Right, but lugging the motor on climbs or slow driving, that diminishes
the internal coolant flow, which IS directly rpm-related.   Lugging also
diminishes the oil pressure and it's flow rate.

  The amount of 'force' required to move the van, that remains equal no
matter what the rpms, but when you lug a motor down, you have to supply
that same amount of  force with fewer (but bigger, harder, more stressful)
'splosions against the pistons and rods and bearings.  Add to that Big Bang
the fact that there is  slower coolant flow and therefor less heat
exchanged at the radiator. In conjunction with the lower oil pressure and
flow, you have a recipe for increased bearing wear, burned pistons, worn
rings and possible overheating...

  Don Hanson

On Fri, May 18, 2012 at 7:23 AM, Mike Miller <mwmiller6@att.net> wrote:

> I thought all vans had electric cooling fans which were unaffected by
> engine speed?
>
> Mike
>
> On May 18, 2012, at 3:11 AM, Dennis Haynes wrote:
>
>  Especially for the air cooled engines you should not really be doing
>> extended climbs at low RPM. Down shift and let it rev. Lugging (when
>> increasing throttle does not increase speed) causes this engine to
>> heat up
>> quickly and low rpm also means low cooling fan output. You need to
>> determine
>> if your problem is loss of fuel or ignition. I believe your 80 still
>> uses
>> ignition points and condenser. A bad condenser can cause loss of
>> spark and
>> be affected by heat. The loss of spark from the points-condenser also
>> effects the operation of the injectors.
>>
>> For the auxiliary air regulator these hardly ever go bad. Check to
>> make sure
>> it is in fact getting power and check its resistance to determine
>> that the
>> heater is not open. Be sure the wiring is not switched with the cold
>> start
>> valve or thermal time switch. This device was used on a lot of
>> vehicles. You
>> should be able to get something close or a good used one.
>>
>