Hey guys,

I don't like getting on your nerves with some parts, but I am trying to figure a way out to make the vacume hose routing easier and, more important, less frightening to look at and work on.

1st question:
Under the RIGHT hand (A bank) manifold, to the rear, is a blue solenoid. Parts number EAC7905.

After searching the "Classic Jaguar Parts" site, there doesn't appear to be an exact position on the 5.3l V12 for this to be APART from this drawing noting towards the cruise system...



I find it hard to understand though, why that would be connected to the cruise control system, as the vacume solenoid is at the rear of the engine. The front of the A bank intake manifold has the vacume take off (IIRC) for the CC bellows... Right? Or is that from the rear of the manifold?

2nd question:
The extra air valve in the A bank side air filter box acts to the take off underneath the A bank intake manifold, right?

3rd question:
The rear manifold has 4 take offs. Mine had a blank on one of them. One is for the transmission modulator, I know that, and the other two seem "random" at the moment. I think one is for the aircon system inside the car (the plastic tube!?) and the other is for a temperature switch - right?

4th question:
Is it really required to adjust to use the hose reducers or would it do with simply using one hose from "front to rear" of those with the reducers?

5th and last question:
To clamp or not to clamp?



I thought my pictures had all the information I needed but found out, that I missed the details I need... Grrrrrrrr...

Cheers guys!

Damien

PS: incase it is needed: my car is an 89 Marelli... Just to make sure it works

 

I think you might be confusing EAC7935 and EAC7905

https://www.jaguarclassicparts.com/u...-from-v-144700


EAC7905 is the cruise control dump valve, mounted way forward on the A-bank, on a small bracket held down by the cam cover bolts.

EAC7935 'solenoid valve' is item #13 in the illustration is mounted at the rear of A-bank

The two look similar to one another

Cheers
DD

 

Hmm, I don't remember removing a solenoid at the front of the engine... And the part I have in my fingers is EAC7905...

 

In the back of my mind there's vague recollection of a small tidbit that says these vacuum solenoids were used for a variety of functions depending on market, emissions spec, model year, etc.

Might take some digging to sort it all out

The cruise control dump valve was orignally part of a recall, if I remember correctly, and later installed as standard fitment...but perhaps only certain markets?

Cheers
DD

 

I don't use the reducers if I can find a suitable size of vacuum hose that allows me to eliminate them.



Clamp vacuum hoses? I don't.


Cheers
DD

 

I ended up with one nipple plugged off as well.

Yes, one is for the climate control. One for transmission. I can't remember offhand what I use the other for.....maybe something for the canister purge system? Here again, I think usage may vary quite a bit due to all the different build configurations.

Cheers
DD

 

Canister purge isn't fitted to my car... I used to know exactly where things went... But that is now 3 years ago...

 

Hi Daim

This may or may not help?



Vacuum Module on 'A' Bank.
XJS V12

 

OB, that is the corner but it doesn't show the exacty routing... Grrr...

And that blue valve ends with a 4, which is what it should but mine ends with a 5...

Jesus! Stoopid cars!

 

Here are both valves. The bottom one is from my car. It is missing a black connector as it broke off. The upper one just has a pluged on airfilter.

EAC7905 and EAC7904

The 05 was on the 1990 scrap car I bought, which was a Marelli without cats. Mine is a Marelli without cats. I assume the difference in parts is just the black filter...

What do you think?

 

Are these helpful?

 

A little. Doesn't totally cover my model but at least a few bits should be the same...

 

I'm inclined to agree although a fellow does wonder of the vacuum 'value' is different as well.

Cheers
DD

 

Any way to test that easily? I mean, the pipe diameters are the same... If I could find the exact Denso number I could probably compare it there or even just ask Denso...

 

I reckon it can be tested, yes, with a bit of experimenting. Presumably the internal switch contacts are normally closed and open at xxx-amount of vacuum.

Or maybe vice-versa? That's where some experimenting would come in

A hand held vacuum pump with a vacuum gauge and a meter across the terminals should show at what vacuum setting the switch opens and closes.

Cheers
DD

 

As it is a solenoid it is electrically switched.

 

Oh, silly me. Gah!

You're right, of course.

I wasn't thinking. The sun was in my eyes and my morning coffee isn't very strong and....and.... !

The electric solenoid opens/closes a valve to allow/disallow vacuum in/out of the switch. I was thinking the other 'way round.....

Anyhow, the test is still sort of the same. Apply vacuum, then operate the solenoid. See if vacuum is held/released.

Cheers
DD

 

Seems like I just found out what the valve does on my car (at least on my one)...

If I can tell correctly, it is used to switch/activate the heating valve... There is one hose that goes to the full throttle switch (on the engine) and that also goes off to the heating system. The blue solenoid gets a vacume from the right side throttle body (take off on top) and as it seems also from the end of the engine (why? No idea). My thoughts are, that the switch just uses both vacume pull offs to get a usable constant vacume... As at higher rpm (no idle) the manifold has less vacume than at idle (closed TBs).

Can anyone confirm this?

 

I'm not aware of the heater valve being controlled by anything except the vacuum valve(s) located inside the cabin

https://www.jaguarclassicparts.com/u...noid-and-pipes


Cheers
DD

 

And the narrow plastic piping, kind of a reddish-orange in the engine bay? What is that for? Or could I be I am looking at something for the Marelli ignition?

This is annoying... Trying to find some explanation for the vacume routing is dreadful...