Date: Fri, 13 Feb 2009 17:38:21 -0800
Reply-To: John Bange <jbange@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Bange <jbange@GMAIL.COM>
Subject: Re: Mocal sandwich plate plus oil cooler equals overcooling
In-Reply-To: <017601c98e0f$f55546b0$6401a8c0@PROSPERITY>
Content-Type: text/plain; charset=ISO-8859-1
> will try to keep this short.
> I am under the impression that The Issue is ........
> it runs at proper cooling system temp,,,,,,,,,but there is bubbling in the
> coolant pressure bottle.
Precisely! There wass boiling upon shutoff, when the coolant stops
flowing and soaks up heat from the hot metal bits.
> ( couldn't quite decipher this : "the bubbles vanish as> soon as the his
> the pressure tank and condense." )
Vanish, as in the bubbles, which are steam, come in contact with
cooler water in the pressure tank and turn back to liquid.
> tell me this ............does coolant disappear in any way, ever ?
Not a bit, with the exception of the one time at high altitude when it
was boiling enough to push it to the overflow tank.
> are 'the only symptoms' that the coolant bubbles and the oil is too cool ?
Ah.... I see the confusion. The boiling at engine shutoff prompted me
to add the oil cooler. The oil cooler completely eliminated the
boiling problem (by cooling down the bottom end) but due to what is
apparently a stuck oil thermostat, it is now overcooling.
>
> in all cases of mysterious unsolvable problems, I say..........go back to
> the basics.
> starting with a leak down test.
I haven't had any of the classic symptoms of such leakage ("air"
appearing in the tank when the engine runs, etc) but I think I'll pull
out the compressor tomorrow and have a look anyway. It is, after all,
an easy test to run.
> It is possible to have a water pump that doesn't leak or show any of the
> common water pump failure modes, and it still fails to pump
> correctly..........but that is extremely rare. The most likely reason that
> would ever occur is a odd aftermarket water pump that's not quite built to
> correct specs in the first place......
Well, since I own two Vanagons and it's time to change the coolant
again ANYWAY, I will probably just get a new one and replace the one I
have. It was 3 months old and very shiny when I bought the van, so it
was technically new when I put the Boston Bob engine in 20K miles ago,
but it is also of unknown origin..... Given that it can't hurt to
have a spare water pump around, why not? The more money and time I
throw at this box, the more it becomes MINE!
Incidentally, I've driven this week with 90% of the cooler blocked
with a piece of cardboard, and the temperature has been more
reasonable, indicating right about 180-ish. That probably translates
to 190-200 actual. An IR temp probe is also on my shopping list. I
will probably drill and tap the sandwich plate for an oil temperature
sensor, given how inaccurate the drain plug sensor location has proven
to be over the years.
--
John Bange
'90 Vanagon - "Lastwagen"
'90 Vanagon GL - "Wiesel"
