Overheating Problem

Some of you may not consider the temperature to be overheating. Please accept that I do consider the numbers too high.

Since buying this rig, it has run over or at 200F on a highway at highway speeds. This morning I made another run to town. My return trip always triggers high temps between Kelseyville and my turnoff at hwy 175. Typically speeds are 55-60 mph which is 2600-2800 rpm...ish. As soon as I turn off on 175 my the engine temperature comes down. 175 is a slower, curvy road. Typical rpm's are very low 2000 to under 2000 rpm.

Here is the fast highway temperature right after taking the exit today with ambient temp at 73F.


and after the slow road. Not level or straight by any means. Just slower.


Clearly my Jeep has an issue but not restricted just to high ambient temperatures since this morning was relatively cool.

In chasing down this issue, I asked the previous owner and he said the engine ran at 180-190F. I pulled the radiator and had it rodded out. The shop owner told me the radiator was maybe 5% blocked. I also replaced the thermostat with a 180° version, drilled the 1/8" hole in it to burp air and replaced ever cooling system rubber hose. Yes, my lower hose had and new hose has a coil spring in it. I flushed the block and heater core. All fluid came out as the cleanest, greenest fluid you ever saw. Not a hint of rust.

So at this time I'm thinking of either a water pump/water flow problem or an airflow problem. If airflow, then either a problem getting air into the radiator or getting air out of the engine compartment.
Here is my front view. Clearly the big Warn winch blocks some air.


and the engine compartment. Also clearly the Wrangler dual battery tray blocks airflow around the passenger side of the block.


My next diagnostics would be to remove the winch and drive to town and then reinstall the winch but remove the hood.

So all of the above is to ask a question.

For those with V8 CJ's and winches up front, do you have issue with the engine running over 200F?

 

Make sure the lower hose has an internal spring and isn't collapsing at higher RPMs.

 

You are basing a lot of thinking on a single source of data.

Are you certain the gauge is accurate??? Even just one loose or oxidized connector could alter the reading.

 

Check tension on water pump drive belt. Make sure the belt grabs the sides of the pully and not down in the bottom of the groove.

 

I posted in my initial post that the lower hose has a spring.

One of next things to do is test with my IR gun.

New belts but I'll check. I have noticed that both PS and alt-air comp belts wrap the water pump pulley.

I should mention that due to ARB air lockers, I have an air conditioning compressor that is now an air compressor. So don't think by looking at the engine compartment photo that I have A/C.

 

Oops! I missed that.

Typically low speed cooling issues are airflow problems and high speed cooling issues are coolant flow problems. Look into anything that could effect coolant flow. It's not likely, but sometimes water pump impellers vanes will corrode to nothing or the impeller can fall off the shaft.

That said, winch/hood tests will tell you if it's an airflow issue.

Also check your timing. Retarded timing can make engines run hot. Make sure the centrifugal and vacuum advances are both working correctly. Wouldn't hurt to pull plugs immediately after a highway run to see if you're running lean.

 

I agree with "Fireball" check timing, and fuel mixture.

A water pump works until it leaks, flow is not usually a problem with the water pump.

 

Years ago I had an 83 scrambler with a snow plow on it. If it wasn’t angled properly at highway speed it would overheat in the winter up in Rhode Island. Never had the problem with the plow off, summer or winter. Problem was the same with the I6 and later when I swapped in a 304 V-8. Don’t underestimate the affect of that winch.

 

I would think that the winch wouldn't make much of a difference for cooling, but you could remove it and see for sure. That's probably going to be the cheapest and easiest thing to do first, before you start tearing into the cooling system.

 

I notice you have an aftermarket temp gauge. Where is the sending unit for the gauge located? is it in the same port where the factory sender was located?
I once owned a diesel truck with a similar problem, it had an after market gauge (direct read tube type) not electric. The truck would get up to 225-230 when pulling hard. But at lite throttle cruse the temp would drop back to 195 (had 195 thermostat) I found that the after market sender unit was installed in the cyl head very close to an exhaust port exit. I moved the sender to the original factory port location and the problem disappeared. I guess it was picking up excess heat near the exhaust port when the engine was pulling hard..
BTW, I have big winch on my 304 and never had any cooling problems with a 180 thermostat.

 

The winch isn't optimal, but plenty of people run that setup. Maybe look at the fan, I recently found out my flex fan was flat, I think from crossing deep water a few years back. Changed it, and it really helped. Water pumps wear out also, not apparent to the eye.

 

What are you comparing this temperature to as being hot? 210 is not out of the ordinary for a 180deg thermostat. Pull the thermostats and watch them in water and I believe you will find that they start opening at 180 then are fully alive much higher...

My tbi doesn't even go closed loop until about 210 and Here's what I've been fighting:
20200301_144110 by Joe with a jeep, on Flickr

Your not even above the boiling point of water at sea level.
If it were me, i'ld pressure check the system and run a 14lb cap. Verify timing and then check the plugs for lean indicators. Ignore that guage and listen to the individual motor and what makes it operate best. It's running the same temp as described by the PO off of the highway so unless he clearly says "on this road at this speed" and it's drastically different i'ld just enjoy it since you are far from damage.
You'll love my truck btw, it runs a different temperature between "sport" and "eco" before you even put it in drive.

 

I might have a head gasket issue.

My relative Randy and I extensively tested with the IR gun yesterday. No smoking gun issues to speak of. Mostly the engine was 180-190 when temp gauge was over 200 but the cylinder heads were over 200. We probed the thermostat housing (where I think the gauge sensor is or it's the temp sensor for the FI) the upper and lower radiator tanks (only 5° difference. Hmmm) the heads, and water pump.
Randy also voltage probed the auxiliary/ winch battery this morning. Only 2.7V. Whups, guess that battery is toast. Poor Wrangler alternator has been trying to charge a dead battery. The CJ has a Wrangler charging select switch and I've selected to not charge auxiliary battery until I replace it.

 

Your FLAPS may have a combustion-gas sniffer to check the gasket issue. A vapor bubble could be giving the high readings at the gauge sensor.

 

Not sure if i can help you any but I have heard from other auto sources that the radiator cap should be the highest point in the system. It's possible I guess that an upper hose that arches up and back down to reach the radiator could have an air pocket in it and cause flow problems. Good luck.

 

I may be out of town with what i'm gonna say but it can point thing out.

As other said, check the fan clutch, may have lost force over time.

Engine bay is fully loader up. Dual battery, ac compressor, seem to be a small power steering cooler. Hot air doesnt have many space to go throught.

Also, going to a lower t-stat is not a fix, a lower stat doesnt mean to have a lower engine temp, it can go the other way. I think the oem t-stat is more around 195 than 180. A 195 stat will hold water in the radiator way longer than a 180 will do. At 180 the coolling system is trying to keep engine below 180 and it wont be able to keep up to that temp. The thermostat never close so water only lose temp for the time it need to go trought the radiator. With a 195 the t-stat will more likely open and close. When t-stat close, the water trap in radiator will lose way more heat meaning that when t-stat open, it will bring cold water to the engine resulting in better and faster cooling with a t-stat that close pretty fast so it could get the cycle again.

2600-2800 rpm is a little high rpm for that speed, engine make more heat but may not be able to cool it down at that speed. The water pump is getting high flow at that rpm, meaning it stay less time in the radiator so i lose less heat. Also winch can divert air flow from radiator at that speed.

One last thing but it's not a big problem, that big air filter is sucking hot air from engine bay. Oem filter draw his air trought the front grill, so normaly is sucking cold air.

 

[QUOTE="johneyboy03, post: 1743876, member: 11593"As other said, check the fan clutch, may have lost force over time.

Engine bay is fully loader up. Dual battery, ac compressor, seem to be a small power steering cooler. Hot air doesnt have many space to go throught.

One last thing but it's not a big problem, that big air filter is sucking hot air from engine bay. Oem filter draw his air trought the front grill, so normaly is sucking cold air.[/QUOTE]

I believe that I wrote the fan clutch is new. Also, this weekend, after pulling off the road with engine hot I verified that the clutch is engaging. Further, while at home and engine warm, I verified fan is indeed sucking air thru the radiator as it would suck a rag against the grille.

Agreed. Very confined engine compartment. One radical idea is to buy a used hood and cut in hot air extractors to vent radiator air up thru the hood like the old Ford GT40's. Of course this would mean I'd have a summer and a winter hood.

Agreed again on engine drawing in very hot air. Another potential hood mod for a summer hood would be a cowl induction setup. The fresh air holes in the radiator support are partially blocked on pass side but I could probably use the hole on the driver's side. Very tight in there.

My mechanic has an exhaust gas sniffer. I'll be towing the Yellowjacket in next Monday for ball joint replacement (alignment shop showed me that passenger lower is definitely loose and pass upper is not snug) so he'll test for combustion gases in the coolant.