I replaced my valley hoses, which went pretty smoothly. But now I have no heat. I have burped the hoses numerous times, both hot and cold, cap on and cap off. But no improvement. The lower hose feels to be less pressurized than the top and easy to squeeze. Any tips greatly appreciated.

Also, after reconnecting everything, I found one plug left over, shown here. I don't recall disconnecting it and can't find a receptacle for it. Is it some sort of diagnostic plug? Can someone identify it? ( The car is running beautifully.)

Can't find his mate.

 

The heater has its own electric water pump - it looks like that might be the supply connector.
Check out RaceDiagnostics thread for how to find it https://www.jaguarforums.com/forum/x...val-how-96841/

 

Thanks, Stumpy. Part of my mystery is that the wires on the plug are pretty short. Don't think they could reach the pump, but I'm lookin'.

 

It looks like that connector is not used in your car. It is professionally plugged with those green inserts.

I have quite a few connections like that.

With my XJR I refill the coolant with the nose of the car higher than the rear, on ramps, and with the heater set to as high as possible.

 

Start by double checking you routed the hoses correctly to the heater valve. From memory, "supply" is at the bottom, "return" is on top.

There are 2 plugs by the brake booster on the firewall. The white one is to the heater valve. It defaults open, so you can disconnect it to test.

Next, check the heater pump fuse.

Next, identify the heater pump relay (one end of the "T" of relays on the engine compartment fuse box).

Next, test resistance of the pump (needs to not be infinity) to the ground. This tests if the brushes have failed. Pull the relay, 87 should be 12V, 30 is the pump. Check resistance between 30 and the ground.

Next, test the motor runs. Do a shunt wire between 87 and 30. You should hear the pump run, but it is very faint.

Next, test if the impeller runs. Remove as much fluid from the overflow tank as possible (a turkey baster tool works great for this), then run the pump again. Check that there is audible gurgling.

Next, check the hose to the heater core. The one with the one-way valve is designed to work with a kink in it. Check it is not collapsed.

FWIW, I ended up at this point with no heat, and all tests passed. As a last resort, I did a good garden hose cleanup of the core (flush and back flush of the core only, at the firewall, with some radiator cleaner) and heat came back with a vengeance.

Best of luck, keep us posted.

 

Fmertz,
Wow, great stuff. I'm sure one of the suggestions will cover my problem. Thanks!

 

Good idea. My driveway has a bit of a tilt.