98 XJ
4.0/AW4

Bought the Jeep August 2012. First thing I did was flush the radiator, new antifreeze, and thermostat.

Ran perfect.

Overheated April 26. The endcaps sprung a leak on the radiator. Took it out.

Bought a junkyard one November 2nd that looked to be no more than a year or 2 old.

Put it in last week. Didnt run it much since it was about out of gas.

Saw today it had a small pinhole leak directly infront of the fan spraying a small stream.

Put some Bars Leak Heavy Duty in it. Wasnt leaking. Was running good.

I was happy.

Let it get up to running temp, and then I sat in it for a few more to make sure it wouldnt overheat.

Guess what? After a few minutes of being a tad bit over 210, it shot up to 250 and I immediately shut it off.

Any ideas what it could be?

 

The passenger side end tank of the radiator and upper radiator hose was hot, but the drivers side end take and lower radiator hose were cold.

 

Gauges shortly before overheating

 

Ouch.

If temp shoots up suddenly, I think there's a good chance there is an air pocket somewhere.

 

That stop leak stuff wasnt my first choice but I cant afford another radiator right now. Plus I know my father has used a few times through the years and says it works good and has never had a problem.

How exactly would I get the air pocket out?

 

Let it idle with the rad cap off, keep the rad full, it should burp when the stat opens. Make sure rad is full before installing a new rad cap. Check coolant level in rad and bottle next several days, motor COLD.

 

Don't sweat the Bars Leaks. You will get a variety of opinions, but it is proven good stuff. Burp it, watch it, run it. And yes, replace the cap.

 

Thanks yall. Ill be sure to do that tomorrow and get back to you. I really hope thats all that it needs.

 

Any chance it sounds like possibly a headgasket? Just asking.

 

Not immediately. You can watch your coolant reservoir bottle once engine is at operating temp. Continuous air bubbling up in there would suggest a continuous air 'leak' into the system, such as can be seen in blown headgasket.

In all honesty, a new to you Jeep with overheating issues is worth overhauling. Especially with you guys in the US, for around $250 you can almost completely renew all cooling components if you want (I know you stated cant do the $$$ atm), something that would cost several hundred $$ here. Investing in coolant system maintenance is probably one of the best things you can do for your Jeep to keep it going for a long time.

 

I'll be the second to say "ouch" on the stop leak. It could cause you more problems down the road. My jeep was crudded with stop-leak so bad I had to replace the entire system and even rusted out freeze plugs on the side of the engine. So, because of my experience, I'm extremely against stop-leak!

But, it sounds like your thermostat isn't opening. Might be worth a check.

 

Dont let it get hot too many times those heads tend to crack easily under temps like that. Stop leak is understandable when on a tight bugdet, but in the long run you will wish you never done it,

 

OP states his upper radiator hose is hot. So strongly suggesting his thermostat is opening.

Lower radiator is normally cooler than upper (if your radiator is doing what it should). If it feels cool as you (the OP) stated, the radiator might actually have a good blockage.

 

Oh right, my bad. Had my hoses flipped around

 

I did a compression test today. Probably doesnt have anything to do with the overheating but its reading really bad.
60
100
45
100
145
155

So yall think I have a blockage in the radiator causing me problems? I completely flushed it out before I installed it.