XJ6 & XJ12 Series I, II & III 1968-1992

Daimler double six 1979 AAV test?

 
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Old 07-30-2016, 07:42 AM
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Default Daimler double six 1979 AAV test?

Hello, Is the a way to be shure that the AAV is closed as it should be when hot. Thanks
 
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Old 07-30-2016, 08:08 AM
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If you are good with mirrors, you can look up the spout when its HOT, and note the slide position.

I am not that good, so I remove them, and its simple.

Daimler double six 1979 AAV test?-aav-3.jpg

Cold setting, or hot FAIL.

Daimler double six 1979 AAV test?-aav-4.jpg

Hot setting, closed 100%
 
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Old 07-31-2016, 06:59 AM
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Thanks fr yr answer Is there no simpler way, measuring pressures?
Disconnecting ATS could indicate a lean condition, if idle gets better, but this is not always due to the AAV beeiing open of coarse.
 
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Old 07-31-2016, 07:51 AM
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Nope.

Unless you can actually eyeball that thing closing when at operating temp (hot) any other tuning you may be attempting is a total waste of time.

I have NO idea if the ATS or anything would give any hints. The D Jetronic EFI system is a very basic/dumb system by todays systems standards. It is purely an analogue system. These engines will run quite comfortably with ATs and/or the Throttle Switch unplugged. The HE with P Digital, no way.

They jam regularly, and that is a fact, so I would suggest if it has not been dismantled and freed up in the last 5 years it will not be closing.

Takes about 15 minutes to remove, including the torn skin from that top elbow, and about 25 minutes to reinstall due to the torn skin, AND, the new elbow giving grief. Silicon Spray on the new elbow helps somewhat.
 

Last edited by Grant Francis; 07-31-2016 at 07:58 AM.
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Old 08-02-2016, 04:44 PM
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Can this provoke a stall when motor gets hot or is the motor just running lean and loosing power?
 
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Old 08-03-2016, 04:23 AM
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Both.

A stumble on acceleration, strange hot running idle due to the obvious vac leak the system is detecting, inability to lower the idle speed with the idle speed adjuster once the engine is AT operating temp, are all symptoms of an AAV having a moment.

ALL that I have been involved with, and there have been too many, have ALL had AAV issues.

Rebuild it, or remove it, is what I do.

It is SIMPLE to rebuild, and time consuming to remove and re-arrange a few things, choice belong you.

IfF idle is lousy, CLEAN the inner bore of both throttle bodies. They get contaminated with "V12 goo" regularly. I clean mine at each oil change.
 
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Old 08-04-2016, 03:59 AM
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Originally Posted by Grant Francis View Post
It is SIMPLE to rebuild,
How did you realised that? With a small servomotor and a temperature dependent servodriver (sparkfun)?
 
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Old 08-04-2016, 05:57 AM
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NAH.

Aussie common sense.

Took it off, did not close, so ripped it apart, honed it out, observed how simple that thing is, ground the LUCAS name off the side, reliabilty will now be superior, reassembled, and sealed with JB Weld, and it worked well.

Just finished Paul's Blue Goose AAV, and noted the wax bulb is getting tired, but it is now working, and returned to him for refitting.

Eventually removed them from all my V12's, and went with an electric solenoid for extra start air, but thats a whole different discussion.
 
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Old 08-04-2016, 12:23 PM
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Originally Posted by Grant Francis View Post
...ground the LUCAS name off the side, reliabilty will now be superior...
Ha, love it.
 
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Old 08-07-2016, 01:12 PM
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I juist read about bleeding the coolant system. I remember when I bought the car, there was to little coolant inside. I guess normally they should have bleeded it. Is it possible that the motor stalls as soon as temp. goes 80C because of air in the cooling system and if so, which mechanism would cause the stalling?
 
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Old 02-05-2017, 02:05 PM
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Originally Posted by Grant Francis View Post
If you are good with mirrors, you can look up the spout when its HOT, and note the slide position.

I am not that good, so I remove them, and its simple.

Attachment 133705

Cold setting, or hot FAIL.

Attachment 133706

Hot setting, closed 100%
Hello, If I suspect a failure to be caused by the open AAV when hot, Is it OK to plug the tube from the air filter to the AAV, in order to proof it? How can I do it without harming anything.. type of plug etc?
 
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Old 02-05-2017, 02:36 PM
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Just remove the air filter cover and cover the tube's inlet hole with your thumb.

Don't leave the tube plugged off for any period of time.

Cheers
DD
 
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Old 02-05-2017, 04:18 PM
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Originally Posted by Doug View Post
Just remove the air filter cover and cover the tube's inlet hole with your thumb.

Don't leave the tube plugged off for any period of time.

Cheers
DD
Hello, Is there reason not to plug off. I heard some people simply take the whole AAV system out of the car... because it regularly jams. It only gives more air when cold, isn'it
 
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Old 02-05-2017, 05:41 PM
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Removal is fine.

But....as to leaving the inlet hose plugged off:

The distributor vent system draws via a tap on the AAV hose as seen in this illustration.....


Extra Air Valve-5.3 Litre - Parts For XJS from (V)139052 to (V)179736 | Jaguar Classic Parts UK


Leaving the AAV hose plugged off exposes the distributor vent hose exposed to engine vacuum....which in turn sucks engine oil right up thru the distributor seals. You'll end up with the innards of the distributor drenched in engine oil.

Ask me how I know

Cheers
DD
 
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Old 02-05-2017, 06:30 PM
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Doug is corect for the HE, but the PreHE has no hose set up for cap venting, unless it has been retro fitted.

When the engine is Hot, and the AAV is closed, there is still an airbleed via a seperate internal passage to allow for idle speed adjustment. With that Inlet plugged that air bleed no longer exists, and the engine usually stalls.

The PreHE D Jetronic that stumbles off idle is one of a few things.

In NO particular order:

AAV not closing
Throttle switch adjusted incorrectly, they are a PITA to adjust correctly.
MAP sensor is leaking vac, or the internal circuitry is out of range.
Vac enrichment switch is inoperative.
Throttle cross rods are adjusted wrongly, as in 1 throttle opens before the other, causing an imbalance stumble as the engine comes off idle. More noticed on the HE, but it still happens on the older system.
 
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Old 02-05-2017, 06:35 PM
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Originally Posted by Grant Francis View Post
Doug is corect for the HE, but the PreHE has no hose set up for cap venting, unless it has been retro fitted.


Thanks for catching that, Grant.

I forgot to flip my memory switch to "Pre-HE"


Cheers
DD
 
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Old 02-06-2017, 01:06 AM
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Originally Posted by Grant Francis View Post

"V12 goo"
V12 goo? Does that require a prophylactic?
 
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Old 02-06-2017, 01:46 AM
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Originally Posted by scatcat View Post
V12 goo? Does that require a prophylactic?
Almost, but none of mine grew extra cylinders, or anything else of use.
 
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Old 02-06-2017, 12:24 PM
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Originally Posted by Grant Francis View Post
Doug is corect for the HE, but the PreHE has no hose set up for cap venting, unless it has been retro fitted.

When the engine is Hot, and the AAV is closed, there is still an airbleed via a seperate internal passage to allow for idle speed adjustment. With that Inlet plugged that air bleed no longer exists, and the engine usually stalls.

The PreHE D Jetronic that stumbles off idle is one of a few things.

In NO particular order:

AAV not closing
Throttle switch adjusted incorrectly, they are a PITA to adjust correctly.
MAP sensor is leaking vac, or the internal circuitry is out of range.
Vac enrichment switch is inoperative.
Throttle cross rods are adjusted wrongly, as in 1 throttle opens before the other, causing an imbalance stumble as the engine comes off idle. More noticed on the HE, but it still happens on the older system.
Thank you both gentlemen!!!
Where is that internal passage and how does it adjust idle speed?
 
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Old 02-06-2017, 10:48 PM
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You will need to remove and dismantle the AAV to see that.

I have refreshed many over the years, and that passage is simply there in the casting, and is an air bleed for idle adjustment when at operating temp.

I have never seen that passge clogged/grubby/contaminated., as it is too large a bore for that.
 

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