hello guys,
I started something what would be to believe a tremendous effort but I have to give it a go. Yup loosening the intake manifold. It 's hard to do and while I ve been doing some work already I just have one question. How to loosening the nuts just under the intake. Above I can see but the 2nd, 5th en 8th nut at the bottom of the manifold, how to get access to them?? Much appreciated.
ROn the Netherlands.
Ron,
What is the year, model, and type of fuel delivery in your Jaguar?
Paul
Hi Paul
It’s a series 3 year 1980 with fuel injection. Thx in advance
Ron,
Thank you for identifying the car you are working on.
I have removed the intake manifolds from a Series III XJ6 (4.2L XK engine with Electronic Fuel Injection) about six time on my Series III XJ6s and parts cars. It has never been easy.
I have been able to remove all the nuts on the bottom front of the intake manifold by removing the air filter housing, the ignition amplifier, and the distributor cap with the spark plug wires still connected and then reaching under the manifold to remove the nuts toward the front of the engine. I removed the battery in order to remove the nuts at the rear. On at least one occassion I had to raise a car up on my lift to access one or two of the nuts that I could not otherwise reach. Putting the intake manifold back on and tightening up all the nuts is a similar hallenge.
BTW, you will probably have a challenge separating the intake manifold from the blick even after you remove all the nuts. There are lots of posts about this in the archives. I usually have to pound on the intake manifold with a heavy mallet, while protecting the manifold with a piece of wood, in order to break the paper seal between the intake manifold and the block.
Needless to say this is not an easy thing to do.
Paul
Thx Paul i’ve read various horrendous stories. I have a vacuum leak somewhere underneath the intake. Cannot find out where. Thx for your kind help
Ron,
how do you know about the vacuum leak, if you haven’t found out where it is? I discovered the vacuum leak by spraying around the intake and thereby could identify the leak at cylinder 1 (explaining why plug 1 was white while all others were sooty and why in idle HT 1 could be pulled without much perceivable difference).
It is a serious job - even with carbs on - and you would do that to you only if you’re dead sure why you do it …
Good luck
Jochen
75 XJ6L 4.2 auto (UK spec)
Paul
Well I had a big backfire. The hose of the air filter came lose. Reattached it and again a backfires. The hose was still in place. The car starts now but dies instantly. If I disconnect the rubber hose after the maf sensor and I close the intake by hand. I cannot feel any vacuum the motor tends to run for 10 seconds. When I pulled my hands back the engine dies. So it draws somewhere air. Obviously I checked all visual vacuum hoses no one is lose. But I cannot see underneath the intake manifold. When I blow. Some sigaret smoke I a vacuum hose some smoke appears from underneath the intake. S my guess for so far it has to come from that area
**
Check the vacuum hose under the AAV, Ron…?
Easiest from underneath, but the AAV can be unbolted to reveal the vacuum hose - it’s a more likely vacuum leak than the intake manifold. I would suggest that a manifold leak should be confirmed by fair means or foul, before(!) the gasket is changed…
Also, routinely after a backfire; check the motion of the AFM for constant and even resistance and no hanging - a backfire may cause damage to the flap. And recheck the connections on the air duct. The throttle butterfly is less vulnerable…
Frank
xj6 85 Sov Europe (UK/NZ)
**
Frank
xj6 85 Sov Europe (UK/NZ)
**
Did all that. Maf sensor flap not stuck all visible hoses connected. It’s driving me nuts. With the elbow of at the throttle body. Covered the intake at the throttle body it with some kind of plastic the engine starts . It seem to be an massively leak. Again it’s driving me nuts
Ron,
I want to make sure that you understand Frank’s suggestions about the hoses to the Extra Air Valve (EAV) also called the Auxiliary Air Valve (AAV) by Jaguar, sometimes even in the same publication. 
I will call it the AAV for simplicity.
The attached pictures show the two AAV hoses, the front one (EAC1596) that you can see circled in blue in the first picture and the rear one (EAC1471) that you can not easily see unless you look up from beneath the car circled in red in the second picture. I took these pictures of the intake manifold that I recently removed from my 1984 XJ6 Vanden Plas that I am doing an engine swap on.
Because it is not easily seen, the rear hose is often neglected until something serious happens, like the engine won’t start. I removed and replaced this rear hose on my two Series III XJ6s and when I did they were as hard as a rock. I have also removed that rear hose from 2 of my XJ6 parts cars and my two spare 4.2L XK engines and without exception that hose has always been in sorry shape, hard and brittle. I have had the hose crack and break easily in my hands as I tried to remove it.
I recommend that you remove the rear hose from your AAV and inspect it for condition as it could very well be the source of your vacuum leak. The AAV is an enrichment device that results in added fuel to the engine for cold starting. If that hose is broken your engine will not have enough fuel for starting and one reason for backfires is a lean fuel mixture.
I usually remove the front hose and AAV first before reaching back beneath the intake manifold to access the rear hose clamp. Access from beneath the car if you have a lift is also possible.
Paul
**
If you close the air inlet to throttle body, Ron; the AFM gives no fuelling information to the ECU…
…nor does the engine get any air except through the AAV hoses and the idle screw. And the ECU probably has a set minimum fuel delivery - keeping things going…
Which is no solution; check the AAV hoses as per Paul - as a beginning…
Frank
xj6 85 Sov Europe (UK/NZ)
**
Thanks guys.
Hopefully this afternoon i have some time to investigate. Will let you know of course. Thx
Ron
well guys you know what. I blew some sigaret smoke into the vacuum pipe near the intake. Went under the car and blew with a air gun through the hose which was full of smoke. I saw som smoke coming from the rear hose EAC 1471 near the valve. I then unbolted the air valve and the vacuum hose was not connected to it. So there 's the air leak. The hose is not cracked or damaged but is rock hard, so I will replace it with a new one. Think it will do the trick. Thank you Frank and Paul a million for pointing me in the right direction. Saved me from hours of work with the intake. thanks thanks thanks
ROn
In this case I’d say smoking has saved you a couple of hours of valuable lifetime;-)
Best
Jochen
75 XJ6L 4.2 auto (UK spec)
Ron,
I am pleased that you were able to find your vacuum leak without having to remove your intake manifold. I know how difficult a job that is, and as it turns out I will be removing one today. I hope that the detached and hardened rear AAV hose is all that was wrong and that a new hose gets your car back on the road again.
Paul
