[T3] oil and heater channel air temperatures

[Jim Adney]

On 22 Aug 2011 at 19:34, Paul P wrote:

> I was doing an oil change, so I took some oil temperature readings
> using a type K thermocouple wire plugged into the multimeter -
> accuracy checked and spot on. 

Interesting. I don't think anyone's actually done this carefully 
before. Keith did it with his Type 4 engine, but I don't think he did 
it with the Type 3.

> Ran car for 20 mins mostly at 100 kph /  62 mph.  Single carb. 1500 cc
> K engine, 1970 notchback, so this 'effort' is maybe equivalent to 70
> mph in a dual carb/FI... Car is tuned up well at the moment. Little
> wind and mostly level roads, and only myself in car.  Anyhow, data ; 

> Outside air temp;  c.18 C...
> 
> Temp. with probe at dip stick end area - 75 C (167 F) - Temp of the c.
> 2.5 litres of oil after discharge-  c 80C-  so a small difference with
> dipstick reading -  not surprising I suppose. I´ll repeat this the
> next time. (By the way I leave a probe in the dip stick tube end - the
> oil filler cap will still fit on easily and you can tuck the probe
> socket away). 

The dipstick area is a rather stagnent volume, so I'm not surprised 
that it doesn't heat up as much as the rest of the oil. Bosch made a 
temp sensor that replaced the sump plate drain plug. That's an 
excellent place. Do you suppose you could convert a drain plug to a 
T\type K thermocouple?

Most sources claim that we're okay as long as the oil stays below 100 
C, so your numbers sound fine.

> Ran the car with the `front´ heaters full on, because I also measured
> the air temperature inside the heater channel, just behind the left
> footwell vent (with both vents closed- thermocouple wire is thin, so
> you can close...)- temperature went to  95- 97C, after engine had heated
> up in 12-15 mins. I always knew it was hot, but was surprised how hot.
> I wonder could this be a useful index of cylinder head temperatures,
> and has anybody else measured their heater channel temps ?  I returned
> along the same route later in the day, with the heaters off, and the
> oil dipstick temperature was 72 C. 

The hot air temp is legendary, and it's heated by the exhaust, but 
I'm surprised that it's still that hot when it gets to the front of 
the car. Of course, it won't be that hot if you measure it on a day 
when you actually need the heater.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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