Hi guys,

I have had two instances now where my 1985 XJS HE V12 almost overheats climbing up a rather large hill near my house, that stretches for a few klms upward. Last time she did it she got a little over 3/4 way to the H on my temp gauge. I pulled over and my atmospheric overflow (mine mounted in my engine bay) was a geyser and I had to let her rest before I went back down the hill. Admittedly it was a 32 degrees celsius day so that didn't help none.

After some deliberation, and some experienced advice, Clarke (o1xjr) and I are going to undertake the mission of getting her back on the N when I come back from overseas in December. So, I've got parts coming and have a game plan, here it is:

* Remove Radiator and take to professional to get it flushed and leak tested.
* Swap out thermostats (82C) for new ones.
* Replace a few of the main radiator hoses
* Get my pressure cap tested, to see if she is good for 13PSI

I wanted to start this thread and see if you guys maybe could add your 2 cents in before the project. Any advice is greatly appreciated. As mentioned I wont be tackling this until next month but getting parts and ideas together now.

Will also be posting results and details here along the way.

Thanks in advance

 

Good luck with the project, a few points to consider:
It would be better get the rad recored, if funds run to it.
Ensure the oil rad and the aircon rad in front of the water rad have their fins cleaned out and the oil and crud that builds up in the gap removed.
15 psi rad caps, not 13.
If you have the mechanical fan, change the viscous drive unit on it for a new one. If this unit is even a bit iffy, the fan is much less efficient
If you still have the OEM auxiliary electric fan, change it for a good quality aftermarket one, as the OEM one is hopelessly inefficient. This is easy to do with the rad shroud out of the car
Ensure the aux electric fan is wired to come on all the time the heater/aircon unit is on (easy to do, just run a wire to the fan positive from the aircon compressor clutch activation wire).
Also a good idea to move the aux coil (on the apron behind the grille) to the side and also move each horn to the side. This increases the clean airflow to the rad.

All this should do it, but you can always do this is if, like me, you really want to improve the cooling to modern standards! Cooling is all and only about clean airflow through the stack...


Greg

 

Cheers Greg.

Yeah I think mine is 15PSI (?) can't remember now.

My radiator has been recored about 10 years ago. How often do most of these rads need a recoring?

As a general rule of thumb, what are we looking at price wise from just a flush to getting completely recored? For example, we talking double your local currency?

Also, I have two electric fans. I believe they were upgraded/replaced some time ago to better the cooling. My auxilary fan comes on when the thermostat turns it on but also I have an override switch in my center console which i can have turned on the whole time.

 

Hi Bro

It's not that hard to take the Rad out, once you have got the bottom hose off, especially the one on the passenger side, which has a second smaller hose coming off the main one and also the bottom oil pump hose on the drivers side of the Rad (UK Spec)

Having struggled the first time, if I had to do it again, I would cut through that double hose with a bread knife, because the smaller hose that spurs off it, invariably gets jammed up, when you get to the stage of lifting the Rad out.

Don't do the same with the oil pipe though!

Get a spanner on that one! You cannot see to undo it, you have to undo it by feel, the good news is not much oil leaks out but some does, so do have something to catch it standing by.

Its not that hard to lift out on your own but much easier with two people, also it is not bolted in at the bottom, there are just two metal pegs dropped into two rubber doughnuts.

If it feels like it won't come out, its that smaller hose getting jammed, which is why cutting it through makes things much easier.

If the Rad feels unusually heavy, its because its full of 'Crud' and once its out check the beam it sits on for any rust damage, clean it, paint it and pump it full of 'Wax Oyl'

Its would make sense at this stage to give the front of the engine bay a really good clean out and check for rust.

Also I wouldn't waste money having it washed out, I would go straight for a re-core like 'Greg from France' suggested because in any event the Matric will be full of Crud and dead flies.

So what can go wrong? You can very easily damage the fins of the Rad when you take it out or put the re-cored one back in.

And that also goes for the Alloy Rad that is in front of that one.

Also take the bottom brackets off of the Fan Cowling, because otherwise it will get jammed up, when you try and get the Fan Cowling out.

Although you don't have to take it out, its one hell of a lot easier all round if you do.

Also note where all the wires connect to, there are lots of them but shouldn't be a problem to a Pro electrician like you.

The whole job looks more daunting, than it actually is but not something that you would want to take up as a hobby, so if you go for a re-core you won't have to revisit the scene of the crime later on.

You don't have to take the bonnet/hood off and I'd recommend that you don't although of course others may disagree on that.

But you do have to take the gas struts off, so you can get the bonnet/hood up nice and high. (that bonnet/hood is much heavier than it looks) so preferably tie it up so it can't fall down.

One of the most awkward jobs 'Could' be undoing the Gas Struts believe it or not!

They either undo very easily or if not are a PIA.

Other than a Case of Beer, Antiseptic and a 'Big Box of Plasters' and you should be good to go.

Unless you want to treat yourself to a 3 ton Trolley Jack, which on these cars is going to be worth its weight in Gold!

 

Thanks for the feedback OB. I have heard so many bloody things about this bottom hose! I hope it wont be too bad.

The oil pipe?? What do you mean? (Remember im green at this lol) You have to disconnect part of the oil system as well? (confused )

Yeah with the rad were gonna take it to the shop and see what the guy recommends on the day, whether or not to get it recored. Hope not.

I have been told by a few others also that taking the bonnet off is unnecessary so that is cool.

And yes beers will be a prerequsite!

Cheers OB

 

I got mine recored by a brilliant local guy for 200 euros (say 180 UKP). If yours is 10 years old and you have an overheating problem, I say a recore would be wise. By the by, I am a bonnet off person (sorry to disagree, for once, with OB who has done all this very successfully bonnet on).

How does the main electric fan come on? It could be that a good part of your trouble is that the electric fans are not powerful enough. You need at least an 11 inch aux fan and a 16 inch main fan both with enough power to really push air. The main fan when on at a standstill should create a noticeable gale out the bottom and sides of the engine bay when you stand by the wheelarch. The main fan relay main circuit must be powered directly from the firewall battery post, also. Approaching 3000 cf/min is needed from the main fan. Also be sure the fan surrounds are as close to the fins as possible. Even an inch back from the rad greatly reduces their effectiveness as it is easier to suck air round the side of the fan outer than through the rad stack.

Also, as I mentioned it is very good plan to make the aux fan always come on with the aircon, and use the thermo switch in the water pump inlet to control the main fan relay, the Grant Francis system!

All OB's stuff very important to check, and a new bottom hose a must so cutting the old one off a good plan. Finally, OB moved his oil cooling rad, and he was referring to NOT cutting the oil feed pipes to that rad (the lower of the two in front of the water rad). You do not have to undo the oil feeds or to remove this rad this at all, unless you want to or it is in a poor state, as you can clean out the fins in situ, once the water rad is out. You may even still have the original tube-type 'long hedgehog' or oil cooler, not a real finned oil rad, and these basically cannot get gummed up, and incidentally let much more air through to the bottom of the water rad.
Greg

 

First off I would like to think that I speak for everyone, in saying 'Massive Respect' for even being willing to have a go!

Its isn't really the kind of job, that any 'Normal Car Owner' would really want to do but XJS owners arn't what you would call normal, instead we are obsessive fanatics, who won't let any job beat us.

Back to the Rad!

The Rad is basically two radiators in one, with the 'Big Bit' cooling the Water to the Engine.


But on the Drivers side of the Rad (UK Spec) on the Left hand side, if you stood facing the bonnet/hood.

You can see a Couple of hydraulic hoses screwed into the Drivers side of the Rad.

At least you can see the top one but probably not the bottom one, which is some distance beneath it.

It certainly isn't obvious that there are two Rads in one, as apart from the two Oil Conections, it looks like a normal Rad.

Removing the Top hydraulic hose is easy but as far as the bottom one is concerned, you can hardly see it as your hand will be blocking the light, so this is the one you have to do by feel.

The only good news being that you know what spanner to use, its the same as the top one.

Its not that bad, its just a bit of a fiddle, which is where those sticking plasters are going to come in handy!

I wound up in A&E just so you won't have to, so beware of all the sharp edges you are going to come across.

The fact that the Rad is Two Rads in one, is what make a 'Brand New Replacement' very expensive and a re-core that much Cheaper because it is very unlikely the Oil Side will be Screwed.

So they will leave the Oil Side as it is (after testing it for leaks) and just re-core the Water part, which forms the main part of the Rad.

So cost wise 'ball park figure' half the cost of a 'Brand New' replacement.

(UK) £200-£250 re-core

(UK) £500 ish! Brand New.

The re-core should be every bit as good as a new one, so save the extra £250 to spend on other Stuff.

Good idea to replace all the belts when the Rad is out but that's up to you.

But before you start to pull it apart, when you turn the Engine OFF that Big Yellow Fan (the mechanical one) Should stop dead!

If it seems to Spin on for a bit, the gizmo that's behind it needs replacing and just in case your wondering, they don't give those away in packets of Cornflakes!

With the bonnet/hood Shut and the Engine Running, that Fan should kick up a Storm and if you are on grass, you will see the grass moving, at the side of the Car.

As 'Greg in France' has said before, it really blows a Gale so if you need to dry your hair now is your chance!

A Rad won't last forever and is bound to need replacing at some stage and anything in between going for a re-core from the off, is only going to store up trouble for later.

Its not really the kind of Job, that you will want to do again anytime soon and with those Temperatures in OZ you don't want that engine overheating, or that £250 will seem like a bit of a bargain!

Time Wise, there are two ways to go.

Either get the Rad flushed out, where they might be able to do it in Situ or go for the belt and braces option of a full re-core.

That of course is up to you but I would go for the re-core if it were me, which in point of fact is what I'm doing on my own Car.

By the time they have re-cored the Rad, if you go that route, it will probably take a week all in to get the Car back on the road.

Which will give you the chance to clean up the engine bay and fit the new speedo etc.

Also check the Steel Beam that the Rad sits on, as this also holds the front wings together@'Greg in France' which was something I found hard to believe but it does!

So now is the chance to clean it off and give it a good coat of paint and fill it with 'Wax Oyl'

Don't be frightened of doing the Job, all on your own if you have to, as I've probably got less mechanical skills than many people on here and so if I can do it so can you.

It looks a lot more daunting than it is!

I'll try and put a pic up of the Rad if I can find one, so you can see where the oil connections go.

 

Removing the bonnet *does* make the job easier from a work-ability aspect. And the rad can be lifted straight up and out.

If you leave the bonnet on then the rad has to be canted over, shifted towards the rear a bit, and lifted clear of the engine bay. I'd say a second set of hands is a must-have in this scenario. And perhaps some heavy cardboard over the front of the engine to protect the rad and help prevent it from snagging against against anything.

I've done it both ways.

When it's all said and done don't forget to bleed the system properly

Cheers
DD

 

Correction, I misunderstood OB's point. I now realise from his last post that he was referring to the gearbox oil cooler pipes, that join the RHS of the rad. I think, repeat think, that on your model, as on mine, these two pipes (out and return) push onto spigots on the rad RHS and are held on by worm drive clips. (ON OB's later car they are joined to the rad on by threaded fittings). The hoses often seem to grow into the spigots and It is easy to wreck the spigots trying to get them off, so you may have to cut off the hoses close to the spigot ends then, rad out, carefully cut the hose off the spigots. Any decent oil rated flexible will do to replace them, or they may have sufficient slack to re-affix anyway.

Greg

 

Time to 'Fess Up!'

I knew the other lugs on the Rad, carried Oil from somewhere but couldn't remember if it the was gearbox or power steering, so thought it was better left un-said than to leave Paul scratching his head in case I got that wrong.

So thanks for clearing that up 'Greg' aka ('Greg in France')

As for taking the bonnet/hood off, I wouldn't want to risk it, in case I graunched the paint work, or the person/s helping me did, although there must be a Safe way to do it, that is unknown to me.

But if the Engine needed Major work then that could be a very different story.

With the bonnet/hood tied up in the Air just on the point of balance, I found I had a lot more room to work than I first thought, so for that reason decided that I wasn't prepared to risk removing it.

Cardboard or even a blanket, laid on top of the engine, then one person on each side to carefully lift it out, then turn it over flat side up and lay it down on the blanket or the cardboard you put on the engine.

Avoiding any linkages connected to the throttle in case they get bent.

Then either lift it out of the way, or else walk the whole thing right off the back of the Car.

You can see the 'Gearbox' oil connections just on the right of the Pic, with the brass connections (though yours may be push on ones@'Greg')

Also get at 'least NEW Bottom Hoses and NEW Stainless Steel Hose Clips.



On the Far side of the Photo you can see the Rad Hose with another one coming off it, get the Bread Knife out and Cut it off! or you will be there for ever unless you are very clever or get lucky.



After a good clean up She looks a lot better.

Take care not to damage the 'Skinny Rad' or kiss your Air Conditioning 'Good Bye!'



Quite a bit of room to work with the Bonnet/Hood tied up in the Air.
And rather than take the Grill out (which is the preferred option) instead I was very careful and decided to leave it in place as the screws that held it in place, were far too corroded to get out.

 

Paul,

The Goose has the trans cooler out the front, so NO trans pipes/hose attached to the radiator at all.

You and Clarke are "young" so bonnet off is purely your choice. The bonnet OFF is simple enough and about 20 minutes. PRE MARK the hinge position with a scriber first.

I do them bonnet ON, and on my own, with an old bed Doona covering the engine and the tops of the fenders, especially covering the a/c compressor pulley that will ALWAYS snag the radiator, as Doug mentioned.

The Goose also has the Falcon (Aussie car), taxi pack hi output twin electric fans, same as all my V12,s.

I did mention by PM that the timing may be a tad retarded, and that will run this engine hot on long hard hills. I did explain to Clarke how to check it quickly, and I "think" he is going to do so when you first rock up???????.

 

Wow this is great guys thanks for all the input. I always value all your opinions.

Grant did bring up a good point in which i totally forgot he mentioned until now, and that is with the timing. This is another area I am green on but as mentioned before, I have only ever had this problem when going up this same bloody big hill, which runs for a few kilometers and is quite steep in some places. (Signs for trucks to use low gear and so on). Obviously something isnt right but yeah, I hope my plan is in the right direction.

At any rate most of the stuff we are doing can only improve the Goose right?

Sounds sensible to definitely look into this timing query before I turn my XJS in to an exploded view found in my workshop manual lol.

Guys again, this is all great info and I thank you sincerely.

 

Paul,

MAAAAAATE, that radiator job is SIMPLE.

I had to take the generator off the Mini today to fit new brushes, and "FAIR DINKUM" I would rather do a V12 radiator any day. There is simply NO room to get that sucker undone, and the get it out of the engine bay.

For those that dont what a Mini is, it is NOT the skirt type HAHA.

 

Spot on Grant, bonnet on and checking timing first. Fans exact same set up Fireball(XJ6) has.

I'll let you know after the job, I have done a Mini generator years ago.


I did a half day, then did the Aussie thing and went to pub with my brother to watch the girls,....and the Melbourne Cup.

Going to check out prices Thursday.

 

ha ha that is a sweet ride though Grant!

OB thanks for posting the pics mate. Internet here is super crapola and I can see the images but they dont quite load. Good thing about the forum is I can revert to the thread when i get home with better internet connection

Might try again later on tonight to view when all the local dudes aren't watching Vietnamese Pop songs on You Tube slowin up the internet tha *******s!

Cheers Clarke your a pal!

Why are XJS's so damn sexy!!!

 

Hi Bro

If the Timing is out, that's one thing but is a possible re-flush such a good idea?

As it sounds as if you are on your way to the cost of a re-core, which you may have to do anyway, if the flushing idea uncovers some problems with the Rad.

Taking the Rad out is not a 'Big Deal' compared to say a problem with the Brakes and with the benefit of hindsight, I know I should have listened to what the guys all said and cut through the bottom hoses with a knife.

In trying to save those Hoses, instead of just regarding them as Collateral Damage, I was only making a lot of hard work for myself and in the event I ever had to do that job again, the next time it would be a piece of Cake (ish!)

 

i dont have any over heat problems even in central Texas 100F temps, when restoring my 78XJS i was aware of the heat troubles.

so redesigned my cooling system!

but if i was to do it over i would use the Australian Craig/Davis system with twin electric pumps ,and all aluminum radiator.(cools the BIG american V8s)

i'm quite sure you would never overheat again!

 

Hi Paul, Had a flat out two weeks but got to see radiator shop today. If we can get the rad to them by 10-11 am we can have it back the same day, even if it needs a re-core. He will pressure test the cap as well.

 

Sounds like a plan man. Many thanks. And also we were going to check the timing first yeah?

Look forward to it. I have not seen a female, beer, whiskey or Jaguar in 3 weeks now. This is torture!

 

No women, Jaguars, or alcohol?
What part of Hell did you land in?
Pete