The rad cap has 2 valves and 3 sealing surfaces....al must function correctly in a "coolant recovery" (open) type cooling system.

 

Ok, I'm ordering parts to pick up today.. Thanks for input.. Fingers crossed..will report back

 

Replaced rad cap, and t stat, still over heating.. Lot of grunge build up in the t stat housing, as well as large hose that connects to he housing. When I pulled the housing there was what appeared to be copper looking build up or rust, or whatever on the inside... I'm sure can't be good..

 

Have it flushed?

 

Grunge doesn't form overnight. Try a flush but I doubt it will do much good. Once a rad is grunged up, it usually has to be taken apart/rodded out or replaced. The heater core is the same way, may/may not get it clean by flushing. Make sure heater core and motor are flushed as good as possible BEFORE installing a new/clean radiator.

 

I'm a heat real technical here... When I removed the housing that holds the t stat, you could see the coolant in the engine, it looked like rusty stuff, so don't know If it's actually rust..Almost reminds me of a crusty fungus, if there is such a thing.. . Is there a way to clean/ flush all that out? Have no idea what the internals for the rad looks like..

 

I bout some flush from Walmart, not sure that it did much good

 

No, no no, go to a shop and have them use their machine to flush it out. The shops with good machines help a lot....they pump the flush fluid through the entire system then suck it out several times, then they fill it up with nice clean fluid, typically runs about 60-100 bucks. I had mine done for like 65 and it helped a TON! You shoulda seen the crap that came out of mine.

 

Yes yes yes... Dang it! I was hoping to avoid that... Problem is what if that don't fix it then I have to buy a new rad anyway?

 

Well in my opinion I start cheap, go for a flush...that's the firs option, go to a rad shop and have them rod it out...that's a second option, or buy a new rad...3rd and most expensive option.

 

Even if I buy a new rad it wouldn't clean the engine part out..

 

That's why you start with a flush.

 

With both the t-stat and water pump removed, u'd be surprised how well a garden hose stuck in the t-stat hole will clean/flush the head/block. Again, coolant doesn't turn rusty over night, years of neglect does. If u replace cooling system components all at once, u only have to drain/refill once. Coolant should be checked on a regular/frequent basis.

 

So there's a sizzle sound by the battery? You may have the same problem I had before I replaced my radiator..

The stock radiator has plastic tanks. Over time, the plastic deteriorates and becomes very brittle. Here's a pic of the problem I had with my old Rad.
Here you can see the upper radiator hose fitting crumbled into a zillion pieces.



I'd say your rad is probably shot... So with that in mind, you should replace the Rad, the water pump (because it will start leaking at some point too), the thermostat/housing, ALL hoses (yes even the heater hoses), and also I'd recommend replacing the heater control valve. The heater control valve (depending on the year your XJ is) is either plastic or steel. The steel will rust, and the plastic will crumble/crack.

it's better to just get all the parts installed at once. That way, you dont gotta go through 4 "coolant flushes" a year like I did

 

'97 up XJs don't have a heater control valve.