RUNNING HOT - Is it possible timing can be off?

I've exhausted every means to keep my 1988 4.0L Comanche cool.
Water pump, thermostat, 3 core radiator, hood vents, Electric fans pulling air, mechanical fan, Water wetter... my Jeep runs hot.

When driving on the road, moving even as slow as 15mph it doesn't heat up. It runs great, it runs fine. Stays at 210, no problem. Sometimes at a red light it will creep up to 220 on a hot summer day.

AS SOON as I get into the woods, and put the Jeep in Low Range and slow down to trail speed the temp begins to climb.
It will quickly climb to 230, 240 and sometimes stay there depending on the temp outside in Ohio. If it's cool, sometimes it will stay there.
Most of the time it will boil over within 20 minutes of being in the woods, but a few trail rides it didn't overhead at all.

It does this only in the woods moving slow.

Is there any way the timing can be advanced?
It's also hard to turn over when starting.. and has a bit of I high idle which I've adjusted down since.

I'm at wits end, I love my trial rig... and I don't want to replace the engine... but I will if I can solve this overheating problem.

I'm looking for clues, answers, suggestions, anything to help?
It seems like it's internal causing it to get hot... not a poor cooling system or fan.

Right now I am in the process of putting 3- 10" pushers across the front
with a 14" low profile Flex-a-lite plastic mechanical fan pulling in back.
This seems like overkill, but I think it'll work.

Could the hood be trapping the hot air when moving slow?
When moving fast the hot air escapes?

There has to be another answer to whats causing this 4.0 to get so hot?

silly question, are you running the closed cooling system or have you converted.
and did you fully burp the system?

the fans will probably help.

Running lean can cause heat issues.

Good O2 sensor?
Injectors clean and working proper?
Cat plugged?

Most of the time I find if I can't get a truck to stop over heating, the Cat is plugged.

Does the exhaust sound high pressure and restricted?

The newer electric fans move more air then a stock 88'
Is the fan sensor on the radiator good?

XJR

Did you drill a small hole in the t-stat? Like the stock one..... Did you burp it? Just did mine (89) Had a hard time burping it, now it runs cool

wolfpackjeeper said:

silly question, are you running the closed cooling system or have you converted.
and did you fully burp the system?

the fans will probably help.

Click to expand...

Silly question? What are you talking about?

It's an open system.

Where is the O2 sensor located exactly?

The exhaust is all new, there is no cat.
The radiator is brand new, 3 Core.

Hole in the t-stat? No.

Burped? It's burped, there is no air in the system.