97 Sport 4.0
141K miles
New Radiator
New Rad Cap
New Hoses
New T-Stat

I just swapped out the radiator with new one from NAPA, changed T-stat, hoses, & cap and bled for air pockets. I did this as she was overheating when I turned the AC on. Temp was running 210 and then would do an IMMEDIATE jump to 250. She'd cool off and be good for about 5 minutes. Driving distance is only 6 miles to work and I MIGHT hit 50mph once.

Everything ran good for 1 day. On my way home, all of 5 minutes into my drive, I turn on the AC and she squeeled like a pig in heat and 1 minute later IMMEDIATELY jumped to 250. I pulled over let her cool off and finished my way home. She hit 250 again just as I pulled into the driveway andboiled over the relief tank...the fan come on as the should, there are no obstructions, and all the hoses are piping HOT, as should be

I've read a lot of the posts and cant seem to find one that matched mine...I need some help here...I'm mechanically inclined having grown up fixing cars, but have NEVER (knock on wood) had his issue.

 

how's your water pump impeller

 

change the water pump, check the lower radiator hose. It should have a spring inside to keep it from collapsing under pressure stopping coolent flow.

 

I'll be changing out the water pump and putting another new tstat in just in case.

As for the lower rad hose...it's good, and NEW.

Thanks!

 

Thanks guys, I also have a hard time finding a specific thread for my various xj issues.My xj has the same problem. I have tried the following:1. New rad. 2. new t-stat (195). 3. New Elec fan. 4. Very thorough flush at a rad shop and a new cap and new 50/50 mix. 5. New coolant temp snsr. I looked at a new water pump, but it seems like a good strong design that cant really wear out, other than the bearing maybe, so I checked how well my pump turned and if it wobbled, and it seemed fine so I left it, now it runs very hot still!!! temp was just below the red today, no a/c on and short drive. The ONLY damn thing left to do is the waterpump! which doesnt look like fun.

 

^they're not that bad...


Has anyone ever tried an air/water separator? My 97 has a similar issue but does fairly well when I'm not using the A/C. I've often wondered if that might not be the solution. We all know the rumor that the 4.0 creates air pockets in its head and these systems are designed specifically for that issue; although typically that's a product of a water pump spending time at high RPMS. Here is a universal system a company I'm familiar with provides to the drifting community. We spend a lot of time in high revs so its a necessary addition for dedicated track cars. The concept can be applied to any cooling system though. The system is only $60 and can be found here



and a diagram of how it works.

 

^No one wants to touch this? I'm going to install one on my motor and see how it turns out. I know it hasn't been discussed before; surely.

 

OK all, this is a little late, but I've been out enjoying the driving! I swapped out the TSTAT, Water pump & clutch fan. I was thinking that it could have been the TSTAT, but as I inspected the water pump (it was the original one), the interior blades were pretty worn out. Most likely in my case, it was a combination. The clutch fan...I probably could have by passed, but since I was already in there, I just went with it. She's now running a cool 190 under everything but HARD uphill driving.

Thanks for all the input and advice. VERY appreciated. Next up...why have my power locks stopped working with the remote (though new batteries) and the Cruise....