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Engine Specific Info and Questions => TDI Engine -General Info => Topic started by: alphawerks on November 29, 2007, 01:16:41 pm

Title: AHU ALH head/piston swap question
Post by: alphawerks on November 29, 2007, 01:16:41 pm

Hi all,

I have an AHU which has had the valves have hit the pistons on two cylenders. Don't ask how, I don't know, I bought it that way. Can any pieces from an ALH fit to the AHU block, ie: head and pistons?
If not does anyone know if the ALH crank would fit in an AZZ that has dropped it's cambelt pulley?

Thanks, Ryan

Title: AHU ALH head/piston swap question
Post by: jimfoo on November 29, 2007, 02:26:15 pm

No idea, but I'm looking for a bad piston for size comparison. Want to sell one of yours?

Title: AHU ALH head/piston swap question
Post by: RabbitGTDguy on November 29, 2007, 08:26:00 pm

Ok...

Head...no deal. ALH heads have a differently shaped oil return galley on the front of the head compared to the 1z/AHU heads. That is def. one difference right off the bat. I can't remember if the other oil passages and coolant passages are different...

Pistons... All TDI pistons for the 1.9 TDI will swap into each block. I have a 1z block that I'm running ALH pistons in (though modified combusion chambers, ceramic coated, etc.)

ALH and AHU pistons are the same. They are quite a bit stronger and less "crack prone" compared to the 1z TDI pistons which are single piece "cast" units.
ALH/AHU units are beefier in their construction, are made from a different alloy and also have brass triuons, and thicker ring lands without going to look at my measurements and pictures from the mTDI motor now in the Mk1.
There was a slight difference on the 1z motors, with the location of the top ring relative to the AHU variation and the later ALH motor. I believe the top ring on the 1z motors sits higher than the ALH ?
Off the top...can't remember.

Can the pistons be used? Yes...

ALH crank to AAZ?

No...the ALH block is slightly longer than the "traditional" external water pump VW blocks... this includes the 1z and AHU motors. The crank in turn is slightly longer to accomodate.

There is a nice thread on here in the IDI forums about AAZ crank repair and how it has been successfully done.

Joe

Title: AHU ALH head/piston swap question
Post by: A2TD on November 30, 2007, 01:00:00 pm

Quote

ALH and AHU pistons are the same. They are quite a bit stronger and less "crack prone" compared to the 1z TDI pistons which are single piece "cast" units.

The pistons I took out of my 1Z were forged, I think the cast pistons were only in the very early 1Z blocks.

Title: AHU ALH head/piston swap question
Post by: RabbitGTDguy on November 30, 2007, 05:46:28 pm

This was a 95/96 block that mine were pulled from...maybe they were cast. I can go back and look. The 1z pistons def. a different in construction, strength and composition than the AHU and ALH pistons from later motors. However, as mentioned...and per the question...they will interchange/fit.

:)

Title: AHU ALH head/piston swap question
Post by: myke_w on December 01, 2007, 03:51:58 pm

good luck finding tdi pistons... I've been looking for sets for the 2 months, all my suppliers are dry... if you find some new, let us know where..

Title: AHU ALH head/piston swap question
Post by: RabbitGTDguy on December 01, 2007, 04:38:51 pm

These are on Ebay quite a bit...have seen others too...

http://cgi.ebay.com/ebaymotors/VW-TDI-Pistons-Rings-Diesel-Golf-Jetta-Passat-Beetle_W0QQcmdZViewItemQQcategoryZ33623QQihZ013QQitemZ230195519123QQrdZ1QQsspagenameZWDVW

Title: AHU ALH head/piston swap question
Post by: myke_w on December 01, 2007, 06:12:15 pm

errr..  :( I meant Nural Brand, those are cheapie Chinese knock offs

 8)

Title: AHU ALH head/piston swap question
Post by: RabbitGTDguy on December 01, 2007, 08:44:36 pm

yah....unfortunately, thats all that has been up as of late :(

Joe

Title: AHU ALH head/piston swap question
Post by: myke_w on December 01, 2007, 10:55:02 pm

When my supplier has them I can do Nurals in std and .20 for 435 a set, but things are dry these days. I've occasionally seen the "HD" ones on ebay for 6xx something now and then, but can't really justify the expense because I know the Nural ones are tough as nails.   Too bad really..

Title: AHU ALH head/piston swap question
Post by: jtanguay on December 02, 2007, 12:47:40 pm

those pistons on the ebay link look like the ones from www.dieselvw.com hmmm......... chinese knock offs?!  would be nice to buy them and see at which point they melt/break/crack/pit.  :lol:

Title: AHU ALH head/piston swap question
Post by: RabbitGTDguy on December 03, 2007, 06:37:40 am

I didn't go to look on the site...I'm guessing since it is www.dieselvw.com that it must be the user "prothe" on ebay? It would be interesting to see "what" they do. I've asked him before when I was in a nozzle search about "who" produces his nozzles, just for general knowledge...and I could never get an answer.
That...I reported to Ebay. We do have the right to know (and I wanted to confirm)

Joe

Title: AHU ALH head/piston swap question
Post by: Slave2School on December 18, 2007, 11:53:02 pm

Do they have teflon or graphite coated skirts?

Title: AHU ALH head/piston swap question
Post by: jimfoo on December 19, 2007, 12:09:40 am

That is what I bought. There is a pic of one here. http://vwdiesel.net/phpBB/viewtopic.php?t=11359&start=30
You can't see it in the pic, but the first ring land has some kind of reinforcement. It's not steel, but it is very slightly attracted to a magnet.