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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
Content-Type: text/plain; charset="US-ASCII"

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.


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