[Vwdiesel] normal idle overheating?

[Tony and Lillie]

The hotter at idle thing is common to all VAG products from that era. 
Basically, the fan has a thermostat that's commonly 5-10 degrees hotter than 
the coolant thermostat. That way, the fan doesn't run all the time, just 
when needed. This is the way my 82 NA Jetta is, my 82-87 4000Q's, and just 
every other VAG from that time that I've worked on or owned. Nothing to 
worry about.

As for the head being hotter, the thermostat is at the bottom of the engine, 
at the water pump. So, I guess that's why the head would be hotter. I would 
think that the water pump would keep things mor even than that, but I've 
never checked it on any of my cars. And, to that note, the head is 
alluminum, which should dissipate heat better than the iron block. 
Hmmmm............Then again, rereading the post, you don't say that the head 
is hotter than the block, but reather hotter than the thermostat. Is that at 
idle when the fans are cycling? If so, once again the idle temp is regulated 
by the fan thermostat, not the coolant thermostat. At that point, and any 
over the rating of the coolant thermostat(180, for example), the thermostat 
is simply open all the way.

Tony

----- Original Message ----- 
From: "Will Taygan" <william at taygan.com>
To: <vwdiesel at vwfans.com>
Sent: Monday, April 20, 2009 1:52 PM
Subject: [Vwdiesel] normal idle overheating?


> It seems my 94 FrankenJetta (gas to 1.6TD) and a new (but slightly
> mangled) head is driving okay.  My gauge seems low, but I'm assuming
> it's because it's a gas gauge.
>
> 1. It runs cold (175? - 1st tick) most of the time.  Thermostat closed,
> radiator cold.
>
> 2. When going up hills it will get up to the 2nd tick, and the
> thermostat (set at 187?) will open.  I know because the radiator gets
> hot - things cool down to 1st tick again.
>
> 3. When idling it will get up to the middle tick, and the fan will turn
> on (set at 195?).
>
> Using an infrared, my readings reading are 5-10 degrees hotter at the
> head than the settings of the thermostat and thermoswitch.
>
> It used to always run cold, and the fan would never come on.
>
> It seems that lots of other folks have the "get hot at idle" thing going
> on.  Is this normal, or is it a sign of things wearing out?
>
> Thanks,
>
> Will.
>
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