Differences of AHL and AHU

Davemacinnh

Member
Joined
May 16, 2018
Location
New Hampshire
TDI
97 1.9tdi
I’m curious if someone has a picture of the rear of these 2 engines. I heard there was a difference but am curious how much difference. Mainly for an adapter plate and crank shift adapter. Thank you!
 

jackfolstam

Veteran Member
Joined
Oct 14, 2016
Location
CA
TDI
MkI Rabbit ALH swap
Did you mean ALH, not AHL?
I'm no expert, but this is what I know: the ALH has a cast aluminum oil pan that has threaded holes that bolt to the transmission. The AHU has a stamped steel pan that only bolts to the bottom of the block.

This is what I am not sure of: I have two Rabbits; one with an ALH and one with an AHU. Both have the same 020 transmission, and thus the same front and rear engine mounts. The AHU seems to sit more vertical than the ALH on the same mounts, so the bolt pattern on the engine block for the transmission mating must be the same, but rotated comparing one to the other. Although, it could be just an optical illusion or something. I could take a picture of the 020 bellhousing tomorrow, but I'm sure you could find that on google.
 

Hasenwerk

Vendor , w/Business number
Joined
Nov 28, 2003
Location
Quesnel, BC
TDI
1982 Cabriolet (BEW|VNT17|Stage4), 1989 VW TriStar Syncro soon-to-be CR TDI (CBEA), 2001 Ford Ranger Edge 4x4 (ALH|VNT17|R520|Stage4)
I’m curious if someone has a picture of the rear of these 2 engines. I heard there was a difference but am curious how much difference. Mainly for an adapter plate and crank shift adapter. Thank you!
The crank and bell housing are 100% identical between the two motors.
 

Exenos

Veteran Member
Joined
Apr 29, 2014
Location
Ontario
TDI
02 Golf
The crank and bell housing are 100% identical between the two motors.

But you do need to take note of the vac pump with an ahu. It sticks out past the block say 3/4"? Might interfere with the adapter/bell housing depending on what you are using. It interfered with mine.
 

Hasenwerk

Vendor , w/Business number
Joined
Nov 28, 2003
Location
Quesnel, BC
TDI
1982 Cabriolet (BEW|VNT17|Stage4), 1989 VW TriStar Syncro soon-to-be CR TDI (CBEA), 2001 Ford Ranger Edge 4x4 (ALH|VNT17|R520|Stage4)
But you do need to take note of the vac pump with an ahu. It sticks out past the block say 3/4"? Might interfere with the adapter/bell housing depending on what you are using. It interfered with mine.
Never had issues with the ALH vacuum pump on the Volkswagen Vanagon or Ford Ranger. It doesn't stick out that much and the coolant flange below it sticks out on both engines as well...
 

Hasenwerk

Vendor , w/Business number
Joined
Nov 28, 2003
Location
Quesnel, BC
TDI
1982 Cabriolet (BEW|VNT17|Stage4), 1989 VW TriStar Syncro soon-to-be CR TDI (CBEA), 2001 Ford Ranger Edge 4x4 (ALH|VNT17|R520|Stage4)
Read again, I'm not talking about ALH.
I was "assuming" you meant ALH, as the AHU has the vacuum pump where traditionally a gasser would have had its distributor and that location in no way would interfere with an adapter plate.
 

Exenos

Veteran Member
Joined
Apr 29, 2014
Location
Ontario
TDI
02 Golf
I was "assuming" you meant ALH, as the AHU has the vacuum pump where traditionally a gasser would have had its distributor and that location in no way would interfere with an adapter plate.
If the bell housing is a large one and if it is not clocked the right way then there is the possibility for the vac pump to interfere. I'll give you a very specific example. An ahu that is mated to a sbc pattern with the engine clocked at the stock 20* angle WILL have the vac pump interfering with the top edge of the plate IF using a plate style adapter. I know this is true because I had to clearance my adapter and part of my bell housing for everything to work on my truck.
 
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