98 xj overheating out of nowhere???

Hey this is my first post but I been reading for two weeks and I don't know that I have a unique problem but I don't see anybody else with the same issues....

I bought my 98 xj 4wd about 2 weeks ago. The guy said that it had a blown head gasket but when I looked and saw the factory water pump I told him there was no way it was blown. Anyway I ate those words whether or not the head gasket was blown then or not.

Long story short... He or someone had wired the fan to stay on all the time so I proceeded with my plan. I changed the water pump, thermostat and wired the fan back to factory. Before I done all this the thing would stay on all the time and I would be at 220 on the temp.

Done the work and it work great for about 150 miles. I was coming home and I had just filled up with gas but I thought I heard a spark knock. It was actually pre detonation. When I stopped at the light the steam went everywhere and then the temp gauge caught up to the situation. It pegged.

If the dam head gasket wasnt blown I was sure it was now.

Plan B. I changed the head gasket, upper and lower hoses, and a fresh thermostat just in case.

I had a really hard time getting it cranked but it did and it ran rough but cleared out. Drove it 20 miles and all is well.

Then it pegged again.... I limped it home and decided to change the radiator.

Done that and it seems to be fine but I've only put 10 miles on it. I'm going to drive it some more tomorrow(monday) but if it does it again then I'm fresh out of stuff to do.

Long post I know so I'll summarize.

water pump, thermo, head gasket with new bolts and a machine shop checked my head(had to take some off but I was still good), new plugs and wires, new antifreeze and a new radiator.

You guys are great and I hope I can return the favor

fan clutch?

$50 part, 10 minuts to change... easy insurance.

Hoses seated properly?

Air in the system?

Fan clutch maybe but this is my 3rd 4.0 and it seems to check out good. But definitely a good point.

Hoses are seated good and I use a spill free funnel which allows you to keep a certain amount ready to go when the thermo does open. These are not idiot proof as you can actually overfill the system and its alot like being bloated but you just cant fart...

for the most part I think that all the air is out but I dont know anybody that could tell you all the air is out.

oh it has 158k on it

+1^ for fan clutch and hoses. Then just pressure test the cooling system with the tester(you can pick 'em up at NAPA or Pep Boys or w/e), make sure it holds pressure, if not, check again for visible leaks, and check the seal on the radiator cap-could be as simple as a bad cap. Double check all hoses, including the heater hoses, check the heater valve-they go bad and start leaking fairly often. Check operation of the heater-make sure heater core isn't leaking or clogged...uhm...if I think of anything else later, I'll post some more. Oh, and make sure the electric fan comes on if you repaired the wiring to OE. Check Coolant temp sensor if it doesn't turn on when hot, but fan motor still works and bleed the cooling system VERY thoroughly with the heater on full blast. I notice my XJ gets grumpy and warms up if she has air bubbles in there. If you're absolutley sure you checked everything and it still does it, do a compression test and hope that a chunk of grease or something didn't make a bad seal on the new head gasket

Squeeze the top hose and see how much sloshing is in there.

Thats what we did on mine and its good right now.

thanks for all the advice! Heres the update

I just drove it about 20 miles highway and through the country and it seems to be fine.

I did manage to flat spot one of my tires almost hitting a ford( I was looking at my scan tool)

never got above 210. I forgot to mention that I had to repair the wiring to the temp sensor also. The re re before me just twisted the wires together and why they were cut to start with just boggles me....

I'm going to let it cool down and check the resevoir and then drive it again. I have to work in the evenings and the drive in is with 5:00pm traffic so I really really want to make sure that it is fixed.

the top and bottom hoses are hard. I was always taught that when the thermo opened then the top hose would soften up a little but I might be wrong.

One good thing though is that there is no coolant pushing out. Something that I been fighting for a couple days now. It seems to be smooth but the hoses being that hard with pressure is kinda bothering me...

last one sorry...

Jeepkitty I did do the pressure test while the engine was cold it showed no signs of leaking

During all of this, did the jeep ever sound like it was growling? more like a gurgling?

I had that before and for me it was air trapped in the top hose.

Took the cap off and burped it with a buddy and good to go.

Mine is a 98 also.

possibly you have some bubble in the system.

Sorry for my stupidity, but how would I extract the bubbles? Or is that a sign of something worse? Blown head gasket or something?

Sorry I left ya'll hanging but thanks for all the help. I got effin swamped the last couple days...

It seems to be fine after the radiator swap. I am running 200 as per the scan tool(cheapo from autozone) but it shows to be consistent with the gauge which is staying below 210 just a little.

I did get a check engine light yesterday but it went off. I checked it and it was a cylinder 2 misfire. I havent drove it since I done that because I had another car I was setting readiness codes on.

I'm going to pull the plug and see whats up because I changed the plugs and wires when I done the head job but did not change the cap and rotor. They looked pretty good so I left them but I know they still might be bad.

I actually didnt get quite the deal that I thought as the list seems to go on and on....

rear wheel bearings
trans service(trans shifts smooth, suprisingly but the fluid is brown as can be)
right side speakers not working
possibly an alternator
exhaust( it is literally falling down)

I will post some pics this weekend though and thanks again for all the help

I have a theory that that the radiator combined with the water pump were the original problem.

The guy had dumped the head seal tabs in there which couldn't have helped the situation.

When I changed the pump and tstat it got better but only for a time. I didn't really find any hard evidence the head gasket was blown and was a little skeptical that I figured out my original problem but once everything was back together then it seemed fine.

I went to the radiator as a last hope but like I said it was definitely part of the original problem.

I have read this several times and would like to say it again.

Try and think through and figure out what the real problem is.

I have worked on vehicles for a living and this one got me but if I would have done it right to start with then I think that I could have avoided a head gasket job.

not all my post will be super long but thanks for reading

XJCasper said:

Sorry for my stupidity, but how would I extract the bubbles? Or is that a sign of something worse? Blown head gasket or something?

Click to expand...

When cool take off cap and add antifreeze, squeeze top hose and watch it bubble, add more afreeze rinse and repeat till the thing stops bubbling.

Check where your hoses are clamped, make sure they are seated properly.

MAke sure you check all the fittings. Especially the t fitting if you have a backflow valve.

Thank you.

I will mess with it next weekend.

My 99 XJ has been overheating lately. The overflow bottle was empty so I filled that up to full. Then I took the radiator cap off and did the burping thing but it seemed like it wouldn't really stop bubbling, just pouring coolant out all over my driveway.

The coolant was all murky brown so I'm guessing that's from rust and the whole system needs flushed and filled again with some rust inhibitor.

The oil is fine, it doesn't look like a chocolate milkshake or anything so I don't think it's a cracked head or popped head gasket.

I saw somewhere about overfilling it. That may be the case. I like to think I'm fairly mechanically inclined but I just don't know what to do here. It's my winter beater and it's starting to get cold out.

Could a stuck thermostat be the problem?

Could be a stuck thermostat and that is probably the cheapest part to start with...

How are the fans?

Factory water pump?

Theres a lot that it could be you just have to start troubleshooting

In my case, my thermostat and water pump are about 2-3 years old, but less than 12,000 miles. I am shy on time, so might just have to hook the battery up to a battery tender and let it sit until I can get it towed to a shop.

Thanks guys
Jason