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Overheat issue

A

austinandtina

NAXJA Forum User
Location
illinois
Hey I have a 94 xj that started over heating the other day so I put a new thermostat in and it was fine until it sat idle then she would heat up. Until this morning when I was going to work I looked down and she was about pegged. So do you guys think it could be air in the system. It does have some nasty rusty milk antifreeze in it but no white smoke and no leaks and no antifreeze in oil so I'm thinking it's not a head gasket. Thanks in advance
 
1. You know you have nasty coolant. You should have flushed the cooling system when you replaced the stat. After flushing, you need to end up with a 50/50 mixture of coolant (I recommend conventional green antifreeze) and distilled water. Never leave tap water in the system.

2. The #1 cause of temp creep at idle is a bad fan clutch. Often ignored, inexpensive, easy to replace.

3. When you dig in, it might also be time to replace the radiator, water pump and hoses if it's been a while. The money you spend on cooling system maintenance is the best money you will ever spend on your XJ. With cooling system, it's pay me now, or pay me a lot more later. If you do the work yourself, replacing every cooling system component is not that expensive.
 
Last edited:
Ok thanks and yes I do all the work myself just bought this xj a couple months ago put new floorpans in it stab links hub units u joints and no trying to address this
 
I don't have a lot of money but I will pick up a waterpump and new fluids and freshen it. Is there a good way to get the fan shrouds out and such or do I have to take the fan blade off first because that's what it looks like
 
Ok, first the distilled water, I have never worked at a shop that used distilled water, it came out of the hose. Unless the water in your area is so full of mineral deposits that it is undrinkable you won't see any problems with proper maintenance. It is completely possible that you have an air bubble, it is also completely possible the thermostat is in backwards. Have seen even experienced techs do that one. Lastly, every part has a proper maintenance interval but replacing the entire cooling system is not the most effective way of solving your problem. If the radiator is working fine, leave it alone. If the water pump is not making noise or leaking, leave it. Especially on a limited budget. Take the fan blade and try to push it toward the engine and then back toward the radiator, there should be no play. If there is, it is in need of replacement. Another indicator is an oily buildup on the clutch itself.
 
Okay ya I was going to flush the system this weekend prolly Fri and see how it goes and thanks for the tip on the fan clutch I've never had to replace those but I sure will give it a look
 
austinandtina said:
Also I've read many different opinions on removing air from the system but what do you guys suggest as the best method
Click to expand...

The 91 and newer 4.0 HO engines are self burping to remove air.

When you get done with rebuilding your cooling system and filling with the proper concentration of coolant, your engine should burp itself of air within about 4 complete heat up / cool down cycles. While these cycles are occurring, you will need to add coolant to the coolant reservoir while it clears the system of air. Be sure to add coolant until the coolant stays at the correct level on the coolant reservoir!
 
Well guys looks like a bad headgasket. So I purchased a new felpro gasket kit, Chilton, and got at it at about 12 today and had some issues with the fuel rail and lines but I just set it aside..couldn't get one of the lines off. Got the valve cover off and broke the rear vacuum lune and front was already broke jb weld fix maybe. I just came inside to warm up a bit 10 degrees outside and no heater in the garage bay. Just in the tool room. So now I'm deciding whether I should take intake manifold off or just unbolt the downpipe. It's just me out there and I was starting to lean towards just taking intake manifold off as long as I don't break the studs off
 
Head is off gasket looked fine called previous owner and he said he replaced gasket but never got head milled or hot tanked. So off the machine shop I flew barely made it before they closed so hopefully it will turn out that it's off a little.
 
Also any idea on replacement parts for the elbow vacuum deals on the valve cover I kinda finished breaking them off. Or is there a good redneck way of making something work. I got them out of the cover completely and there isn't much left
 
Check your spark plugs, I had a perpetually overheating MJ, one day i did a compression test for shits and giggles, found severly worn spark plugs, down to nubs. Replaced with proper gapped autolites, and it runs like a dream.

Sometimes it can be something outside the normal scope of checks.
 
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