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Date:         Fri, 7 May 2004 15:57:54 -0400
Reply-To:     ROBERT DONALDS <donalds1@VERIZON.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         ROBERT DONALDS <donalds1@VERIZON.NET>
Subject:      piston fit and the Boston Bob school of cylinder preperation
Comments: To: Zoran Mladen <zmaninco@yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

Zoran The without guess work book says that the type 1,2,3,4, engines should have .0016ths to .0023ths clearance new and a wear limit of .008ths. The wear limit is not something that will still give full service but it would most likely make some noise and burn a little more oil. The vanagon book says the WBX engine new spec should be .001th to .002th with a wear limit of .008th The WBX cylinder does not wear as fast as its air-cooled counter part due to the fact that it is a wet sleeve (its surrounded by water) and even a cylinder with 100k shows little difference in size. The weak point of the used WBX piston and cylinder set is the ring land wear and that cant be compensated for or corrected. The end result of reringing old pistons is is oil consumption, some crank case pressure and a small loss of over all power.

To answer your question I ridged hone and additional .0015ths with a course stone and then switch to a finer stone and that takes .005th off in just a few strokes so the clearance is aprox .003th and that's about twice the clearance of the stock new set and my finish not as course. yes I think the new sets are to tight and have seen problems with the stock clearance and finish. The rings that are made today have been machine lapped before they ever see a cylinder and the cylinders dont need to have as course a cross hatch finish as the they come threw with.

going faster miles an hour with the radio on I remain Bob Donalds Boston engine

all rights reserved ----- Original Message ----- From: Zoran Mladen To: ROBERT DONALDS Sent: Friday, May 07, 2004 1:29 PM Subject: Re: Roadhaus....partial solution for helping!

Hey Bob,

In terms of increasing the piston to skirt clearance, how distance are you looking for? Bentley says max is about .006" if I recall, maybe .005"...

Z

ROBERT DONALDS <donalds1@VERIZON.NET> wrote: When I first read the post about Larry's engine trouble I emailed and then called him to go over the symptoms and offered him my thoughts and things I would check. the lower end of the current engine does not sound suspect from what I could tell. the valve train and the head is most likely in need of a good going over and then he will see if he really needs an engine. I told him to keep in touch and have not heard back at this point. The melted piston could be from a lean condition or preigition but the preignition tends to blow out rod bearings before the piston melts. On my engines I increase the piston to skirt clearance by honing the cylinders. This is common practice on racing and industrial engines in severe duty applications and I consider the vanagon a severe duty application. Some of you air-cooled types might recall that VW had a tech bulletin on the type 2 and van engine that called for this increase in piston to cylinder clearance. The type 2 engines melt pistons all the time when they are not busy dropping seats So I am waiting to hear from Larry about his engine diagnosis

going faster miles an hour with the radio on I remain Boston Bob ----- Original Message ----- From: Ben To: vanagon@GERRY.VANAGON.COM Sent: Thursday, May 06, 2004 3:11 PM Subject: Re: Roadhaus....partial solution for helping!

Mmmmmmm..... good point, but what about the others customers with the same problem! Ben

David Brodbeck wrote:

On Thu, 6 May 2004, The corruptor wrote:

I think that the crank is the problem, am thinking of a bad rod a alignment / faulty and defective main bearing, but now we are getting deap, maybe Bob or others can comment on my diagnostic. Even the core as been change, so i also rule out a bad sleeve matting surface, remember, always the #1 going out in flame, different case and head, now i don't know if the rods or crank is the same???

If it's always the same piston burning, has anyone thought to flow-test the injector for that cylinder? Maybe it's running lean on that one cylinder.

David Brodbeck, N8SRE '86 Volvo 240DL wagon '82 VW Vanagon Westfalia Diesel

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