Opinions wanted on cooling a 5.3
 

'ello everyone.
When I purchased my 91 5.3, someone in its past has removed the engine driven fan and replaced it with a 16" electric fan. The auxiliary electric fan is still there.
My question is:
Would you replaced the engine driven fan? Or stay with the electric?

I'm not sure what I want to do at this point. It was left sit because it overheated in traffic. It would seem that a fair amount of money was spent chasing what I think was just blocked airflow from debris that was allowed to accumulate between the condenser and radiator.
The whole engine driven fan is gone, the bearing housing, fan, clutch, and shroud.
Thanks

Hi 71

From the way you have described things, its sounding like a 'Sticking Plaster' has been used to cover a 'Big Problem'

Many of us get Paranoid, if the needle on the Temp Gauge Barrel ever moves over half way

As a V12 Engine that's been 'Cooked' can be 'The Kiss of Death'

With the possibility of a dropped Valve at sometime in the future, though hopefully you'll get away with it

I'd never buy an XJS with a V12 that had been 'Cooked' or you could end up with a very expensive Parts Car

First and foremost it would seem the problem is with the Rad, which could be in need of a Re-Core but as far as the Fan is Concerned

I fitted Twin Electric Fans in my Car 'Cherry Blossom' but went back to a Mechanical Fan, as it made my XJS

Sound like a Sewing Machine!

Having said that, many have Switched to Electric Fans and are happy with the results but before you decide which way to jump

You need to ensure the Radiator has been sorted out, as the space between the Condenser and the Radiator

Gets blocked with debris as you have found out

Just be very careful that you do not damage the Core

borescope inspection shows the inside of the radiator to be very clean

and yea, I bought it knowing that it could possibly need the heads to come off and bought it at a price reflective of that.

At this point I am cautiously optimistic that they will not, unless they "tick" when I finally get it running.

Steve
AKA 71 MKIV
91 Jaguar XJS convertible classic edition
71 Spitfire MKIV

All mine have been twin Ford Thermo since 1995ish.

NO issues at all.

As for fan noise, NOPE, but that would depend on the fans fitted, and the blade design.

Sorting the rest of that cooling system first is paramount, as Alex has mentioned.

Our Summers are 45C+ and the V12's are fine.

These are good reading in my opinion:

Attachment 211339

Attachment 211340

Attachment 211341

The usual problem is that the fan clutch gets weak with age, then you have an engine that overheats chronically when going slowly. At this point, either replacing the clutch, or installing an electric fan, fixes it. Which one you do, depends on preference. However, even a 16" electric fan doesn't shift as much air as a properly working mechanical fan.

The usual problem I have found with V12's is debris gets in between the AC condenser and the radiator and blocks the airflow. The only real way inspect and clean is to remove the radiator and inspect. It absolutely cannot be done with the rad in the car.

I don't have temps as high as Grant does, but I have had the car is 40C heat with the stock mechanical fan and it was fine. The system will cool the engine if everything is in good working order, but often things degrade and people don't address the fundamentals before condemning the stock system.

Electric fans have a lot of variance in efficiency, the PO of mine put in electric fans and I still had chronic overheating. I took everything out, found the rad was 80% blocked. With a clean rad, I put back a mechanical fan and then the car cooled. I could stand beside the car at idle and feel the flow of hot air coming out from underneath. I couldn't feel any air movement with the electric fans he had put in.

I ran a gallon of Metal Rescue in my cooling system in addition to fitting a semi-truck size full flow spin-on coolant filtration system, between the suspended rust bits and grey silt paste I must of pulled atleast a coffee mug's worth of crap out, resolved the overheating issue right quick. Mechanical fans are fine just make sure you don't have cracks in the fan or it will disassemble and shred the engine at 4500rpm.

I also must recommend buying OEM coolant caps from Jaguar in the UK, they're the best possible ones you can tell by how heavy and solid they are.

While the radiator is out I would have it re-cored or rod cleaned. They get gunked up inside from years of Jaguar additives and other crap.

I also have Ford efans and they do a good job of cooling the V12 in our hot +40°C summers. My take is -OEM's spend a lot on R&D so if you install fans from a car that has similar or more power you will be fine.

Part of the problem is that the popular spin test for fan clutches is kind of useless. You can get a laser tachometer on EBay for $10. Proper test procedure here :

http://fanclutch.com/PicsDocs/BorgWa...ives_Only).pdf

Everyone here has an opinion on cooling. MY opinion is, that the original cooling setup is more than sufficientm it was tested worldwide under some of the most harsh conditions.

The most important part of the cooling system is the maintance. Keep it up to spec and the engine will not overheat. I'd recommend a coolant change every 2 years. New thermostats every so often. Make sure the area between the radiators is clear and all will be fine.

The V8 will drop the valve seats more commonly than the V12. But people don't go through the same effort as people do for the less prone v12...

AN electric main fan is fine, if, and only if:

• It is a really high quality item made by a top notch fan maker such as SPAL, or an OEM item from a top notch car such as a Merc of BMW, or modern Jaguar
• It is at least 16 inches in diameter, preferably 17,
• It draws at least 23 amps when running. That is to say a Proper Big Fan, less power will not do the job in extreme conditions, and
• You fit a reliable controlling system to activate it when required.

My experience is that Grant's fan system (see his attachments to his post above) is the absolute best, and I have it on my car. The OEM system, as long as the rad/condenser is regularly cleaned out (which also applies if you have an electric fan) and as others have said above, the fan clutch is renewed is absolutely fine.
I have found that the advantages of an electric fan (if all conditions above are met) are improved fuel consumption; noticeably less engine bay noise, better cooling at low speeds/traffic; one drive belt gone, and better access to the front of the engine.

But, OB, you had them running full blast all the time with no controller! But I agree with the rest of your points!
Cheers
Greg

Hi Greg

During initial R&D I experimented with just one of the Twin Electric Fans running and She still sounded like a Sewing Machine

So I went back to a Mechanical Fan and all is good so far

My efans are slightly louder at idle than the original mechanical fan but I have them running flat out all the time, I'll add 2 speeds when I pull the engine. Although they are not intrusive.

You can add a low speed with BIG metal case resistor and a relay to switch it in (and out) with a thermoswitch.

I also found the Ford fans at a wrecker for $50 and this was wayyy less than replacing the original fan.

You are right about the current draw Greg, the Ford fans draw about 80amps as they start and I have 40 amp fuses in each side as this is what Ford used.

thanks to everyone so far.
So more questions, Grant, Do you remember what fans you put in? and are they available here in the US or are they some Australian domestic stuff, and same with the thermostats. I really appreciate the work you've put in, but the parts houses around here look at me funny when I give them those part numbers, and tell them they are for a Peugeot.

With the twin cooling fans, have you found the alternator to be adequate?

I'm still in the "so what have I bought here" phase, so there's still time.

Steve
91 Jaguar XJS convertible classic edition
71 Triumph Spitfire

The fans I use/used were from a 1996 EF Falcon Taxi Spec Aussie car.

This is a snap of the fans I used.

Attachment 211390

BUT,

They are NLA from Ford, and teh Chinese stuff is crap.

BUT #2

Since then MANY cars a Efan cooled, and there a hundreds of options. Like already said, look at the fan pack from a similar HP car. remembering HP is heat.

Some report using the Jag X300 Efan unit, but I doubt it will fit as easy as the Ford unit, that basically slid straight in.

Damn you guys have it tough with spare parts idiots. I have a Gates stat cross over somewhere, and when I find it I will give you a USA Part #. Dont hold your breath, you will go Blue, as I am back to 6 day working weeks again.

I replaced the alternator with an XJ40 Bosch 120 amp earlier in the time, coz the Lucas went AWOL. Plenty of balls in that for anything you want to run. Again, alternators are simple to upgrade, just get WAAAAAAY outside the Jag box and look at it from many angles. The single V drive is NOT a hurdle, just a pulley change.

Wondering what you got??????????, maaaaate, you got a Jag, and a V12 to boot. You are part of a RARE breed of humans, and you will need a sense of humour to survive, but survive you will.

My main advice is" DO NOT overthink anything, these are SIMPLE cars, and that is fact. Abused, neglected, uncared for, YES, and that is why we own them now.

Found it.

Product | Gates

On the right is a long list of cars that also use this stat, and some will be in the USA.

That is the Gates OZ part #, and is teh 82C number.

this making a living thing always gets in the way don't it? I can have the cash to play only by working during the time I have to play. Have a little struggle doing both at the same time.

Yea, all the horror stories, it's still a mechanical thing, and once I started separating it into systems, wasn't so bad. Mine sat for 6 years, so I wanted to make sure of some things before attempting to start it.

Thanks for the part numbers, I'll do some snousing and see what I come up with.

Steve
91 Jaguar XJS convertible classic edition
71 Triumph Spitfire MKIV
"Never underestimate the perversity of an inanimate object"

For what its worth, I drive daily in Florida with the (mostly) factory system. The only "mod" is that I replaced the electric fan when it died with a newer style, but still 11" or whatever it is.

I have small leaks at the top hats, so if my car ever starts to run warm is because coolant is low or something is broken, like a T-stat or fan clutch. Either way, it runs just fine in 100 degree weather with the stock system, it just needs to be all in working order.

From my own experience, I would guess that 90% of overheating XJS problems are from the thermostats going out.

Hi Steve

I did my cooling system up based on advise from Grant Francis....ford twin thermos, stuck with the 1 - 1/2 pass brass copper system and the thermostats recommended by Grant.

Of note in my adventure was that the coolant hoses, thermo's etc were all in serviceable condition...even the rad cores were OK...see the attached photo of the externals of the radiator when i pulled it.....this would not have got me through and Australian summer.....!

anyway .....everything was renewed in the heating and cooling system ...yep heater hoses.....water rails - changed to copper....etc....and the needle sticks on half way .....and boy does she give off some heat in summer....

Pretty much followed the advise of the form members

all good

Darren

On a related topic; my 1985 car came from the factory with a rather old-fashioned oil cooler (the item under the condenser in front of the rad). It was a tube about 1 inch diameter with loops of thin wire welded to it looking like a long thin hedgehog. The more modern cars have a conventional looking cooler, as does mine now.
The point is this: the older style of cooler did not, repeat not, fill the gap below the condenser. There was loads of free space top and bottom of it for air to directly hit the radiator fins. In my mind there is no doubt that the older cooler allowed better radiator cooling than the modern style oil cooler does, purely because of better airflow.
As soon as I fitted a new modern OEM oil cooler, my car ran hotter; not overheating mind, but hotter. I did not like this much, so I removed the bumper and tested the car. INCREDIBLE! coolant temps were far lower. Anyone who does not believe it, just try it.
So, bumper back on, I cleared the air path as much as I could with a slot in the bumper about 18 x 3 inches and I moved the horns and the auxiliary coil out of the airflow. In total these mods gave over 100 square inches of clean airflow (rather than turbulent airflow) hitting the stack. Moving the coil and the horns alone gave about 40. These mods made a huge difference, particularly to the speed with which coolant temps reduced after a traffic stop, once the car got moving. "Clean" air hitting the rad stack is the absolute key to improved cooling, once all the basics are fixed.

Would I be correct in assuming that the facelifts, without the front coil to get in the way, would offer better cooling?

Also, with the better airflow, is that just air getting rammed into the rad, or does the fan actually pull enough even at a stop for opening up the front (bumper holes, etc.) to make a difference?

Presumably, slightly; but the front bodywork of the later facelifts is different, so I cannot say.

The bumper slot makes a huge difference once moving. None or not much at rest, I would think.

Thanks for your replies. Mine's an early facelift, before the bloated bumper, so I assume it's essentially the same as the pre-facelifts, with the only difference being the grille design. There's quite a large, open space in front of the... aircon cooler? Oil cooler? Can't remember what the large rad in front of the main rad is. At any rate, there's a fair bit of room for air to move in there.

Can you post close up pics of the bumper mod? I've wanted to do the same thing.

The one in front of the coolant radiator is the condenser for the air conditioning system, the oil cooler is much smaller and mounted lower down. I'm assuming by open space you mean deck space, like what the coil rests on? This is just part of the design of the front end, the rads are fitted as close to the engine as possible to maximize space, so you are left with some blank space up front.

As long as everything is up to factory spec, the XJS should cool just fine. I've driven in stop and go traffic in Miami as well as 130+mph for stretches on the highway without any cooling issues. Nowadays you can buy a beast of a radiator for only $200-300 bucks. I would definitely pick that first over cutting holes or adding dual electric fans, if you want to go past factory spec.

Condenser, that was it. Thanks. I'm not sure where the coil in a pre-facelift is, but probably, yes. Seems they could have shifted the condenser cooler a little further forward, made it easier to check the main rad condition, but perhaps they had their reasons.

The first thing I did for my car was order an aluminium radiator from Wizard, along with new 88-degree thermostats, hoses, and a new main fan. So long as there's enough coolant in the system, stopped in summer traffic the car will reach a needle's width past the middle, but stop there (generally!). These days, as it's only very early spring, she drives along distinctly on the cool side.

Is there any downside performance wise to this running 'cool' ? You'd think 90-degrees would be where you'd want it at regardless. I know my car has an entirely different personality once warmed up its not like modern vehicles that just GO from dead cold.

I should add that when I say "on the cool side" it's only a couple of needle-widths at most to to the cold side of the middle. If you go by the later facelift gauge, with just one single "normal" zone flanked by "cold" and "hot" it's still firmly in that "normal" range. It's just a reflection of the fact that the engine is getting cooled more by the colder air we have now than the hot muggy air we get in summer. And generally after about 30 minutes of town driving she's up to precisely halfway anyway (though drops back a little at speed).
But it is more reassuring than having it running on the other side of the middle mark....

Broadly speaking, 180-200ºF (82-93ºC) is where most modern (post 1950s, let's say) engines like to run in terms of overall efficiency and longevity. Jaguar used both 82ºC and 88ºC thermostats in the V12s.

The main thing to avoid is the 'cold enrichment' for any long period of time. The cold enrich tapers down quite a bit as the engine begins to warm up and is pretty much all done by the time coolant reaches 150ºF or so (70ºC). Even with an 82ºC thermostat you're well out of that territory

Cheers
DD

i use a standalone engine temp gage,Digital readout in 2 degree increments, most important coolant sensor mounted on left /rear cylinder heads(tossed out the sticky AAR valve), 180 stats, and use outside trans cooler,.

never in 24 yrs have temps beyond 195F even in 100+ ambient!

average is 185F 95% of time.

you can flip the pic !!!!Grr.

Where is your sensor located and the readoutscreen ? I've been debating what engine related mods to do on the car now that I've got the rear end parts sorted (shop time pending) and I was thinking of fitting a series of digital gauges to a LCD screen either inside the center console/armrest or in the same location as the trip computer which naturally doesn't work anymore.

Here is the closeup, rubber cover over bumper off at this experimental stage. In the end I slightly reduced the width so I could get the license plate up on the LHS side of the bumper, as when I first slung it below it ruined the stability as it affected the airflow to the spoiler.

Ruined stability how?

I've thought of either having a shop fabricate a slightly larger front spoiler or your method with the a vent in the bumper, didn't the race cars (twr) have larger spoilers?

Because I had the license plat fixed below the bumper to start with. It interfered with the airflow to the spoiler. Once I moved it up so it was on the bumper, but to one side so the slot was unblocked, all good. If you look at the photo in post 33, you can just see the plate hanging below the bumper.