On Feb 22, 2011, at 6:00 AM, Richard Jones wrote:

> I think the thermostat doesn't move the flaps after
> engine warm-up.  It just helps the warm-up happen
> faster.

I'm not sure whether you're right. I think that on a long down-hill
grade the thermostat actually does respond and move the flaps. Why
wouldn't it? The length of the bellows is directly related to the
temperature of the fluid/gas inside it. It might not be quite as
responsive as the proposed electrical device.

>
> How about an old-fashioned "choke cable" from under
> the driver seat to move the flaps?  Do they even
> make choke cables anymore?  I put one on my '61 bus
> when the Solex choke didn't work right....

My bus was originally a diesel, so it has the start cable, and I'm
going to use that as a work-around.

> I think I have the bug thermostat on my '81.  Is that
> NLA, too?

Yes. The company that made these bellows thermostats is no longer
making them. After-market dealers like Bus Depot and German Supply
have the bug thermostats, which can be modified to use with the bigger
engines. But the prices are $80 and above -- supply and demand, so
fair enough.

The thermostat was a nice mechanical solution to a problem, but it
required a supplier's commitment to tooling in order to provide it.

I don't know whether these devices could have been competently
rebuilt. I do know that running the engine without a functioning
thermostat has no immediate consequence. As long as the the flaps are
in the fail-safe open position, it just takes longer for the engine to
warm up, and the engine cools down under certain conditions. So while
there is demand for the NLA part, there isn't sufficient demand that
there is someone willing to leap into the gulf.

Today, if a car company were designing an aircooled engine from
scratch, I'll bet they'd go for a step motor, circuit board, and
thermistor rather than a mechanical thermostat.

Mark