k5ranger

So my son calls from California...I live in North Carolina, and says his jeep(1990 4.0 w/ closed coolant system) overheated and blew the cap off the tank. He got a hotel for the night and let it cool down. Next morning he drove two miles to a friends house. By the time he got there he said the coolant guage was maxed out and there was smoke coming thru the dash vents...so bad that he had the a/c blower motor running and the windows down to clear the smoke away. ( I couldn't help but laugh at that sight). He did fill the system with 50/50 coolant before driving to a friends house. Any suggestions as to what would cause this? No previous issues up to this point.

minni-me

heater core bro just by-pass it you can get a kit for like 15 bucks at advanced auto

minni-me

its the 2 hoses on the left of the valve cover gasket and fallow to the fire wall and look under the carpet in the front passanger floor board my gfs grand Cherokee had the same issue

OleBlue

It overeated and blew the cap off due to pressure. Something in the cooling system is wack. Time to go through the whole system and see whats broke and fix it.

We need alot more info to diagnose any one thing it could be. Just have him start by filling it back up with water and buying a new bottle/cap. If its leaking from anywhere, i.e. water pump/hoses/radiator, then theres your cuplrit.

He drove it and got it hot enough to steam him out of the jeep? Its almost 100% chance that he blew the head gasket/warped head, so theres a whole other can of worms.

There is a southwest chapter forum on here, ge ton there and see if someone knowledgeable is able to take a look at it for him, Jeep owners like to look after other Jeep owners, =D.

k5ranger

thanks for the replys. I hope its not the head gasket...that will send him over the edge. we had a good jeep relationship here in n.c., now he needs one in the twenty nine palms area.

OleBlue,....as far as the head gasket goes, he drove it approx. 2 miles. you think that's enough to warm the engine enough to smoke? I really have no exp. with head gaskets.

minni-me

if it is I got a kit for it but I wouldn't even mess with it easier to replace the motor if it pm me ill give it to you new kit just don't need it

minni-me

how to figure it out...


head gasket or block: milk shake in the water or oil

water pump: its going to leak out the weep hole coolent is the easiest to see it due to it not boiling lol

radiator... well you know it will dump everything you put into it

hoses will leak

thermostat change it I just did mine was 8 bucks at advanced auto

my jeep blew the bottom radiator hose drove it with the motor sizzling... didn't know it was over heating motor is fine changed the oil hose thermostat and everything was fine I don't recommend it at all but my **** is a tank

minni-me

but smoke thru the vents Is the heater core if I believe but you never know till you tear it apart

OleBlue

2 miles is easily far enough to destroy a motor with no/low coolant. You said the temp gauge was pegged over into the red so he will be lucky if he didnt cause damage to the motor. It doesnt take any time at all once its that hot.

As for the heater core, its very possible it could be a leaky heater core causing the smoke through the vents and possible that it caused it to overheat in the first place. But thats not saying he didnt damage other things today when he drove it.

If it is the heater core, it is about a 6-12 hour job to replace it. Easier to bypass it for now as minni said. Hes just gonna have to have someone check it out.

Have him check the oil and tell you what color it is, if its black you are ok, doesnt mean gasket isnt blown but that its not blown in a spot that lets water into the oil. Could still be blown letting water into a cylinder and steam out the exhaust.

Sorry for jumping to the extreme on ya lol, i hope he didnt do any further damage, just have him start with the basics. Find where it was leaking first. The heater core is located on the passenger side behind the glovebox area, if its leaking it will be noticeable on the passenger floor. Have him check his heater valve also, for leaks. Tell him to put water in it and run it and look for leaks, if there is water in the oil, dont start it or that engine could go bad very fast. Water and bearings dont mix well.

minni-me

thanks blue I forgot about the steam I would change the fluids asap! I went high mileage with mine a bit heavier and better coating after over heating

minni-me

pick up a thermostat though youll need one once they over heat they shut once the warm up it over heats again but good luck go cheap to the most expensive things good luck and if you need that head gasket lmk it sitting in my garage collecting dust

k5ranger

Thanks for all the replies. The problem ended up being the coolant tank and cap. Tank busted and sent fluid on to exhaust which caused the smoke. Why it cams in the cab...who knows. He was able to drive 3.5 hours back to base without a single problem.
A big thanks to the Firestone in San Diego , Ca for getting my son on the road in a timely manner. As well as a thanks to all who replied with suggestions and advice.