skmpmm2002

OK I finally have time to re diagnose my overheating issues.
I have the 2004 grand Cherokee WJ w/4.0 engine no clutch fan only electric


So far I have changed the thermostat, changed the water pump, flushed the system( I think I did that right) ,changed radiator cap, added two 8 " fans as pushers and am still getting overheating even when the ambient air temps are 70 degrees.
The coolant was brown when I brought it home.


I am wondering what else to check before giving up.

Any help would be greatly appreciated

Thanks
I gotta get this fixed as well as the rear main seal leak before "the Boss " will let me lift it and get bigger tires....

dave1123

Are you getting good air flow thru the radiator? Bugs and debris will cause overheating. Is the A/C condenser clean?

skmpmm2002

Yes both are visually clean

dave1123

Okay, there is a trick to getting all the air out of the head on the 4.0. What I do is take out the temp sensor on the thermostat housing when refilling the radiator. When coolant flows out of the hole, put it back in and finish filling. Some of the older Wranglers had a petcock in the thermo housing just for this purpose. If this is not the problem, you've got a blockage somewhere. Take the block drain plugs out and punch out the rust behind them. There may be an accumulation of rust scale in the bottom of the block. How did the water jacket look when you changed the pump?

IDK where you're located, but it sounds to me like the PO didn't run the correct amount of coolant/water ratio. An 04 shouldn't be crapped up this soon. I think a chemical flush is in order.

Also, make sure the valve cover isn't leaking and running down the back of the block. This will look like a rear seal leak. If you do change the valve cover gasket, clean out the head oil drains.

skmpmm2002

I am located in central Florida
The engine itself was full of crud on outside when purchased. When I replaced the waterpump and thermostat I cleaned it well before removing as to not get crud into the openings.

It looked clean in waterpump and behind it and same with thermosat.Yes i do have a leaking valve cover gasket was going to change that my next day off.

Block drains are located?? bottom of engine i'm assuming one on each side of block?my haynes manual doesn't show them. I need to find a better service manual.

So after valve cover and drain blocks i'll flush and refill with temp sensor off of thermostat and then back on after fluid comes out. Any other suggestions?

I really appreciate all of the help from the Forum Members. Its nice to have a place to turn other than an expensive shop or dealer.

bigbadon

What is the indication that it is overheating? Is it boiling over into the coolant reservoir? Are both heater hoses getting hot? Is upper radiator hose getting hot? How bad was the brown sludge? If it was the result of neglected OAT your radiator and heater core are probably plugged and regular flush chemicals WILL NOT clean it.

mariner2629

Make sure that your fans are turning in the correct direction the air is supposed to be flowing from the grill to the engine. Dont think that just because you plugged int he factory connection it is running in the right direction. I replaced my fan several times before i realized that the Stealership had the fan running in the wrong direction and all the ones i put in afterwards were also running backwards.
After I got it running in the correct direction my overheating problem was solved.

dave1123

IDK exactly where the block drains are because I've never had occasion to pull them on my jeeps, but they should be a 1/4" tapered pipe plug just above the rounded section of the block above the oil pan. There should be one on each side, usually between the #3 and #4 cylinders. There may be only one.

The head oil drains are in the head just inside the valve cover mounting flange. One in front and one in the rear. Look for them on the corners next to the valve springs. They drain the oil down into the camshaft lifter area and into the oil pan. Some engines only use the pushrod clearance holes for drains, but on V8s, They tend to crap up and cause valve cover oil leaks. If oil is held in the head higher than the gasket surface, it will leak.

A classic example of this is small block Chevy's trait of that puff of oil smoke when started cold. Everybody says "Your valve seals are bad." Not so. Oil is held in the head high enough to cover the valve seals and allowed to drain into the rear cylinders after shutdown. Simply cleaning the drains solves the smoke problem. On the Chevys, this is just a 3/8" drilled hole thru the heads and block. A 1/4" drive extension pushed thru cleans them out easily.

As I've said before, I've owned 2 jeep 4.0s and haven't had the opportunity to open one up yet, so I'm not sure what the drain plan is, but you should be able to tell where the oil drains and weither it's doing so properly. Please post your findings so others will know what to look for.

Mariner's suggestion about fan direction is a good one. It's possible someone got the wiring backwards and the fan is running in the wrong direction. You should be able feel suction in front of the grill when the fan is running. Hold a cigarette near the grill and watch the smoke. The fan is a permanent magnet motor so if polarity is reversed, it will run backwards.

I hope I didn't bore or confuse you with my long post. You're right about the Haynes manual, it doesn't go deep enough into anything, but it is the most available at a cheap price.

skmpmm2002

All (3) fans Two pushers and stock puller in the right direction. I put the two 8 inch pushers and it helps but still not fixing the issue. They are on a switch to manually turn on when needed. But I still get above 240 and and starts to run like crap when in heavy traffic. Next block of days off I'll dig in and see about other stuff.

Bigbadon
As in "overheating" ......gauge reads over 240, idle starts to fluctuate and will stall and won't restart if it gets any higher till temp drops. All hoses are very hot and cannot put hand on them. Not seeing any coolant in oil yet and am hoping to catch before it gets to that point...when purchased the fluid was Brown but not "sludge like" when drained and flushed. Right now it's still light green after about a month........ Any other suggestions to flush the entire system????

Bustedback

Change the radiator, I bet the tubes are plugged.

bigbadon

If upper radiator hose is getting hot as soon as temperature comes up to normal that is a good sign that your circulating water. If your head is cracked on the exhaust side you may not see any coolant loss. The hot exhaust gas will blow into the coolant causing it to overheat. There is a test kit available to check for this.

dave1123

Here's something to try. Remove the thermostat. If it still overheats, you've got a flow problem. I'd be willing to bet Busted is right, your radiator tubes are plugged.

skmpmm2002

Ok I'll try that first.Thermostat's much easier to get to.

dave1123

That was my thought exactly, don't pull the radiator if you don't have to. Years ago when radiators were brass, you could have the radiator "rodded" out, that is cleaned out like a boiler tube set with an actual rod. Today's radiators are so thin, they'll leak if you look at them crosseyed.

Do you know what kind of water was used in the system? By that I mean hard well water? The rad may be plugged up with calcium lime scale, in which case you'll have to fill it with CLR or Lime-away and let it sit for a long while. You could fill the entire system with a 50/50 mix of CLR and water and idle it for a while, AFTER you remove the thermostat. That way you'll clean out the heater core as well. Be sure to BACKFLUSH the system afterwards because anything broken loose can still plug the system if you don't.

On my WJ, the heater hose from the thermostat housing goes into the bottom fitting of the heater, allowing air to escape to the water pump. If it's connected the other way, it can create an air bubble in the heater core, slowing flow. I always wondered why GM used a 1/2" supply hose and a 3/4 return hose, but that way, you couldn't plumb it backwards.

I'm on a well with very hard lime water. I buy premixed coolant and only use distilled water to add whenever I need it. In my house, all the in-line shut-off valves are so crapped up, you can't move them. They are only 20 years old because I redid the system in 1993. The water heater is also 20 years old and I'm beginning to wonder how crapped up that is. When I replaced the old one, it weighed about 200 pounds!

Bustedback

Dave, change over to a tankless water heater. Unlimited hot water and you're not heating 40 gallons of water all the time.