[T2] Replacing pushrod seals

[John Anderson]

Scott, there is quite a few write ups, by me, and others on type2.  My words are I think under my lifter adjustement article, but there are many.
 
In short, I don't use sealant, ever.  It will just leak later.  O-rings work by a known calculated compression between the two lands, they only work as designed if they can move, if you goop them up with a solid they don't move.  It helps for a while, but eventually they leak again.
 
There are 2 things to note here.  Nothing will ever stop leaks from increased blow-by, or mechanical wear of mating parts, and with time that is going to be an issue.  Again sealant will seal them for a while, but a while only.
 
Next to note and I don't recall when anymore (and this presumes original engine) there was a subtle change in the push rod tubes, and the bore dimensions, somewhere in there, perhaps 1700 to 1800, I don't recall.  Earlier was ever so slightly smaller, but eventually all got superceded by the same parts.  But small tubes in later holes will leak easier, and were a possibility for some time as a stash of early tubes were found/sold NOS some time in the late 90s.
 
Also the tube land itself wears a bit causing the O-ring to loose some compression as well.  But generally speaking new Viton rings, installed with oil, with scrupulously clean mating surfaces will last a long, long, time if blowby isn't bad, and if the bores in the case and head haven't been gouged by some hapless idiot.
 
John
 

________________________________
 From: Scott Busby <swbusby at gmail.com>
To: "type2 at type2.com" <type2 at type2.com> 
Sent: Monday, March 3, 2014 2:44 PM
Subject: [T2] Replacing pushrod seals
  

So I took off the bottom tins, and I do see drips at the bottom of the
pushrod seals where the pushrods enter the heads. I've done lots of work on
my bus, but I haven't done this one before. It looks to be not too bad, as
long as I can keep things organized and clean.

How often you you guys have to replace push rod seals? Do you use just oil
on the seals, or a sealant?