Good evening, gents.

I fixed the wiring on my xjs and got it going again after 5+ years of sitting, and I'm still trying to work out some kinks. One of the things that I'm running into is that even on a highway cruise with no traffic it tries to creep up beyond the "normal" range on the temp gauge, and the aux fan is always on after I turn the car off. I'm thinking my radiator may be plugged, at least partially. At any rate, I'm never getting rid of this car (my parents bought it new, long story. Suffice it to say, it will be with me forever.) so I'm not opposed one bit to investing in long-term fixes. I know some of the members here have gotten nice, new aftermarket radiators that have fit the bill and I was wondering if someone could point me I the right direction to obtain one that will increase my cooling capacity and keep the motor happy! I've thought about a stock replacement or getting mine overhauled (re-cored? I'm not sure what the procedure is.) but if there is a better solution out there I'd like to do that. As always, thanks in advance!

 

Good for you on the car. Just how I feel about mine. The radiator: I sugest you do as follows:
Remove it and clean out the fins, and also VERY important, clean out the fins of the oil radiator and a/c condenser that are in front of the water rad (the fins may be oily so something to dissolve the grot, then blow them out with compressed air). If the fins are Ok and the rad is not rusting out etc. after this, and you can see though all the rad fins easily, then that should do it.


If the rad is rusty and leaky, a re core or a new one is best. In the US Wizard make very good ally rads which will solve all problems, but expensive. A re-core is a good compromise - the rad company uses the side tanks etc, and just fixes in a new matrix, go for a matrix with wider spaced rather than closely spaced fins if you do this.


Also before the rad is out test that the viscous coupling on the main engine driven fan is OK. It should freewheel when the engine is cold and progressively tighten up the drive to the fan as the engine gets hot. These do go bad and it is a wise thing to change it anyway, IMO. Also, to be safe, buy a new hosekit and change all the coolant hoses if they have not been done to your certain knowledge in the last 5 or 6 years.


Also, just thought of this, good plan to change the thermostats for new ones as well. Make sure you get the specially required type for Jaguar V12 ones with the "jiggle pin holes" in the big disc part and the smaller disc that closes off the cross pipe, like this type:http://www.terrysjag.com/product/XJS...S/EBC3577.html
The jiggle pin is in the front of the pic, and when fitted to the car should be at the TOP (12 o clock) position in the thermostat housing casting. The purpose is to allow trapped air to bleed out when the thermostat is closed.
If you do all this and change the antifreeze every two years, the system will be 100% for years and years
Good luck with it
Greg

 

Thanks for the coolant system overhaul procedure, Greg! I'll get those steps done over the winter. I can say for certain that no maintenance of any kind was done while it sat, the short story is my parents sold it to a guy who parked it in a field and I bought it back from him years later.

I was thinking of re-doing hoses and stuff anyway, I'll go ahead and remove the water rad and clean all 3 while I'm at it like you suggested. Is there any reliable/accurate way to "bench test" the water radiator at a shop or something to see if its flowing well, or do you just have to stick it in the car and see how hot it gets after cleaning the fins?

 

It might just need flushing and bleeding properly which is a lot cheaper than just throwing money at it to start with.
Cleaning everything out of the fins is a good start anyway.
Does the auxiliary fan stay on for a long time or does it stop eventually? It should run on for a couple of minutes after switch off if it has kicked in.

 

If you have a genuine radiator shop in your area (a shop that specializes in servicing and rebuilding radiators), you can take it to them for a flow test to see if you need a re-core or just a professional clean/boil/flush.

Once you have gone to the trouble of pulling the radiator...

(which you should do regardless of radiator capacity due to the age of the car. You will be absolutely amazed how much debris, leaves, hair, etc. gets sucked up and stuck in the area Greg referred to. First time I did mine I thought a gray haired cat had died in there.)

...you may as well do the belts and hoses. Replace your fan clutch, and if you have the old yellowish plastic fan replace it with the black plastic version.

 

Steve, The Aux fan runs for a few minutes and shuts off, the time varies based on how long it has been driven (and ultimately, I assume, how hot it is.) It wasn't working before and I replaced a relay and it works just fine now. I drove it last night and it wasn't on when I parked, so that's something I guess. The hoses will need replaced anyway so I'll do those and give it a thorough cleaning first for sure, but I'm more in a "I'll just redo it because I'm going to have the car forever and it will eventually need it anyway" mode which is why I asked about replacements. I like to try and plan ahead (as much as we can with these things, anyway) and wanted to do a little research before I replace it a year or two from now.

Mac, I've got a good shop in the area that has already cleaned out and redkoted my gas tank for me, I should have thought of taking it to them for a flow test. They seem pretty honest and I think they would give me a fair assessment of the condition.

I was thinking about that too, The belts/hoses haven't been replaced for some time. They don't seem to be cracked or anything, but you can never be too careful. I'm sure the car wouldn't complain about a new set of belts.

The primary fan is the yellow plastic one. What's bad about that fan? Again I only ask so that I can continue learning, If you say it has to go then I believe you. I'd just like to know why. Is the black plastic version in a newer XJS, I take it? What years should I look for?

 

Over time and extended exposure to the heat of the engine bay, the original fans are prone to cracking and eventual failure. When they fail, it can get ugly. The black fans use an improved type of plastic.

I would highly recommend, if you haven't done so yet, to download Kirby Palm's book, and read the entire section on the cooling system. You learn a lot about the system, and how to keep it in proper condition.

You'll want to do his recommended placement of additional foam to help focus airflow and keep debris out (very cheap insulation foam from the hardware store).