Date: Sun, 27 Sep 1998 13:27:17 -0400
Reply-To: John Anderson <janderson@IOLINC.NET>
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: John Anderson <janderson@IOLINC.NET>
Subject: Re: 1987 Replace Heads - Thermostat Problem (long)
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>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
The black stuff is the non-acetic acid stuff speced by VW, the red stuff is
common parts store crap, there are many differences.
>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
Actually quite common, my old bug guy mechanic told me that for years before
he heard about the JB fix he just bead blasted and slapped on the good
sealant. Claims that he typically got another 50-75k out of the heads after
that point.
>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
Typical and the more dangerous leak, this is the one that blows expansion
tanks and the like, once coolant works past those long enough to degrade the
metal seal ring all hell breaks loose. I'd clean up the tops of the barrels
where those O-rings seat VERY well with sandpaper, a pick to clean the
groove, then a scotch bright. And a little silicone grease over the O-ring
and the whole area on reinstallation is a must, the "dielectric" stuff is a
good commonly available silicone only grease.
>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
This is good stuff if you mean in the Elring kit, once dried it will stick
just like the stuff you took off. My real gripe though, Ron's Elring kit
DOES NOT COME with the second sealant, the one you are supposed to use on
the head cap nuts, yellow pasty stuff that does not dry. His Victor-Reinz
sets come with both. Recently when I did Pat Horrocks heads I found myself
suddenly faced with no correct sealant to use on the cap nuts from the
Elring kit, and actually I had some of the yellow stuff left but did not
have it with me. I ended up using the black silicone both places as I had
no choice, already had the bead layed and you only have 15 minutes or so to
get them on. But this sort of sucks cause I like to let the stuff set
overnight then recheck the torque once in the morning. With the hardening
sealer you can't retorque the nuts less you risk breaking the seal. A minor
annoyance but one people should be prepared for, I don't get why the Elring
kits come without the other material.
>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.
Hear, hear, another thing, like all plastic pieces "it cracks" the lower
housing manifold part which bolts to the head particularly around the inset
brass pieces. On Pats I also noticed that this piece is cast aluminum
instead of plastic, hers is a '90 syncro, my '87 and '90 both feature
plastic parts. Is the aluminum a syncro only thing, or a better replacement
part (her heads had been putzed with once before.)
>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
Probably only because it has been deformed by the wedge of the thermostat
housing cover, best always to order this one new as well, Ron has them for a
buck or so.
>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.
Actually the yellow O-ring is I believe for the thermostat housing to cross
coolant pipe joint on a 1.9, but is probably the same size and OK to use.
To me the yellow seems to be a silicone ring of lower hardness, maybe a 50
durometer or so, regardless fine to use. Another thing to look at here,
when I installed some junk quality Mark Stephens rebuilds on my '87 (WILL
NEVER EVER DEAL WITH THEM AGAIN, but I've had little luck with AVP as well)
the flanges these seat against were terribly pitted and would have leaked
like seives, I had to mill .040" off both heads in those locations to get a
smooth sealing surface. A common person would not have had those resources,
and having to JB this surface on a just rebuilt head would be ludicrous,
this was actually the least of the problems with the MSHP heads and after
fully returning one for unuseable pitting around the combustion chamber
where the little green O-ring seats I felt luck merely having to mill the
two I ended up with. I'd be interested if AVP is any better. My Chevy nut
friend whose mill I was using was laughing his ass off at me for paying
anything for the heads and really got a jolly when I (of course) got screwed
for my cores which easily had to of been superior in condition to what the
"rebuilts" had been before the were repaired.
>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,
May have been the 1.9 part (not sure if they differ) or who knows what, the
gasket set has a lot of spare parts for carbed models and all kinds of
things.
>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
DING, DING, DING, hence the heftier aluminum version, I should have read
this far down before my earlier comments, but goes to show it is a
predictable failure.
>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
>like to get rid of?
Sort of unlikely, O-rings rely on compression, RTV will just make a wedge of
sealant, about a 50/50 shot I'd guess. I'll note though, look around town,
nothing magical about O-rings for this kind of service, sizes are in fact
relatively standardized even between metric and US. Go to a hydraulic
place, one who sells hose and usually power transmission stuff and bearings
and the like, only the cross sectioninal diameter (thickness for an o-ring)
is majorly critical, the actual diameter needs to just be about right for
the right stretch (these are generalizations, I've designed 30ksi seals for
rocket motors, but for 15 psi in a Van, close is close enough.) Most
available will be a Buna formulation which should be A-OK. A close match to
the small one you had but of the thickness nearer the "triangular" one would
be just fine, should cost about a buck if you find one close.
Nothing I hate more than coolant myself, I'd rather have a gallon of oil
poured on my head than a teaspoon of coolant run down my arm, for some
reason that is the slimiest crappiest feeling.
John
janderson@iolinc.net
