Can solve the problem of overheat by replacing twin pans?
 

Hi.
I am restoring 1975 xj12c.
I want to ask for help because there is a problem during the restoration.

https://cimg5.ibsrv.net/gimg/www.jag...412a1d60ec.jpg


A while ago, the original radiator leaked coolant, so I purchased aluminum radiator from SNG and replaced it.
Currently, Thermostat 82c (EBC3576), Radiator cap 16psi (CCC6707) and engine Fan Clutch (C45015) are replaced with new products.

After 30 minutes of start-up, while idling, it overheats. This isn't normal, is it?
(This is a picture of a temperature of a coolant taken 30 minutes after the start-up.)


https://cimg6.ibsrv.net/gimg/www.jag...882e969a9f.jpg



So I'm thinking of replacing it with a twin electric fan.
I'm asking for an advice on which electronic fan(part number, brand, etc) is suitable for my car.
And can anyone tell me if there are things I should be careful when installing electronic fans?



https://cimg7.ibsrv.net/gimg/www.jag...e8633859e3.jpg

The existing, mechanically driven, fan needs to have the cowl around it or it doesn't draw enough air through the radiator. This is particularly important at lower speeds when you're relying on the fan. At higher speeds the ram-air effect is sufficient and the fan has less of a role in cooling, in fact it has a clutch to idle it above certain revs, (the finned thingy aft of the fan). Replacing with electric fans will likely still leave you with this problem.

I agree!
In fact, I virtually Eliminated ALL overheating, especially at low rpm in afternoon city traffic, by extending the fan's reach (with a spacer) a mere 1/2 inch, so it's now completely enclosed in the fan shroud.

Operating temp Never gets above the 'r' in Normal, even on the hottest days in the heaviest city traffic.
(';')

I agree the problem is the shroud around the fan, not the fan itself. Ever since people started trying to get more power from their engines overheating has been a problem. When I was growing up cars were going from six cylinder to v8s, then big v8s, then air conditioning, then more traffic. Cooling was always playing catch up. There is tons of information available on the web on the physics involved and they all start with the shroud. The only people wanting you to use electric are the people that sell them. New cars use them and hot rodders use them because they are trying to wring one more mpg or one more horsepower from their engine. We just want old school reliable cooling. Research radiator shroud design and then tweak it like Elinor did.

Jeff

.

That's really hopeful news.
Can I ask you more about the way to extend the fan's reach?
Thank you.

Hosung

Thank for for your help.
Can you explain more about the "COWL"?

Hosung

I want to restore my car as close as possible to the original. That's what I also hope to do, too.
It's good news for me that I don't have to replace it with an electric fan. I'd like to find a good way to use my fan as it is.
Your reply gave me a boost. Thank you.

Hosung

Here is a good write-up. These folks sell fiberglass replacement fans (not electric)

https://www.flex-a-lite.com/blog/the...roud-position/

keeping the car original is great but Jaguar was known for weak cooling systems and a failure can fry your engine, especially the V12. Keep it original except where you can make it better.

Jeff

I'm not quite convinced that you're actually overheating.

What were the ambient conditions during the 30 minutes of idling? 18ºC? 38ºC? It makes a difference.

How long did it take for the needle to get that high? Would it keep climbing if you continue to idle, or does the needle settle at that point

What happens when you drive the car?

The V12 cooling systems do not have much reserve capacity. Holding a 100% constant coolant temperature under all conditions probably just won't happen. But if it reached the 2/3 mark (as the pic shows) very quickly under mild ambient conditions and/or keeps climbing up-up-up....there's a problem.

Cheers
DD

Fan extensions are available at almost any parts supplier in a wide variety of sizes.
https://cimg6.ibsrv.net/gimg/www.jag...048ef3af7b.jpg

This allows the fan to extend into the shroud (cowl across the pond) just the right distance for maximum cooling effect.
https://cimg9.ibsrv.net/gimg/www.jag...00e7cdfeeb.jpg


True, this is a V-8 but the principles are exactly the same.

You might notice too, e-fans come with their own built-in shroud. This is the reason they seem to be so much more efficient.
(';')

HI.
Will the problem be solved by simply replacing a fan with an fan clutch?
Thank you.

Hosung

Hi.
The ambient temperature was about 15 degrees and the car hood was open. The needle climbed slowly.
And the time I took the picture was 30 minutes after I idled it. Since then, coolant has flowed out.
When the axel is pressed or drive, the needle drops down and coolant doesnt flow.

Do you think my jag is in normal condition?

Hi.
Thank you so much for your reply.
So you're telling me that just putting a spacer between a fan and a clutch works?

Hosung

Not normal.

Coolant shouldn't be flowing out. And at 15ºC ambient the cooling system should be able to hold a lower coolant temperature.

Did you bleed the cooling system?

Cheers
DD

Hi.
I just changed the radiator to aluminum. I didn't do anything to the cooling system.
Step on the accelerator to speed up the fan, and the thermometer drops down.Could there be a problem with the fan clutch?
What should I do?
I'm thinking about what to do among the many tips.
Thank you.

Hosung

MMMMMMM, Pre HE V12, oh boy.

Mongrel to bleed, I will find my bleed write up later and edit this thread with it.

You state a new thermostat, SINGULAR, and I hope that is a typo, as the engine has 2. There is also a write up on these that I will attach later, as Jaguar, AND the aftermarket suppliers got the stat wrong, and it is too short, and that prevents coolant flowing through the radiator as it is meant to do, and the engine will NEVER run at the correct temp, no matter how many fans etc are fitted.

Question, so I find the correct info, is this a Carby V12, or Fuel Infected????????, different cooling system, and I reckon you are EFI from the snaps, but I dont know for sure.

The fact is lowers when engine speed is increased, indicates air in the thing.

The PreHE fills through the LH header tank, and then the system will find its own level within that tank, and YES, when first filled it will spill some out as it expands, and once it finds its own level, that will cease, UNLESS you keep filling it up, then it will keep spilling it out, until you stop topping it up, that cycle will continue for a very long time. Mine ran at about the bottom of that filler spout, COLD, when using a torch to peer down same spout, and it ran at N or O no matter what, and yes, it had Efans, and it mattered not if it was our 3C winters, or 44C summers, A/C on or off, it sat steady.

Be back when I find the write ups.

My car is an injector-type V12.
And it's a typo. The two thermostats were replaced with genuine ones. :)
I'll wait for you to come back.
Thank you very much for your help.

OK, understand the beast now.

2 attachments:

1) Bleeding the system, and the PreHE is at the bottom, BUT, the top section has a lot that applies to the PreHE.
2) V12 stats fiasco, meaning Jaguar got it wrong, and that was back in the early 90's, and the stats they had were too short, NOT good at all, and havoc is reeked by using them. I understand you have replaced them, and that is NOT a 5 minute task, but are they too short?????, sadly, until they are removed and measured at "full open" you will never know.

Have fun.

I bought thermostats and radiator banjo bolt with the help of your materials. I'll put them on and tell you what happened. Thank you so much.