Date:         Wed, 20 May 2009 20:58:12 -0700
Reply-To:     Robert Fisher <refisher@MCHSI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Fisher <refisher@MCHSI.COM>
Subject:      Re: Thermostat soup: A comparison.
In-Reply-To:  <BAY132-DS75F7E0415D70A93F44F72A0600@phx.gbl>
Content-Type: text/plain; charset="us-ascii"

It was overheating at idle only largely because the tranny was shot and the
van wasn't rolling; in other words I couldn't make a comparison. I knew the
radiator fan was working because I remember jumper-testing it and getting
both speeds, which means it wasn't cycling on its own or I wouldn't have
bothered. I don't remember if I checked the coolant lines at the time it
first overheated... I think when I realized it was getting too high I just
shut it off (the light hadn't come on yet).

I wasn't having an overheating problem before when the van was moving; this
first came up during one of my start-up and idle sessions when I was dealing
with something else. Before it broke down the needle would commonly sit
about one needle's width above the led and drop slightly on the road or when
the fan was on.

I swapped in a working used tranny last weekend and bled the system (I had
already put the new thermostat in for GP). While I was bleeding it the
needle went back up to the 'normal' position and held there; eventually the
fan came on. It sounds kind of raspy and anemic to me, but it's moving air.
It cycled several times and the needle held steady.

Bleeding this thing by the standard method is no fun because one of the POs
lost the bleeder bolt in the radiator and put a regular bolt in, which leads
to hot coolant spew when I'm trying to do the bleed. I've given some thought
to rigging up a pet-cock type thing but I haven't done it yet. I think at
this point I'm going to try the tall-pipe method from the Samba.

When I got back from my test drive the needle was still holding steady at
'normal'. I turned the van off and opened the hatch. The expansion tank was
full and there was a little bit of burbling in it (not good, I know). After
everything had cooled I opened the overflow tank and it was nearly empty, so
I filled it to the mark.

I haven't driven it since (it's non-opped and I'm getting it ready for the
smog check). Today I was doing some other things and it just occurred to me
to check the overflow tank (I can't see through it anymore) and coolant came
pouring out- it was basically full. So was the expansion tank.

I remember when I first put this engine back together it took me about three
tries to get it bled properly, so it's entirely possible that's the problem
now, but I'm puzzled by this overflow bottle filling up. I had the nose up
for a while, so I suppose it could have just been gravity draining it back,
but I would've thought the pressure cap would've prevented that. I replaced
the cap when I put the engine together several years ago, at the same time I
got the other thermostat. I don't have a rig for pressure-testing this
system so I was thinking I might get another cap and use the old one for a
pressure tester. I understand that the burbling can be caused by a number of
things ranging from the relatively benign to the catastrophic so I don't
want to run the thing much.

So I can pressure test the system, do a leak down test and look for bubbles,
bleed it again and so on..., but what's up with the overflow filling up on
its own? Is the cap bad, or will it just do that from having the nose up, or
did I not let it cool enough before I put more coolant in the overflow?

More thoughts? : )

Thanks,
Robert

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Dennis Haynes
Sent: Monday, May 11, 2009 6:11 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Thermostat soup: A comparison.

Does it overheat at idle only? If so then the thermostat is not the problem.
If it was failing it would always over heat, especially at speed. You say
the radiator fan is working. Does that mean it is cycling on its own? If it
is turning on by itself that one more indication the t-stat is OK. When the
fan is running, does the return become noticeably cooler than the feed? The
radiator may be plugged or an internal baffle is cracked and the coolant is
not actually flowing through it.

Changing parts until it works is rarely effective. Another possibility is
that a prior water pump failure damaged the engine case and reduced capacity
at low speed is the result.

Dennis


-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Robert Fisher
Sent: Monday, May 11, 2009 8:15 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Thermostat soup: A comparison.

Stock '87 GL overheats at idle, radiator fan works on both speeds but has
little/no effect. I got a new thermostat (FLAPS special) and pulled the old
one. I don't remember what brand the old one is but it was supposed to be a
good one and it is far beefier in construction; iirc I got it at the local
import parts place back when but they were closed so I got this new one. Old
one is maybe 7 yrs. old, but does not have a lot of miles/cycles on it.

In boiling water, the new one opens to about 3/8" fairly quickly and also
closes fairly quickly. The old one opens (to my surprise), but to a little
less than a 1/4", and takes its sweet time opening and closing. On the one
hand, I'm thinking I might run the new one for the meantime, get myself
another 'better' one and swap them out keeping the FLAPS thermostat for a
spare. On the other hand, the old one didn't really give me much for my
money. I normally keep a spare around; I don't know what happened to it,
hence the FLAPS piece.

I know there's widely varying quality in these things, sometimes even within
brands and I've found them dead out of the box, which is why I check them (I
don't recall seeing one that 'partially' worked, however). I've also seen
ppl argue for strictly OEM thermostats here on the list but I'm a long way
from any VW dealer.

Thoughts? Recommendations?



Cya,

Robert