I would flush radiator and back flush heater core.with and without thermostate. Put a new thermostate EVERY YEAR cheap insurance.I would put the CLR in the heater core if it gives you any problem,if you did not buy it new then you may want to feel both heater hoses with your hand and high temp.ether hose cold proubly and a heater core problem,posible thermostate.when changeing water pump time to upgrade,also time to check thermostate housing for rust, pits may be time for new one.I alwways use a new gasket with the bead not silacon.

 

Funny you mention that. I've read up on this lately (quite a bit this morning prior to your post, actually) and saw that a lot of the same advice had been given to other people over the years. The valve cover gasket was one of the first things I replaced when I bought the XJ, and that was back in August. However, I knew then, too, that the truck needed the rest of the work that's been discussed here, so I barely drove it after swapping out the VCG.

While the XJ sat in the basement, it would drip (VERY slowly) a little oil from the bottom of the oil pan, and was doing so as recently as the last week or so. However, since replacing the water pump/fan clutch and driving the Jeep around with some regularity lately, I haven't seen any drippings from the oil pan area. So, I'm wondering if maybe the oil that was dripping was just residual stuff from the bad VCG, and now that I'm driving it around a bit, that stuff's working its way out.

Either way, it's a very minor leak at the moment. Even if the RMS needs to be replaced, I don't think it's an urgent matter. Certainly nothing I want to pay someone to do right now, at least (I've read/watched plenty of material on RMS replacement, and I'm not ashamed to say that it's beyond my tool kit and abilities).

 

They do rent tools.

 

Yeah. And I may very well have everything I need. I guess I should revise my previous post: instead of "tools," I suspect the job is beyond my abilities, and definitely beyond my level of confidence.

 

Which? valve cover or rear main? We can walk you though either one here step by step.

 

Rear main. Valve cover replacement was the first thing I did (with help).

I appreciate the offer. I'm four or five days in without a leak from what I thought was a bad RMS, so I'm just going to keep an eye on it for now. If it comes time to replace it, though, I'll come crawling back for some help. Between you guys and Bleepin' Jeep, I can't imagine there's much a guy can't figure out how to do wrt XJs.

 

New, but related, question for you or anyone else:

After I replaced the water pump and fan clutch (and thermostat and rad cap), I'm pretty sure I added too much coolant during the refill. The overflow tank was sitting at the FULL line, and after I let it idle for a minute or two, coolant began to pour out of the radiator fill spout and onto the ground. It stopped after a few minutes, and it's ran fine since. No leaks (that I've noticed) and no overheating.

I drove it for a little while last night, and when I shut it off it burped a little more antifreeze from the radiator cap again (spilled onto the ground). Not much, but I still found this odd. Could it still have a bit too much coolant in the system, and if so, is what happened a normal result of that? Or should that excess have flowed back to the overflow tank, then vented out from there once it reached max capacity? Can both occur, or am I looking at an additional problem?

 

When you say it "burped a little more antifreeze from the radiator cap", where did this antifreeze go? Into the reservoir as it should? If so, it's normal for air to be finding its way out of the system.

Did it burp out of the cap and leak onto the ground? Then, you likely have a clogged hose to the reservoir or your cap isn't sealing right.

 

Sorry. Edited my last post for clarity. It spilled from the radiator spout/cap onto the ground.

 

Any antifreeze that exits the cap should go directly into the reservoir. Check to see if your overflow tube to the reservoir is stopped up. As the pressure increases/decreases with heat, coolant should pass between the reservoir and radiator freely.

 

My brother-in-law (XJ guy for 20+ years now) said it might be as simple as having not properly "burped" the air out of the system when refilling it with coolant, and that the splashing/overflow was a result of pockets of air being forced out. Sound legit?

 

Tbone shared the facts here... If your radiator cap seals (there are two) are good, then any excess air should also pass through the coolant reservoir when warming up. Then this second seal on the cap creates a vacuum to pull coolant back into the radiator when it cools down. And after a few heat up, cool down cycles there shouldn't be anything coming out from the cap at the radiator at all unless the cap seals are bad.

 

So I checked the hose that runs to the reservoir, and it isn't clogged. I added 50/50 to the reservoir FULL line, then started it up with the radiator cap off and the heat on full blast. After running for a few minutes, the coolant that was visible in the radiator began to rise and fall, eventually rising to the point that it overflowed again. It continued to do this until the temp gauge hit 198 or so, then the coolant (in the radiator) settled back down to a normal level. I let it run a little while longer; no temp changes, and no overflow repeats. The levels in the overflow reservoir never changed.

Thoughts?

 

The only reason for coolant to come out of the radiator cap is that it's not sealing. Either the cap seal is bad, the rad. neck is tweaked, or you didn't get the cap on right. You can't overfill the system. You can overfill the reservoir, but all it'll do is spit some coolant out the breather.

The reservoir level should settle after a couple complete heat cycles and any air is out of the system. When looking at the level in the res. it may be higher when hot vs. cold.