Jtdunn

Hey guys,

I know there are already plenty of threads about overheating, and I have read most of them, but I am pretty puzzled here and really can't figure out why my jeep keeps overheating. Any input would be greatly appreciated.

So my 87 2.5 Cherokee has always had cooling issues on really hot days and in traffic. The car has 110k and runs great other then the overheating. Recently I let the car sit for a month or so while I was away on a trip and when I got back it was overheating almost immediately. I started out by replacing the radiator and installing an electric fan. That didn't help. I then replaced the thermostat and the waterpump and checked the fan clutch. Still no luck. I thought maybe I just bought a bad thermostat or had a blockage so I replaced it again and flushed out the block, heater core and every hose and replaced the coolant temp sensor while I was at it... Still overheating. Initially I didn't suspect the head because the car runs great and there were no signs of coolant in oil or viceversa. I did notice bubbles coming out the radiator when the cap was off but I figured that was just because I had drained and refilled the system. However after waiting about 30 minutes for the cooling system to burp the bubbles only got worse. I finally concluded that I must have a blown head.

Now two weeks later after replacing the head gasket and having the head resurfaced and checked for cracks by a machine shop I am in the same situation. After bolting everything back together the car fired right up and ran great. The problem is I am still getting large bubbled from the radiator cap and the car is still overheating. The only other thing I can think of is that maybe the block is cracked... I really hope not. I was hoping maybe I am missing something very simple. If any one has any ideas I would be extremely grateful.

Thanks,
Joe

Jeep Driver

No coolant loss?????


You installed the correct water pump? there is a CW and CCW pump.


You burped by removing the temp sender?


How is it you have a fan clutch AND a Efan?

What signals your Efan?

Jtdunn

Yea I jacked the back of the car up and burped by removing the temp sensor.

I have the stock mechanically driven fan but I also installed a small electric fan in front of the radiator that I can manually switch on and off with a switch.

I was suspicious of the wrong pump so I removed it and inspected it. Like an idiot I returned the original core before thinking to compare it with the original and see which way the impellers point. But it is spinning clockwise and the impellers appear to be pointing the correct way to be pulling coolant from the block.

Jtdunn

and the only coolant loss is when it overheats and pukes out the radiator cap

Jeep Driver

Do you have the serpentine belt? Of so, CCW.

Firestorm500

Cracked or warped block.

Cracked or warped head.

That's really all it can be at this point.

Whatever happened, it is blown into the water jacket, not the oil passages.

Jtdunn

yes, it's a serpentine driven system and the belt is on correctly (I've tripple checked to make sure)

And yea when the head was off I had it pressure tested and resurfaced so that really only leaves the block... I just figured that if I had such a severe crack in my block I would be seeing some other symptoms or the car would be running poorly. Maybe I will try one of those liquid block repairs and see if by any miracle that works.

Firestorm500

Not all head cracks show up on the bench.

Did anybody check the block deck surface for straightness?

The block sealer will probably seal up your heater core and the rest of the cooling system.

Jtdunn

Yea you are probably right about the sealer. I decided to get one of those combustion gas test instead. Good news is it is not detecting any combustion gases coming out of the cooling system. I did the test three times and it didn't change color at all. I am thinking that maybe I should recheck the waterpump... Again... Maybe it's not circulating and the bubbles are just the coolant boiling.

DFlintstone

Maybe get it up to temp, then power brake it with the bottle pretty full and see if it bubbles.

My 84 with a 2.5 had a cracked head. Usually did OK running around, but any trip ended up being a scene trying to get water back into it. (once in wind so strong water from the jug blew sideways before reaching the filler.

We can always take "Sunshine" here with a grain if salt>>> "The block sealer will probably seal up your heater core and the rest of the cooling system."

Agreed though, that stuff is never the answer except for a tad of Alumaseal for a pinhole in the heater core.

Firestorm500

It's not the water pump.

Jtdunn

Alright, so I am thinking that maybe the coolant is just boiling and it's not bubbles. Pretty sure it's not the block or head, the upper radiator hose gets very hot but the bottom stays cold. So it must be a circulation issue. All passageways are cleared, is there anything that could cause this other then the thermostat or pump?

toasterknight

A clogged radiator could stop flow. stuck thermostat.

Firestorm500

He said he has replaced those one or more times.

I don't see where numerous replacements could all be bad.

Nothing he has done seems to have helped. Therefore, it is something he hasn't done.

Or the head is still bad, even though it has been "checked".

Jtdunn

Hey, so I fixed the problem. Sure enough it was the wrong water pump, impellers were pointing the wrong way. For some reason I was under the impersonation the cooling system flowed the other way. Next time I will be triple checking new parts with the original! Thanks for all the feed back.