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Engine Specific Info and Questions => IDI Engine => Topic started by: bigblackcaddy on October 09, 2008, 11:02:26 pm

Title: Brand new AAZ head precup peculiarity
Post by: bigblackcaddy on October 09, 2008, 11:02:26 pm
Should it be flush or is the that little trough on the top edge normal?  All four are like this, so I'm guessing it was meant to be that way (or somebody screwed up four times exactly the same)... but why?

(http://lh3.ggpht.com/dancowles/SO7tZG4kpDI/AAAAAAAAAMU/yo6ZWU7cels/DSCF3263_Small.JPG)
Title: Brand new AAZ head precup peculiarity
Post by: blkboostedtruck on October 10, 2008, 07:56:43 am
they should be flush! sounds like it was not finished yet?
Duane
Title: Brand new AAZ head precup peculiarity
Post by: zukgod1 on October 10, 2008, 08:15:25 am
Doesn't sound right that's for sure.

Can ya post up a pic?
Title: Brand new AAZ head precup peculiarity
Post by: VW_Commuter on October 10, 2008, 08:20:44 am
That looks like a dropped pre-cup waiting to happen.
Title: Brand new AAZ head precup peculiarity
Post by: bigblackcaddy on October 10, 2008, 09:12:06 am
I tried to imbed a pic.  It's working for me, but I guess some of you can't see it.

Try this link (http://picasaweb.google.com/dancowles/Caddy#5255398830788355122)
Title: Brand new AAZ head precup peculiarity
Post by: zukgod1 on October 10, 2008, 09:42:00 am
That's not a very good pic to see what we need to see.

Your saying then the pre cup is sticking up above the machined surface right?


(http://lh3.ggpht.com/dancowles/SO7tZG4kpDI/AAAAAAAAAMU/yo6ZWU7cels/s640/DSCF3263_Small.JPG)
Title: Brand new AAZ head precup peculiarity
Post by: blkboostedtruck on October 10, 2008, 09:56:54 am
I can tell it's up high! and looks like the edge is broken away!
if left like that you would prolly drop the precup and the HG gasket would not seal?
Duane
Title: Brand new AAZ head precup peculiarity
Post by: bigblackcaddy on October 10, 2008, 10:26:00 am
Sorry, I didn't describe it very well.  The precup is flush with the head surface, but that groove along the top side is what concerns me.  I meant should it be flush all the way around, i.e. no groove.  I think blkboostedtruck's "looks like the edge is broken away"  comment is directed at what I was looking at.  All four are "broken away" the same though, so it looks like it was intended, which is why I ask.
Title: Brand new AAZ head precup peculiarity
Post by: zukgod1 on October 10, 2008, 10:56:09 am
Ok so its flush, that's solved then.

The part that looks to be missing would not have came that way from the factory and I cant think of a reason why a machine shop would do that either.
That area is stepped so unless all the material is missing I don't see it being a issue.


I don see it being a problem however, I would peen a couple spots around the precups so there is less of a chance of them falling out.


From what I can see that head is in great shape.
Title: Brand new AAZ head precup peculiarity
Post by: subsonic on October 10, 2008, 03:47:02 pm
Who is the head maker?  Where did you get it?
Title: Brand new AAZ head precup peculiarity
Post by: jtanguay on October 10, 2008, 04:12:47 pm
i would consider peening the area around the pre-cups to ensure you don't drop one...  anyone have the link on how to do it?
Title: Brand new AAZ head precup peculiarity
Post by: autoholic on October 10, 2008, 04:20:07 pm
Looks like alot of pitting for a new head.
The peening idea sounds like a good one, but I'd be somewhat scared to do it, fearing I may actually loosen it. Dropped prechamber; that would make a hell of a sound!
Title: Brand new AAZ head precup peculiarity
Post by: rallydiesel on October 10, 2008, 04:44:01 pm
I agree with the pitting comment. That surface looks quite rough. I would hope you'd get it milled before using it cuz you're asking for a head gasket failure as it is now.
Title: Brand new AAZ head precup peculiarity
Post by: autoholic on October 10, 2008, 04:53:22 pm
Now you got me thinking on that dropped precup scenario. I searched around but did not come up with any one who has has it happen. The precup is captured by the HG/head though right? so what happens, does it get loose and rattle around till it disintigrates? whatever it is that actually happens, it sounds nasty, I should look into peening mine too since I'll have my head off again this weekend.
Title: Brand new AAZ head precup peculiarity
Post by: dino1 on October 10, 2008, 06:06:49 pm
there appears to be wd-40 or some type of oil on the head, the oil has picked up some dirt and that is the pitting you see. Look at the edge of the head where the fluid has built up.
Title: Brand new AAZ head precup peculiarity
Post by: autoholic on October 10, 2008, 06:18:41 pm
Oh yea, looked like pitting at first glance.
Title: Brand new AAZ head precup peculiarity
Post by: rallydiesel on October 10, 2008, 07:04:44 pm
Quote from: "autoholic"
Now you got me thinking on that dropped precup scenario. I searched around but did not come up with any one who has has it happen. The precup is captured by the HG/head though right? so what happens, does it get loose and rattle around till it disintigrates? whatever it is that actually happens, it sounds nasty, I should look into peening mine too since I'll have my head off again this weekend.


This happened to jimfoo. In fact, I think almost every breakdown has happened to jimfoo!
Title: Brand new AAZ head precup peculiarity
Post by: jtanguay on October 10, 2008, 09:17:47 pm
i'm pretty sure the oil is there to prevent things like corrosion/pitting... if it is wd-40 though, that stuff actually eats certain metals... i think because it dissolves oils etc...

i personally think that peanut butter would be a better choice than wd-40.  the hard part would be cleaning it off when time came to use it.

hopefully whatever is on that head is not wd (water dispersant) 40!

Relevant topics on pre-chamber problems:

http://www.vwdiesel.net/phpBB/viewtopic.php?p=94048&highlight=peening#94048

http://www.vwdieselparts.com/forum/viewtopic.php?t=7799&postdays=0&postorder=asc&start=30

PEENING - Picture courtesy of libbybapa!
(http://i13.photobucket.com/albums/a269/libbybapa/IMAG0098-1.jpg)
Title: Brand new AAZ head precup peculiarity
Post by: jimfoo on October 11, 2008, 12:41:10 pm
Quote from: "autoholic"
Now you got me thinking on that dropped precup scenario. I searched around but did not come up with any one who has has it happen. The precup is captured by the HG/head though right? so what happens, does it get loose and rattle around till it disintigrates? whatever it is that actually happens, it sounds nasty, I should look into peening mine too since I'll have my head off again this weekend.

(http://www.66rover.com/TDIswap/TDI%20Parts%20121307/slides/2and3.JPG)
(http://www.66rover.com/TDIswap/TDI%20Parts%20121307/slides/CupTop.JPG)
(http://www.66rover.com/TDIswap/TDI%20Parts%20121307/slides/piston.JPG)
Ummm, here is what happens.
Title: Brand new AAZ head precup peculiarity
Post by: bigblackcaddy on October 11, 2008, 06:45:51 pm
You guys figured it out.  The "pitting" is just oil on the head that picked up fuzz and dust when I tried to wipe it with an old towel.  It was in a plastic bag when I got it and had this light oil all over it as a preservative I assume.  

Thanks for the carnage pics/threads.  Ugh.  What is involved in peening?  Looks like you could just get a rounded punch or something and smack it with a hammer.  The groove in the edge of the precup might actually be a blessing in disguise... If you peen along that edge the head material would get slightly pushed out and keep the precup from falling down better than just tightening it in the hole.

Head is Kolbenschmidt from BleachedBora.  Some more pics here. (http://picasaweb.google.com/dancowles/CaddyMotorRebuild#)

Extra Credit: Can anyone explain what this little ball is for? (http://picasaweb.google.com/dancowles/CaddyMotorRebuild#5256072754229829122)
Title: Brand new AAZ head precup peculiarity
Post by: blkboostedtruck on October 11, 2008, 08:04:03 pm
ahh now you say from bleached bora! if i would of known that!
his stuff is quality that he gets his hands on! to me it sounded like you got the head from a questionable joint and was not sure about it's machining work and the pics. were deceiving!
now i know where it's from! put the dam thing on and run it!
show pics. of your burnouts now on    :shock:
Duane
Title: Brand new AAZ head precup peculiarity
Post by: jtanguay on October 11, 2008, 08:31:51 pm
Quote from: "libbybapa"
I don't really want the extra credit, but if I'm not mistaken, that ball plugs the end of the oil gallery that is drilled lengthwise from which each of the lifter bores are fed.  The other end of that gallery would be the oil pressure switch.

Andrew


i too wondered what that thing was... thanks!
Title: Brand new AAZ head precup peculiarity
Post by: mk2diesel on October 12, 2008, 07:41:40 am
yes they DO drop  :oops: ... hit valves / pistons / head  ....     then its replace the head / that piston / HG  / timing belt / valve cover gaskets /  ETC     ....
Title: Brand new AAZ head precup peculiarity
Post by: TurboJ on October 12, 2008, 08:22:56 am
That's an aftermarket head and they all habe that same crease. According to a specialist, it doesn't cause any problems. Just let it be that way  :)
Title: Brand new AAZ head precup peculiarity
Post by: subsonic on October 12, 2008, 10:38:05 am
Quote from: "TurboJ"
That's an aftermarket head and they all habe that same crease. According to a specialist, it doesn't cause any problems. Just let it be that way  :)


Its a kolbenschmidt head.  OEM Head.
Title: Brand new AAZ head precup peculiarity
Post by: CoolAirVw on October 12, 2008, 12:06:26 pm
Quote from: "autoholic"
...... I searched around but did not come up with any one who has has it happen.


(http://i91.photobucket.com/albums/k286/coolairvw/Jetta%20Engine/Head%20Carnage/bustedPCchambercloseup.jpg)

Mine fell after head work. The following thread discusses the problem.  

http://www.vwdieselparts.com/forum/viewtopic.php?t=7799&highlight=
Title: Brand new AAZ head precup peculiarity
Post by: autoholic on October 13, 2008, 01:32:55 pm
Ok, I'm sold on peening them, I want to avoid that carnage. I have the head off now, but discovered that my problem is not the head or gasket, it's a cracked block!