Date: Fri, 14 May 2004 12:17:04 -0400
Reply-To: "Warner, Jeff (DSIO)" <Jeff.Warner@DLA.MIL>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Warner, Jeff (DSIO)" <Jeff.Warner@DLA.MIL>
Subject: thermostat soup too
Content-Type: text/plain; charset="iso-8859-1"
Jim,
I just made some of that soup a couple days ago. I'm having virtually the same problem. We should keep in touch on this one.
In a nutshell here's what I've seen/done:
Three years ago our '87 GL started overheating. I noticed that the distribution valve was cracked and leaking so I parked it because we were in the process of replacing it with a Westy.
Fast forward to about one month ago. We gave this van to our 16 year old son for Christmas so now we're back to trying to fix this problem. Replaced the distribution valve. No other leaks. Seems like the thermostat will not open soon enough or stay open long enough. Bought another thermostat. Same problem. Cooked both of them together and found that the new one was junk. Stats in the Bentley state that the thermostat needs to start opening at 185 and should be fully opened by 221. Also fully opened is a minimum of 8mm. The new one was barely opened at 200 and never opened fully (made in China, bought at NAPA). The old one (made in Germany) worked well and was fully opened by 210. Also, in answer to your question, opening and closing are rather slow processes which I think compounds our problems as I'll discuss later.
Another item worth noting about the new unit was that the disk or valve or whatever you want to call it that is supposed to close off the bottom coolant circuit of the thermostat housing when the thermostat opens, was 2mm larger than the opening! So even if this thermostat did eventually open all the way, it wouldn't work properly anyway. It went back to NAPA with comments.
Noticed that the new thermostat had a hole in its perimeter with a jiggle pin. The old one had no hole. Going on the assumption that I might be getting an air block in front of the thermostat, I drilled a 1/8" hole in it and oriented the hole towards the front so that it would be directly under the bleeder valve. Saw some improvement but not significant. Bought an infrared thermometer so I could better tell what was going on. Could tell when the thermostat opened and closed. I'm generally seeing temperatures of 190-195 before the thermostat housing and in the crossover hose when the thermostat is closed. Seeing about 195-200 going to the radiator when it is opening and about 185 coming back from the crossover hose to the left head. The heads themselves are seeing about 215-225. About 215-220 at the tank and at the bottom of the thermostat housing where the temperature sending unit is when things start getting hot. The radiator barely gets warm enough for the Stage one fan to come on occasionally but this is when it happens. So the gauge is usually at about 3/4 when the fan comes on and it stays on for a fairly short time. As the engine gets even hotter the fan comes on no more often. Haven't heard stage 2 fan at all. In the past it would have been going off big time at these temperatures. Fan switch is new and circuits are working.
I'm getting no air out of the radiator but a fairly constant stream in the tank. Have to wonder if I've got an exhaust leak into the coolant but have not been able to prove it. Even bought some dye to test this and got nothing approaching positive results. Tried temporarily pinching off both head return hoses to see if the bubbles stopped and they did not. Have got some foaming but not all the time. Tried another known good cap and saw no difference. We don't have e-tests around here so I've had no luck finding a shop with an exhaust sniffer.
I'm bleeding with the back end up as I've been doing successfully for years. Even tried it with the front up by the book for giggles. Stopped giggling a few days ago. Did a rudimentary test of the water pump for flow with the thermostat cover off and saw pretty darn good flow. Also, rigged up a garden hose connection to the forward radiator hose at the thermostat and saw real good immediate flow back from the radiator through the crossover hose and out of the radiator bleeder even with the hose pressure turned way down. I've always kept this system pretty well flushed. I don't believe there's any clogging or kinks.
Other notes. Van runs great. Very good performance as in the past. Once it starts to get hot it just keeps getting hotter. It simply seems like there just isn't enough coolant being diverted to the radiator for a long enough period of time to do any good. I don't like this design for coolant flow with the thermostat. It seems very counter productive and I have to wonder just exactly how good it can possibly flow when the thermostat is only partially opened since it would seem that the flow is butting heads in this condition. I've ordered a colder thermostat and am currently building a wide open non-thermostat to see what affect it will have.
Something that occurred to me last night and I'll have to test it is I think having the cap on might be forcing the temperature up quicker. Got a very good bleed with my last test last night and saw almost no bubble action in the tank while the cap was on. I think I'm going nuts.
At least my Westy is doing well and I've just about finished my big brake conversion. Woooo Hooo!
Oh yeah, when my wife walked into the kitchen and found my son and I cooking the thermostats, she didn't say anything at all. She just walked away with that look on her face.
Jeff Warner
Galloway, OH
'86 Wolfy Westy "Barry"
'87 GL Weekender "Van Band"
Date: Thu, 13 May 2004 17:44:17 EDT
From: Jim Morgan <JM060356@AOL.COM>
Subject: thermostat soup
Good evening all,
I am making a batch of thermostat soup, ( wife is real happy ), And i am
wondering
how long should it take to open fully? I am experiencing coolant bubling in
the tank but the radiator is stone cold as well as the big hose on top of the
theromostat housing. Should this thing open as soon as it is submurged in
boiling water or does it
take some time? It seem to take about 2 min to open. I think this thing is
done but I have never had a thermostat fail closed ?
Jim Morgan 86 Gl
210,000.0 "bread box"
Westlake,Ohio
jm060356@aol.com
