www.tdiclub.com

Economy - Longevity - Performance
The #1 Source of TDI Information on the Web!
Forums Articles Links Meets
Orders TDI Club Cards TDIFest 2016 Gone, but not forgotten VAG-Com List Unit Conversions TDIClub Chat Thank You




Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW B5 Passat TDIs

VW B5 Passat TDIs This is a general discussion about B5 Passat(>98 (2004-2005 in North America)). Non TDI related postings will be moved or removed.

Reply
 
Thread Tools
Old October 15th, 2016, 20:57   #1
db123
Veteran Member
 
Join Date: Dec 2007
Location: Ottawa, Ontario, Canada
Default Cylinder Head Resurfaced now which Head Gasket to use

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.

Last edited by db123; October 15th, 2016 at 21:17.
db123 is offline   Reply With Quote
Old October 16th, 2016, 08:45   #2
QuickTD
Veteran Member
Default

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.
QuickTD is offline   Reply With Quote
Old October 16th, 2016, 08:54   #3
zzdiesel
Veteran Member
Default

So then if the engine hasn't been opened up before just use the same thickness gasket?
zzdiesel is offline   Reply With Quote
Old October 16th, 2016, 09:33   #4
db123
Veteran Member
 
Join Date: Dec 2007
Location: Ottawa, Ontario, Canada
Default

I understand what you're saying now. I just did some more searching and came across this post: http://forums.tdiclub.com/showpost.p...39&postcount=8

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

Dan

Quote:
Originally Posted by QuickTD View Post
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.
db123 is offline   Reply With Quote
Old October 16th, 2016, 17:20   #5
peiphil
Veteran Member
 
Join Date: Nov 2012
Location: Tignish PEI Canada
Default

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 !
peiphil is offline   Reply With Quote
Old October 17th, 2016, 10:53   #6
oilhammer
Certified Volkswagen Nut Vendor
 
oilhammer's Avatar
 
Join Date: Dec 2001
Location: St Louis
Fuel Economy: fantastic
Default

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.
__________________
oilhammer
www.cardocautomotive.com
oilhammer is offline   Reply With Quote
Old October 17th, 2016, 19:35   #7
peiphil
Veteran Member
 
Join Date: Nov 2012
Location: Tignish PEI Canada
Default

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 !?
peiphil is offline   Reply With Quote
Old October 17th, 2016, 20:40   #8
QuickTD
Veteran Member
Default

That theory holds if the head has a concave combustion chamber. This is a diesel, the head is flat.

Picture it as a flat slab (which it is). You can machine all you want off of it, compression won't change at all.

Valve protrusion is a minor factor but valve/seat recession would easily take care of that on an older engine.
QuickTD is offline   Reply With Quote
Old October 18th, 2016, 04:54   #9
oilhammer
Certified Volkswagen Nut Vendor
 
oilhammer's Avatar
 
Join Date: Dec 2001
Location: St Louis
Fuel Economy: fantastic
Default

Quote:
Originally Posted by peiphil View Post
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.
__________________
oilhammer
www.cardocautomotive.com
oilhammer is offline   Reply With Quote
Old October 18th, 2016, 08:06   #10
Vince Waldon
Veteran Member
 
Vince Waldon's Avatar
 
Join Date: Apr 2009
Location: Edmonton Alberta Canada
Default

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.
__________________
Vince Waldon Edmonton AB Canada

Note: The above is to the best of my knowledge- but at the end of the day simply interweb opinion, worth EXACTLY what you paid for it, and if used done so at your own risk.
Vince Waldon is online now   Reply With Quote
Old October 18th, 2016, 10:56   #11
oilhammer
Certified Volkswagen Nut Vendor
 
oilhammer's Avatar
 
Join Date: Dec 2001
Location: St Louis
Fuel Economy: fantastic
Default

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.
__________________
oilhammer
www.cardocautomotive.com
oilhammer is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cylinder head gasket Thom.milburn VW MKIII-A3/B4 TDIs 12 January 13th, 2014 14:48
1.9 AFN. Resurfaced head, use same gasket? kfet TDI 101 12 September 7th, 2013 08:09
Cylinder head pits in head gasket mating surface glenn1179 VW MKIII-A3/B4 TDIs 16 May 20th, 2013 09:33
cylinder head and head gasket holes mauroper TDI 101 15 May 5th, 2010 17:30
which cylinder head gasket? akliven TDI 101 1 November 30th, 2007 20:04


All times are GMT -7. The time now is 15:07.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright - TDIClub Online LTD - 2017
Contact Us | Privacy Statement | Forum Rules | Disclaimer
TDIClub Online Ltd (TDIClub.com) is not affiliated with the VWoA or VWAG and is supported by contributions from viewers like you.
1996 - 2017, All Rights Reserved
Page generated in 0.17580 seconds with 11 queries
[Output: 105.15 Kb. compressed to 89.39 Kb. by saving 15.76 Kb. (14.99%)]