I'm having a similar issue. I inserted an inline rad fill cap and plugged the resevoir to act as overflow. Reaced 5/8 hose for heater lines and scrapped the
Heater control valve (purpose of this?) but when it warms up it stays hot. Occasionaly on startup it idles excessively high but will cease if I wait or restart. Are you saying that heat issue may be t stat issue?

 

Could be a possibility, unfortunately. Although for the longest time, the air box square hole on the front has been covered with cardboard, by the previous owner. I only recently removed it, since I've been using my snorkel. Dirt really couldn't be causing this problem, or really adding that much of a factor though, right? I'll check the filter to see if there's much, but what do you think?



Thanks

 

Does the missing cap leave the end of the filter element open? If it does, that's not good.

 

So I'm checking some guides out on eliminating the HCV. I can't seem to find a straight guide. Just posts on people wondering if they should do it. I know 97+ XJs eliminated it, but what side effects should I expect? So when I buy new hoses and replace them, where are they going, once the HCV is out of the picture.


Thanks

 

The 3/4" hose goes from the t-stat cover nipple to the large nipple on the heater core (at the firewall). The 5/8" hose goes from the water pump to the small nipple on the core. Don't forget to pug/cap the vacuum hose. The side effects are less chance of heater core plugging up due to no circulation thru it for months at a time, less places for leaks to occur, less hose clamps, cleans up the engine compartment a bit.

 

So I removed the HCV, I pretty much had to. I was going to remove the hoses, but while my father was helping me, the top hose connector on the HCV broke, lol. So I ended up following this diagram and it seems to have worked. Drove around with no issue. I also noticed on the hose that is on top next to the radiator hose, that's pictured on the first page, had a slit in it, which was causing the leak.

 

Not sure if that's a pic from a '92 FSM but, it says the same thing as the '98 FSM, "plastic tanks....stronger than brass tanks....".

 

I think that's a 97 in the diagram. Found it on JeepForum and saw 97 labeled around it. Which wouldn't that make sense? Since the HCV was removed in the 97+? I don't think anything was damaged, had a little hard time with one of the clamps, but other than that it's all good.

 

Reading through this post is like Dejavu!
This overheating / leak is EXACTLY what I found on my 95 XJ - right down to the crack in the hose!
I would like to add my 2 cents worth though. have a look at the hoses going in and out of the heater core. I found mine were blocked with residue.

I need some help though.
I read somewhere that you should "burp" this system. Due to the upper radiator hose running a path that takes it higher than the filler cap - it can capture an air bubble?

Does anyone here know how to burp the system?

 

I used all new hoses. Bought 4ft of each diameter that was recommended here and they worked great. I also would like to know about burping the system, lol.

 

Fill the system with coolant, let the motor idle with the rad cap off, keep the rad full of coolant, continue to idle until 'til top rad hose is hot and coolant/air burps burps out of the rad, install new rad cap. For the next couple of days, when the motor is cold, add coolant as necessary to both the rad and recovery bottle. Check weekly, motor cold.