Not familiar with V12s. I know that all the cars I have owned (mostly v8,and a boxer12 bb512, a Pratt r2800 dc-6 engine r18) I can start it and it takes a while to get warm. You can still almost touch them after driving.
i recently purchased a Daimler Double Six and it gets incredibly HOT even after just 2 minutes! Is that how they are or is there something that needs investigating? I plan on installing 2 temp gauges (one on each side) to see if they get the same readings…. The dash gauge stayed Cold. Only idled it 4 minutes and i can’t even touch it !!!!

 

Doesn't sound right.

But, where are you touching?

Cheers
DD

 

thanks. Beautiful car. 99% original Swiss delivery (Geneve)
so I touch the top of the cylinder (not the exhaust manifold) (near the logo)
the driver side untouchable after 1 minute of idling from cold.
passenger side touchable warm to hot. Not like the driver side..
coolant is present. I removed a hose and it’s there. On both sides.


43k km

 

With Doug here for sure, dont sound right to me also.

Going out on a limb here, and "assuming" it is a Fuel Injected version???? The Carby beasts oh boy, they be different in so many ways.,

If you are touching the camcovers, maybe, as they do get HOT, real quick.

Cooling system castings, etc, no.

Retarded timing, mmmm, at a stretch, so the real thin section of that limb.

Have a read of the attachments, I am leaning to a stuck stat, or maybe both,

That low distance since the Mid 70's, also has me thinking the cooling system is FULL of mud etc, including the block, heater core, radiator, etc. Sadly, all that lack of use is now coming home to roost.

Bleeding the EFI PreHE cooling system can really test your sense of humour, well, my 3 did to me, the HE's were a breeze.

 

Very interesting info. The car has been well maintained over the years. Has had radiator ..expansion tank.. replaced. The coolant is in very good shape, clear and bright. The previous owner replaced fluids every 2 yrs..
I ran it today from cold and it didn’t feel as hot as quickly. The covers get hot, but I could touch the cylinder head, coolant manifold.. I’ll use infrared thermal imaging and see where it heats up as it idles.
yes v12 injection

 

Grant,

Yes the cam covers get hot quick.. I can touch the cylinder heads a bit longer..

Are you sure you need 100% closed bypass when the thermostat is fully open ??

« Now this is 2 mm at least too short to close that by-pass port 100%, and that port needs to be closed 100% for the cooling system to work anywhere near correctly«

in balanced flow system it is required to have some bypass to flow back in the motor to prevent localized boiling..

not sure how the internal passage plumbing is but if you have 100% of flow to the radiator then the bypass channel could boil as it doesn’t get at least a bit of bypass flow from thermostat… 2mm is too much? Maybe 1mm will suffice or a hole in the plate? But no flow at all thru the bypass might be an issue I think…

 

The cross pipe will not boil! The ports must be closed off by the thermostat when it is fully open, for proper cooling. Remember that there is a large connection between the water pump and the cross pipe.

 

I have NO idea, and at my age now, not bothered at all.

Mine all have that "new" set up, and many, many more, and the cooling system issues they were having were solved with the longer stats.
That port is actually closed by the disc prior to the stat getting to full open, coz IF it gets to fully open its lost control of the cooling system. Look at it, its a steel disc on an alloy face, never in a 100 years will it seal 100%, never designed to I reckon, so some bleed through will occur.

Stats DO NOT simply open and stay there, they are constantly altering the orifice, and that is cooling system design, SOOO, that by pass pipe will see some f;ow at times.If that siax is ac\tually a little bit, about 30% of coolant is recycled.

This includes, S2 & 3 6cylinder as well.

I experimented for a very long time, and a Radiator Specialist I knew well hit on the By-pass, albeit a Caterpillar 3208 engine. Once I did the PreHE Infected engine, the coolant temp was so stable I then suspected the sender or gauge, and that was a summer here of 44c, so I called it fixed, and did the rest of mine and others.

 

Which ones you prefer tridon or dayco ? I am about to tackle the project.
ill do the fuel hoses and the cam cover gaskets. Anything else I should do while in there?

I’ll take the hood off and the front for easier access.

 

Dayco for me, simply coz we had them in stock at work.

luv that statement, "what else while I am in there", oh boy, that is a obe BRAVE V12 owner, and WELL DONE from me.

Bonnet/hood off, NAH, that will create more work refitting and aligning than you need. Its not that bad for access, at least its NOT a HE.

Go to the next Tech Section, XJS, as that is where most of the V12 crowd lives, and they be the same, just got 2 doors, HA.

Camcover "D" seals, dont forget them when ordering the gaskets.
HI-Temp RTV, for those seals.
Timing cover rubber plug. Easy enough at this time.

Have a read of the sticky in the XJS area, Oil Leaks, its the same engine, so same issues.

Spark plugs, simple on a Pre HE.
HT leads.
ALL the water hoses, that will keep you out of "Mums hair" for a whole day.
ALL the belts.

At the rear of each head, IN the tappet block are Banjo Bolts, one each side, DO NOT TOUCH THESE. I have never had them leak, its always the "D" seals. They only "grip" by about 3 threads, and if you do try and tighten them, chasing the leak that does not exist, AND you strip the threads, irs engine OUT to fix it. SOOO, whenever that engine does come out, get the longer Banjo Bolts that are around, and change them, there are plenty of threads in the Tappet Blocks, its just a Jag thing from the Leyland days.to use what they had and they are really too short. BUT left alone, they will see you out.

Injector tip seals.

 

Good info. Thank you very much.
I have to figure out how to pump down the Air Conditioning and depressurize the system. Do you protect the inner plumbing with nitrogen before taking apart? Messed with several AC from my warehouse and it’s important to keep the system free of moisture. It’s a r134 refrigerant.

 

Why do you need to depressurize the AC? It can stay intact for thermostats and spark plug changes. If you do take things apart, what I do is pull vacuum and let it sit for a while, and then turn on the vacuum pump again and this will remove any moisture. But I would leave it alone if you don't have the right tools.

 

I want to remove the radiator to flush it and also access the water pump to check the bearings. I really want to remove the hood and work slowly and meticulously. I don’t like to have anything in the way. Of course if I’d just do the cam cover gaskets I’ll leave the AC alone. I want to do most of the to do list at once. It’s not fun to do things over and over again..