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Author Topic: Very little boost on my mTDI ALH Vanagon install  (Read 22427 times)

Reply #30November 04, 2018, 11:15:03 pm

libbydiesel

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #30 on: November 04, 2018, 11:15:03 pm »
Any progress or update with this?

Reply #31November 05, 2018, 03:41:12 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #31 on: November 05, 2018, 03:41:12 pm »
I haven't really had much time to apply to this project, but this morning I tried a few of the last straws in my meager arsenal.  I swapped in a pressure regulator from a 4BT pump and the overflow banjo bolt regulator from another pump.  Additionally, I installed a small low pressure pump in the feed line just after the tank.  This is really just to help with priming the system during fuel filter swaps and the like.  It's triggered by a toggle switch in the engine compartment, and is only intended to run very briefly.  It allows flow through the pump when it's not turned on.   

Nevertheless, there's no love for me after all that.  It cranks and cranks, but doesn't even sputter in the least.  It's got to be an issue inside the pump.   
'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #32November 05, 2018, 08:45:28 pm

libbydiesel

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #32 on: November 05, 2018, 08:45:28 pm »
Ugh, I'm very sorry to hear that. 

Reply #33November 05, 2018, 10:59:50 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #33 on: November 05, 2018, 10:59:50 pm »
This vid shows the supply pump buried all the way up in the front, so it appears the whole thing needs to come apart.  Ugh, indeed.  Unfortunately I don't have any choice but to do this work myself.  I'll practice on my "learners pump".   

https://www.youtube.com/watch?v=_01gEg2ZMwg

I'm saving these here so I can find them later.

https://www.youtube.com/watch?v=RkDsEQx82do

https://www.youtube.com/watch?v=pLSefeFnF4w

https://www.youtube.com/watch?v=n94BvDvDJgM
'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #34November 06, 2018, 06:17:07 pm

libbydiesel

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #34 on: November 06, 2018, 06:17:07 pm »
Yes, the vane pump is at the very end of the case.  It is not terribly complicated, though.  Mark any adjustments and keep all the wear items in their same locations (e.g. camplate rollers).  Taking pics as you progress through the disassembly would be wise.  Post up any questions.  It's not as hard as it might seem but still does take care and a clean work space. 

Reply #35November 06, 2018, 07:47:21 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #35 on: November 06, 2018, 07:47:21 pm »
Thanks again for all your help.  Since I've never serviced an ALH (I assembled this, but servicing is different), is it possible to find TDC, and then slacken the T-belt tensioner and then remove the pump without having to disassemble the lower cover and crank dampener? 
'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #36November 07, 2018, 07:32:04 pm

libbydiesel

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #36 on: November 07, 2018, 07:32:04 pm »
Yes, it is possible.  With the pump removed, the belt will have a tendency to jump this way or that around the crank sprocket.  Be extra sure that the cam and crank both are at TDC and pump pinned on reassembly.   

Reply #37November 07, 2018, 09:52:06 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #37 on: November 07, 2018, 09:52:06 pm »
Thanks, I'll tear into it tomorrow and report back with what I have found. 
'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #38November 09, 2018, 01:04:41 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #38 on: November 09, 2018, 01:04:41 pm »
I pulled the pump yesterday.  Is there a DIY solution to the triangular bolts on the side of the pump?   
'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #39November 09, 2018, 05:51:23 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #39 on: November 09, 2018, 05:51:23 pm »
To answer my own question, I modified a Craftsman 1/2" six point socket with my Dremel so that the inside profile matched the triangular head of those bolts.  I'm currently trying to figure out how to remove the dark grey cylinder in the bottom of the pump body, so I can get at the supply pump.  So far I haven't found any obvious problems
'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #40November 09, 2018, 07:49:18 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #40 on: November 09, 2018, 07:49:18 pm »
I've got it completely taken apart, and the only issue I've found is some scoring on the pump housing, but this is not in the supply pump section.  Thoughts?



'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #41November 09, 2018, 08:22:58 pm

libbydiesel

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #41 on: November 09, 2018, 08:22:58 pm »
That looks normal to me.  The vanes of the vane pump all move freely?  The key/keyway of the vane pump are in good condition?  Have you pulled out the high pressure piston?  Is that all fine?  Have you tried pulling a vacuum on the fuel supply line and confirmed that fuel flows without issue from the tank?

Reply #42November 09, 2018, 10:09:35 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #42 on: November 09, 2018, 10:09:35 pm »
Everything I've observed with the exception of that wear on the housing appears to be operating well with no abnormal wear or stickiness.  I'm not sure what the high pressure piston is, but I have everything pulled off the pump, though I didn't remove anything from the upper cover.  I blew compressed air through my fuel filler neck and fuel flowed fine through the hoses and filter.   

I know this is getting a bit ahead of myself, since I'm still chasing a running condition problem, but how difficult would it be to swap over my 4BT pump head when I reassemble this thing?  I'm kinda surprised at how different the plunger housing is between the Cummins and LR. 
'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #43November 10, 2018, 05:57:55 pm

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #43 on: November 10, 2018, 05:57:55 pm »
Here are the plunger housings from the 4BT, LR and a Prothe unit I bought probably a decade ago, when my ignorance was even more chock full of ignorance.

'87 300TD (OM606)
'90 300D (OM602)
'89 Vanagon Bluestar (ALH)
'01 EV Weekender (AXK)
'04 Passat Variant (BHW)

Reply #44November 10, 2018, 11:18:55 pm

libbydiesel

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Re: Very little boost on my mTDI ALH Vanagon install
« Reply #44 on: November 10, 2018, 11:18:55 pm »
By 'high pressure piston' I was referring to the plunger. 

Have you confirmed that there is not any issue with the fuel supply to the pump (tank, filter, etc...)?

I probably wouldn't recommend swapping the fuel distributor/ plunger assembly at this time.  It would add another unknown to the equation. 

I would reassemble, pull fuel through the pump until full, and try running with supply and return submerged in a container of clean diesel.