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Overheating on the interstate...

S

St3mpy

NAXJA Forum User
Location
Daphne, Alabama
I have a 95 manual 4.0 xj, and at highway speeds I always overheat. When ever I get on the highway speeds, I can watch the temprature steadily rise until it hits the red zone. Usually I end up stopping at a gas station to let it cool down. I also overheat while offroading too. I was thinking maybe a blown head gasket, since I loose coolent, not very fast though. I usually have to refil the overflow bottle once every month or two. I don't see it being burned in the exahust though, and I'm not too sure on what coolent in oil is supposed to look like. I don't have any signs of coolent on the ground though. I havn't done any work towards this, meaning I havn't replaced the radiator, cap, ect. Any thoughts?
 
Years ago, when I had the legendary GM 5.7 diesels blowing head gaskets, I would remove the radiator cap(when cold of course) and start the engine. The coolant would imediately have bubbles in it if a gasket was blown. I know the XJ radiator cap is way off the the side of the radiator, but have you tried that? Have you checked your radiator to see if its plugged up with bugs, leaves, debris, etc.?
 
First things first. Replace the cap with a new 16lb one. This is very common.
 
Is this a stock vehicle?
 
Nope, no bubbles, but my coolent is pretty dirty. Guess I should have looked into this more before I made a thread about this, oh well. I'll flush the system and relpace the cap and see if that helps.
 
St3mpy said:
I have a 95 manual 4.0 xj, and at highway speeds I always overheat. When ever I get on the highway speeds, I can watch the temprature steadily rise until it hits the red zone. Usually I end up stopping at a gas station to let it cool down. I also overheat while offroading too. I was thinking maybe a blown head gasket, since I loose coolent, not very fast though. I usually have to refil the overflow bottle once every month or two. I don't see it being burned in the exahust though, and I'm not too sure on what coolent in oil is supposed to look like. I don't have any signs of coolent on the ground though. I havn't done any work towards this, meaning I havn't replaced the radiator, cap, ect. Any thoughts?
Click to expand...
If you have a bad cap and continue to add tap water you will soon plug the system. If you need to add water more the once per year, find out why.
Always add distilled water so you don't add deposits
 
St3mpy said:
Nope, no bubbles, but my coolent is pretty dirty. Guess I should have looked into this more before I made a thread about this, oh well. I'll flush the system and relpace the cap and see if that helps.
Click to expand...

I'm going to guess you haven't regeared for the 31's (I haven't on mine). So what gears are running and is this a stick or auto?

Kent
 
Simple en-expensive check, thermostat sticking closed, buy a new one under $10. Water pump bad will generally be bad all the time and leaking out of bottom of pump through the weap hole.Only the fan system to look at after this being the system " supposedly" does not overheat all the time. Manual fan clutch can be rocked back and forth front to back to check for bad bearings, should be no play front to back. As for the water, "tap water will not plug your system" Myth , B.S. Never used distilled water in any rig I owned including a 1977 van with 650,000 miles on it, original radiator. I am leaning towards the intermittent sticking thermostat.
Good luck with your mission.
 
As for the water, "tap water will not plug your system" Myth , B.S
Click to expand...

True in some parts of the country but, it sure will if you are adding make up water all the time as OP stated.

True in some parts of the country but, it sure will if you are adding make up water all the time as OP stated.

Water TDS’s (Total Dissolved Solids) as they are called varies greatly across the country. If you live in town and have a Municipal water system the TDS’s and PH are controlled.

I’m sure you have heard of so-called Hard Water most water is the US is hard water. Where I live the water is so hard that if my Hot water heater lasts 3 yrs it’s doing good, so I figure if my tap water can plug/ruin my hot water tank in three years I don’t want that water in my radiator.

Every time you lose water in your system through a “bad cap” any solids that’s in your water stay behind so every time you add more water you add more solids.

Raw water from your own well can be totally safe to drink but can be very corrosive. I can’t even wash my car with mine because it leaves spots or streaks.

So IF you have treated water it is just fine to flush and Fill your radiator with, but if your adding water monthly it will plug your radiator
 
MACH90XJ said:
Simple en-expensive check, thermostat sticking closed, buy a new one under $10. Water pump bad will generally be bad all the time and leaking out of bottom of pump through the weap hole.Only the fan system to look at after this being the system " supposedly" does not overheat all the time. Manual fan clutch can be rocked back and forth front to back to check for bad bearings, should be no play front to back. As for the water, "tap water will not plug your system" Myth , B.S. Never used distilled water in any rig I owned including a 1977 van with 650,000 miles on it, original radiator. I am leaning towards the intermittent sticking thermostat.
Good luck with your mission.
Click to expand...

If the thermostat was sticking closed, why wouldn't it overheat all the time, not just at highway speeds ?
 
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