Date: Sun, 24 Mar 2002 13:19:41 EST
Reply-To: VW85Westy@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Peter Krogh <VW85Westy@AOL.COM>
Subject: Coolant Rising Mystery
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Okay, folks, I am thoroughly stumped, as well as going broke and sleepless
over my rising coolant mystery. The short story is that I got a new engine
last summer, ran fine for 5000 miles, then coolant starts to creep up. Have
heads pulled and evaluated, no problems and re-installed. Problem still
there. I don't know what the next step is, and I need help. My theories:
1. there is a hairline crack in one of the heads that only shows up when the
head is hot.
2. There is a leak somewhere in the cooling system where the pressure is
lowest, say where the returning coolant enters the water pump, and it sucks
air in there intermittently. More on that below.
3. It is leaking in from somewhere in the block
Here's the long story:
I ordered a new AVP rebuild last spring and had it installed by a mostly
vanagon shop on Maryland's Eastern Shore, Dick's Autohaus. They did an okay
job but were a little sloppy. Eventually, the van was running right, and I
put 5000 trouble free miles on it last summer.
At about 5000 miles, I noticed the coolant level rising. This was after the
van got hot once (about 2/3 to 3/4 the way up to the red) but did not
overheat. (Heat tabs on heads intact)
Eventually, I had the heads re-torqued and this seemed to help for a little
while. At the end of our long summer sojourn, I noticed that the coolant
pipes were rusted, as well as the Radiator, and I decided to replace the
cooling system before pinning the problem on the engine. Replaced radiator,
long pipes, most of the molded rubber hoses. Coolant rise still there.
I had the van checked by Wheaton Service Center, by their factory trained
mechanic, and he could find no hydrocarbons in the coolant, and had no real
suggestions beyond radiator cap. He did a pressure test and said that it
held pressure fine.
Eventually, I took it back to Dick's and had them pull the heads. They found
a rolled O ring on one cylinder, but other than that, no sign of leaks or
overheating. We sent the heads back to AVP and they said they checked out f
ine. Dick reinstalled and I drove it home
Coolant level still rises. When I say rises, I mean that it will go from
normal, to spewing coolant out of the top of the expansion tank. This
generally takes about 60 to 150 miles. I can let the air out of the
radiator, bleed the van, and the coolant will return to a normal level.
I have noticed that (in general) in-town driving does not make the level
rise, only highway driving of more that 15 or 20 miles. My theory is that
air is getting into the cooling system, but can bleed itself out in town.
But when the motor is running at extended high RPM's more air gets in than
can be bled out , and it collects in the radiator, forcing the coolant to
rise.
Last time I had a big burp in the expansion tank, I took the van by a local
shop and tested the air for CO2. The test was negative. Concurrently, I
found a slight leak in the cooling system in a part I had not replaced, the
front heater core valve.
I had a theory that because the heater was high up, it would be an excellent
place for air to enter. As the van cooled, perhaps a leak in the front
heater core would suck air into the cooling system, which would be
recirculated on the next drive. So I bypassed the front heater and valve
altogether by attaching the supply and return together above the spare tire.
Problem still there.
Could the problem be the water pump? Several years ago, I had the water pump
replaced, but the flange was warped. The shop machined it as best they
could, but it would still leak coolant on the first cold day of the winter.
When I had the new engine installed, they had some trouble with the water
pump. Because of the excess milling, they said, when they bolted on the
water pump, and torqued it down, the bolt punctured the pump. (I think this
was the language they used. I am unfamiliar with the geography of a water
pump and flange) They (I) had to buy another one , and by using shorter
bolts, were able to make it fit. I see no sign of coolant leaking anywhere,
but I wonder about the pump.
The pump is one place that the system could get pressurized. Is it possible
that a defective pump could introduce air into the cooling system? Is it
possible that a less than perfect connection on the low pressure side of the
pump could be sucking in air during extended high RPM? This is perhaps the
one part of the cooling system that has not been touched since new engine
installation (I assume that it is left alone during the head R&R)
Here are my questions:
1. Has anybody ever had air getting into the cooling system that was *not* a
cylinder head/gasket leak? Can it come from the block?
2. What are the next diagnostic steps? I will have the system pressure
tested, but last time it bore no fruit. I will also have the CO2 checked
again. Any suggestions on how to test it more thoroughly?
3. Any suggestions on who could help me with this. I am in the Washington
DC area, but would be willing to drive a while to find someone who knows
vanagons, and could help me.
I've owned this van for 16.5 years, and would hate to have to junk it after
spending $6500 in the last year on a new motor. In two weeks, I will be out
of the warranty period for the head R&R, and I need to find out if this is a
problem with the engine or some other component. We test drove EV weekenders
last week, and, although they're nice, they are no Vanagons.
Any suggestions appreciated.
Peter and Zippy.