so here's my dillema!! please read!!!

I apologize ahead of time if this is a little long but I wanted to give everyone as much info as I can .

so, last summer my 97 xj w/4.0 and auto tranny started over heating. i changed the thermostat to a 180 degree. problem solved except for long hills on main roads, then it would run at about 225-230 and I would leave it running when i got to the top just to the cooling system do its job to prevent any possible engine damage. this spring after a few rides, I noticed that it was running hot again. and it was only when i was driving on main roads. when I was wheeling it never over heated unless I got stuck in a hole and needed some skinny peddle to get my self out. so I started all over, checked t-stat, its good, changed coolant, cleaned out the radiator, etc. seemed to run a little hot but never overheated. so, went wheeling probably half a dozen times no problems. the one night a buddy of mine and I did this trail that was slimey as hell and had alot of good sized water bars. i tried going over one of the water bars and came down hard on it. I got turned around, decided to call it quits and go home before i broke something. I shut the jeep off and the radiator cap released(brand new cap). so I started it back up to let the fans go to work. is started hard, needed to give it gas to start. let it run and after about five minutes it started to knock a little. the knock got progressively worse so i shut it down. I thought maybe I had cracked th oil pan when I came down hard. checked the pan, no leaks. check the oil, had plenty. so I headed out cause I didnt want my jeep to be stuck in the wood if the motor seezed up. on the way down, everytime I hit the brakes, oil pressure died down and the motor stalled. got it started and for the rest of the way out the motor knock BAD. I got it to the road and as I was crossing, the jeep shut off. couldnt get it started back up. called my dad to come pick it up. the next day I went to start it up, it started fine and ran great. the exhaust had some blackish, oil/fuel smelling liquid. pulled the dipstick and the oil had a gas smell to it. after the jeep ran for a minute or so, I shut it off and tried starting it up again. had to give it gas to start. acted like it was flooded. what could be my problem?

again very sorry for the mass amounts of info.

thanks~

Check your compression. Possible head gasket problem.

i could be wrong but if the head gasket was bad, wouldnt the oil be milky because of anit-feeze mixing in with it? I was thinking it might be getting to much fuel. maybe a fuel pressure regulator problem. the head gasket was my first thought. but the oil looks good.

rcliftedXJ said:

i could be wrong but if the head gasket was bad, wouldnt the oil be milky because of anit-feeze mixing in with it? I was thinking it might be getting to much fuel. maybe a fuel pressure regulator problem. the head gasket was my first thought. but the oil looks good.

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Well, then you purchase a fuel pressure gauge.
I think the fuel pressure regulator is in the fuel pump of your Jeep 97. :lickout:

Pull your plugs and have a look at them too.

X2 on taking a look at the plugs. Running a 180 tstat will make the plugs foul out early and lead to gas in the oil.

interesting. I didnt know that. would that lead to possible overheating as well. seeing as the fuel would then be mixing with the oil, thinning it out.

pull the pan and check to see if you cracked a skirt

The fuel injection system is designed to run with a 195 tstat. If it runs below this temp, the system runs rich like having the choke on with a carburetor. I do not think this would lead to overheating though. That is a different issue. Running with one plug fouled out might cause overheating and strange noises in the engine. Make sure your fans are running right. Adding a switch to the aux fan would help too. You can search for lots of information on the fans.

tomcat said:

pull the pan and check to see if you cracked a skirt

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cracked skirt?

I would think that if I had fouled plugs it would run like a bag of ass. but it doesnt. when you first start it it runs fine, it just seems like its over loading with gas.

I had thought about hooking up the aux fan to a toggle!

It is a cooling system, each part dependent on the other, to keep the engine cool. Service your cooling system. Replace any parts that are worn or under performing. Keeping the temps under 215-220 on the 4x4 trails should be as easy as falling off a log.

The cooling system consist of :
radiator
radiator cap
coolant
195* thermostat
water pump
mechanical fan and fan clutch
electric fan
hoses

Is the radiator clogged with mud and grass on the outside or are the tube plugged with deposits on the inside ? The water pump may be turning, but are the pump fins worn down ? The fan turns, but is the clutch worn out ? Are the radiator hoses old and spongy and collapsing when stressed ?

Gas in the oil can be a sticky valve, a leaky injector, a cracked head, a failed head gasket, or maybe something else.