Date: Tue, 13 Sep 2005 08:00:33 -0700
Reply-To: Shawn Wright <swright@ZUIKO.SLS.BC.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Shawn Wright <swright@ZUIKO.SLS.BC.CA>
Subject: Re: How hot is your coolant?
In-Reply-To: <EDEMIFILICBALHHKHLLJAENOCJAA.JParkins@RTHCorp.com>
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On 13 Sep 2005 at 10:39, John W. Parkins <JParkins@RTHCORP.COM> wrote:
> Hello All, I've been trying to determine the normal operating temperature of my
> coolant in my '87 Westy. The thermostat "starts" to open at 185 F according to
> Hayes manual. Therefore, the temp is greater than 185 F if you are to get ANY
> use out of your heaters. The thermostat is fully open at 221 F according to
> Hayes. I think the thermostat must be fairly well open if you are to get any
> reasonably heating in the cabin. In addition, the radiator fan kicks in between
> 192 and 201 F. Now, the coolant in the radiator will be cooler than the coolant
> at the thermostat housing due to the cooling effects of the radiator fins, even
> when there is no airflow over the radiator. The fan often kicks in when idle for
> long periods. So the coolant temp at the thermostat must be over 192-201 F under
> these conditions. Note that the 2nd speed kicks in between 203 and 223 F. Thus,
> the coolant at the thermostat must be higher than this when the second fan kicks
> in.
The heater loop bypasses the t-stat, allowing heat before the t-stat opens. How long
does the fan kick in at idle? Longer periods could be the result of slow water pump
flow. If the fan quickly goes out when the engine is held at 2000 rpm, this would
support that theory. I don't recall my rad fan ever staying on longer than maybe a
minute or so idle/low speed conditions. Driving around a campsite in 1st gear, after a
long hard drive would result in a continual cycle of on/off of the rad fan every 30-60
seconds or so for a few minutes.
> I checked the temperature of my coolant in the coolant tank (not overflow
> reservoir) to be 210F. I think this is high, but not high enough to do any
> damage to the engine. The needle reads pretty high on the gauge. I asked a
> dealer, and he said that the coolant could easily reach 210F, but I'm not
> convinced.
How did you check the temp in the tank at 210? I would think at this temp that
coolant would probably rush out when the cap is removed. Keep in mind the system
is designed to hold pressure up to ~14psi, which effectively raises the boiling point of
the coolant, which is already considerably higher than 212F if the mixture is correct.
This helps prevent localized boiling in hot spots, which could otherwise cause a
vapour lock condition.
> Anybody have data on the coolant temperature during idle after warm up or
> any other info? I'm trying to determine if my temperature reading system is
> working correctly. So far, the sender and gauge seem to be OK. Maybe it is the
> electronics for the low level indicator that is throwing things off. These
> electronics tie into the temperature sender signal.
Do you mean the stock gauge? I've never had reason to add an aftermarket gauge,
as my '88 always ran cool, at most about 1 needle width beyond the LED. Normal
cruising would centre it over the LED. This was with the old 2.1L engine.
Shawn Wright
http://zuiko.sls.bc.ca/~swright
'85 Jetta D
'88 Westy 1.6TD 5 speed
(see progress at http://members.shaw.ca/vwdiesels)
'82 Diesel Westy