Found my leak !question is what is this part called ?1990 xj 4.0 aw4 (closed system) It's got a small vacuum line going to inside the cab passenger side. Need to replace this whole set up due to the top hose leak. If anybody knows thanks in advance. I need the upper hose fitting on the tank, with the vacuum cannister attached. Don't know what this is called? Someone have a part # is it available ?

 

Pretty sure it's the heater control valve and lots of folks here have eliminated the valve and plugged the vacuum line. The Factory eliminated it on '97 up XJs.

 

Yep that's what I'm seeing so far guess it's not too complicated 3/4. And 5/8 fitting? I don't want constant heat would this be a problem after the bypass fix?
Thanks!

 

Subscribed for the fitting sizes so I can be prepared to delete mine without multiple trips to the store. )

 

Cut the valve off the tube. Splice a hose in.

 

Thanks for the help on this guys -cruiser, thanks for the pics too. It actually started leaking from the (top hose )from that permanent metal fitting.
So I'll be doing the bypass today.

 

My cool air and AC work just fine after deleting the heater control valve so dont be worried about that unless your blend door (or whatever it is called) is stuck open to heat.

 

Good to know its pretty hot here year round don't need any extra heat .

 

Just an update,
I originally went with Napa brand Heater control valve,for my 90 closed system for a quick fix.
"Fail army" it started leaking a few blocks down the road! Had to have it towed back to the house also.
Now it's bypassed and runs much better... So it's tight for now. I kids regret not going to the hardware store and not getting nice brass Tees though. So today I learned that even new parts can fail.

 

Get new cut-to-fit hoses and get rid of the tees

They are different sizes, btw

 

I had to splice my heater hose when I had to replace the rusted out bypass tube off the water pump. I originally used a plastic fitting that I got off of the dorman help rack that was made for this purpose. It lasted a month before it started leaking. It actually melted from the coolant heat. I replaced it with a metal one and its been fine for a year. The point is, dont trust a plastic fitting for this purpose.

 

Your cooling system must get REALLY HOT!

If plastic were bad in cooling systems then why are radiator tanks, heater core tanks, coolant pipes, water control valves, water pump impellers etc commonly made from plastic on all sorts of cars directly from the factory?

I think you got a dud.

Cruiser, thanks for the tip.

 

Just glad I eliminated that piece of junk .
It used to knock sometimes when the fluid would get low , and I couldn't figure out wher I was losing fluid old heater valve,was the the problem..
Now it's almost too quite.

 

I meant not to trust the aftermarket plastic hose unions, get the metal one. Yes my jeep runs at 210 when hot. It softened up the plastic (melted) enough to make it crack. When I removed it I could see that the nipples were melted and distorted. It was a dorman part made for that purpose.

 

What tip?