New to the forum.

I've read in detail about the V12's overheating problems, including in this forum, but needed some more precise feedback from experienced folks.

I have a 1989 Jaguar XJS V12 with 40k miles. The car is in immaculate condition. The engine bay is beautiful. Clean as can be. I'm the second owner, and have only run into minor problems with car (new hoses needed, new seals, etc.)

After reading the below, can you tell me if my car is operating at the right temperature.

When I start the car, it takes a few minutes of idling or driving to get up to the N. Will usually sit exactly at middle of N, or on low side of N.

On the highway, again, it will sit either at the N, or below the N (half centimeter below the N).

In light traffic, this will move towards the top of the N, with top of bar being flesh with top of N.

In heavy traffic, gauge will go to top of N, at some points start to move a taaaaad above it, bar not fully above top of N, and then usually will then pull back to Top of N / near top of N (assuming fan turns on).

This is in May weather.

Even when I push the car, high speeds, high RPM, temperature always behaves, have seem some say "NEEDS TO BE BELOW N ALL TIMES", but have read varying accounts.

Should I - Bleed radiator? Should I add after market fan? Is a lower temperature thermostat fan switch good enough in my case? Do I do nothing?

Appreciate your help guys

 

If there is the slightest doubt about air in the system then, yes, bleed the system. Very important. There's a bit of a technique required. We can give details if needed..

Your gauge readings sound good to me but the instruments can be flakey on these cars. Most of us use a hand held infra-red thermometer to get a rough idea of the actual temperatures as the gauge needle moves up-down. Years and years ago I remember comparing readings with other owners and, for example, 'middle of the N' varied by as much as 20ºF from car-to-car

It's important to remember that coolant temp alone isn't the only consideration. The V12 has a semi-partitioned cooling system so coolant *flow* to *all* areas of the motor is critical.

Cheers
DD

 

Thanks Doug. I'm not a car guy by trade so this is all a bit new to me. Any instruction for a "first-time bleeder" would be welcomed. All I know is I absolutely love this car and want to keep it in the best shape possible. Not the easiest thing to work on for starters if you're not used to a lot of work in an engine bay, but to the extent I can do any of this by myself that would be great.

 

I agree with Doug.


You may consider doing a coolant drain and fill and also make sure the thermo switch/electric fan still works. I have done all of this and my car runs at the bottom of the N or even slightly below. I actually switched out the original thermo switch and went with a new one that switches on at a lower temp.

 

I would also recommend replacing the coolant as a matter of course; unless you have detailed records with the car you won't know how long it has been in there.
Filling and bleeding is quite straightforward as long as you follow the sequence; somewhere in the stickies is a link to Kirby Palm's book (bible more like) on the XJS; an absolute must to download for any XJS owner.

 

Do you guys have any detailed instructions on flushing. Seems like Palm just says to take it off. Was hoping i could drain, flush, refill, bleed, rock n roll

 

Doug has one someplace in the threads that he has posted... Just do a search.

 

Doug, found your instruction on bleeding but not flushing out system. If you guys can help me find where this is described i'll give it a try this weekened.

https://www.jaguarforums.com/forum/x...r-flush-37512/

 

XJSFan - Does the clean rad + aftermarket fan switch check the box for traffic on a hot day?

 

 

I'd strongly suggest you go through the trouble of removing the radiator. Then back flush it with water and radiator flush solution if necessary. If there is sediment there no better way to get it out. Both V12's I've owned had significant about of sediment on the bottom of the radiator rendering 15% of the radiator useless. The out side of the rad probably could use a cleaning too. After awhile the cooling fins get clogged and/or coated with road grime which greatly reduces cooling efficacy. A small electric power washer with a wide spray patter and some soap will clean up the fins quickly.

 

I do not understand what you are asking me?

 

Does the combination of a freshly cleaned radiator and an aftermarket fan switch keep the temperature within normal range on a hot day in stop and go traffic.

 

I agree on all points.

And I've seen the lower 30% of XJS radiators fully blocked by leaves and debris. This external blockage is very common....almost 'a given'.

Remove the rad, clean it inside and out, reinstall, bleed system. Do it once, do it all, do it right....get it all over and done with in one slug.

Cheers
DD

 

It will help but you need to start with a clean/healthy coolant system.

 

Equally important is a good fan clutch. Many are weak.

My personal experience is that the stock XJS V12 cooling system, in good condition, will cope with gridlock traffic until ambient temps hit about 90-95ºF. After that, it struggles and after 10 minutes or so you'll see the needle start creeping upward.

Mine never boiled over...but there were a few times where I was a little nervous

Stop-n-go traffic isn't so much of a problem, IME. It's those absolute gridlock conditions where you're at a dead standstill for 10-15 minutes or more that are a problem

Cheers
DD

 

YES THEY ARE.......mine boils when its stopped for any length of time in traffic...Nearly stopped traffic before the 'bridgegate' affair, last year trying to cross the GW bridge in NY !! Lucky for me there was a place to pull up and wait till it cooled down.

 

Thanks guys - Doing this weekend. Guess we'll know how well it works on the first hot day!

Doug - a follow up. Is there still a discernible difference in well maintained OEM radiator vs. new aluminum radiator?

 

I can't say, sorry. I've never tried an aluminum rad. Others swear by 'em, others claim 'no difference'.

Cheers
DD

 

I would just clean out the original radiator and drop in a 82/77 thermo switch(original is 85C). BUT I do live in Wisconsin and hardly ever get stuck in stop and go traffic. Most of my driving is rural... My 90 XJS, the electric fan kicks in if my temp gauge is in the middle of the N(hardly ever gets there) and usually turns off within 60 seconds. I have to let my car sit and idle for 10 minutes after a hard run for it to get even get close to the middle of the N. I did this after I replaced the original switch a week or so ago, just to make sure the new switch worked. If the fan is running and I turn off the car, it will continue to run until the temps drop.