Hi

I have a 1999 Jaguar XJ8 which i bought in May. Lovely car, comfortable and fantastic to drive.

For the first time the other day i needed to use the heater in the Car as its been getting a bit chilly, but the heater only blew out cold air or at the most a very faint warm air.

Has anyone experienced this problem before or know what the cause could be or where to check

Thanks

MArk

 

Check both the heater control valve and the secondary, electric water pump.

 

Thanks Ken.

Do you know where these are located by any chance?

 

The components are all part of the hose maze under the intake manifold. The valve assembly is sort above the water pump area and there is a bracket securing all this mess to the firewall.

 

Are these located in a different spot on an xjr?? My car is having the same issue.

 

On my XJR, it was the Aux Pump. The brushes were worn OFF, literally, just wires hanging...

I was able to solder in new brushes, thus saving $400 for the new pump. I have heard that there is an Aux pump on a ford that fits this that only runs about $150. Likely, any 12v Aux Pump with the same diameter hose fittings would do the trick.

Mine is located on driver side firewall near fender. 1999 XJR Kinda tight for large hands, but an easy replacement. Remember to pinch off the hoses when removing, or be sure to have the CORRECT coolant on hand, as a mix of the wrong coolant can cause coagulating and plugging of system (So I've Heard).

If you get heat occasionally when the engine is up to temp, then it's probably the Aux Pump. The occasional heat is when the Thermostat opens and forces a small amount of water through the heater coils.

 

Ok.

i've got a new pump for it which im hoping will be delivered soon.

Do Jags require a special coolant as im concerned after reading your quote "be sure to have the CORRECT coolant on hand" that i might use the wrong one and clog up the system?

Thanks

Mark

 

I believe the 99 models use the Dex-cool. Go with the same color that you take out.

 

Thanks Ken

Mine is an orangey colour

 

Do the 98's use the same coolant??

 

Sorry for bombarding this thread with questions but i have just one more!

I am assuming that when i change the heater pump i have just bought i am going to need to bleed/drain the heating system.

Does anyone know where i can locate the bleed valve to do this? or if there is an easier way.


Thanks again

 

I am having the EXACT same problem. Please let us all know if the pump resolves your problem...

Thanks...

 

BTW, I was looking at this on AllData and it appears there is a control valve which allows (or disallows) coolant to flow into the heater core and an electric pump.

So if I understand this (which I may not :-) ), it could be either of those? I get no heat whatsoever out of my 99 XJ8 but the A/C in the summer is awesome. No overheating problems either.

Any tips/suggestions for isolating the electric pump or the control valve as the problem?


Since it looks like the previous owner put in some sort of coolant leak sealant crap in it (judging from the coating of crap inside the water outlet pipe, which I replaced) - I would be surprised if the sealant gunk seized up the valves and/or pump.

Thanks!

 

From what I've gathered on the forums, that "Sealant Crap" may not be, but could be, the result of mixing the wrong coolant with the original coolant. My understanding is if that is done, it coagulates like you describe, and can possibly clog up the cooling system, especially the heater coil which has small tubes which clog easily.

So, in this case, it could be a number of things. Heater coil clogged - diverter valve not operating from being stuck, broken, or not getting electricity - Aux heater pump not working due to stuck, clogged, broken, or no electricity.

On my 99 XJR, I've done a complete (Very Complete) flush of all the fluid and replaced with a good quality 100K coolant off the shelf so that I do not have to find the Jag coolant every time I need to do something to the cooling system. I don't remember off hand what coolant I used, but it was one recommended on these threads. I'm sure a search will bring the results. I also had the sealant looking coating on everything, so I assume the previous owner mixed coolants. I'm sure a lot of oil change/repair shops may not be aware of the danger of mixing fluids, and they just top off with what they have. When I did the flush, a lot of crap came out, I'm assuming from the heater coil, among other places, because my heater now works better than ever. My aux pump was also gooey when I disassembled it for repair (my brushes were worn off, so I replaced them).

To find my problem, I tested the Aux pump when disconnected, and it was not running when I applied power. My next step would have been to test the diverter valve to see if it operated when power/vacuum was applied. (I don't remember which it uses) You could also bypass the diverter valve with a small coupler, if you get heat, you know where to start.

PS: The drain on my XJR is on the lower left of the radiator facing the engine. It's like a wing nut.

 

As a rule, a fault with the heater bypass valve will mean that you can only get hot air from the system. The valve is normally open when de-energised and this allows hot water to pass into the heater matrix (pumped by the aux pump). If you get only cold or luke warm air, then this is usually a symptom of a failed aux pump which will be either seized, burnt out or brushes worn out.

 

My pump seems to be working fine. I energize it and it runs.

I am not so sure about the bypass valve. I probably don't understand how it works but the solnoid only seems to move the valve a little bit (if at all).

I am trying bypassing everything (pump/valve) and see if I get heat.