AAZ Vanagon boost peaks holds for a second then drops off after adjusting fuel

[RockOcean]

Hello, wow it's been a long time since I have posted on here. I hope everyone is well.

I have had my K03 set at 15psi for quite some time now. Recently I noticed my egts getting a little high so I decided to turn in my max fuel screw a half turn to see if that brought them down a little bit.
Well after I did that my boost at half throttle now goes to 10psi which it use to do (would only hit 15psi at 3/4 to full throttle) hold there for a second or two then quickly drops off to like 3 psi. If I stay off the pedal and then get back on it, it continues to do this. Sometimes the boost does not go back up to 10psi.. I turned the fuel screw back to where it was and it still does this. I tested the line going to the boost gauge for leaks which is all good. When I tested the wastage actuator it worked but I noticed the wastegate flap was stuck closed. So I freed that up and took it for another spin and got the same results. I then disabled the wastegate actuator entirely still got the same results.

Is it possible that adjusting the max fuel screw could cause this? Or did my turbo just bite the dust at the same time I adjusted it? Or could it be something in the IP? The turbines look good with no signs of them hitting the housing, but it does have maybe 1mm of in and out axial play.

The engine is a little tired with #4 cylinder low on compression so I have been thinking about a rebuild or maybe finally going AHU m-tdi. Are the AAZ & AHU turbos interchangeable? I have read that the housing is a little bit bigger on the AHU turbo but will it still bolt on and will my AAZ intake pipe fit to it? What is a good source for the LR 300TDI pumps lately?

I have settled in Montana and don't travel much anymore since my last post. I also picked up 3 more Vanagons! One to use as a donor to fix all four corners that were rusted out on my van. I got a smoking deal on an old Adventure Wagon that has no interior in the back which I plan on restoring. Then I found an 89 Carat that had been in town for 6 years after being rolled. It had the 16" wheels I had always wanted and lift springs so I snatched it up. Also has a good auto trans & runs! Then I finally just got the wheels on my van with some 16/235/70 Falken Wild Peak tires. I'm looking forward to hopefully painting the rest of the van this summer, we'll see tho if I put an AHU or rebuild the AAZ again I might have to wait.


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[fatmobile]

 It seems more like a turbo issue than a max fuel screw issue.
 Can't help you much on what will fit in the vanagon.
 You could PM libby, show him a link to this post.
He knows a lot about running diesels in vans.

[RockOcean]

Well I changed out the turbo cartridge and it still does the same thing. I am not too familiar with the IP but isn't there a diaphragm in there that works with the boost pin? If this diaphragm went bad would that cause the sudden lose of boost pressure? My IP has been leaking out of the aneroid at higher boost for some time now. I have also noticed when the engine is warm it holds the boost fine but once at operating temperature is when it will hold for a second then drop right off.

I think I am just gonna bite the bullet get the pump rebuilt, and rebuild the engine. It's something I have been putting off for a couple years.

[ORCoaster]

Yes, the boost pin is controlled by a diaphragm.  Just pull the top off and see what is going on there.  Not a hard thing to see, but getting it out can be a problem sometimes as it gets caught on the little pin at the bottom of the boost pin.  I find wiggling the throttle to help get the whole assembly out. 

[RockOcean]

There was a lot of oil in there I imagine due to all the blow by. I had no trouble at all getting it out while I was taking this photo it shot out all by itself. Would this mean something has broke off down there? These are the only parts that came out, the diaphragm connected to the boost pin, an upper spring seat, and the spring. The boost pin is flat on one side but fits in there anyway you position it. It was also interesting to see that the aneroid just screws out and there is no o-ring for it. Any idea where I can source a new diaphragm and aneroid? Or would the aneroid not leak if there was not a ton of oil in there? I purchased a Bosch Seal Kit 1467010059 & The Shaft Seal 1460283312 for a complete re seal that I might attempt myself. A guy in town wants to charge around $500 is that a little steep, or have prices just gone up that much?


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Springnboostpin by RockOcean.com, on Flickr


I am not sure if I am referring to the aneroid correct but it's 336 in the diagram (top center right) that has been spraying oil and fuel in the engine bay for quite some time when hitting higher boost while running normally other wise.

VEPumpExplode by RockOcean.com, on Flickr

[ORCoaster]

I am not sure where you can get a new diaphragm for that booster.  Did you find a hole in it? 

If oil is coming out of the little rubber hose then you have a leak.  It is just an air vent as boost air pressure is applied from the top, the air under it needs to go somewhere.  So that vent hole is what does the job.

Can you clean up the diaphragm and seal it with a rubber gasket seal?  That is what I would do.  Only because I don't know of any place where I have seen a replacement for that part.  Giles maybe? 

The flat part of that boost pin is the side where you get the most enrichment.  So in taking it off I bet you didn't mark the location of it first.  There is a little dot on the rubber part and I generally make sure it is lined up with the steepest slope of the pin.  You can vary the enrichment from least to most by turning that pin away from the left side of the aneroid or towards the right. 

As you have found it turns around in that hole 360 degrees but you generally only position the pin facing right, face in between, or face at the left-hand side.  Those are the low, mid, and high enrichment positions.

Between facing the pin in different directions and changing the position of that spring base down in the throat of the body you can get different amounts of boost at different times.  The base of the spring should turn up and down.  Mark it for where you are now and if you turn it so it comes up it applies more tension on the spring and thus you don't have the boost come on as soon.  Turn the base down and it allows the boost to come on sooner as the tension on the spring is now less. 


All changes need to be done in a systematic method and written down.  It might be weeks of driving between changes and will you remember if you turned it one way or the other?  Probably not.  Oh, and only change one thing at a time.  Don't move the position of the pin and change the tension on the spring.  You will not know what is really making the difference if you do.  One thing at a time, write it down, and take your time.

 

[fatmobile]

 The liquid you are seeing in the LDA is most likely diesel fuel.
 The pin inside, that rides against the boost pin needs an o-ring to keep the internal pump pressure out of the LDA.

You don't get that in most seal sets.
 It might be #91 in the picture.

I have been able to get separate seals and o-rings for my pump from the local bosch service center.
 Otherwise the DGK-121 seal set has one and also comes with the 19?mm mainshaft seal.

[RockOcean]

There is a hole in the diaphragm that you can see in one of the above photos.

I see what your saying about clocking the boost pin but I think mine is different. Or are you saying I can adjust it so my mark isn't dead center like you can see that it has been set at. For the spring too there seems to be no adjustment any way you would turn it since the base of the spring is flat and the bases where the spring rests are both flat also.

FlatBoostPin by RockOcean.com, on Flickr

FlatSpring by RockOcean.com, on Flickr


There is definitely a lot of oil in there that is why its black as well as diesel fuel. So there should be no diesel fuel in there? And the O Ring would be at the end of the max fuel screw that stops it from entering there. Shoot pretty sure I ordered a DGK-121 seal kit in the past but everything I looked up said 1467010059 is the part number for AAZ Pumps and then 1460283312 does not come with it which is the 17mm Shaft Seal.

As for the replacement diaphragm wouldn't this one be  it >> https://www.ebay.com/itm/173668735805?fbclid=IwAR1PFpgtIZBBFc8VlleOYlROy8C1bujhSUswlnVwz4hZWAgL00Py2KBpLZ4

It says its for Cummins but the DGK121 seal Kit also shows fitments for Cummins as well.

[fatmobile]

 Right, there is supposed to be no diesel or fluid under the diaphragm.

 The little port coming off that lower section keeps that area at atmospheric pressure.
 So when there is a hole in the diaphragm it lets gasses from the boost line enter and flow through the LDA spaceship.

So that might be only motor oil, instead of a diesel fuel mix.
 
 Your pin is flat. I haven't seen one of those before.

The o-ring I'm talking about doesn't go on the max fuel screw.
There is a small pin that rides on your flatflatty shaft. I'm going to call it a shaft because we have 2 pins here and it will get confusing.
 Normally there is a taper on that shaft, and as it lowers due to more boost, the pin will ride further into the LDA.
 As it comes back up the ramp on the shaft will push the pin back into the pump.
This moves a lever inside and reduces fueling when there is low boost, to keep smoke down.
That's what the LDA does, it keeps smoke down when boost is low.
There is an o-ring around this sliding pin that comes out of the pump.
 To keep fuel from following it into the LDA.

That's probably the right diaphragm on ebay.

[ORCoaster]

I have never seen a boost pin like that one.  Very unique and if it has a variable slope to it I guess it works the same.  Just no way to adjust it as I mentioned.  That takes a round pin with a ground-off shaft.

[libbydiesel]

That is the typical AAZ "joke pin".  You would see a decent improvement in performance and adjustability with a 'normal' boost pin or with grinding a steep slope on the pin.  The spring should match the profile of the boost pin and so replacement of the entire top of the pump with one that has a better pin and spring would give a better end result.

$500 is steep for just a reseal.  It is not hard to do provided you make marks to return adjustment screws to their prior position.  The diaphragms are available.  I recall seeing them on ebay.  If the engine has blowby/oil mist and the diaphragm has a hole, then the oil will pass the hole in the diaphragm and collect below. 

[RockOcean]

Thanks for all the great info!

I ended up sending in my Pump to Omega Fuel Injection outside of San Diego. They do really great work, I had them reseal a pump ten years ago. They said my nozzles are not spraying as they should be and that cleaning them would not fix it. Looks like there are multiple options for nozzles with many of them being hard to come by. Do you have any suggestions on which Part #'s work best and a good source for them?

[RockOcean]

Where are the springs available from? I can not find them anywhere.

[fatmobile]

What springs?

[RockOcean]

The Boost Pin Spring, I see a bunch of Pins for sale but no springs.