Cylinder Head Resurfaced now which Head Gasket to use

db123

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2005 Passat Wagon
I had to have my cylinder head resurfaced... the machine shop removed the minimum amount they could which was 004"(.1016mm). I had the two hole gasket installed prior to the work. From the chart below (my internet research) I believe I now need to goto a 3 hole gasket. Would the experts agree?

**Piston Protrusion**| H | Head Gasket Thickness
0.91 mm to 1.00 mm | 1 | 1.45mm
1.01 mm to 1.10 mm | 2 | 1.53mm
1.11 mm to 1.20 mm | 3 | 1.61mm

Obviously there's a huge concern when going with a gasket that's not thick enough, but what about going with a head gasket that is too thick? Has anyone ever measured the piston protrusion on their car to find that the wrong head gasket was installed at the factory? I do have a dial indicator w/ magnetic base, but not the VW specialty tools shown in my Bentley Manual that I had for my old '00 Golf tdi. Is it possible to accurately measure piston protrusion using just a dial indicator and magnetic base?
Thanks.
 
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zzdiesel

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05 passat tdi Geared BSM and Bewcam 2nd 2005 deleted ,converted and bew cam stage 2 Malone3 tune.
So then if the engine hasn't been opened up before just use the same thickness gasket?
 

db123

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I understand what you're saying now. I just did some more searching and came across this post: http://forums.tdiclub.com/showpost.php?p=3548539&postcount=8

I'm going to contact the machine shop to make sure they have done this before I pick it up.

Dan

You always choose the gasket based on piston protrusion, head machining does not factor in. The gasket thickness is used to adjust compression ratio, not valve/piston/head clearance.

If the head has been off before it is possible that the wrong gasket was used. You can use a regular indicator and base to measure protrusion. Just set up the indicator on the stand with the plunger close to the base, zero it out on the deck then move it over to the piston and measure the height. Be sure to wiggle the crank back and forth a bit to make sure you are getting the highest protrusion, the TDC marks are not always dead on.

The valves have probably sunk in the head a fair bit if the car has some miles on it. I wouldn't worry about excessive valve protrusion due to the head machining.
 

peiphil

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The way I see it is the head gasket raises the head by its own thickness
Each gasket choice is about 4 thou thicker than the next one
So the second choice should put you right on if the machine shop took off 4 thou.
If nothing was hitting any thing before you will be good !
 

oilhammer

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outside St Louis, MO
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There are just too many to list....
You choose head gasket thickness based on the block, rods, crank, and pistons. NOT the head. This is why new shortblock diesels from Volkswagen come with a new head gasket taped inside the box in a plastic bag. The cylinder head has nothing to do with it, it is based on how far out of the block the pistons potrude at TDC.

So if you took a 2-notch gasket off, you put a 2-notch gasket back on.... even if you reworked the head, even if it is a DIFFERENT head, doesn't matter.
 

peiphil

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Sorry Brian disagree on that one!
Iknow you know your stuff but 4 thou off the head will lower it by 4 thou.
This would raise compression although slight.
To make this more clear lets say he was to put on a head gasket say 100 thou thick
don't think it would have enough compression to even run !?
 

oilhammer

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outside St Louis, MO
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There are just too many to list....
Sorry Brian disagree on that one!
Iknow you know your stuff but 4 thou off the head will lower it by 4 thou.
This would raise compression although slight.
To make this more clear lets say he was to put on a head gasket say 100 thou thick
don't think it would have enough compression to even run !?
Disagree all you want, this is a diesel, there is no combustion chamber in the head. Totally FLAT. Plain and simple. Been this way since the late '70s when Volkswagen first started making diesels. Not sure why this subject keeps coming up and is so difficult for people to understand.

Now the valves' position in the head *may* change, but usually when a head is resurfaced, the valves and seats are also slightly machined or ground, so that geometry doesn't really matter. Although a competent machine shop always checks the stack height as a matter of course before and after anyway.
 

Vince Waldon

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Apr 25, 2009
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Edmonton AB Canada
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2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
To approach this a slightly different way....look at the top of the piston. See the big hole? *That's* the combustion chamber...completely untouched when you shave 4 thou off the flat top you bolt on. :) :)
 

oilhammer

Certified Volkswagen Nut & Vendor
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outside St Louis, MO
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There are just too many to list....
Yep. That is why when people build up diesels for lots of power (intending to run lots of boost) they often shave the piston tops down and/or open up the combustion chambers, to lower the compression. Makes them a bear to start in the cold, but once they are warmed up you can really pile the boost in and since they do not have the parasitic losses of the high compression they make tons of power.

Of course, having to use a squirt bottle of kerosene down the air inlet to get them started like the tractor pullers do would be a pain on a daily driver, LOL.
 
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