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VW MKIII-A3/B4 TDIs This is a discussion about MKIII-A3/MkIII Jetta/Golf (<99.5) and B4 Passats (96,97) TDI's. Non TDI related postings will be moved or removed.

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Old January 10th, 2018, 14:01   #1
Veteran Member
Join Date: Apr 2008
Location: San Jose, CA
Fuel Economy: B4V - 37 combined; ALH - 53 best highway so far
Default Input/Advice

I've come across a B4 that's had an ALH swapped into it by a shop on the Trusted Mechanics list. The turbo/manifold are still 1Z, tranny is also original B4.

Lots of plusses for me in this combo, but what are the (potential) minuses? Swap was done 100K miles ago (don't know how many miles on the ALH prior to the swap).

Last edited by MarsBar; January 10th, 2018 at 14:42.
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Old January 10th, 2018, 16:14   #2
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Join Date: Mar 2011
Location: Northern MD
Fuel Economy: Race: 12mpg, Gandma:65mpg

as long as the price tag is right, should be fine! no other draw backs than usual
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Old January 13th, 2018, 09:25   #3
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Join Date: Nov 2007
Location: Nobleboro, Maine
Fuel Economy: And the miles just keep ticking away

The only drawback I can think of is not being able to follow one manual for diagnosis. Otherwise the ALH is a much more robust motor, although not as simple.
'97 B4: 453,000 miles Malone 3, PP520's, Stage 2 cam, SBC3, ARP studs, 2 1/4" exhaust, 2.5" Cat, no mufflers or EGR.
'96 B4V: 356,000 miles Malone 2+, PP520's, 6 speed, 02J short shifter, E-Codes, G60 brakes, Evo plate, DMF, stainless exhaust, heated leathers, cold weather package
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Old January 13th, 2018, 12:20   #4
Steve Addy
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Join Date: Aug 2002
Location: Iowa
TDI(s): 97 Mk3

^^^ what he said.

I wouldn't hesitate to buy it if the price was attractive but again you'll need to remember what book of knowledge (Bentley) you need to draw on for the different parts.

Based on what you're saying the 'core' engine is ALH but most of the ancillary stuff is all original AHU/1Z. I'm assuming then they have left the earlier electronics installed and simply adapted the engine to the older ECU etc.

You'd get the benefit of the ALH oil filter stand setup, which is decidedly easier than AHU/1Z but you'd also get the timing belt driven water pump, which I never thought was a good idea tbh. The cam driven vacuum pump is probably neither here nor there in terms of benefit, the older style was super reliable though.

Give an update when you've made a decision!

97 Jetta TDI, 90 B3V TDI, 92 MB 300SD

You didn't poison the coffee, did you? Not anymore than I usually do.
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Old January 13th, 2018, 20:10   #5
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Join Date: Oct 2012
Location: waupaca, WI
Fuel Economy: 40-42 with a lead foot.

due to your location in the peoples republic of cali (assuming that info is up to date), you also need to know if it will pass emissions...

I havent lived there since 2010 so i dunno the current state of affairs at the DMV but they werent exactly helpful for anything except emptying out my wallet when i lived there...

I would think that this is kinda the best of both worlds, especially if the B4s body is in OK shape. I love the B4s, and i like the ALH, but i HATE HATE HATE the fact that there is a motor mount in the way of the timing belt on A4's... not an issue in this case.
2003 Jetta TDI - 11mm IP, R520s and FMIC from the Red Death, HE221W (shooting for 26PSI), 1.8T pancake, DIY 3" OMI, still working on the DIY tune... its a learning process.
1996 Passat TDI - "Red Death" RETIRED. Had: Malone stg 1, 11mm IP, R520s, GT15/17 hybrid, FMIC, ETC
1997 Passat TDI wagon - Running donor or beater for sale, rough body
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Old January 13th, 2018, 23:23   #6
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Join Date: Jun 2010
Location: Free Mustache Rides
TDI(s): 98 jetta
Fuel Economy: 50

B4 should be good for KKKalif. Diesel smog starts with 1998s. You know, until some stooge figures out they can add $500 to the overall state budget by rolling the date back to 97.

a motor mount in the way of the timing belt on A4's... not an issue in this case.
Interesting. So the extra mount on the ALH goes unused, to no ill effect?

Last edited by turbodieseldyke; January 13th, 2018 at 23:25.
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