Finally had a chance to install the correct thermostats. The result is much better, as you can see in the picture bellow. Halfway through making a new fuel injection harness, things are coming together!

 

Simple cars are they not?

That is the temp all mine sat at, and that takes into account the gauge "accuracy" issues that haunt some owners.

Its got oil pressure
Nearly out of fuel
Volts need a kick start though.

NO complaints in my book.

 

Yeah charging is still something I need to sort. It jumps up with engine speed, but is definitely low at idle.

 

Not sure here but did you do an alternator upgrade ??

Reason I mention is that I've seen pulleys recommended that aren't necessarily suited to the alternator installed. The alternator being such that below x rpm it doesn't produce anything, typical alternators need approx 1800rpm before they generate anything.

Problem here is that the V12 tickover is slow and the standard alternator doesn't have a small enough pulley, but a smaller pulley would stress the belt - probably - but the optimum size for a V12 would be 60mm or so. This is of course based on my numbers, I have an approx diameter of the crank pulley of 148mm and the alternator pulley is 67mm, this is a ratio of 2.2 : 1 approx - which at 750rpm tickover is only 1650 alternator rpm or so. To find the ratio divide the crank pulley diameter by the alternator pulley diameter, multiply the resulting ratio by tickover rpm to give alternator rpm.

 

I have replaced the fuel injection harness with one I built. Its not the prettiest but it's functional. The engine definitely runs more smoothly now and magically, the charging problem has been solved. I think there must have been a short in the harness. Now on to the windshield wipers...

 

How good is the V12 (Double Six), once you get that catch up done, and kick "Freddie Fiddler" out of the area.

Well done.

Looks, HA, as long as it works, who cares in real life. Tidy up can be done later.

 

Good stuff good stuff good stuff.

My voltmeter reads way lower than that while my alt digital meter will be reading 14, 14.1, 14.2, 14.3... Damn barrel guage will hardly move...

Happy for ya over here!

 

Well here's a conundrum. Coolant seems to be moving from the radiator to the expansion tank, and then on to the ground. My understanding is that as the coolant heats up it expands, moving into the expansion tank and that it would be pulled back as it cooled. It seems to not be doing the second part of that. Would a bad radiator cap on the header tank cause this? Its new, but feels a little funny when tightening. When I replaced the thermostats I needed more coolant to fill the radiator than I took out, which I thought was strange. My theory is that the radiator cap keeps the coolant in (I would have noticed if it were pissing fluid) but lets air in. So coolant goes to the expansion tank and then gets replaced by air, instead of being pulled back. Does this seem like a reasonable theory?

 

Kind of but not quite. There are two caps, one is a fill point, the other is on the tank on the inner wing - they are not the same despite what many claim, the fill point cap is a sealing cap and has a higher lift pressure (20 psi) than the tank on the inner wing, the latter should have a 15psi rating - I've seen a lot for sale that are flat out wrong. The tank on the inner wing should vent to a recovery tank located behind the rear splash panel under the left wing, it is from this that the system should draw coolant back in - the only place coolant should end up on the floor from will be this location behind the front wing and even then only if the recovery bottle overflows.

 

Yes, it is the recovery bottle that is overflowing. They are both 16psi.

 

Then they're incorrect, one should be 20 and the other 15 - but if you're blowing coolant out that's not a good sign - have you ever refilled / bled the system ?

 

The whole system is new. It seemed fine, but hot, because I had 90C thermostats. I changed them for 82C ones a couple of weeks ago. It seemed fine, but I haven't really driven the car much. Sorting through other issues. Today I was trying to get it to charge at idle (I did, smaller pulley spins the alternator faster) but after only running for a couple of minutes I saw a puddle of coolant forming on the ground. I opened up the bleed valve on the radiator, shined a light in, and it was almost dry. I can fill it up again, and I will, but I need to figure out why the coolant isn't returning from the recovery bottle.

 

This is why the caps are different - the cap on the fill point should not permit air back in - it is a sealing cap not a venting cap - you may find that it is a standard radiator cap and is allowing air to be drawn in - path of least resistance and all that.EAC4192 is the fill point cap, CAC5095 is the tank cap.

You will see on many many sites that they list these two as one and the same - they absolutely are not.

 

Tried to find something that explained how these things work - one of the caps on our system must not allow air back in - the filler cap near the engine. The other cap must be designed specifically for a closed system or coolant leaves but cannot return.

Cool Cat

But I'm a little concerned if you're lifting a 16psi cap to the point where it vents - you may have an air lock or something in there - a quick search here should yield a few results for bleed V12 cooling.

 

And Jaguar now lists CCC6707 for both of them...

 

It does I agree - and it is incorrect but only a real specialist would know. Talk to Jon or Ben Thomson at Simply Performance - that's where I got mine.

 

Sorry ​​​​​​@garethashenden for asking on your thread..
Are both caps those with the spring underneath, only 1 rated at 15psi and the other at 20psi?
The 20psi works as a sealing cap because it has a higher pressure than the other cap?
I think the normal caps without spring has no pressure indication?
Thank you.

 

Actually, Ben, I disagree with the different cap poundages point you make. The spout cap at the front of the V cannot vent to air even if a 5 pounds blow off cap is used. The spout cap is NOT a system-sealing cap, it just vents to the purge system when it blows off, (of course it should not leak, but that is another matter).This is because when the inner sprung seal lifts, the vent merely goes to the purge system (ie stays within the pressured system, it does not go to a unpressured separate system). You are, of course, 100% right that the wing header tank controls the system pressure, which should be 15 psi, AND that the wing cap should vent out to the atmospheric tank in the wing, and the system should only draw coolant back from there via the wing tank. My point is that it does not matter what the blow off poundage is in the spout cap. Even Jaguar for some unknown reason were wrong about it on the HE!
Before I modified my coolant system to have a gravity purge system and no central spout, I had a solid cap on the top of the centre spout and coolant could pass into the purge system without hindrance. This made exactly zero difference to coolant temps or anything else.
Finally, my view is that the system should be filled first via the wing tank (with BOTH caps off) until that is full, then that cap replaced, and then through the spout! But this, like oil, has has many opinions as there are owners!

Sadly, this mod (the idea for which I have to thank Grant Francis) is impossible for later ABS equipped cars, as there is just no space available.

 

Greg is correct.

The filler spout cap has NO affect on the system pressure. In fact, if you measure the depth of the cap, top seal to lower seal, and then the depth of the spout, top lip to lower lip, the cap is most likely too short to contact the lower seat. I have used a Blank Cap here forever, as I did on the Series cars with the 6 cyl engines.. SAME system specs, just done a different way.

The top seal, under the metal section you grip to remove that FILLER cap is the most critical part of the whole cooling system. If that sucker does NOT seal 100%, the system is doomed.

Same for the PRESSURE cap on th3 metal header tank for that upper seal. If it does not seal, the system will vent to the atmospheric tank, and suck air in via that upper seal as it cools.

Caps that blow off at a lower pressure than spec, COMMON AS MUD. I run 13lb on all the V12's, and my NEW cap, CPC Made in Aust, rated at 13lb, blew off at 4lb, as did most of the stock at work at that time. I went through the entire stock of caps, 100's, and rejected 80% of them as out of spec by more than 1lb. Found a 13 that blew off at 13, fitted to the beast, NO more issues, AT LAST.

Bleeding the system, covered in that Sticky at the top, BUT, if you have lost coolant due to stat replacement etc, you MUST manually drain that metal header tank BEFORE filling the system. That applies to the HE only. The trapped air, trying to escape, as you fill SLOWLY, via the filler spot rail 1/2" hose that goes to the header tank, CANNOT escape if coolant is in that header tank, it is a "water seal", like "S" pipe in the kitchen sink.

Simply filling that system, and driving off is FATAL. Your car, of course, your decision.

I am NOT arguing with Jaguar Part numbers. I spent many years as Parts Manager with Jaguar, and the mistakes, rationalisation of parts, etc was terrible. The thermostat fiasco is one we all know of. Fixed now, I believe, but that took 10 years since I reported it.

Sooooo, the upper seal on BOTH caps is more important than the pressure. If that system is NOT sealed to the outside world 100%, you will be chasing Temp fluctuations forever.

 

Sealing caps shouldn't have springs - why Jaguar did that I don't know - a radiator cap isn't a cap because it has a spring either, some are designed to let air back in, some are not but most think a cap is a cap is a cap ... it isn't ... just like thermostats.

Think about this in engineering terms, this is not all about system pressure, although part of it is. In an expansion situation you need the expansion tank cap to lift before the filler cap - this pushes into the recovery bottle. When the system cools and pulls vacuum the cap on the filler neck must NOT allow anything back in - aka air - it is desireable for the expansion tank to pull excess coolant back from the recovery tank.