Hello,

I am restoring the Jaguar xjc with the V 12 Pre-HE 5.3 engine.
I want to solve the problem of rising coolant temperature when idling.
Thankfully, With the help of several members, there is progress than first, but there is still a way to go.
I replaced the cooling system as follows.


1. Aluminum radiator exchanged (c44096a)




2 .Banjo bolt exchanged


3. Exchanges of Fan clutch(hayden 2747)
4 .Radiator fan(ebc4553)




5. Replace the thermostat (TT228-180)
6. Supplement cooling fan exchanged (Spal 30102054 11")






The coolant temperature went up to 100°C in 30 minutes of idling (Today's temperature was 28°C , The supplement cooling fan operating temperature is set at 88°C)
And the temperature went up even higher up to 110°C, so turned on the fan at the front of the engine and the temperature dropped.

The radiator fan does not seem to generate enough wind at idle.
Is it a problem with the newly purchased radiator? Or is it because the fan's speed is low?
What if I remove the fan clutch and make a direct connection? ( Solid Fan Clutch )
Please advise me what to do to solve the coolant temperature problem.
Thank you in advance.

 

OK, you have been busy.

The LH electric fan switch in the water pump inlet spout is measuring "cooled down" coolant. Normal system, as Jag made the car,with 82c stats, gives top hose temp of 94C +/-, then the radiator cools the fluid by AT BEST 15C, so around 80c would be expected. The lower hose temp is more stable than top hose temps, hence the position of that switch in most cars.

Once it gets to the set temp, and all I have had are 85C, the LH fan is activated.

NOW YOUR CAR BASED ON WHAT YOU NOW HAVE.

82C stats, so 94C APP top hose and the alloy radiator should achieve 15C drop easily, so 79C would be a rough estimate of your system.

BUT

You have seen 110C, drop that by 15 (radiator), gives 95C bottom hose, that fan should be ON, even with an 88C switch.
At your 100C the radiator drop should see 85C bottom hose, so 3deg below that switch.

Your outside fan cools the thing, ODD at best.

A solid fan with that plastic fan, NOT a good idea, blade failure could happen, they are not designed to rotate that fast.

More thought:s this late at night, and clutching at straws a bit:

Is the engine timing set at 10deg BTDC or better. These engines will run very hot if retarded just a few degrees, especially at idle.

The temps you are stating, are they the dash gauge, or from an independent source?

Has the water pump impellor been verified as intact, and not eaten away from corrosion??

When was the engine block last flushed of mud (messy task, and water pump off to do so) they do build up badly, and hot spots will reek havoc with cooling efficiency.

I'll keep thinking.

 

Looked the new radiator, and I cannot see a spigot for the heater/header tank hose on the lower hose spigot. Is there one there?, or what has happen with that hose.

Maybe it me????

 

Thank you for your trouble.

Is this a hose you are saying?



I modified like the picture below cause the new radiator didn't have that.






The temps I am stating is from an independent source.
I replaced the water pump impellor. There is no damage.

My engine is in very good condition. no knocking, No hesitation.

What angle is the best fit for the engine timing?
I heard 18 degrees is a good angle at 3000 rpm. I don't know how to adjust this.

Can you tell me how to set the engine timing?

 

OK, well done on what has taken place so far.

Timing is subjective, I use 10deg BTDC as a base for any V12.

The PreHE is a 9:1 comp ratio engine, so can handle more "Advance" than the HE engine.

I have NEVER set the timing with this 3000rpm nonsense, I am simply NOT that brave to be under any car with :stuff: whizzing around at the end of my nose.

Yours MAY have the Vac Retard capsule on the distributor, I dont know. OR, it may have the Vac Advance unit, Jag played a lot with different markets.

This PDF should help. but ask if something is not clear.

I will ask as I dont know:
Is the heater system still intact, or has it been by-passed?



Your engine runs, 98%

 

Just a few thoughts:
Are you 100% sure that electric fan is turning in the right direction to get air through the radiator from the front to the back? Once you are sure it is correct, hot wire the electric fan so it is on all the time and test the tickover cooling then.
What is the clearance between the shroud and the engine driven main fan?
What revs is the engine ticking over at?

 

The fan is fitted in the right direction and the distance between the radiator and the fan is approximately 40mm.






The rpm at the initial start is about 750 and 600 to 650 when it stabilizes.




Thank you for your trouble.

 

The PDF is helpful. Thank you.
I pushed back the timing a little. Unfortunately, there is no big difference.





What is the heater system you are talking about? I'm not sure what that is.

Hosung

 

Heater system, climate system, whatever.

Many people in Tropical areas by-pass the heater, as its not needed, or its leaking.

The HOT liquid is supplied from a fitting in the rear of the A Bank cylinder head,

This goes TO the tap, and then TO the lower spigot of the heater core, the upper spigot is the RETURN liquid that connects to a steel pipe running down the LH chassis rail, and terminates at the vertical spigot of the radiator, the one you fitted on the alloy unit.

The mistake is to simply connect the HOT liquid hose direct TO the return pipe, thus by-pasing the tap and core.

BUT

This simply supplies HOT (the rear outlet is the HOTTEST on the engine) directly into the pre-cooled liquid of the radiator, which in affect pre-heats it with 110c+ liquid, AFTER being cooled by the radiator. The engine is then seeing liquid MUCH hotter than it should, and that reeks havoc with cooling.

I was working with a guy in Manila with a 1991 V12, and his "mechanic" had by-passed the heater as I described above, and there was NO way they could keep it cool, or stable, and many thousands of $$ spent trying to sort it. I asked the same question to him, OOPS. They then simply capped the outlet spigot, at the A Bank head, and the return pipe, stopping the flow of liquid, thats all, and the temps were stable, even in Manila traffic.

Worth an ask, I know not what has been done in taht area on yours.

 

I take it that you did replace BOTH thermostats? In your original post you mentioned replaced thermostat (singular).
Have you tried wiring the electric fan so it it always on and seeing what that does for your temperatures?
Have you measured the temperatures of the coolant coming out of the radiator? If so, what are they?

 

Now things are going smoothly.
I tested with a head block tester and the result was all right. And I left the heater on and did one more air-drain operation.
Today's temperature was 18 degrees and the auxiliary fan started to run at 85 degrees, kept the temperature at 103 degrees for about an hour. Is this normal?
Assuming normal, I'm going to proceed with the next task.
I want to ask you other questions.
1. If I turn on the heater, the a/c works. Is this to cool the fuel? Will that be a problem if i connect the a/c switch so that I can manually turn off and turn on the a/c?

2. I ran the heater today and there's warm wind coming from the vent on both sides, and cold wind coming from the vent on the center. Why is that? Am I mishandling the controller?





3. The fuel tank is on the left and right, and when the right side is selected, the oil on the right side seems to pass over to the left. I wonder if It is supposed to burn the left fuel first.

Thank you for your help in many ways.

 

RE:2. AC is always on in these cars unless you put a switch in the compressor wire to manually turn it off.
I'm told this is not for Cool air but for Dry air in the Foggy, Dank climate of the UK. Makes sense to me.

After the system reaches the selected temperature the "Auto" feature kicks in with cycling of compressor/heat to maintain that temperature, more or less: at least that's how mine works.

RE:3. My car (Series 2) has tanks T'd together just forward of the right tank (looks factory), both fuel pumps still in the tanks but disabled. The external pump draws from both tanks but favors the left tank by 50%; upon filling, Right tank may take 4 gallons, Left tank takes about 8 gallons. I have drawn fuel down to below 1/4 tank in the right, the needle for the left simply stops moving at some point, and fuel is drawn from the right tank.

I've often wondered myself if it was designed this way on purpose.
(';')

 

Goodo.

As Elinor has stated.

1), Fuel cooler, HA, whatever the intention, they leak, and cause issues you dont need. I remove them during the A/.C upgrade, and fit a switch for the Compressor, and never had an issue. Leave it there, and fit your switch, nothing sinister will happen.

2) The Delanair 2, in your care, is a complicated work of art. There is a set procedure to adjusting and setting the flaps that do what they do, and I have not touched one in 15++ years. There are MANY write ups on teh procedure in here. It WILL test your patience MORE than the cooling system, fact.

3) The fuel system has a series of solenoids that allow fuel to be drawn AND returned from/to the selected tank. Again, its been years, but many threads on here about the system. Laziness, from lack of use, is the main issue, and sometimes, simple using the system regains normality.