I'm having the dreaded "no heat on the driver side." I posted about this about a year ago and had the heater core replaced. It worked beautifully for a couple of weeks but then went right back to cooler air again.
I've read several posts and they say to check the auxiliary coolant pump which is near the top of the radiator? Unless I'm totally overlooking it, I can't find it. I even changed my coolant expansion tank last weekend and I still can't find it. What does it look like? Where exactly is it? Many thanks.

 

On my xjr, it is under the expansion tank, bolted to the radiator shroud with one bolt. I think that the hose on the back of the expansion tank connects to the pump inlet. You need to remove the aux thank to get it out. You should be able to hear it run when the engine is on. Also, you should get great if you set the heater to max heat and Rev to about 2500 rpm to increase the flow. Brushes wear out our you can replace.

EG.
Many vehicles use similar pumps that may be adapted to fit.

 

I'm having a similar issue, the driver's side gets warm but not hot. I changed all of my coolant hoses back in the summer (except the one that goes under the intake manifold). When you have pulled all of those hoses (including the one from the radiator on the left to the engine, you can see the pump. I never tried testing the pump since it was summer so I wasn't thinking about heat. With the hoses in place, it is almost impossible to see, let alone get to. You can't get to it from underneath either. So not sure how you test if it is running or not (don't know if it will run with the ignition on but the engine off but maybe you can hear it then (can't get your hand to it to see if it is vibrating). The brushes in the pump in my '97 went out; replaced them and everything worked like a charm in that car.

I've seen people post about flushing the heater core with little success, and frankly, I'd prefer that it be the pump rather than a plugged core since while it is a pain to get to, it has to be easier than the heater core. When I changed the coolant, I did a flush of the heater core, but also used a wet-dry vacuum to pull from it (and the rest of the cooling system so when I filled it with 50/50 coolant, it would still be 50/50). Worked well sucking everything out.

Let me know if you are able to tell if the pump is working/running. I need to do the same thing (may try again to see over the weekend).

 

It's in the same place on the NA 4.2 as well. I had to unbolt it while changing hoses but never pulled it out or checked it. BTW, I had a problem getting water to go through the heater core (cold air) for a while, even running at high RPMs. We finally started to get some heat (by accident) after parking it on a friend's steep driveway nose up for a few hours. I guess that angle got rid of some air bubbles that were trapped/blocking the flow.

 

Jim,

I managed to get just a glimpse of it from underneath the car. I'll show pictures of where it is and where to look.

1. First, to locate it, put the car on ramps and take off the cover/shrowd. Use a crawler to roll head first under the front of the car. Spot the oil filter. With that on the left (in the following picture the oil filter is at the top of the picture, but you're rolling in under the car from the left and looking up in that picture), look up through the gap on the right of the filter, and you should just see the hoses and the top of the pump.



Here's a closer view where you can see the pump. In this picture, the oil filter is outside of the picture on the left.



2. With the engine off but the ignition on, the pump does not vibrate. I was able to squeeze my arm/hand up to the pump to feel it. I also pulled the plug on and off and it made no difference. I doubt the plug leads are long enough that I could access the ends with a volt meter to see if power is supposed to be supplied now or not. Something to look at, but I'd love it if someone can respond as to whether they know if the pump should be on at this point or not. If it is supposed to be, then my pump/brushes are bad.

 

dsetter and Gordon,

First of all, thanks very much for the pictures and descriptions; as with so many of us, time got away from from. The Amazon part that was linked says it's not an exact fit for an '05 VDP. However, I've been buying most of my parts from Gaudin Jaguar online. If you take a look at their Parts Diagrams, it looks like Item #5 in the Cooling System/Water pump description:




It's about $78. Do you think that's the one?
Again, many thanks for your help on this; I need to tackle it.

 

No, that looks like the water pump itself. It would look more like #9 (which does not look like it).

 

In the Gaudin catalogue you have to go into the HVAC section and it is item 9 there. Price $151 plus shipping.

 

What he said. This is the auxiliary pump I got from Gaudin a couple of weeks ago.

 

Lagonia, how did you determine your pump was bad? Were you able to check voltage going to the pump to confirm it was getting power but not turning? Or something else? I tried several things and never felt the pump running. I don't know if I can to the plug to unplug it and get tester leads up to it from below. If not, I have to take half the top side hoses off to get down to it. I'f I'm going to do that, I'd sure like to know it is the pump before I take all that stuff off.

 

I had to replace the radiator that was leaking and when I got the stuff out, I realized there may have been a leak from the pump as well (it was cruddy) so I replaced it too w/o testing it. Once I did that and realized that I had heat now (woo! hoo!) I went back to the old pump and applied 12 volts across the terminals with my power supply and the pump did not work.

Testing it in situ may be difficult. Taking it off is really one bolt, two hoses and an electrical connector. The upper radiator hose needs to come off. Not too bad of a job.

 

When I was replacing all of my hoses (except that nasty one that goes under the intake manifold--still got to get to that one), I did the one bolt for better access when changing the heater hoses. I just didn't want to have to take a couple of hoses off (and waste the coolant) just to get to it.

I think I'm going to try to see if I can get leads to a volt meter onto the plug to see if / when I'm getting voltage. But if not, I guess I'll just pull the top hoses, etc. so I can get to it and put more new coolant in.

 

While changing a leaky expansion tank due to cracked bleed hose, I also saw that a number of other hose assemblies were 'puffy'.
I elected to change the whole connection and hoses to the expansion tank
C2C19596
#14 below


https://jaguarpartsinternational.com...gramCallOut=14

While I had the AUX pump out I also checked it for operation as the heat has been rather anemic. I checked the voltage and found it did not have 12V, even with blowers on.

Turned out just the fuse was blown, F8, 10A in the trunk fuse box near the mattery

 

what does the aux coolant pump do? if it stops working will it make the car run hot or is it for transferring coolant through the heater core?

 

what sensor tells the aux coolant pump to start pumping?

 

It runs whenever you have the climate control on, no sensor.

 

​I'm new here. Have an 07 XJ8. Auxiliary coolant pump is at radiator, under expansion tank. On other comments connected to this link asked what it's for. I'm far from an expert but what I read is turn the key on but don't start the engine and the pump should start running. From what I gathered, it sounds like a primer or bypass pump going to the heater.

 

It's not a bypass pump, I would call it a booster pump. Jaguar reliased that at low rews the main water pump driven by the engine does not circulate enough water to have a good heating in the car, so they added the electric pump.

Best regards,

Thomas