I've recently purchased a 98 XK8 done 63k miles. After reading all the warnings here, and having confirmed by the dealer (Jaguar) thatthis car had not had the necessary upgrades, I decided to go ahead and have them done.

So I've just had the secondary cam tensioners, water pump and thermostat replaced with the recommended repacement units, to give me piece of mind.

Hoever, one issue that is worrying me is the heater. Although it is the middle of summer here, a test of the heater has shown there is a problem with something in there. (Heater, hoses, valves?).

Even after 20 minutes of round-town running, the heater never raises above warm, even if theswitch is set to maximum heat.

Yet as soon as we hit motorway speeds, or the engine is revved, the heater starts throwing out good heat. When the car is slowed back to slow speeds or stopped at the lights, the heater quickly reverts to mildl warm at best. The mechanic who did the upgrade work today also flushed the heater core at the suggestion of another member here, and in the process he discovered that the valve between the one of the two hoses on the firewall only opens when the engine is revved. If the engine is revved that hose gets hot, but as soon as he let the engine run back at idle, that hose cooled significantly.

He thinks it could be the sticky valve sitting betweenthose two hoses,but won't know for sure until this unit is removed and opened.

Before we go to further expense I thought I'd ask here if there is a known issue, and ifthis valve is a replaceable part?

Or could there be another cause that would only raise it's head at low engine speeds?

I'd be gratefull for the congegated wisdom's thoughts.

Bruce (Bruiser)
New Zealand

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I believe that's why these engines require an auxilliary coolant pump, and that yours has failed.

 

Thanks JagtechOhio

Theonly Jaguar agent in Auckland, NZ,charges like a wounded bull!

They quoted $1550 for the upgrade parts and $2,200 labour ($110 hr+)for the upgrade work I've just had done by another large automotive centre who actually did the job for $1,100. The parts I sourced from asupplier who deals in both new and secondhand jaguar parts in a town some 80 miles away. His own driver is a 2000 XK8 convertible, and heis currently parting out two 97-01 XK8's, one with lightfire damage around the front-rightheadlight, and the other was in a nose-to-tail. Both were written off by the insurance companies due to the airbags having deployed, apparently this makes them un-viable asrepair options. His new genuine Jag parts are typically 25% cheaper than the ******* in town.

Before I go down that road, would you recommend the huge cost saving I can achieve by buying asecond-hand auxillary coolant pump (if the supplier has one)?

And is there an easy way of determining if this is what is causing the problem?

Where can I find this pump? I assume it's in front of the firewall behind the engine itself?

Thanks for your assistance,

Brusier

 

It's low on the front bulkhead, at the top of the transmission tunnel. Easiest quick check is to listen to it with a stethoscope, you will hear its motor running if it works.

I wouldn't hesitate to replace a failed pump with a tested used component. You can search around for generic brushes and modify them to fit, I have read posts by owners who have successfully repaired failed units.