Jeep Wrangler Forum banner

Hot in 5th gear?

4K views 14 replies 8 participants last post by  Nubby55 
#1 ·
Ok forum this is not one I have seen ever on the forum.

I have a heat problem at 55mph and above if I go into fifth gear even at 1500 Rpm's to 2000rpms I start to over heat if I am in fourth or less than 55 I stay right around 200 to 210.


I do have a dual core radiator brand new it does have plastic so it is not all aluminum with new 13psi rad cap and new coolant. It is not an electric fan but the clutch for the fan is brand new. The fan shroud is one I cut to fit from a s10 or small dodge pickup.

I have flushed out the system no more rust new water pump and thermostat I have a DANA 44 in the back with 4.30 gears running 32's

I have burped it and removed all air pockets

Do I need to go electric fan or a 3core?

I would like to drive this to the beach and right now I would not make it in my opinion.


Chief
 
See less See more
#2 ·
Are you running a 50/50 mix? If so you might try just water. It has better heat transfer properties than the glycol in antifreeze.
 
#5 ·
Chief

When you out the fan clutch in did you get the fan back on pulling air in the right direction?? My thoughts this is a weird one.

Hope you get a fix.

Jokerchief
 
#6 ·
The reason I ask is up to about 55 the fan pushing air forward may the be overcome by speed and the lower RPMs reduce pump output
 
#7 ·
I don't really understand the description of your problem? Are you considering 210 "overheating" because it isn't... That's pretty spot on for normal operating temperature. Your thermostat opens at 195 degrees, and it will remain above that for the most part which is what you want.

Have you pulled any codes? Do they mention anything about being overheated? Because there is a code for that if my memory serves me right. Has the cap blown off puling antifreeze into the overflow? I guess I just don't understand your description. If you are saying you get to 210 on the highway in 5th gear I'd say it's pretty normal. I find it hard to believe you "overheat" going down the highway at 55, but have no problems idling or sitting in traffic.

Also the temp gauges aren't accurate.
 
#8 ·
One more thing, plain water may transfer hear more efficiently, but mixing antifreeze 50/50 raises the boiling point. And if it boils lower it blows off lower and you lose coolant, which is way worse than the lost efficiency by adding glycol. Plus it creates a hell of a problem in the winter if you are in a state where the temp goes below freezing. Not to mention the glycol lubes the pump, etc.
 
#9 ·
Joker chief yes I checked the fan by putting a towel in front of the grill it sucked it in good so I am thinking my air flow across radiator is good especially since I can idle in heavy city traffic and barely get above 210 with heater running on high.


Snowgoer I am saying it is overheating in high gear because I can watch it go up past 210 almost to the redline in the gauge when I will exit off the Highway and get out of 5th into fourth or lower and then proceed to watch it cool down to 210.

We have a belt line around the city with exits about every 2 to 3 miles so I can test it very well.

So I also changed all the temp gauges as well forgot to mention that this was a project when I got it so it had no radiator no fan and thermoStat was bad.

I agree this is a strange one which is why I am reaching out I have tried all the normal things like air bubbles and water pump.

Chief
 
#10 ·
I am thinking I may pressure test the radiator to make sure I am not clogged I know it is new but perhaps there was residual crap that got in and blocked the radiator.

Also wondering about the bottom hose for the radiator not sure if it is collapsing on me I do not remember for sure if their is a spring in there to keep it open.

I found a really old thread about this same issue others were having they finally went to a dual core all aluminum radiator and that fixed it so I may be going that route.


Chief

Chief
 
#11 ·
It almost seems like your thermostat is staying closed longer than it should and then when it opens you're fine. I recently went through 2 thermostats in 3 weeks in my 89 4.2. The first one was bad. There should be spring in the lower radiator hose. There are no codes for an 89, so that's out. Running 210 is normal. I also agree that you could have a bad water pump impeller. I would say replace or check the thermostat and make sure there's a spring in the lower hose. If that's ok then I think you have to look at the water pump.
 
#12 ·
Ok so I did some research on the spring in lower hose supposedly that is only needed for factory installation if radiator fluid they use a vacumn system to pull coolant through and the high pressure vacumn needs a spring in lower hose to keep it from collapsing after factory; spring is no longer needed due to lower pressure 9-16psi for normal operating pressures.

Says newer hoses do not come with spring for that reason so if lower hose collapses then you have issue with radiator cap or a clog somewhere in the system.

Now I think I am more confused rather than less!

I am very sure water pump is good and running in correct direction I have a serpentine belt and yes I have a rev direction brand new water pump.
So I am leaning towards a clog some where.
 
#14 ·
I replaced all of the radiator, heater hoses and thermostat in my 89 4.2 last month. I bought the hoses from Quadratec. I gave you incorrect info. in my previous post regarding the lower radiator spring. I just checked and I don't have a spring in the lower radiator hose. I don't have any issues. On the hottest days I run at approx. 210. My hoses don't collapse. If you're not actually overheating, which you would be doing going into the redline, maybe your temperature sending unit is bad or you still have air in the system causing your temp. sending unit to react like that. This seems like a unique situation. I'm stumped at this point.
 
#13 ·
So you can cruise at 55 in 4th all day no problems. But shift to 5th, stay at 55 and it starts to over heat.

The only difference is now you are at a lower RPM. Maybe you are really lugging the engine and it is dumping gas to move you in 5th. Causing it to run hotter and your cooling system can't keep up.

What RPM are you at in 4th at 55? Go that same RPM in 5th and see what happens. Depending on tires may still be lugging
 
#15 ·
This a one of a kind, have the coolant checked for gas, your head gasket may be leaking under hard work on the engine.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top