View Full Version : Cooling System Questions?

08-07-03, 09:06 PM
Hi All

Ive been the proud owner of a Dax for a couple of months now, I didnt build it Iam almost embarrassed to say (wish I had) so Iam a little lacking in some areas on its upkeep and maintainence, so if anyone can help me I would be very grateful.

First up the Dax is built with a 1979 Jag 5.3L V12, I have the haynes manual and Jag manuals but reading the Dax buil manual it says the radiator is a custom unit and the header tank is from a Rover so first question, what should the coolant level be in the header tank, I currently dont have any visible fluid there when the car is cold. I checked as the other day there was a little puddle of fluid under the car. This seems low to me.

The next question is having spotted the little puddle Iam now a little concerened I have a leak in the radiator, though I have yet to see any puddles on the garage floor. So I was wondering if the use of one of the off the shelf radiator weld bottles would be a good idea?

The last question is there a published or reccomended procedure for topping up and or flushing and refilling the coolant on a dax, ie should the engine be running, are there any valaves that need to be open etc.

Hope thats clear for all :O) As I say any help would be great.

Many thanks


09-07-03, 01:06 PM
Chris, I used to have 1974 Jag V12 in my Dax. The radiator was from the XJ12 donor, modified by Dax. It had a bleed tap in the top left hand corner of the rad, when viewed from the driver's seat. If you have this you should open it while filling the cooling system. I also opened it after a coolant change recently to get rid of any residual air, with the engine running and hot. Worked a treat. Ian.

Mark Cooper
17-07-03, 11:15 AM
HI Chris,

I also have the V12. After much messing around with a seemingly always empty header tank, I took matters in hand by adding a new tank on top of the passanger footwell and running a new pipe to the old header. I replaced the sprung pressure cap on the old header with a plain cap, and used the pressure cap on the new header.

This fixed the problem of air locking, empty header, puddles under the car from displaced water (when presurised), and pretty much fixed everything coolent related.

The new header is a simple alluminium affair -- very small, because space is limited, but it is an excellent filling point. It is higher than all engine parts so you don't get air in the heads, and it also means that the old Jag E-Type header remains full.

Mark E. Cooper
Impulse Books UK
08707517412 (Fax)