Another overheating XJ

Yes, I searched... :doh:

My 98 XJ is overheating, I think I have a bubble in the system. I recently flushed it, and changed the thermostat and radiator. I 'had' a blown head gasket, but we put some stuff in there and it fixed it, (cant remember what it was called) this was 4 months ago or so, and untill thursday it was fine.

I realize my head gasket might have blown again, but at this point (because I'm broke, damn Christmas) I used another bottle of the magic stuff. Now I think the head gasket is selaed back up, it was never too bad, not enough to smell, but my buddy has this turkey baster looking thing with blue liquid in it that turns yellow if it sniffs exhaust gasses, so we think we're ok there (for now, I know)

I cannot get this thing to burp!

I have a hot upper rad hose, a cool lower hose, 1 going to the heater core is hot, the other is just warm at best, and no dash heat... I'm not circulating. I have it parked up hill in my driveway.

I pour water/coolant into it till its full and run it till it gets hot --sometimes it will overheat, when this happens the gauge on the dash jumps up fast, not a steady climb, but a POW! hot. It doesn't go all the way, just to the first of the 2 orange lines. If I let it run it will drop back down, not a slow decline either, a BAM! back to 10* over normal wich was 210 straight up, all the time, freeway, off roading, McDs drive thru... Always 210*

--Anyhow, I top it off, run it, wait a few minutes, the rad cap is coolish still, so I pop it and fill it again. I don't think I'm getting anywhere with it though. It takes the water, but never seems to stay full.

What's the trick to burping these things? I've never had so much issues with a cooling system in my life.

Radiators with a cap are self-burping. You don't have an air bubble, you have a neglected maintenance issue.

The heater core ( and maybe the radiator too ) is clogged with magic dust that is no longer "fixing" the head gasket leak, and you need to diagnose and replace the other worn out/failed cooling system components that are contributing to your overheating. The coolant you keep topping off is going somewhere, hopefully not into your crankcase.

The oil is fine, not foamy. I flushed the radiator and the heater core... What's my next step?

The wild swing in temperature is radiator cap opening and closing. I would replace the T-Stat (try a Murray brand made in Israel) and the radiator cap. Make them test the cap at the counter and make sure it works as labeled!!! Many do not!!!! Test the T-stat in boiling water first.

Sounds like the water pump may not be pumping? Have you replaced it?

I just replaced the T-stat friday, but the cap... that came with the radiator a few months back. I just happen to have a cap on my TJ, I'm gonna go try it right now.

Check the overflow line for cracks... replaced $200 worth of parts on my eclipse and almost pulled the head because I was losing coolant and had no.clue where is was going, it was a crack in the line going to the bottle. About every 3 days id top it off with 8 oz of coolant, and it was causing me to be in the lower 230 range every couple days.

Not sure if its the issue but its something to check for free.

I replaced the cap with the one off my TJ, still getting hte wild changes in temp and no heat inside. It's too dark and too cold out to change the T-Stat out right now but the one I took out a few days ago is good, I boiled it.

I'll put it in tomorrow morning and look at the lines again.
Thanks for the help guys.

So I'm looking for some sort of blockage,

I ran water thru the heater core in both directions
Water thru the rad fill cap, and out the T-stat housing
I believe the water pump is working, I can see water movement when engine is on.

I would like to flush water thru the block, not sure how?

Breezio69 said:

Check the overflow line for cracks... replaced $200 worth of parts on my eclipse and almost pulled the head because I was losing coolant and had no.clue where is was going, it was a crack in the line going to the bottle. About every 3 days id top it off with 8 oz of coolant, and it was causing me to be in the lower 230 range every couple days.

Not sure if its the issue but its something to check for free.

Click to expand...

That is something often overlooked!!!!

subaru had a campaign for leaking head gaskets.. they put magic crap in the cooling system that completely blocked the radiators and heater cores.. if your'e lacking funds, disconnect the inlet/outlet hose for the heater core and try to flush it, do the same with the rad.. even a few tubes in each blocked off can screw up the who deal..

Never heard of this happening on an XJ factory cooling system YET, but I had a very odd problem, just like yours on my Nissan Diesel in my 85 Jeep several years back. Every thing except the head gasket leak test implied a head gasket leak, but the test said no. I finally after about 2 years of detective work discovered that the water pump had a gasket seal leak at the head-block gasket face that never leaked coolant under pressure, but DID SUCK in air on occasion (at peak load, peak RPMs on the highway on a long drive at max speed for the little diesel engine), as the leak was on the suction side of the water pump it only sucked air when the water pump was at peak RPMs and the engine was good and hot (which only happened in the summer days under peak load conditions). New water pump and gasket fixed it 4 years ago.

I have heard of water pump shaft seals letting air on some engines!

Dirt22 said:

....I believe the water pump is working....

Click to expand...

I would suggest you confirm this with a physical inspection, especially with an abused/neglected cooling system.

.

skidj2x said:

subaru had a campaign for leaking head gaskets.. they put magic crap in the cooling system that completely blocked the radiators and heater cores.. if your'e lacking funds, disconnect the inlet/outlet hose for the heater core and try to flush it, do the same with the rad.. even a few tubes in each blocked off can screw up the who deal..

Click to expand...

Under normal conditions the "magic crap" does not cause any problems, and it seals tiny leaks as they occur, even from the factory it was a factory fill from before WWII and was still a standard additive in the late 1990s, and probably still is today. But if it is getting inside the system from somewhere, over time it can clog the inlets of the core tubes. But so can the coolant ingredients themselves!!!!!!

X2 on the water pump, ask me how I know...


What does your coolant look like now? Clear, murky, is there build up of mud on the cap?

LYKOS said:

X2 on the water pump, ask me how I know...


What does your coolant look like now? Clear, murky, is there build up of mud on the cap?

Click to expand...

Was not even murkey, looked like a small animal poo'd in the system. It was bad.
Flushed the hell out of it, tried all the obvious stuff, then a buddy come over and said "Dude, pull your water pump"
Being all out of ideas, I did... These things s'posed to have fins on them? LOL, Mine didnt... new water pump and she never ran this cool... seriously 10* cooler than it ever has.

Thanks guys, Now I don't have to ride my harley to work in the morning in the rain! :cheers: