Haley208

I’ve got a ‘90 xj 4.0 that I’m having some problems with. Back in January a hose from my coolant reservoir split (not surprising I think they were the originals) and my heater valve went out. I was blowing coolant and steam everywhere, it did get to the point where the car shut itself off from being so hot. After letting her sit she fired right back up, and has continued to start every time I try.
Finally out around to replacing the hoses and heater valve yesterday. That fixed my leak but now it’s not circulating. The top (red) hose running from the firewall to the thermostat gets hot, but the line from my coolant reservoir to thermostat (blue) and top radiator (yellow) hose will not warm up at all. And the radiator stays cold as well. My neighbors suggested an air bubble somewhere along the line (which makes sense because the coolant is bubbling in the tank) or possibly the lower radiator hose? I thought maybe thermostat because if it’s stuck open then it’s not getting hot enough to send back through. Any help would be appreciated

Saudade

Hard to tell from your pic as it appears that some of the hoses are not connected (no heater valve)..

However, the closed system is a bear to burp all of the air out.

Some folks take the upper radiator hose off and pour coolant into the radiator it until it's full. Then try not to lose too much when you reconnect it. Some park facing downhill to elevate the bottle a bit more while running the engine (still on the cold side).

You can also vacuum fill it with the right tools.

Regardless of method, it still takes a few hot/cold cycles to purge the air out.

Here's my '88. I used the same colors just to make sure you have it connected correctly. Basically the expansion bottle and the heater core are connected in parallel. The heater valve simply blocks flow to the core inlet when no heat is needed.

Haley208

I posted the wrong picture 🤦🏼‍♀️ here’s an updated one of the heater valve connected. Somebody told me it could possibly be the water pump so I’m going to pull that tomorrow and put in a new thermostat while I’m at it. Going off your pic, I think it’s connected right. We have like no decent inclines so I’ll try pouring it in the top radiator hose and see if that moves anything along. Thank you!

cruiser54

Put a new Mopar thermostat in it.

Haley208

Putting one in today

lawsoncl

X2 on the closed system being a bugger to bleed. I found loosening the temp sensor at the back head works well for letting the air out of the head.

Jim Malcolm

Park nose-down on a steep hill while doing it, if you can. Or jack up the rear as high as you can... Being at the back of the engine, it really helps in getting the air pocket to move to right under the temp sensor...

Haley208

Pulled the radiator because things still weren’t circulating. It was full of sludge, guess that’s the downside they don’t tell you about k-seal. Was able to get a new radiator put on and a new lower radiator hose and now she runs like a dream again. Also slapped on a new water pump and thermostat since I had everything off anyways. Thanks everyone!

Rogue4x4

Thank you for the update WE LOVE SOLUTIONS HERE!!!