Finally got the old son of a gun running and took it around the block! Don't mind the wonky gauges...alternator seems to be working and the car doesn't have a full tank of gas so I still need to work that out. The temp did read a little high in the end so hopefully that's just an improper gauge reading too. 😬

https://streamable.com/ilej4

all it took was months of time and some help from you fine people.
List:
one dead injector replaced
new plugs
new wires
distributor cap
ignition coil
Built a new injector harness
new fuel pump and filter
cleaned and patched fuel tank
surge tank cleaning and filter
butterfly set
dead ignition pickup will def spin you for a long loop
and finally...Working junkyard AAV!

 

Good work, it's always uplifting to have win.

Once you have worked on it for a while your confidence and knowledge will grow, then you'll be helping out new members, just like OB..............

 

I can only agree with Warren on this. The more ypu look into the V12 the less complicated it will be and the more understanding will be there.

I've rebuilt a few engines in my short life so far, but nothing as complex as the Jaguar V12. Bit the more and more you look into the details and Follow hoses etc, the less 'holy moly' it looks

 

944
How did you diagnose the ignition pickup was faulty, please?

 

I think you've earned "Jagman" status. Well done !

Cheers
DD

 

I did a couple generic searches for reasons with spark and fuel a car won't start. Then I started reading about the pickup and how it basically acts as an on/off switch. I knew I had spark but it didn't seem like it was getting the on/off like everyone was saying. I replaced the module in the amp and since that didn't work I figured it had to be the pickup since they're connected. When I took it out the wires somehow severed at the spot where it enters the distributor. I think you might've said that's a thing that happens?

 

yeah once you get over the shear size and lack of room it's not so bad.


Having a car with more cylinders and displacement than my other project and daily together is always funny to think about. I've read so much about the engine I think I know where most of the hoses go now. Ha

I got it knowing its it's a project with work to be done, but there were a few times where I told my wife...I'm done, it needs a shop. Glad I stuck with it, way more satisfying.

 

Yes, it is very common that the wires fail where they exit the diff casing. Very well found.

 

Well the car starts and runs great now but one problem... it's wanting to overheat it seems. I replaced the thermostats, coolant temp sensor, coolant temp sender.... the aux fan does not seem to kick on. It will turn on when I turn the ac/fan on so the fan does work. I don't know if it's the relay or fan switch? I was wondering if the gauge is just reading wrong perhaps so I used an ir heat gun on the water rails and the temps got almost to 90c and at that point the gauge was right about at the H. Could it be the gauge reading too high? Isn't 82-88c where the car runs?

 

I also read that a bad advance can make it run hot? I recall the diaphragm on the advance being able to blow air through it. Can just the diaphragm be replaced?

 

Very possible that your gauge is wrong. More likely than not I'd say.

Just use a laser thermometer, or good Multimeter thermal probe to verify actual temp at steady running temps. You can modify the gauge to read correctly if you find it is wildly off. If you need instructions for that just ask and I'll dig them up.

 

the fan isn't kicking on which I don't know is worrying or that it's just not even hot enough? What temp should I finally shut it down if it just keeps climbing?

 

If you have a valid thermometer then the thermostat housing should be between the thermostats rated temp and it's full open temp. In any case it should be under boiling. Much over boiling and the pressure caps will release steam.

What temp should it run at is more complicated. What temp it IS running at is a better question.

my aux fan never kicks in. Because the temp switch never closes. It's tested good. No a/c either.

 

I'm forever mis-remembering when the fan temp switch is supposed to close. I have 94ºC in my brain but I could be wrong.

My car has a gauge with numbers and the fan kicks on just as the needle passes 90ºC



In and of itself there's nothing wrong with 90ºC.



Yes. The old barrel gauges are notorious wonky

On my XJS, years ago, the bottom-middle-top of the "N" represented approximately 82º-90º-93º respectively, as shown on my infra-red thermometer. The "H" would probably be something like 120ºC.

On Series III cars like mine, with numbers on the gauge, there's a green band (OK range) from 90º to 125º. As high as 125º seems out of the 'safe' range to me, personally, but there you have it.


If you have 82º thermostats it'll run at least that hot. If you have 88º thermostats it'll run at least that hot.

How high it goes beyond thermostat rating depends on when the thermostats are fully open (some production variance here) and how good the rest of the cooling system is....and driving conditions. I'd expect an 88º 'stat to be fully open at 92º or so.

More important than coolant *temperature*...in my opinion...is coolant *flow*. The engine doesn't care if the coolant is 82-88-95º or even higher (within reason) as long as coolant is flowing to all areas. This is hard to confirm, naturally. Making sure the system is absolutely clean and properly bled is about as good as you can do.

Anyhow, if the temp goes to 90º and stays there I'd wouldn't worry a bit. I don't see anything wrong with that....if you're confident that the flow is good.

Cheers
DD

 

Ok cool. I think maybe I just got a bit paranoid because all the stories of these engines catching fire and warped heads etc. I think I need to let it run a little bit more and see if it starts to creep up past 100c. I'm not sure why I am trusting the gauge when it seems no other part of it reads correctly from gas to charge.

 

A lot depends on the conditions.

In cool/mild weather ...let's say under 80ºF....the system should have no problem holding steady at around 90ºC or even less if you have an 82ºC thermostat. If it doesn't you probably have a problem lurking.

In hot weather in city traffic or up a long grade or such the temp might go higher. Mine does, as did my previous V12. Some consider this overheating or a problem. Others don't. But it shouldn't keep climbing up-up-up.

Cheers
DD

 

Have you ever taken out the radiator? The gap between the radiator and condenser seems to attract all sorts of debris. The radiator may be significantly blocked with grass, leaves and tree fluff.

 

yeah to be fair we have had a fall heatwave and the temp was 90F degrees in Illinois today! I'll give it another go tomorrow and try to see where/if it plateaus.

 

i haven't taken it out. I've heard a lot of people get crap between it and the oil cooler? Is there an easy way to just kinda separate them and spray a pressure washer in it?

 

Unfortunately, no. It isn't that bad of a job to remove the rad, just a pain.

I tried a number of ways of cleaning the rad before just pulling it, and there was a whole lot of junk I wasn't able to get out with the rad in place.