I know this has been debated already and I get the two sides:

1.) the stock radiator works so why mess with it.
2.) a different design would be an improvement.

I am interested in converting the car to a single pass radiator with a 2" Inlet and 2" outlet, equaling connecting the two hoses, with two thermostats to the 1 inlet.

Reasons:

simpler design ultimately providing better reliability.
cheaper radiator cost

I am talking about creating my own mounts etc. to get this fitted. Has anyone successfully fitted a single pass radiator into this engine bay? any links to it?

Is there an aftermarket single pass radiator that is known to be useable?

In the end I may go stock, but I am still interested in learning how to get this to work. I enjoy customizing things on this car and making improvements with newer technology. Its one of the reasons I like Jaguars, they can be improved upon in certain areas.

 

link to a previous discussion:

https://www.jaguarforums.com/forum/xjs-x27-32/single-pass-double-pass-102961/


picture of a y adapter for the two top hoses:

 

I did install something like you are taking about, made by Becool and purchased from Summit Racing. I'm not at home so don't have access to everything or consistent internet but tell you a few quick things. I went this route thinking it would be quicker and not much harder than waiting for a recore to get done - wrong on both points for me but I do believe it would be quicker next time now that I learned some stuff. Price I think came out about the same or maybe a bit more than a recore. Better performance? - don't know, the old one was cooling fine in spite of it's crappy condition, I replaced it because itit was leaking on both sides of the core. Three new one it's also working fine now.

Things that caused problems included, Trans cooler fittings were different and very hard too match, new radiator was a little thicker requiring altering the fan shroud mounting, making the crossover pipe and hose tee was very difficult (for me anyhow), had to make a new spacer for the air bleed banjo.

Now that it's all done it works fine. If you decide to try it I'd just recommend assuming that you'll run into some problems like these, and it will take longer than you thought, depending on your skills (mine are just sort of medium). Good luck!

 

Thanks for the input. My main reason for thinking of going with a single pass is really money. You can get a radiator big enough to cool this engine for $150 - $200. Making it fit is another story and getting one with the trans cooler attachments.

Could one just use a universal trans cooler as a separate entity? I see them running for $50 - $100. Any benefit of doing this?

 

When I had my radiator rodded by the local radiator shop, I had the right inlet removed and placed under the left inlet. This created a full double pass since the baffle in the left end tank wasn't removed.

I ran the right coolant hose across the front of the engine and connected it to the top inlet. This gives it a bit of pitch to allow air to escape out the bleed screw on the radiator. The left hose is nearly level with a slight pitch upwards as it enters the radiator.

So far, I have had no issues. It was easy to bleed, and I've idled it for extended periods in 90+ degree weather. Keep in mind, I have dual electric fans. Also, my A/C is nonfunctional at the moment. Next summer will be the real test. I'll try to post some pictures later.

 

A single pass is less efficient, and if you're going to go through all the mounting headaches that Eaa alluded to, you'd eat up any cost difference as well.

Now if you said you were going to go triple pass rad, and route the outlet of the radiator to the heads first and exit at the block, then I'd sit upand take notice.

 

All forms of racing use multipass radiators for a reason, they are far more efficient than single pass. Manufacturers use SP because they are cheaper to manufacture.

If I were you I would take your stock radiator and have it rod cleaned/ recored. It will more than likely end up cheaper in the long run, once you factor in all the fabrication required to modify for a SP.

I live in a HOT climate and with a stock radiator my car will idle in traffic all day 40°C with AC on.

 

Fitting these is pretty straightforward and seems to be efficient enough. I have fitted one for my 4L80E trans. They have an added benefit of taking a very small heat load off the radiator and usually result in a lower cost radiator as well.

 

Here are the pictures I promised. I hope these help to give you some ideas. The radiator modification, pipes, hoses, and clamps cost me less than $200.

 

As Baxtor says above, this is a Grant Francis recommendation too. I have done it, and completely bypassed the in-rad gearbox cooling. This has the added safety benefit that no water can get into the gearbox if the cooling coil fails inside the rad.
Here is a pic of the fitment on my car just before the pipes were connected, works brilliantly, plenty of space in this location.

Greg

 

I've often added an external trans cooler but always in conjunction with the in-radiator cooler, never to replace it outright.

My worry is lack of ATF cooling during long idling periods where there is little or no airflow across the cooler. In such conditions the ATF would still get some cooling via the in-radiator heat exchanger.....were it still in the loop.

I'll confess, though, that I've never researched (nor actually measured) how quickly the ATF heats up when the car is stationary. It might be a non-issue.

GM didn't think it was an issue 50 years ago, as I discovered while working on a '64 Corvette. The Powerglide transmission has only an external cooler.

Cheers
DD

 

Doug, I started with the rad and the extra cooler in series, and the extra cooler was never more than fairly warm, even after long high speed runs. So this summer I changed to the external cooler only (which is what the great WoOz who advised me about positioning, recommended to start with). Even an hour in hot Paris traffic jams seemed to be fine. All in my quest to simplify wherever possible.
Greg
Greg

 

I don't believe the problem with cooling is the rad design. It's more of a lack of airflow thru rad. The engine bay isn't big enough to let the air escape. That's where the louvers in the hood come into play

 

I might be wrong but I thought part of the idea of an in radiator trans cooler was not just high temp regulation but also low - by that I mean it would maintain around engine temp even if its cold out. Not an issue in a hot climate but could be some places. I know my land cruiser shifts differently until it warms up.

 

I have to Agree. That's why my bonnet is having louver’s pressed into it as I type.

Trans coolers! Another reason to ditch the auto and go manual.

 

so increasing airflow would be the better solution?

the idea is to improve what is there and provide the absolute best system possible regardless of price. this does not mean dong anything unecessary. if the current radiator is adequate and there is no benefit to go to a different radiator, maybe just adding 4500 cfm worth of air with the stock system is what is needed. ...there are places for air to escape, so more cfm will find those places...

why did jaguar seal the hood? they clearly had a reason for this and were knowledgable in vented hoods etc... they did not just seal it without considering ventilation. they obviously misjudged, or not... just road that fine line between good cooling and excellent cooling. ...so should removing the trunk seal be a part of improving the cooling? or does that force the air to flow down to a more needed part of the engine for cooling?

 

The stock radiator is more than up to the task of keeping the V12 cool. I know a guy who had an XJS twin turbo race car, this thing had SERIOUS horse power. He spent a heap of money trying to keep the thing cool, could not do more than 1 lap of Mount Panorama Bathurst without the ting overheating, this was with a custom Aluminum Radiator, he decided to go back to a STOCK V12 radiator and the thing never overheated again.

If you are running a stock engine you do not need bonnet vents. Even modified driving in a street situation does not require vents. If you plan on having the thing at full throttle a lot then vent will be needed.

Here is what I would do for a stock car.

Stock radiator, re-cored or rod cleaned.
A set of Ford dual thermo fans Google Ford AU thermo fans, these fit with minimal mods.
Ensure the foam packing around the radiator is in good condition or replace it.


If you plan on major powerups then start upgrading things like
Modified water rails etc.

 

great info! so the dual fans is the only mod I will stick to. I google ford AU thermo fans and from what I can tell these are dual 12" fans. ...nothing shows up in us ebay. a bunch of things on australian ebay. .... must be semantics. so v12performance has it right with the dual fan set up... it can be done much cheaper though. I will look into getting my own dual setup based on high cfm and the largest fans that will fit. do you just wires these up to the water pump switch? ignoring the aux fan switch. or is one of them an aux fan?

maybe two 14" would work? I can get a shroud made for about $50. maybe 12" is more than enough.

all I know is as soon as my fan kicks on I get a drop in my temp to below the N. I believe I have a bad clutch or switch, as I get sporatic high temps. I looked once and it was above the N. I was about to pull over and it suddenly dropped to below the N. normally it is ok. I seem to be getting occasional switch or clutch failures. the radiator appears to not be the problem, though it is still getting recored. The quote I got for recore was $350. after this discussion regarding stock I feel it is the way to go. not to include its less wasteful than just throwing it out and getting a new one.

here is what I found googled au thermo fans:

 

This is exactly the same symptom as my car had when I bought it. Intermittent overheating. Being a Marelli the overheating is not compounded by retarded ignition.

Recored Radiator, New thermo fans, Same 85°C thermostats, and a flush has fixed the problem.

She will now idle all day with AC on in traffic and not get hot. Once on the motor way the temps drop and cycle as the thermostats open and close. I've turned the car off a few times after a long haul and the second fan (the one on the thermoswitch) is not running.

 

Warren has basically covered it all, one of the best mods is the twin thermo fans of an Au Falcon. Mind you I am guilty of NOT doing the mod yet, have all the bits but more pressing matters than that take my time, most likely when I do get around to doing it, it will be same time as I do the Motor/Gearbox transplant.

From what I have read, Jaguar made the car as a Luxury Grand Tourer, not a sports car, so in their wisdom keeping down the noise was paramount, to do this we need plenty of padding and sound deadening that added the extra bonus of trapping all that wonderful heat under the bonnet to cook all the goodies that make it work, the bonnets needed heat shielding to save the paint on them. The only ventilation exit point was down the tunnel via the gearbox and there is not much room there either.

As for vents I personally think
A:they look good
B: they look good
C: they look good and finally
D: they vent the hot air away from things like injector electrics wiring and all other bits on the top of the motor.