02 Overheating - I Need Ideas

[GeneralJon]

I'm at the end. I got nothin' left. Been fighting to save my Libbey from overheating and I'm losing the war... Any help or ideas please!
Couple weeks ago I notice the temp floating a bit over center where it has ALWAYS been. Nothing terrible, just a little warm, and it recentered when I was moving (I assumed due to airflow). This was 2 days before I left for a 600 mile roadtrip. She was due for a oil change anyway so I checked the coolant when I changed the oil (oil looked good, btw; "Atta girl, not missin' a drop!") and it was a little low, about halfway between empty and the cold fill line. I didn't think much about it and she ran like a champ for the next two weeks. In fact she gave me a bit over 20 mpg average for the trip!
Then about a week ago I took the fam out to our fav local mexican food (about 6 mi away) and I was in the red as I limped her into the parking lot. I popped the hood and she was dry as a bone. I got her home and filled 'er up scratching my head as to where to coolant went. I filled up again, taking time to let it settle then topped it off again. I also replaced the cap (just under $4) The next day on the way home from work the temp went red again. Coolant? Gone. Also, the right side of the radiator was cooking but the left side was cool to the touch. "AaHaa!," says I. Must be that durned thermostat. But that still didn't solve the coolant mystery in my mind.
So I replaced the thermostat then took her for a spin. And, uh oh, that wasn't it...
So I carefully inspected all the hoses and the radiator. And I found a very small crack on the right (facing the KJ) side of the radiator. "AaHaa!," says I. It looks kinda small to lose all that coolant but there goes the pressure on the system! No pressure, no circulation! Right?
So last night I replaced the radiator. Got one brand new from my local stealership (everyone else had to S/O 7-10). New coolant. No leaks. Idled for 30 min and the temp was in dead center. Coolant level good. Not doing the happy dance yet. I took it out on the road and didn't get 1/2 mile when the temp went thru the roof. (censored)
What's left?
The water pump? No leaks, no noise. I haven't opened it up to look at the fins though... But wouldn't the engine overheat when it idles if the WP was shot?
A bad thermostat from the auto parts store? How likely is that? I plan on pulling it out tonight and boiling it just for laughs. That sucker better open...
Blown head gasket? The dipstick looks great. Oil isn't milky. No watery stuff dripping off the stick. Again, execpt for the heat she purrs like a kitten.
Slipping drive belt? Replaced it a Christmas. No squeals. Good tension. Looks fine.
A friend suggested that the timing being off could make it heat up. I've never heard of that before but maybe... But, again, she runs great.
I am going to rent a pressure tester from said auto parts store as well. Maybe there is a leak somewhere else? A pressure leak that doesn't leak fluid?
Please guys, help me out here. Any ideas???

 

[Corwyyn]

You might have a freeze plug that has corroded and let go, I'd try filling it up and checking underneath for any coolant draining out from the bottom of the engine.

 

[tjkj2002]

Just because the WP doesn't make any noise or leaks does not mean it's good,my '96 Tauras was that way.How many miles are on your KJ? I would be suspecting the water pump and/or bad thermostat.Maybe you got the wrong T-stat,most places I have found that say they have it it's the wrong one,best bet is to get one from the dealer(along with the special plastic gasket,can't reuse the old one). Did you properly bleed all the air out of the system,it's not like the older cars where you just add coolant and go,there is a special process for bleeding the air out.Idling the engine is at zero load so may not over heat,under load is when they tend to overheat,also did you take the plugs out of the new raditor? They almost always come with plugs to prevent internal contamination and are easily over looked.Just some suggestions.

 

[indieaz]

Water pumps don't really go bad...that's like saying you have a wrench in yoru toolbox that 'went bad'. If your water was VERY rusty it's possible the blades could have rusted on the water pump/fallen off/jammed it up...but incredibly unlikely.

You are still loosing all your coolant or no after the replacing of the radiator?

Bad thermostat is still a possibility...you can try boiling some water on yoru stove and drop the tstat in - see if it opens up.

I haven't changed the coolant in the jeep yet...but most modern vehicles require the systems to be bled. IF this wasn't done when you added water you could have a big air bubble in there. IF this is true the vehicle woudl slowly warm up, then when it went to cycle water you wouldn't have proper flow...the air bubble gets uber hot...and the temperature will shoot up very quickly. I would be most suspect of this.

 

[GeneralJon]

Corwyyn:
Thanks for your post. Hadn't thought of a freeze plug... I haven't seen any coolant leaking from the engine at all. I've even had cardboard under the engine with no drip marks. And after draining the system twice I haven't noticed ANY rust or artifacts in the fluid.

jkj2002:
I am approaching 90,000 on the original WP.
Funny story (not really), I actually DID have the wrong thermostat initially. Pulled the old one and saw the new one was about 30% SMALLER! I had to make a replacement run and, of course, the store apologized. Then charged me $15 more for the correct t-stat.
About the bleeding; this is plausable in my mind. I read that this system should kick out air on its own so I haven't taken any direct measures to bleed it. I did notice a hex nut marked "bleed" on a part just before the radiator inlet. Not sure how to go about this... Suggestions?
About the plugs... Um, it was getting pretty late last night and I admit I didn't check for plugs in the new radiator. Will look it that tonight!

Indieaz:
I thought the same thing about the WP. The fluid has always looked fine and it is hard to imagine a lot of corrosion in the system without some other indicators. I plan on opening it up tonight to inspect though. I want to boil the new t-stat and it is alot easier to get to without the radiator! Also gonna check those plugs...
Haven't seen any coolant over night. Will look at the cardboard when I get home from work.
Sounds like a good bleeding will go a long way!

Thanks guys! I keep ya posted.
Always open to suggestions!

 

[richre1]

hey generaljon.
ok here is your synopsis.
i am a lead tech for a jeep dealership so ill give you the causes of this problem. the statements that you have made about the waterpump or tstat are true, i highly doubt your tstat is defective if you bought it from a auto parts store not saying it isnt possible but in all my years i yet to buy a defective tstat. second if this problem has been happing even before you changed the tstat radiator and coolant then your fluid is going somewhere.
i hate to be the worst news for you but it is leaning towards your intake manifold gaskets or your head gaskets. more likly your intake manifold gaskets.
my honest opinion to you would be to bring it in to a jeep dealer and have them diagnose it. also the jeep kicks out the air itself so bleeding would not be the problem but couldnt hurt.
the only reason that bleed screw is there is for us to release pressure when servicing a very hot engine but also for bleeding air ocassionaly.
any questions feel free to email me directly at
[email protected]

 

[JeepJeepster]

Your jeep is over heating and the fluid is evaporating. Thats normal..

Youve said so much so Im not sure when its over heating. Does it overheat at idle and when driving down the road? Or when idling.. Or driving down the road?

If its doing it at idle AND when driving down the road, then I would say water pump. Only thing about that, the coolant is not highly corrosive in the liberty, or so I thought.. Possibility that Im wrong. 90k is good for a water pump.. It is in my book at least.

If its doing it when driving down the road, then I would of said radiator.

If its doing it at idle, please tell me you made sure the fan is working. Both high and low speeds.

 

[indieaz]

richre1,

If his intake manifold gasket was blown and coolant was getting into the ehxaust system he's be smoking pretty good - particularly if his entire radiator was draining in what sounds like only an horu or two of driving.

OP: are you blowing bluish/white smoke out your tailpipe?

 

[tjkj2002]

richre1,

If his intake manifold gasket was blown and coolant was getting into the ehxaust system he's be smoking pretty good - particularly if his entire radiator was draining in what sounds like only an horu or two of driving.

OP: are you blowing bluish/white smoke out your tailpipe?

You are right and I haven't heard of many KJ intakes going out like that,my best guess is you need to bleed the system correctly.The KJ cooling system holds like 14 qts(for the 3.7),that's 3 1/2 gallons.Most of the time these new closed cooling systems do not like to "burb" themselfs without some help.

 

[thecause17]

The coolant isn't evaporating...not at a rate that fast anyway...If there isnt a visable leak somewhere, but the coolant is disappearing, it almost has to being burned off, by way of leaky intake mani gaskets, or a head gasket, allowing coolant into the combustion chamber. It was getting into the oil at that rate with that much coolant loss that oil would probably look like hot chocolate. It wouldn't necessarily smoke if that's the case(burning it off). My old Ranger was leaking coolant into the combustion chamber and burning it off...it never smoked, although it wasn't a leak of this magnitude.

If you can get access to a system pressure tester like this http://www.sjdiscounttools.com/sta12270.html that might help you diagnose it. If it's a waterpump, it should show up there I would imagine.

 

[JeepJeepster]

If his gauge is getting into the red, I have no doubt that its evaporating.

If its not getting into the oil(he said his oil looks good), and its not leaking(he said the cardboard was dry), then tell me where its going? It could be the heater-core leaking, but then he would smell antifreeze on the inside of the jeep.

 

[thecause17]

I did say where it could be going....into the combustion chamber and out the exhaust...I've had it happen before, read my post. If you think the engine is evaporating a gallon+ of coolant in a matter of a few minutes I hope you're right, but it's unlikely. Think about how long it takes to evaporate a gallon of water on the stove...and by adding a coolant mix and system pressure to the system, the boiling point of the coolant raises to about 265 degrees F. The last two times I've seen coolant disappear that fast was one was a bad rad cap causing air in the system, and boil over to the overflow bottle, and the other was a bad head gasket pressurizing the system, and again causing the overflow to fill up and spill over empyting out all of the coolant, both only did it while driving and not at idle, and both were very hard to see because by the time you popped the hood the coolant was so hot it evaporated off of the surfaces under the hood.

I hope you're right that it's evaporating because of the heat...but something is still causing it to overheat.

 

[papasmurf42482]

overheating

Just my 2 cents worth but the 3.7 has a dry intake manifold as in no coolant running through it so leaking intake gaskets would not cause overheating. Also I've had 1 of these engines severly air bound before and it can cause these problems. It was a new engine that I built for an 06 Grand Cherokee, still the same 3.7 though. Just open that 10mm hex plug on the inlet on the upper rad hose and let it run and bleed all the air out.

 

[Atrus]

From my experience with other cars, air in the system can definitely make it overheat horribly, so bleeding it helps. I still don't see where the coolant went to leave a void for air to get itno the system. My only thought is the combustion chamber, but if the intake is a dry system as mentioned, than I dunno.

I say external leak despite there being no drips. It's pooling or evaporating or something IMO. Do you smell coolant burning?

 

[indieaz]

From my experience with other cars, air in the system can definitely make it overheat horribly, so bleeding it helps. I still don't see where the coolant went to leave a void for air to get itno the system. My only thought is the combustion chamber, but if the intake is a dry system as mentioned, than I dunno.

I say external leak despite there being no drips. It's pooling or evaporating or something IMO. Do you smell coolant burning?

Unless i'm misreading the OPs post (fort he 10th time in a row...) - he did i dentify a crack ont he radiator which was cuasing a leak. The radiator was replaced, since then he has not seen it acutally leak. He has not indicated that the coolant level shave been low since then, only that it's still overheating. So, it seems to me if the thermostat checks out ont he boiling water test that he probably needs to bleed the system.

 

[Atrus]

Unless i'm misreading the OPs post (fort he 10th time in a row...) - he did i dentify a crack ont he radiator which was cuasing a leak. The radiator was replaced, since then he has not seen it acutally leak. He has not indicated that the coolant level shave been low since then, only that it's still overheating. So, it seems to me if the thermostat checks out ont he boiling water test that he probably needs to bleed the system.

Whoops, misread the OP - I took it as he thought it was leaking but it wasn't as he's still losing coolant. Your view makes more sense.

Then yes, undoubtedly bleed the system. That'll make the temp gauge skyrocket like no other, plus it's free to do, so take a stab at it. Make sure it's up to temp.

 

[myjeepwalks]

any updates?