Hey all, as my name implies I'm in Stamford CT. I need one or two O2 sensors replaced, which I just don't want to DYI. More importantly, I have no heat after changing all the hoses. None even at 70mph. Pump should be okay and everything worked fine prior to hose job. So I want some old-timer who really knows the XK8 intimately. I'm assuming somehow I misrouted something, but I can't figure it out. TIA!

 

It is my understanding that the XK8's have a water pump for the heater. Having no heat after changing the hoses you might check to see if you accidentally unplugged the the pump or damaged the wiring harness.
Just guessing I don't know the Xk8 intimately but I am an old timer

Jack

 

I can't say for sure, but I don't think it's the pump as I don't get even a hint of heat at 70mph. Pump supposedly fails open, so should get some heat just from moving even if pump not working.

 

Not an expert nor an old timer but not for nothin…
if by changed hoses you mean the coolant hoses, don’t overlook the tank located behind your (US models) passenger side fender. Open your passenger door and look through the jamb with a flashlight and see if this tank is empty. Or you could pull off the inner wheel well(pretty easy actually) and check it. You might have air in the system and/or an empty overflow tank causing your no heat issue. Or could possibly be another issue. If you do find this tank empty, pop the top off it(after wheel well liner is removed) and use a hose attached to a funnel to put some coolant in it, I think it’s supposed to be about half filled. Then check that the under hood overflow tank is properly filled. Then remove the cap at your thermostat t-housing(front of engine) start the car and put heater on full hot, fan high, no recirculation button on and let it idle till it warms to operating temp, and thermostat opens. If coolant drops down in any of these three locations, add some to proper level. Cap off the t-housing and go for a quick ride to make sure everything circulates. Let it cool down and check all three again. It’s overkill I know, but is fail proof. If problem still persists, check back in and we can move on to next plausible cause. Good luck

 

Thanks! I'll take a look once the snow here quits.

 

This might just be an airlocked heater core.

Ensure the expansion tank behind the front right wheel well is half full.

Old timer trick: Raise the front of the car on wheel ramps or floor jack and jack stands, remove the thermostat tower cap and refit loosely, remove the coolant reservoir cap, start the car and set the heater and blower on full heat. The airlock will not get enough coolant flow to clear it until the thermostat opens - when it does open you will see a visible drop in the coolant level, top up and secure the tower and reservoir caps.

Go drive the car for 2 - 3 miles with the heater running, if you have an OBD2 tool use it to keep an eye on your engine temp (the dash gauge is useless), when you get home let the engine cool and then recheck coolant levels at the thermostat cap, coolant reservoir and expansion tank. There should be no or very little air gap anywhere other than the expansion tank.

One question.....did you test the thermostat before installation ? Not unusual for a new thermostat to be DOA.

 

Interesting possibility. I'll give it a shot. Thanks.