuel onto the manifold casuing it to light up.

anything els I should be looking into that could cause this to happen?

 

brake fluid will ignite on the exhaust manifold, I've come across alot of crash vehicles that caught fire after impact because of brake fluid/clutch fluid (which is normally DOT 3 brake fluid)

 

X2. Had it happen to myself.

 

Exhaust temps reach 1k degrees pretty easily. Your engines a contained explosion. Trace the hose for the clutch and find the break.

 

I just replaced the slave cyl and master cyl 6k miles ago. I guess with it having 210k on the odo I should have considered replacing the hoses.

I knew exhausts on sleds easily broke 1000f, just wasn't sure how hot the exhaust on cars got. Never had a EGT gauge on a car to see!

Basicly, I just wanted to double check that I was not over looking something that could have caused this, but a broke line is the most probable cause.

 

Talk to atmos, he's a pro at this

 

^ x2 with a smile.

 

Haha i was bout to say same thing x3 he is a pro at burning up xjs but his didnt make it home

 

Seen diesels exhausts reach 1200+ before. Hell, in college we ran a test engine hard and made the turbo and the exhaust manifold glow white... little nerve racking on a cat 3406e.

 

Ya a diesel in regen will reach 1200

 

Well the hose is broke. No parts store around here can find one, and recomend to make one from brake line.

Does anyone know if the hose from the master cyl to slave cyl from a Dakota would work?

 

Fixed mine with a length of quarter inch braided hydraulic hose and PEX fittings from the home depot store cost me about 15bucks.

 

Make sure you check your vacuum hoses as well. The one that goes from the to the MAP sensor is very important, and the plastic melts easily

 

 

caterpillars hit 16-1700 to burn the fuel in regen.... ****s cookin.