I thought I'd take the time to write my experience of the XJS aging and maintaining. Sure I'd like pointers but this is more for the over all cooling and maintenance issues and the deterioration of over time.

After purchasing I drove my 1990 XJS for one summer just as a Sunday driver for the most part. Like most of these cars I experienced overheating issues. Fans working properly, I would bleed out the cooling system almost every time I took it out. Being new to the scene I wasn't sure with what I was doing and what to expect. Bought a new Jaguar set of thermostats and they made no difference when installed. I could get the car to run cool for 100 miles or so but sure enough the temp gauge would creep up. A few times I could hear the coolant boiling as I parked it in the garage. This past summer I decided to jack it up and go through the cooling system which lead me to many more issues. If you own one of these cars with the V12 and it hasn't been kept up on here is what I'd expect to repair before calling it "road worthy".

~ Radiator pulled and brought it to a radiator shop. Mine had debris clogging up the bottom 25%. Surely enough to cause overheating. Radiator is in good shape however, just a steam clean as it pressure tested fine.
~ Header tank had a crack leaking coolant under pressure.
~ Water rails (this is a biggie) the more I looked the more problems I found. Water rail pipes showed signs of corrosion and seeping at the pipe gasket. I took them apart, replaced the pipe with stainless steel, cleaned up, new seals. I modified the front passages to reduce the water flow hopefully increasing flow to the rear where obviously it was running hot. The gaskets at the rear were leaking as well. The modification wasn't quite done to the specifications I have seen ( 4mm and 10mm hole at the passages) instead I found stainless 5/16 washers and took a small router with a carbide wood bit and cut out the shoulder of the passages to set the washers flush to the surface. Epoxied the washers in so now even if the epoxy fails the washer is held between the gasket and passage port. This should increase water flow to the rear by 40-50% I assume
~ Intake gaskets, I was able to remove the bolts to the Intake manifolds by putting socket on the and turned them out by hand. No wrench needed. They weren't really even snug. Obviously leaking. New gaskets.
~ Thermostats, even though I replaced them last year I replaced them again with Moto Rad 180 degree stats. These are fail safe and they claim to move a considerable amount of coolant more than stock ones. I tested them in a pot of water with the stock ones and they do open faster and further creating a bigger passage for coolant flow.
~ injector seals, what injector seals? The back half had none of the smaller seal that goes to the intake manifold. New seal kit, no problem.
~ Air tubes, the back three on each side were clogged with the old injector seals that melted. Cleaned them out with a drill bit and air hose as well as where the connect to. Should work properly now.
~ Coolant hoses, replaced all of them. At the high side of the heater hose I added a brass T fitting. This will allow me to fill and make sure I don't have a air pocket in the rear from now on.
~ Heater valve, using Kirbys advise I replaced it with the plastic one he recommends.
~ Fuel rail, all fuel hoses and pintles replaced.
~ Air Cond deleted. Kirby recommends a hole in the front bracket to help move air. My AC hoses are shot, I live in a decent climate so I decided to delete the AC entirely. Lost about 60lbs and opened up the "V" nicely.
~ Cam cover gaskets, they were leaking at the rear pretty bad.
~ V belts, replaced
~ Spark plugs, replaced and properly gapped, new mag core plug wires
~ Distributor, New cap and rotor. Old rotor was cracked. Cut off the brass post and filled void in cap with silicone as per Kirbys recommendation to prevent a Marrelli fire.
~ Coils, 2 new ones


Next on my list;
~ Dual electric fans, again saving weight and increasing air flow. There is a company I found on EBay that sells a nice kit, aluminum shroud that fits Chevrolet trucks. This shroud is within 1/4" width as the stock one and 1/2" in height. I might see if they will sell just the shroud so I can choose my fans, the kit is about $200 which is half the cost of most designed for the XJS, although I will have to make my own wire harnesses.

~ Swirl pot for the cooling system.
~ K&N air filters and I intend to make my own cold air intakes
~ Exhaust, I plan on a set of high flow cats, resonator delete, and muffler upgrade.

Now the cold weather is setting in so she will be on the road next spring. Hopefully running as cool as a cucumber and a little more pep in her step. I think the combination of the repairs, loosing two pulleys, shedding a few pounds, cold air intakes and freeing up the exhaust will really make this kitty pounce.

 

Really good maintenance, very effective I am sure. Congratulations. Have you got a link please to the fan and shroud kit you mention?
Greg

 

Here it is. Not quite the one I was looking for but I'm sure I can make the shroud work. http://vi.raptor.ebaydesc.com/ws/eBa...=1479053448032

 

Blockage across bottom 25% sounds on a par or better than most! Amazing how little maintenance poor radiators get. I recall all the horror stories out here in hot Australia of boiling early E-Types. Best upgrade we did once we acquired our S1 E was to chuck the old core (7yrs old from new, 33% blocked) and re-core with new and thicker multi-tube core. Could not pick it from stock once header tanks/shroud refitted and never again (in 37yrs) had a single overheating problem.

Similar experience with V12 VDP, and I expect to do same with recently acquired S3 XJ6 and XJ-S. Yesterday on the coast here, temp reached 36C (97F) and this is still Spring! For us, as in say Arizona summers, starting with a top shelf radiator is mandatory . . . and minimizes temptation to flirt with lower temp (or no) thermostat. Your cooling needs may differ, but IMHO, clogged radiators are yet another penalty for mothballing but not flushing cars across long winters.

No . . . not decrying the mothballing . . . for many, your climate makes that sensible . . . but, after hibernation, how many owners multi-flush the entire cooling system every year before use?

Cheers,

Ken

 

I spent the last three years going over ALL the wiring under the hood/bonnet on my 1984, and replaced all the things you have plus some, I have differant posting on the project with pictures

 

So you are telling me you have done nothin to the brakes?

I've rebuilt the rear calipers and master cylinder, though my car was parked for 13 years.

Interesting to see anyones take on those dumb coolant rails. Mine weep but they look like they will be a PITA, so I ignore for now lol

 

I had the rear calipers replaced last year. We have yearly inspections here in Pa and the mechanics usually are pretty strict about those types of issues so my guess is the fronts are good.

The water rails really aren't that bad. There are some that claimed they replaced the seals and pipe without removing the manifolds but I would certainly recommend doing it all since the rear gaskets are prone to leaking.