[clint357]

I have a 1993 XJ 4.0 that runs below 210 at 40-50 mph. When I get on the E-way at 70-80 it runs up to about 230-240. I do have a winch on TOP of my bumper. Any ideas before I take the winch off this weekend?

 

[Chris99XJ]

Maybe that winch in restricting air flow ???

 

[HarleyMama]

Change out the Thermostat to a 160, add and extra cooling fan to the radiator and mount a control switch to the dash, this way when you see the temp rise you flip the extra fan on and off as needed.
Works great.

 

[sQUEAK003]

burn it

 

[Lothos]

sounds like the t-stat is messed up actually. replace it with the right one.

 

[PavementPounder]

Change out the Thermostat to a 160, add and extra cooling fan to the radiator and mount a control switch to the dash, this way when you see the temp rise you flip the extra fan on and off as needed.
Works great.

Don't do any of that shit.


You're driving a 14-year-old vehicle. The first thing you need to do before you do anything else is take a close look at the radiator itself and see how many fins are missing. The winch is blocking air, but it shouldn't make a difference like that - especially at speed when there airflow is significantly increased.

What's happening is that when you drive faster, the coolant is being made hotter bythe increased rate of combustion in the motor and also circulated faster through the radiator. The faster it goes through, the less time there is to cool the coolant. If the radiator's cooling capacity has been reduced, the vehicle will overheat every time you drive faster and cool down when the rpms drop and the coolant stays in the radiator longer.

If any fins are gone, replace it. It doesn't matter what the fuck else you slap on your vehicle's cooling system if the radiator is not taking the heat out of the coolant. Start there.

Don't change the thermostat to something that isn't supposed to be there. XJ's are intended to run at a NOT of 210. If you change the NOT, the motor will not operate as efficiently. I don't know why people think that lowering the operating temperature of the motor is the solution to cooling issues. (Probably because its cheap.) You solve cooling issues by increasing the vehicles cooling capacity, not by making it run colder.

 

[Kawierider]

First and foremost, check your coolant. Low coolant will def. give you 'weird symptoms' like, overheating.

Next I'd check the radiator. like PP said. If the outside looks good (no mud, missing fins, etc) and the inside looks good (coolant not nasty colored, no corrosion, etc)

The T-stat is an option, Replace with a 195 degree t-stat, which is OEM temp. You prob can run a 180 but there is no reason to really do it. DO NOT take out the T-stat and run w/out one. The opening and closing of theT-stat, and the restriction it provides slows the coolant and gives it time to cool in the radiator.

FYI, your engine monitors coolant temp and partially bases your fuel delivery on this temperature. At colder than 195 temps it will probabley pump in more gas which is great for power on modded engines but not so good for fuel economy and emmissions.

 

[scorpio_vette]

X23562514516

everything that was already mentioned

1)fix stock cooling system. the stock system handles temps fine
2)upgrade/improve cooling system if required

3) DO NOT PUT A BANDAID ON YOUR COOLING SYSTEM. it's cheaper to fix the cooling system than to damage your motor, loose fuel economy, etc..etc..etc..

common problems on XJ's. clogged/bad radiator, stuck/faulty thermostat, worn water pumps. and while you're at it, i like to ask people when was the last time they changed their radiator and heater hoses. usually the confused look means "never.....should they be replaced???".

 

[Lothos]

dont forget tranny lines for those with integrated coolers. I need to do mine as a matter of fact, but its such a mess.

is there a benefit to replacing stock heater hoses with braided ones?

 

[PavementPounder]

is there a benefit to replacing stock heater hoses with braided ones?

Yes, they reflect the moonlight beautifully when you overheat in the dark.

 

[Lothos]

Yes, they reflect the moonlight beautifully when you overheat in the dark.

cool, i'm going to get a set right now then.

 

[sQUEAK003]

y noy burn it.....its funner

 

[clint357]

Thanks PP, That's what I was thinking is that there isn't enough heat transfer from the radiator. I figured that I was going to have to get a new one, but I wanted to make sure that there weren't any little tricks that could get me out of the overheating without pulling the rad. I am also running a full tank of straight water right now, so with actuall coolant it would be into the red. I'll take a closer look at the fins though for bent ones or mud or whatever though. Thanks guys.

 

[71jeepster]

Thanks PP, That's what I was thinking is that there isn't enough heat transfer from the radiator. I figured that I was going to have to get a new one, but I wanted to make sure that there weren't any little tricks that could get me out of the overheating without pulling the rad. I am also running a full tank of straight water right now, so with actuall coolant it would be into the red. I'll take a closer look at the fins though for bent ones or mud or whatever though. Thanks guys.

Coolant actually helps run cooler not hotter, straight water could be part of your problem as well.

 

[clint357]

so, who has a radiator for me?

 

[clint357]

I'm pretty sure water has a higher specific heat than coolant

http://www.cbrforum.com/archive/threads/water-vs-coolant-in-radiator-for-track-day-16633-1.html

 

[PavementPounder]

Coolant actually helps run cooler not hotter, straight water could be part of your problem as well.

I'm pretty sure water has a higher specific heat than coolant

http://www.cbrforum.com/archive/threads/water-vs-coolant-in-radiator-for-track-day-16633-1.html

That's correct. Coolant raises the boiling point of the mixture and lets it run hotter. If he had coolant in the radiator, it would allow the motor to get a lot hotter before overpressurizing the system, running a much higher risk of damage. By using only water, he has created a "fuse".

 

[Lothos]

water is the best coolant. coolant is merely to prevent the mix from freeze as well as prevent corrosion and blockage.

 

[zjkid]

water is the best coolant. coolant is merely to prevent the mix from freeze as well as prevent corrosion and blockage.

coolant also raises the boiling pt. like PP said.

 

[Motor Slut]

By using only water, he has created a "fuse".

And he runs the risk of eating his waterpump, destroying the radiator, and possibly killing his headgasket.:woot:

If you are going to run water at least run distilled water with water wetter. It will save you $1000's in engine and cooling system damage.