Above normal overheating problem

[Woodzy]

Howdy! I’m a college student, currently away from home, which is about a three-hour drive. I have a 1998 TJ Wrangler that’s been in my family since I was in middle school. Over the years, we’ve replaced the radiator, the lower radiator hose twice, the harmonic balancer, and a few fuses.

Recently, I blew out the lower radiator hose again, but I didn’t think much of it and replaced it like usual—that was about a week ago. Since then, my temperature gauge has consistently been reading above 210°F. We also installed a homemade shut-off valve for the heater to keep it off during the summer. When I turned the valve to the off position, the temperature, which had been in the red while driving, dropped to about the 2 o’clock position. However, I haven’t been able to get it to idle back at the normal 210°F.

How can I fix this? Could it be the thermostat? And is it safe to drive that distance in its current condition?

 

[ChasUGC]

The most common problem with the Wrangler cooling system is that there is a mixture of different coolant types used in the vehicle. This can cause the coolant to gel, and severely reduces the cooling efficiency and causes abnormal high pressures that can cause hoses to blow and leaks in the heater core and radiator. Check your overflow bottle for the radiator and look for coolant gelling and casting sand or piles of rust in your overflow bottle. The rust and casting sand will settle to the bottom of the overflow bottle. Open the heater core valve and flush the system until it is clear with preferably distilled water. You really don't want to have a valve that prevents the coolant from circulating, because it can allow rust to build up in the heater core. It doesn't hurt to use a coolant flush product to remove rust in the system. Follow the instructions on the product which normally requires letting the system get to normal operating temperatures with the flush in the system. Repeat the flush until the system is clear, preferably with distilled water. Then, fill it with the recommended coolant type, and don't mix coolant types. Burp the system with the cap off, and then refill it to the top. It doesn't hurt to replace the thermostat because that can be clogged too. Use the manufacturers recommended thermostat temperature type. I've lost a few radiators and a heater core because of mixed coolant types in my cooling system in the past. I solved this problem by flushing my system and never mixing coolant types again. Good Luck.

 

[macleanflood]

I'd start with a combustion gas test or a cooling system pressure test...you might have a blown head gasket and you're over pressurizing the system. For whatever reason that lower hose is the weak point....at least my guess. Blackstone also does oil analysis to check the oil...but usually if it's a head gasket it's getting milkshaked.

Are you still using the original constant tension clamps?

Here's some good reading....

Thread 'Jeep Wrangler TJ Cooling System Overhaul FAQ'

Jan 23, 2017

Should I replace my entire cooling system at once?
It's a wise thing to do, yes. Let's say you buy a used Jeep Wrangler TJ with 100k plus miles on it. Well, first and foremost you have to know that as I'm writing this in 2017, your vehicle is anywhere between 20 years old (if it was made in 1997) to 11 years old (if it was made in 2006). Either way, if you have no record of the cooling system having been replaced, then you're on your stock cooling system, and even if the miles are lower, that's still a lot of time for a cooling system. Plastic and rubber wear out over time, as...

• Chris
• Replies: 331
• Forum: TJ Resources

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Thread 'Part numbers and resources for constant tension hose clamps'

Nov 3, 2019

I've compiled a list of part numbers for the constant tension hose clamps for our TJ / LJ cooling system over the last couple of years. Due to various reasons, my Jeep now has worm gear clamps on it and at this time of year when the temps get cooler, I start getting leaks at the ends of some hoses, requiring a little tightening of the clamps. I'm going to be overhauling my cooling system sometime soon, so I thought I'd post up these part numbers and some links. Thanks to @Jerry Bransford for providing a link to Clips and Fasteners on a similar thread on another website...

• MountaineerTom
• Replies: 115
• Forum: TJ Resources

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-Mac

 

[BathiasRei]

I agree w Chas/Mac, pressure test and a few flushes is relatively cheap, easy with a proper funnel and only takes an afternoon or so. While your there thermostat is easy to replace and you can test old one with some boiling water. (assuming head gasket isn't bad)

Have you been leaking or weeping coolant out of the thermostat or water pump before it blew off a hose? Did you burp the system after adding coolant and did you add the right coolant? It seems more likely that the coolant would just bubble through the reserve bottle if you were overheating when it blew out unless the hose wasn't tightened all the way or the clamp was giving out imo.

I wouldn't recommend driving it outside of really short trips as you're risking warping the head along w/ many other issues

 

[TheBoogieman]

I'd start with a good chemical flush and run it for the amount of time specified on the label. I ran mine for 6 hours with good results, and no more running slightly hot.

 

[ChasUGC]

I'd start with a good chemical flush and run it for the amount of time specified on the label. I ran mine for 6 hours with good results, and no more running slightly hot.
View attachment 597583

This^. And follow the instructions like suggested, and flush the system afterwards with water until the water is clear. Clean out your overflow bottle too, as you don't want junk backflushing into your clean system. Collect the initial flush in a bucket and take pictures and post them here. If it looks horribly rusted, then this is likely your problem. Replace your thermostat.

 

[CharlesHS]

Another good cooling system flush is THERMOCURE.

https://g.co/kgs/J3MaAZ2

 

[bohuggabee]

Howdy! I’m a college student, currently away from home, which is about a three-hour drive. I have a 1998 TJ Wrangler that’s been in my family since I was in middle school. Over the years, we’ve replaced the radiator, the lower radiator hose twice, the harmonic balancer, and a few fuses.

Recently, I blew out the lower radiator hose again, but I didn’t think much of it and replaced it like usual—that was about a week ago. Since then, my temperature gauge has consistently been reading above 210°F. We also installed a homemade shut-off valve for the heater to keep it off during the summer. When I turned the valve to the off position, the temperature, which had been in the red while driving, dropped to about the 2 o’clock position. However, I haven’t been able to get it to idle back at the normal 210°F.

How can I fix this? Could it be the thermostat? And is it safe to drive that distance in its current condition?

Hmm. There is a simple hillbilly trick to use. Since you are having hose pressure issues. That means either your clamps fail or there is a blockage to the flow of the coolant. So just flush the system. run 75% distilled water in the cooling system. Then create some leak. Doesnt matter much where. But that extra steam will clean the system . So do it more towards the engine block. Run it. Drive it. Wont matter. Refill. Do it again. Rinse and repeat. The steam will tell you if the thermostat is stuck and it can even fix it if there is gel. If you have an old hose. Put it on. Puncture it. Its a very small hole is all you need. Clean your engine after though.... Steam means flow. Higher flow. From higher pressure will then wash it internally without using any special equipment. It will run the engine cooler. If its gelled, or mineral deposits? You can still displace that into the new radiator hopefully. It deposits where there are cooler areas. Then watch the temperature. If it doesnt run cooler. Its probably the sensor or another sensor. Or heat soak. Could even be injectors losing their seal. It can be many many things.

 

[Artsifrtsi]

We also installed a homemade shut-off valve for the heater to keep it off during the summer. When I turned the valve to the off position…

The Jeep needs to circulate coolant through that circuit, you should not just stop that flow… you need a bypass there, not a valve…