Date: Mon, 12 Sep 2011 02:49:56 -0400
Reply-To: Bill Glenn <idahobill@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bill Glenn <idahobill@GMAIL.COM>
Subject: Re: Water pump impeller wore into case
On Sun, 11 Sep 2011 21:09:46 -0500, Tom Lambas <twlambas@GMAIL.COM> wrote:
>Thanks John and all who replied,
>
>The do nothing option seems the best.
Tom,
At higher RPM with substantial coolant flow, that gouge in the case will
likely allow only a small proportion of the coolant flow to escape the
hydraulic "push" of the impeller; at lower RPM and lower coolant flow, the
proportion of coolant escaping the effects of the impeller will likely be
higher relative to the flow, but it's hard to say whether it would cause a
problem during extended idling. You have the anecdotal experience of one
list member for whom such a gouge was not a problem.
Last winter I proactively replaced the water pump on my waterboxer, since
its history was unknown to me, and reliability is paramount to me since I
travel to camp in some very remote places where outside help is simply not
an option. Upon removing the pump, I discovered a similar but deeper gouge,
not caused by that pump, but apparently by a previous water pump whose
bearings had failed. I chose to repair the damage, engine in place; the
procedure was as follows:
1. At the location of the water pump, I stuffed a small rag into the
openings in the case to prevent the introduction of any foreign matter.
2. Using a Dremel with a flexible shaft and a small milling bit, I cleaned
and scuffed the damaged area, and degreased it, prior to the application of
JB Weld. Don't shortchange this step because you want the JB Weld to have
the best bond possible to the case.
3. Because it's such a tough spot to work in, I didn't want to overdo the
JB Weld and create a tedious filing/sanding operation to flush the JB Weld
to the surface of the case. I needed a way to form the JB Weld to the
proper thickness and decided that the new water pump itself could be the
form as long as the needed clearance between the case and the face of the
impeller could be maintained.
I placed a straightedge across the end of the new water pump to determine
the clearance to the face of the impeller, and noted that a piece of 20-22
gauge sheetmetal would nicely fill the gap. I cut a circle of sheetmetal
the same diameter as the impeller and stuck it to the impeller with grease,
and also put a very thin coating of grease on the front side of the
sheetmetal to keep the JB Weld from sticking. Just to make sure the
sheetmetal did not move when I installed the water pump as the form, I put
the water pump in the freezer for fifteen minutes to solidify the grease.
4. I applied the JB Weld to the case in sufficient thickness with a small
stick, and installed the water pump, without the gasket.
5. After letting the JB Weld cure overnight, I removed the water pump, and
used the same small milling bit on the Dremel/flexible shaft, positioned
perpendicular to the face of the case, to remove the JB Weld molding flash
(the squeeze-out) from the openings in the case. A small hardwood block
wrapped in very fine sandpaper was used to ensure that the JB Weld was
flush with the face of the engine case.
6. After vacuuming out the openings in the case and removing the rag, I
removed the sheetmetal and grease from the face of the impeller and
installed the water pump in the normal way.
Again, I can't say this was necessary, but I chose to do it.
Bill
