Date: Sat, 22 Sep 2001 16:02:49 -0700
Reply-To: Calvin Bruce <zippydoodah@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Calvin Bruce <zippydoodah@EARTHLINK.NET>
Subject: Re: head gasket problem ?
In-Reply-To: <200109221323.tqpsq6.5r5.37tiu0o@eagle>
Content-Type: text/plain; charset="us-ascii" ; format="flowed"
All this talk about how the system pressurizes while heating up. See
the Bently manual for a basic description of cold and hot operating
pressures. The cap is designed to open at a specific pressure to
allow the coolant to "overflow" into the overflow tank. Then as the
system cools the vacuum created in the cooling system pulls fluid
back under normal circumstances.Now when things go haywire-->
"Test #2
Start the engine cold with no pressure indicated on the gauge. The
pressure in the cooling system builds to aprox 7 lbs at normal
running temps looking around for leaks. But if the pressure builds
quickly to around 15 lbs the pressure is coming from one of the
cylinders through the inner head gasket. This can also show up as a
coolant pressure loss in the fist test. In extreme cases the cylinder
can fill with coolant, and will not turn over. This is know as
hydraulic lock, and if you suspect this pull the spark plugs and try
to turn the engine again. Pulling the plugs from the engine allows
water to escape from the spark plug holes."
Frankly, sounds like a head gasket problem, actually the upper
cylinder "o" ring allowing exhaust gases into the cooling system,
(see below). I'm having the same problem and am just about ready to
pull heads and inspect and or replace the head gaskets myself....
Should be your standard torture. I'd rather roll around in broken
glass. But, oh well, I can't afford the $2000+ at the shop... I'm
expecting about a $1000 tops, if the heads need to be replaced, yet
again, due to the infamous corrosion problem. Yeah, yeah, I use
distilled water and non-phosphate anti-freeze but there it is
again....
Check out the following, pay particular attention to the pressure
test.... I also understand if you take the van to a smog station the
people can be persuaded to test for exhaust gas in the cooling
system, a dead give away... Good luck...
A description of head problems is available at:
http://www.vanagon.com/ then under "Problems, then Head Leaks." In
particular, to quote from the site and take notice of the SECOND head
gasket problem:
------
What is the head gasket problem, anyway?
Tim Smith writes:
Coolant leaks out of the engine, by squeezing under the fat rubber
head gasket on the head side. The gasket is flat, no groove or lips,
so the path is easy for the coolant to get through. Coolant creeps
under the gasket edge from day 1 in a new engine, due to water
pressure and the use of a soft gasket material. The coolant becomes
trapped under the gasket, and creates local corrosion pockets. This
is known as 'crevice corrosion' and is due to bad engineering at VAG.
Once the aluminium head starts to corrode in the pockets the 'rust'
puffs up a bit allowing more coolant seepage deeper under the gasket.
The process continues until it reaches the outside, whence it starts
dripping. The hardening of the rubber with age, and the repeated
expansion/contraction of the water jackets aggravate this problem as
the van ages. The only fix if leaking is new gaskets and perhaps new
heads. Small leaks/drips may respond to BarsLeak. This is one type of
head leak, and is definitely fatal. This problem may suddenly appear
in late fall as colder overnight temps. are encountered, causing the
water jackets to contract enough to leak out the weakened gaskets
seal. Look for drops of coolant under the van.
The second type of head gasket leak is coolant over the top of the
internal cylinder barrels, past an O-ring and large thin metal
gasket. This allows coolant into barrels, giving some white
smoke/missing on startup, but more importantly loosing coolant and
letting combustion gasses into the coolant circuit. This is usually
noticed when the overflow tank suddenly fills up with a hot engine,
and draws back in while cooling. This leak is less common than the
first, and gives longer warning time. It can sometimes be fixed by
retorquing down the heads.
-------
Now, Bently says, never recycle the coolant. Always renew. the same
Web site has a discussion on fluid, "the blue stuff."
-------
Now, from the same site above, same area, "Problems, then Head Leaks"
How do I fix the heads myself?
Bob Donalds of Boston Engine has written an excellent technical
article on replacing your heads.
*
A Gearheads View of Wasserboxer Head Replacement
Pressure Tests for the Cooling System
Test #1
The first test of the cooling system is done when the engine is cold.
A cooling system pressure tester can be installed in place of the
radiator cap. Pressure in the cooling system and hot coolant are not
something to be treated lightly. Use caution, and never remove the
radiator cap from a engine that has been run even for even a short
time. After installing the gauge, pump it up to 10 pounds. Look
around for leaks if the gauge shows any pressure loss. Common trouble
spots include heads, hoses, water pump and rear heater core. If you
smell something sweet when you turn the heater fans on, it may be a
coolant leak at one of the heater cores, or simply the O-ring at the
rear heater valve leaking. Because there is often more then one leak
in the system, it is necessary to continue pressure testing until the
system holds pressure.
Test #2
Start the engine cold with no pressure indicated on the gauge. The
pressure in the cooling system builds to aprox 7 lbs at normal
running temps looking around for leaks. But if the pressure builds
quickly to around 15 lbs the pressure is coming from one of the
cylinders through the inner head gasket. This can also show up as a
coolant pressure loss in the fist test. In extreme cases the cylinder
can fill with coolant, and will not turn over. This is know as
hydraulic lock, and if you suspect this pull the spark plugs and try
to turn the engine again. Pulling the plugs from the engine allows
water to escape from the spark plug holes.
-------
Now it sounds like your cooling system is being pressurized. There is
only one or two major ways this can happen.
Good luck...
Calvin...
>
>
> >>>>Date: Sat, 22 Sep 2001 11:35:31 -0500
>From: John Rodgers <jhrodgers@CHARTER.NET>
>Subject: Re: head gasket problem ?
>
>Malcolm Stebbins wrote:
>
>> I DIS-agree with the statement right below (by John
>> Rodgers)
>>
>> > If the system is operating correctly, as the coolant
>> > expands when it is rising to operating temperature,
>> > coolant will flow from the expansion tank into the
>> > overflow tank. That is proper.
>>
>
>Malcolm, in my experience my statement is true. Perhaps further
>explanation is needed.
>
>The cooling system with it's expansion tank is a closed system with a
>pressure relief valve which is in the pressure cap. The overflow tank
>behind the access hatch to the oil filler tube is just a catch tank. It
>is vented to atmosphere. On my 88 GL there are three little vent holes.
>
>The pressure relief valve is the expansion tank pressure cap.
>
>When the system is properly filled, with the engine cold, the coolant
>volume should be at it's minimum.
>
>So with coolant volume at its' minimum, but completely filling the
>system, applied heat is going to result in expansion. That heat comes
>from the engine. Expanding coolant must go somewhere. Granted there may
>be a little flex in the system that may accommodate some expansion, but
>it is not enough to satisfy the needs of the volume of expansion that
>will occur. When the pressure of the expanding coolant reaches that
>pressure setting of the pressure cap, the valve opens, allowing the
>expanding coolant to overflow into the overflow tank, preventing loss of
>
>the coolant. Mind you that the pressure in the system is still high
>enough to prevent boiling.
>
>If all is well, and there are no combustion leaks, there should
>absolutely be no gases in the expansion tank. So the system should be
>completely full. The radiator, the plumbing, the engine, the pump, the
>expansion tank. All full. In addition, if all is operating properly, the
>
>overflow tank should have coolant with it's level somewhere between
>minimum and maximum, and the overflow tube will also have coolant in it.
>
>As the coolant is cooled by air through the radiator, the thermostat
>opens and closes regulating the engine temperature by way of controlling
>
>the coolant flow. When the engine is warming up, the thermostat is
>closed. When it is warm, it opens and allows the coolant to flow to the
>radiator. As long as that coolant is in normal operating range, the
>coolant is in the expanded state, and the system will store the overflow
>
>for later use.
>
>The cooling system in the ENGINE with the thermostat included, is a
>closed system of it's own. With the thermostat closed water continuously
>
>circulates through the engine. On a cold start, especially on a cold
>day, the thermostat keeps the coolant from flowing to the radiator,
>until the water circulating in the engines' own circuit is warmed
>sufficiently. Then it will open .... maybe. Depends on how cold it is. I
>
>lived in Alaska a very long time and learned about Vanagons and
>thermostats! Some days were so cold that I don't think the thermostat
>opened at all. Engine was a greedy little beggar for all the heat it
>could hold, and I was about to freeze my buns off in the seat up front.
>Couldn't get enough heat out of the heater to count.
>
>But back to the operation of the system....
>
>In normal operation, especially in moderate to cold climates the coolant
>
>can do a lot of expanding and shrinking. It is mostly noticeable when
>you shut the engine down. The engine and the entire system start to give
>
>up heat. This heat loss results in the coolant beginning to shrink. As
>it shrinks, if it did not have a coolant supply somewhere to add to the
>system, it would draw down and collapse the expansion tank or hoses,
>etc. or cause an air leak somewhere and draw a big air bubble into the
>system. However, if the system is tight, the system has extra coolant
>stored in the overflow tank. As the coolant in the system shrinks, the
>pressure in the system drops, and is now out of equilibrium with
>atmospheric pressure. The system pressure is lower. With the pressure
>in the system lower than atmospheric, back suction is created or a
>siphoning effect as it were,(I know, suctions don't exist - they are
>just pressure differentials) and coolant is drawn from the overflow
>tank, through the tube connection from the overflow tank to the
>expansion tank pressure cap, through the cap into the expansion tank,
>thus keeping the system filled to capacity.
>
>If in the passage of time, combustion gases begin to accumulate, they
>will show up as a big bubble in the expansion tank, displacing coolant
>to the overflow tank. This bubble will expose the electrodes on the
>coolant level sensor, and the blinking light will come on. If there is a
>
>sufficient volume of combustion gases present, it may force coolant to
>
>completely fill the overflow tank and then from the overflow tank onto
>the ground.
>
>Once a big gas bubble is present, the enormous expansion and contraction
>
>of the gas (Boyles Laws) prevents the coolant in the overflow tank from
>returning properly, and thus a cycle is set up to cause more and more
>coolant to be lost or fail to return to the system.
>
>Now if all is well with your engine, during your operation of it on a
>day to day basis, you will experience over time, some coolant loss, and
>this will show on your daily check of oil and coolant levels (you do at
>least a daily check do you not?). If all is operating ok, if the
>coolant is at or slightly minimum during your start for the day, add a
>little coolant - bring it up halfway to Max, or fill by the book.
>
>I hope this long winded explanation is sufficient to explain my
>statement above.
>
> As you said, this system is pressurized, however slightly, to prevent
>the coolant from boiling, so do be careful if you must remove the cap
>when the system is hot. Put a rag over it or something, or better yet,
>let it cool down before pulling the cap for service.
>
>Regards,
>
>John Rodgers
>88 GL driver<<<<<
>
>
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