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-   -   Help!!! Over heating 4.0 Grand Cherokee (http://www.jeepforum.com/forum/f310/help-over-heating-4-0-grand-cherokee-1749746/)

Robert1964 11-02-2013 11:46 AM

Help!!! Over heating 4.0 Grand Cherokee
 
I'm brand new to this forum and I'm looking for help. I have a 99 Grand Cherokee 4.0 that is over heating. New fan and relay and radiator recently installed. Drove it a couple weeks with all these new parts with no problem. All of a sudden, it over heats. Fan is running fine and when I opened it to replace the thermostat, it did not even have one. I've put a thermostat back in it and when you crank it it runs great. No water in the oil. But when you crank it, the temperature rises and never stops. Is this a blown head gasket or possibly something else.

new2site 11-02-2013 01:12 PM

Try burping the radiator (although the fact that it was fine for a couple weeks AFTER the radiator replacement wouldn't seem like this would be the problem) If you do see a lot of air bubbles replace radiator cap too if radiator didn't come with one.



Maybe your heater core's clogged up although this shouldn't cause major overheating like you're getting.
Get any piece of pipe with the inside diameter of your heater core hoses and bypass your heater core (join hoses together) and see what the needle does.
Any large hardware store (Home Depot / Lowes ) should have something to fit that bill....plumbing department: pvc,galvanized, or copper pipe...etc..

Robert1964 11-02-2013 02:29 PM

Thanks....I'll try burping it....been sitting a while now so I'll have to charge the battery. But its worth a shot.

michiganmaveric 11-02-2013 02:30 PM

Possibly a bad new thermostat or installed wrong. I would pull it again and see what happens.

new2site 11-02-2013 02:52 PM

Quote:

Originally Posted by michiganmaveric (Post 17375418)
Possibly a bad new thermostat or installed wrong. I would pull it again and see what happens.

Yep...could be...take it out and boil it on your stove...

Robert1964 11-02-2013 03:30 PM

It was overheating without any thermostat in it at all......I've put a 180 thermostat in it myself and yes its in the right way.....LOL....made that mistake once as a teenager and make sure these days not to do it again.

MuddyWJ 11-02-2013 04:41 PM

It's a possibility that you have a busted water pump. It's the only thing left untouched correct?

michiganmaveric 11-02-2013 06:05 PM

Quote:

Originally Posted by Robert1964 (Post 17376586)
It was overheating without any thermostat in it at all......I've put a 180 thermostat in it myself and yes its in the right way.....LOL....made that mistake once as a teenager and make sure these days not to do it again.


Sorry I did not pick up on that it was overheating before. Like MuddyWJ said, check your water pump.

new2site 11-02-2013 06:28 PM

Quote:

Originally Posted by MuddyWJ (Post 17377898)
It's a possibility that you have a busted water pump. It's the only thing left untouched correct?

I was thinking that too..but usually they start leaking profusely out the weep hole..and I assume he hasn't noticed any leaks/coolant level drops.
Possible the shaft broke between pulley and impeller...but not common.


Quote:

Originally Posted by Robert1964 (Post 17376586)
It was overheating without any thermostat in it at all..

I realized that you had stated that after my last post...had a little brain slip.

MuddyWJ 11-02-2013 08:30 PM

Quote:

Originally Posted by new2site (Post 17380018)

I was thinking that too..but usually they start leaking profusely out the weep hole..and I assume he hasn't noticed any leaks/coolant level drops.
Possible the shaft broke between pulley and impeller...but not common.

I was thinking more like the impeller itself is broken. Correct me if I'm wrong but aren't they plastic from the factory.

michiganmaveric 11-03-2013 04:20 AM

Quote:

Originally Posted by MuddyWJ (Post 17382890)
I was thinking more like the impeller itself is broken. Correct me if I'm wrong but aren't they plastic from the factory.

I don't know about factory, but one I got from NAPA was and disintegrated the impellers after about 3 years. Started to overheat when driving 60MPH then would cool when idling. No blades left on the pump.

Robert1964 11-03-2013 12:21 PM

Thanks.....I'll check the water pump first chance I get.......I've never had one loose the impellers but if they are made of plastic, then thats a real possibility.....All my water pumps (on other vehicals) have started leaking out the weep hole first. I will be pulling the pump after hearing this. Its the only thing I have not checked. Thanks for the info and any more info will be greatly appreciated.

McGR 11-03-2013 01:30 PM

The plastic impeller cut loose on mine a few years back. It wasn't until after replaced the radiator and thermostat, that I figured out what was going on. This is not your typical leaky seal type water pump failure. In this failure nothing leaks the impeller simply breaks loose from its shaft and no longer circulates coolant.

Robert1964 11-03-2013 02:42 PM

Now I'm really suspecting the water pump after hearing this......I'll be pulling it tomorrow......Anyone else had this issue? I'm so hoping this is the problem and not a head problem.

rep-tile 11-03-2013 08:06 PM

Quote:

Originally Posted by Robert1964 (Post 17400450)
Now I'm really suspecting the water pump after hearing this......I'll be pulling it tomorrow......Anyone else had this issue? I'm so hoping this is the problem and not a head problem.

I doubt that a busted head gasket would cause overheating; it's the other way around. Now once it gets to operating temperature and the thermostat opens, grab the upper hose (a good idea to wear gloves), you should feel it is under pressure. If that's not the case, that could be a sign the water pump is gone.

IMO it's either the water pump or the CTS is giving you a wrong reading (in that case it's not overheating). You might want to get one of those IR thermometer and check the actual temperature at the thermostat housing and compare to the gauge reading on your dashboard.


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