Hi, I am a member of the Shriners Organization and purchased my XJS to drive in parades. Drove yesterday in a Memorial Day Parade and the vehicle overheated after about one half hour of driving. Are these just not good parade vehicles or is this abnormal?
Thanks

 

V12 or I6? Also, what year?

The V12 needs a good cooling system. The stock design is mostly fine, but it needs to be in tip top shape. Especially if you’re doing long amounts of time at low speed. There are a couple of write ups here on how to maintain the cooling system, reading them is where I’d start.

 

thanks 4.0 6 1995 facelift 2+2

 

nope. The 6 cylinder facelifts do not have cooling issues.

Either the fan clutch gave out, or the radiator is clogged.

When was the last time the coolant was replaced? Anyone check the thermostats?

If you spin the fan by hand, while the engine is off, how many rotations do you get?

 

The XJS is also well known for debris getting sucked in-between the radiator and AC condenser, blocking the radiator. I have seen them over 50% blocked. If the car is overheating, the first thing to do is make sure the cooling system is 100% up to specification.

 

This was my problem when I got my XJS, this forum helped me. I had at least an inch of hair, leaves, pollen, you name it stuck between the condenser and the radiator. A hose out, a nice bristle brush, never a problem again. Also I had the fan clutch issue it was seized.

 

My car must have spent a lot of time near the beach. I got several pounds of sand out of the fins. After I pulled the radiator out of the car I held it up to the sky and I couldn't see the sun through the fins they were so plugged with sand.

 

Hi, I get very little rotation of the fan spinning it by hand. Coolant and stats replaced a year ago. Front of the radiator does look dirty and kind of tucked up. Can this be cleaned without removal?
Thanks for the help.

 

Effectively I'd say no ...

The fan should move but it is not entirely free, it gets stiffer as it heats up - at least it should.

 

Fan sounds about right. When you spin it by hand (again, engine off) you really shouldn't get a full spin, so I think that's probably functioning.

The auxiliary fan should come on when the engine is hot. Many of us have modified the wiring so that it comes on when the engine gets hot AND/OR the air conditioning is turned on. I wonder if hot weather + slow driving + no aux fan cooling is to blame.

I don't doubt that the radiator fins are clogged either.

 

Thanks I will look into the aux fan situation. Was the wire change easy to do?

 

Easy enough. You'll need a relay.

https://www.jaguarforums.com/forum/x...fan-mod-97626/

 

Unless you know it has been done, I would pull the radiator and have it cleaned out and inspected. Mine was 50% clogged. If you over heat the engine you will have much bigger problems.
There are some good threads about replacing the aux cooling fan with a more capable fan. Sounds like a good option for a slow moving parade car. But you may solve you problem by having the radiator serviced.

 

The design of the airflow through the lower part pf the rad is such that the late 4 litre big-bumper is notorious for cooling problems when the vehicle is stationary or driving in slow traffic.

This is not because the radiator gets blocked or the fans fail, it's because the airflow, particularly with oil contamination from any oil cooler leaks, destroys the cooling fins in the lower part of the rad. They literally just end up corroding and getting blown out. You then end up with a car which runs fine when it is moving with airflow across the rad core. But when you're stationary, particularly with the aircon turned on, there is not sufficient heat dissipation possible without the cooling fins, and the car overheats.

So, pull up the rubber shroud flaps on the engine side of the rad and have a look at the state of the fins in the lower third of the rad. If they look like the attached pic, that's probably your problem and it's time for a new rad. (Ask me how I know!)

Good luck

Paul

 

That is most enlightening, Paul. I have always thought that the big bumper versions must be iffy on radiator airflow.

 

Once you get it all sorted out. Devise a way to prop up the bonnet about 2” up for engine heat to escape fast, while you parade around. Its just a small hack for low speed driving.

 

In a parade yesterday same issue again After 25 minutes car almost reached the top of the temp gauge. Got out of the parade and it cooled right down after driving a short distance. Question? Has anyone used a product called Under 40 in a 4.0 engine and did it help. My reasoning for question is when I worked for Rambler we had 6 cylinder aluminum engines. They ran well for the most part but if the owner ever put an additives in the radiator it ate the engines up. First usually a head gasket but it for worse from there. So I’m a little concerned about putting anything in the 4.0 engine. In reading is seams to work in other cars with overheating problems.
Thanks for any help

 

I did this not sure but it may have given me a few more minutes.

 

I've driven my 96 in neighborhood parades before. Hot days. No AC, top down. No temp problems.

You either need to address the aux fan issue, if you have an issue, or probably recore the radiator. No need to buy a new aftermarket radiator. Recoring will make it good as new, and you know it will fit and connect without any need to be creative.

You can add the Under40, but the cooling system for the XJS is adequate without it. Spend $50 and remind yourself to add it back in anytime you have a coolant system change, or just fix the system you have so you don't have to think about it again.

Not sure where Lansdale is, but if it's in PA, then you have plenty of options. Reading has a radiator shop. Drop it off and you can probably get it back a week later and spend about as much as a new aftermarket radiator.

 

Asked my shop it’s about $500 labor and recore. Does that sound about right?