Date: Wed, 11 Feb 2009 01:18:12 -0600
Reply-To: Max Wellhouse <dimwittedmoose@CFU.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Max Wellhouse <dimwittedmoose@CFU.NET>
Subject: Re: Mocal sandwich plate plus oil cooler equals overcooling
In-Reply-To: <6da579340902101754s1ce9d136x61dc0e2fba6eb3e1@mail.gmail.co m>
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John: I have no accredidation with regards to thermal engineering,
but My homemade oil cooler system I had on my 79 Loaf worked
perfectly. I have no BTU numbers or anything like that, but I did
have AN8 hoses across the board. If you suspect a faulty thermostat
valve in the sandwich adapter, I'd suggest getting it out of there
and replacing it with one that has no thermostat and then add an in
line thermostat slightly downstream ofthe outlet port. Perhaps
getting the oil thermostat a ways away from the quickly warming
coolant would help. It might be a good thing to have the oil
thermostat away from the exhaust pipes as well. The in-line oil
thermostat I had was from a company called Amot Valves and it had the
flexibility of allowing you to take it apart and change the spring
tension internally so you cold modify both the opening and full flow
temperatures as you saw fit. Mine would begin to open at165(F) and
have full flow at 185(F).
Something else to consider is perhaps finding a smaller cooler if
this one is providing the overkill you speak of or maybe experiment
with placing the cooler where it doesn't get quite such good
airflow. My cooler had it's own air supply/duct work independent of
the air going to the cooling fan and ultimately the cylinders as I
didn't want hot external oil cooler air recycling through the
cylinders.. The cooler itself was a Harrison AC evaporator from a
1975 Monte Carlo and although its design looked a lot like the
factory cooler, it must've been 3-4 times the size of the one in the
fan shroud. If your cooler is one with the "fins around copper
tubing", I believe that those flow a lot of oil through there and I
think I might be concerned with AN 10 hoses that your oil pressure
would be suffering. Do you have a pressure gauge to go with your
temp gauge? I guess another question I'd have is where you are
measuring your oil temp? In the crankcase? Just before the oil goes
into the cooler? Just after? Have you tested the sending unit to
make sure it's accurate? I would test mine occasionally by turning
on the ignition and removing the sending unit while still keeping a
ground wire on it and put it's tip in a pot of boiling water keeping
the wires from getting wet. It would read in that 210 F range every
time. That was at probably 400' above sea level at the time.
If everything checks out, I'.d have to say you indeed have a cooler
that is too efficient or removes too much heat from the engine and go
find something a bit smaller or reduce the airflow to it and make it
less efficient. There have been many on this list warning of having
a motor that runs too cold.
Something else to consider is making sure all the oil from the cooler
doesn't drain back into the crankcase when the motor is shut
off. Several experts warned me to make sure the cooler was at
crankcase level or lower so the oil level in the crankcase was
accurate when you pulled the dipstick in the morning. If there's no
way to mount the cooler at crankcase level, then perhaps adding a one
way valve in the line so "what's in the cooler, stays in the
cooler".would be a way to go, but if you have an extra quart of oil
in your system now, and that oil drains back into you crankcase, it's
going to have you thinking your oil level is overfilled at startup
and once the thermostat is opened up your crankcase may bell be a
quart below where it's supposed to be and that can't be good for the
bearings et al.
Feel free to shoot holes in this thinking.
DM&FS
At 07:54 PM 2/10/2009, John Bange wrote:
>Since I've never been happy with the way my oil temps climb above
>220degF when laboring up and over hills in my tool and part laden work
>Vanagon, I went and bought an oil cooling system. The Mocal 19 row
>cooler squeezes in nicely behind the left taillight and gets great
>airflow. Unfortunately, I'm now seeing EXCESSIVE cooling. Even after
>roaring up the mountain pass at 65mph+ with half a ton of junk in the
>back, my oil temp gauge barely manages to break 150degF. Previously,
>before the oil cooler install, I'd see almost 225degF after a run like
>that. My first notion was that perhaps the sandwich plate thermostat,
>which is supposed to close the bypass hole at 180degF, was stuck and
>was pushing oil through the cooler all the time. When I got to work
>this morning the oil cooler was hot to the touch, so it's definitely
>seeing oil flow. I'm wondering, though, if perhaps it's not the
>sandwich plate thermostat stuck shut, but that the bypass is too
>small. It's not a very big hole, and the cooler is plumbed with AN-10
>hoses (a bit under 5/8" ID) which is pretty sizable. I can imagine
>20W50 oil being thick enough to create enough of a pressure
>differential across that bypass hole that enough oil would be pushed
>"the long way 'round" through the cooler, reducing the oil
>temperature. Am I over-imagining, or has anyone else ever run into
>something like this? I'll likely be pulling the sandwich plate off and
>stove testing it in my wife's best cooking pot this weekend to sanity
>check the thermostat, but I'm still curious... am I going to have to
>install a manually operated flap to block airflow to the cooler just
>so I can reach adequate operating temperature?
>--
>John Bange
>'90 Vanagon - "Lastwagen"
>'90 Vanagon GL - "Wiesel"
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