Date: Sun, 27 Sep 1998 11:06:39 -0700
Reply-To: Rich Dunsheath <"rdunsheath(not this)"@AKAMAIL.COM>
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: Rich Dunsheath <"rdunsheath(not this)"@AKAMAIL.COM>
Subject: 1987 Replace Heads - Thermostat Problem (long)
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Howdy!
I am in the process of doing the "slap in rebuilt AVP heads and new head
gasket" stunt in my 87 wasserboxer. I was getting exhaust gas into my
coolant, but nary a leak. I was shocked to find that although the
surface of both heads were pitted pretty badly, neither leaked a drop.
It looked like the heads were done at two different times as one head
was a Spanish AMC and was stuck on with black stuff and the other head
was German and red goop had been used. The black stuff was the good
stuff. It stuck to the head like glue but didn't stick to the rubber
head gasket; I had to use a knife to cut it away from the head, so that
I could check the head's condition. The red stuff stuck to the rubber
gasket instead of the metal head. I think we agree that we are trying
to protect the head, not the gasket. I was surprised to find that even
though the head was pitted pretty badly, and no JB Weld or anything else
was put into the pits, the black goop protected the heads and the heads
did NOT leak. My problem was that the little green o-rings on one side
had sort of melted/degraded to the point that although no water was
getting into the cylinder, gas would push past the o-ring when running
at 70 mph.
I used the stuff that came in Ron's gasket kit, the German stuff. It is
black, but I don't think it is as good as the black stuff that was in
there before. The German stuff had some of the solvent separate from
the goop as I was putting it on. It also seemed to get a surface sheen
in just a minute or two, like it was skinning over. It didn't seem too
sticky either. I pulled on/rubbed on the German stuff that was squeezed
out from between the head and the gasket after it dried, and it didn't
seem to stick to the metal very tightly. Anyone have any ideas about
what kind of black sealant the DPO used that stuck to the head so well?
While I had everything apart, I put in a new water pump and a new 80 C.
thermostat. I have grown to hate the thermostat, particularly the
thermostat housing. The thermostat on the 86 and later Vgons it stuck
up high and forward in the engine compartment. It has 372 different
hoses coming out of it in all directions and each hose has a metal clamp
that is released by squeezing two extended tabs with a pair of pliers.
On my Vgon, these tabs were strategically located so that it was
impossible to get a grip on the tabs with pliers.
In my first go-around with the thermostat, I removed the cover by
removing the four bolts that go through the cover and screw into brass
inserts that are pressed/glued into the lower section of the thermostat
housing. The problem here is that only the two rear bolts are readily
accessible because the front two bolts are located under the firewall.
With much struggle and by getting a small box head wrench into a crevice
between other miscellaneous mechanical and electrical stuff, I was able
to loosen the forward bolts about a 1/16th a turn at a time until I got
them off. I opened up the housing, pulled out the old thermostat and
dropped in the new one.
The new water pump from the Bus Depot came with two new o-rings and a
new gasket, but the new thermostat didn't have any o-rings in the box.
Bentley said always replace the o-ring. I checked out the old o-ring,
it has an odd looking triangular cross section, and since it seemed
undamaged, I popped it back in on top of the new thermostat. Struggled
to bolt the housing together.
When it came time to add antifreeze after I had everything buttoned up,
I poured the coolant into the expansion tank. After I topped up the
tank, I looked under the van and saw coolant dripping on the floor.
Crawling under the van, I determined that the leak seemed to be coming
from between the thermostat housing and the head. Due to the location
of the thermostat housing, it was very difficult to see much when I
removed the housing from the old heads. The housing is attached to the
head with two 6 mm allen head bolts. When I removed the housing the
second time, after I had filled up the cooling system, I got a nice
Prestone 5 year/50 thousand mile/no phosphate/orange stuff/$6/gallon
sweet sticky bath. This time I removed a little metal shield that fits
onto the thermostat housing with two small screws; this protects the
housing from the heat of the exhaust pipe as it come out of the head
just below the housing.
I could now see that the housing has a groove that accepts an o-ring and
that there was no o-ring. I don't know where it went. It wasn't stuck
onto the old head; it wasn't laying on the floor; it wasn't on the
housing. Fishing around in the plastic bag of gaskets that came in the
engine gasket kit that came with the head gaskets, I found a yellow
o-ring that seemed to fit the groove snugly. Why is this o-ring
yellow? Dang if I know, but it fit the best, so I stuck it in.
While I was looking for this o-ring, I found what I thought was a new
o-ring that goes on top of the thermostat within the housing. This
o-ring was round in cross section and a bit thinner than the old one,
but I thought it would work. I went through the pain in the neck
process of opening and bolting close the thermostat housing with the new
o-ring in place. Managed to lose a little hide off of my hands in the
process.
I rebolted the thermostat housing to the head. It didn't leak between
the housing and the head anymore, but now it did leak between the upper
and lower sections of the thermostat housing. The new o-ring was too
thin and I needed to put the old one back in. One more time through the
miserable process of opening the housing. Since there was coolant in
the system, it was flowing up out of the housing while I was trying to
replace the o-ring. At least this time I was not under the van, so no
shower. However, since the coolant was trying to flow out of the
housing, I was having trouble seating the o-ring on top of the
thermostat. I thought that I eventually got the o-ring seated properly.
I bolted down the top of the housing once again. Man I was getting sick
of fighting with this housing.
As I was snugging down one bolt, I had a sinking feeling. Instead of
getting tighter the bolt just kept turning. I surmised that the
pressed-in brass fitting that the bolt screwed into had slipped in its
plastic housing and was spinning happily. German engineering! I
thought that it was going to be a b*tch getting that bolt out of there,
but that happily, since I had a brand new thermostat in the housing, it
would be years before that bridge had to be crossed.
I refilled and bled the coolant system. No leaks. I took it for a test
drive. Flashing coolant light. Back at the ranch, I noticed seeping
between the housing sections. I was going to have to cross the bridge.
After trying a bunch of stuff with the thermostat housing still in the
van, which didn't work, I decided to remove the entire housing. I
somehow removed the 372 hoses attached to the housing and fished the
bugger out of the van. Got another Prestone orange Koolaid shower.
On the bench, the brass fitting still spun. Finally, I drilled a small
hole into the brass fitting from the bottom and also from the side. I
was able to stick a screw driver into the notch I had created by
drilling and stop it from turning.
When I opened the housing, I found that I had mangled the old o-ring. I
had not seated it correctly when the coolant was flowing out.
Now I have no o-ring for the housing. I guess the engine gasket kit
does not include one. My local VW dealership doesn't have one and it
takes them a couple of weeks to get in parts.
Question: Can I just put in a bead of RTV form-a-gasket stuff on top of
the thermostat and bolt the housing together? It looks like this might
work. I'll order a replacement gasket, but I'd like to get the show on
the road.
Anyone have a used thermostat housing sitting around that they would
like to get rid of?
Well I feel better having vented. I hope my problems with the
thermostat housing will help other listees avoid my errors. I know I
have learned by searching the archives on the various topics before I
start working. I find the information and tips in the archives very
helpful as an adjunct to the Bentley and Haynes books.
BTW, the archives seem to be down over the last three days. Anyone else
having trouble accessing the archives?
--
Regards,
Rich Dunsheath
***************************************
Bryan, TX (1 hour north of Houston,
3 hours east of San Antonio,
3 hours south of Dallas.
Near Texas A&M)
1982 Vanagon Santa Maria (Mary)
1982 Vanagon San Diego (Sandy)
1987 Maroon Vanagon Aggie
