I agree. Just wanted another opinion without first introducing bias.

Checking with an IR gun the back definitely seems to run the hottest. However I did pull cylinder one as well and it looks pretty similar.

 

For the heck of it, go back in with RC9YC plugs and see what happens.

 

Well I just pulled the thermostat and went for a drive.. It definitely took longer than normal to warm up but once it did it seemed to give around 205 at idle and climbing about a four mile hill by my house at about 45-50 mph it got a hair above 210. Definitely running cooler but there is obviously still an issue. Anyone know what an XJ should run at with no thermostat? I could try running cooler plugs but feel like that would be another bandaid.

 

I wish you guys would quit pulling the thermostat out, you're not fixing anything by removing it.

 

Duh. Read the whole thread; I was troubleshooting. Anybody have something helpful? Maybe the best reman head? I'd love to get that new aluminum edelbrock unit but there's really no reason for it. Looks like there's a new casting promaxx one too with good reviews. Thoughts?

 

Duh. I was troubleshooting a sticky thermostat. So I'm leaning toward a faulty head. Anybodu know the best reman head? I'd love to get that new aluminum edelbrock unit but there's really no reason for it. Looks like there's a new casting promaxx one too with good reviews. Thoughts?

 

I really think you may be ok and if you're not leaking fluid- just drive it. Whats the worst that happens? You need a new head.

 

Hello,

This is Carlos, I.m new at this. I've read all your questions and all the answers because I'm interested on this subject too. how's your jeep running since you removed the thermostat and are you still running it that way please.

 

I've only run it twice like that and both were short trips used for diagnosis. For having a max cool radiator, hesco high flow pump, and otherwise better than stock cooling system I should be running much cooler with no thermostat. Yet it's still getting above 210.

Removing the thermostat really doesn't hurt anything but it doesn't help either. It takes longer to warm up and enter closed loop so you're going to get worse gas mileage. If ambient temps are cold your heater won't work. If your cooling system is working properly it will never heat to appropriate temps and always run in the startup loop negatively impacting gas mileage by running too rich among other negative impacts.

 

Interesting! Have you hear that there are two different kinds of fan clutches? I know one of them is called thermo and the fan runs loose when the vehicle is cold and the fan hardens when warm/hot pulling more air when it needs it (forgive me for the lack of words) the other one works the opposite the fan it's hard when is cold and when it warms up it gets loose. I hope I'm making some sense :

The reason I say these is because I'm having over heating problems as well, and that's my next move, to get a thermo fan clutch.

What are your thoughts?

you're more than welcome to call me, maybe I can elaborate better over the phone. 951/264-6974 Carlos

 

That makes sense but I haven't heard of it before. What I have heard of some people doing is using a fan clutch from a ZJ (non-max cooling) it pulls harder yet still fits in our XJs. May be worth looking into.

 

Here's the fan your referring to. Actually if your OEM cooling system is in top shape your good to go.
http://www.napaonline.com/Catalog/Re...0038%2b2038004

 

Don't do that. Other than for diagnosing a problem or flushing the cooling system, do not run without a thermostat. It's not there to make your heater work faster, that's just a byproduct of its function.

The purpose of the thermostat is to provide consistent operating temperature for your engine(vital for proper oil performance & gas mileage), and to ALLOW THE WATER IN THE RADIATOR TIME TO COOL DOWN BEFORE CYCLING BACK INTO THE ENGINE. Without the thermostat, your coolant will continue to get hotter & hotter, especially at low speeds. I've dealt with many cars with mild overheating issues where simply switching to a "hotter" thermostat cleared it up, giving the radiator more time to do its job.

OP, stating the painfully obvious, but make sure the thermostat is not installed backwards? Also a long shot, but has the distributor been messed with? If the timing is too high, consistent high rpms(highway speed) can cause abnormally high temps.

You may need a head, but eliminate all the simple s**t first...

 

Pulled my T-Stat Saturday, this is what I found. The one on the left is a MrGaket high flow all brass bla bla busted t-stat. The one on the right is the Napa superstat that I replaced it with. SO far so good but I haven't driven it in 109 degree afternoon AZ heat yet.

 

Thanks for the post. A lot of good info on thermostats. I love simple solutions even if they mean I messed up but the thermostat is in the right way. I'm fairly positive it's not possible to install backwards because the housing won't allow it (doesn't fit).

I did pull the distributor not long ago for an unrelated issue. My Jeep runs so good though I'd be very surprised if timing was wrong. I'd think you'd have to be pretty far off to cause heating issues and then I'd notice misfiring or pre-detonation. I'll dig my timing light out and check though. Like you said I want to eliminate everything else first.