How Hot is Hot?

[ron3865]

I have am '88 Westfalia with 70000 miles on a GW2400cc motor. I've only had it for a few months and only driven on level roads with a very light load and the temp needle sits right over the red coolant level warning light. I think it has a 192 degree thermostat.
So here are a few questions for the Vanagon wizards:

1. What is the temp when the needle hits the high white line? or is that "tow truck time"?
2. The low mark is about 1/8 inch thick. Does this mean anything.
3. I know both stages of the fan work (I haven't yet removed and tested the sending unit) so when should I expect to hear them?
4. I don't believe I seen a temp gauge before that didn't have a red line. I wonder why the Vanagon doesn't have one?

[Syncro Jael]

Dead center in the LED warning light is around 180° on my van. As checked by an infrared gun.

A full needle width above is 200°.

Again this is on my van and you can purchase an infrared really cheap and take the guessing out of it.
_________________
1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat)

[[email protected]]

The level is a little wonky. Middle of LED seems like were most fall. My low speed fan goes on at a little above the LED. Basically sitting in traffic on a warm day. I used to hear the high speed fan before i fixed my low speed and since have not heard high speed. Like Jael said you need infrared if you really care, but as long as you are near the middle you are fine.

[Wildthings]

Check your owners manual. This is the owners manual for a '85 which will be close to what you have but not the same.

https://www.thesamba.com/vw/archives/manuals/1985vanagon.php

[?Waldo?]

[Slate]

Trust the red light, and if it comes on, note where the needle is when it comes on. Then you'll know where YOUR van's needle point when it's over hot (which is not the same as overheated).

The temperature sender is not very linear in it's response. When cold it's resistance value changes more per 10 degrees (in ohms) than when @ 180 degrees. The end result is that when at 180 degrees the needle does not move very much and you really have to see the light come on and see where the needle is at that time.

I learned this when trying to characterize the sender on my Subaru engine in my Westy against the VW meter, and this is true of all senders of this type although the meter can be calibrated to compensate for this, which the VW meter does not do.

I pulled the sender out and characterized it's resistance (ohm) value against a temperature standard as I heated it up in water on the stove. Then I used a potentiometer to see what the gauge did and ultimately, decided that I'd be better off watching out for the light and looking at the OBDII value, if I really wanted to know what the temperature was in degrees, rather than "where over the red light the needle is". Lacking OBDII, I'd use an aftermarket digital sensor but unless you really want to know, but IMHO, just watch out for the red light.
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Hey Wildthings, thanks for the link to the "Owners Manual"