Date: Tue, 21 Sep 1999 23:23:30 -0600
Reply-To: John Rodgers <inua@CYBERMESA.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@CYBERMESA.COM>
Subject: Re: Expansion tank leak
Content-Type: multipart/alternative;
William, I was having similar problems with my coolant level sensor and
replaced it. They are inexpensive, under $10.
Back last winter I had a lot of work done on my "88 GL van. Tranny
overhaul, flush coolant system and refill, replace belts, muffler,
cat, the whole enchilada, etc. When it went back together, everything
seemed to run fine. But when the engine was shut down, after a few
minutes there was this big "POW!" in the back end(the engine hatch was
still open). The mechanic went to look and the coolant level sensor had
been blown out of the expansion tank and
Close inspection showed the threads on the sensor were worn as were the
ones in the tank where the sensor threads in. Replaced the old sensor
with a new one. Warmed engine, shut it down, blew out the coolant level
sensor. The sensor threads were turned backwards. Now this was a real
puzzle.
Before it was brought in for work, the expansion tank cap did it's
thing. Opened and passed coolant over into the overflow tank, no
problem. So this was a bit of a puzzle, There was no reason for the cap
to be under suspicion.
Close inspection revealed the threads in the expansion tank were really
worn down. With the tank threads worn, it was decided to replace the
expansion tank, and get a new cap and coolant level sensor.
This was done.
The coolant was topped off according to Bentley. The engine was warmed
thoroughly, then shut off. In a few minutes the coolant level sensor
blew out of the the new tank!! And the threads on the sensor were
striped. We were all stunned. Me, the mechanic, and the helper.
Well, a call was made to the Bus Depot to order another, and the problem
was brought up for discussion. I was told that this sounded a bit like a
stuck thermostat, and they recommended replacement. So I bit and ordered
the stat as well.
This time, however, with the tank open, the engine was run. A heat
sensing gun was passed over various parts of the engine as it warmed
up. It wa a revelation to me. You could tell where things were
happening, and in this case the plumbing at the rear was warming, the
heads were warming, etc, but the stat was doing nothing. So afte a bit,
the mechanic shut it down and replaced the stat. I also decided to go
back and replace the new expansion tank cap with the old one.....I was
suspicious of the new cap....it didn't look like the old one.
Once the old cap was in place, and the new stat installed, coolant
topped off, the engine was run again. The handheld heat sensor dutifully
measured the temp in each location an displayed it digitally. You could
see in an instant when the thermostat began to open. In a bit, the temps
was up to normal for the vaious locations.
At last everything worked.
Have not had a coolant problem since.......until recently.
About a month ago I starting having problems with the level light coming
on. It would come on at odd times, just crusing down the road. At first
it spooked me, but I knew I had plenty of coolant. Finally I scrutinized
the sensor. No evidence of leakage. Then when I pulled the sensor wire,
there was the culprit. The sensor was leaking coolant up through the
point where the sensor electrodes pass through the top of the sensor.
Cleaned and dried this and sensor worked fine for a little while, then
malfunctioned and lite came on. Replaced the sensor, and problem is
gone.
One thing just for your information. When I was having all the problems
with blowing out the sensor, I discovered that there is apparently a
kind of circulating loop on my "88 that provides coolant to the heads
even when the thermostat is closed. Seems to be some sort of head
protection mechanism to keep them from overheating. when thermostat is
closed or stuck closed.
I know how disconcerting it can be when this light come on and you are
out in the middle of nowhere. And beleive me, we have a lot of nowhere
here in New Mexico.
Hope this helps.
John Rodgers
"88GL Driver in New Mexico.
William Wedenoja wrote:
> There was coolant under the left rear of the engine so I took a look.
> White powdery substance on a coolant pipe. The coolant looked to me
> to be coming from the top of the expansion tank, around the sensor.
> Took it in to a shop. The mechanic says there is a leak on the side,
> where the two pieces of the tank come together, so we ordered a new
> one. Straight-forward. The part should be in today. We'll get it in
> tomorrow. But in the meantime the coolant warning light on the dash
> has started blinking all the time--even when the engine is stone cold
> . Although the temp gauge reads normal. I thought, ok, we're low on
> coolant. Added some to the overflow with no result. Pulled the cap
> off the expansion tank, thinking it would be low--but it's full to the
> brim. This I don't understand. Could it be simply a bad sensor?
> Does it sound like the coolant flow is restricted somewhere too? Or
> do I have excess pressure in the system? I searched the archives for
> the past 21 months but didn't find an answer. We don't see many
> vanagons around here, so it's probably impossible to find a mechanic
> that has a lot of experience with them. Therefore, I'm turning to the
> list before this mechanic gets too deep into it. BTW, we took the
> westie 2300 miles in June from Missouri to South Carolina and back and
> the gauge stayed steady at just above the warning light. We then took
> it 6700 miles up to Canada, across western Canada, then down the coast
> to San Diego and back to Missouri. The gauge ran up to 2/3 on a hot
> day on the interstate heading north. Was fine in the Rockies. But we
> lost a little coolant. Discovered a leak in a coolant pipe which was
> replaced in San Diego. On some steep grades heading to Jerome and
> Prescott, Arizona the needle went all the way to the top and the fan
> came on momentarily, but other than that it behaved ok, so I don't
> know if we have a cooling problem. I have given some thought to a new
> radiator, though. Any advice on the expansion tank leak and on keeping
> cool in general would be appreciated. Thanks,Bill'88 westie
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