on 3/18/02 7:46 PM, Bob D. at bobmgtd@insightbb.com wrote:
> Both my MGB's and TD's engines run too cold when the weather is cold, say
> below 40F.
> They both have new thermostats, I figure they can't both be bad.
Agreed.
> Could it be the cold air
> running across the engines that is causing the overcooling?
I was thinking about this myself, and I would guess that it is a factor.
> If the thermostats are closing
> properly, I would think the coolant temperature in the radiator wouldn't
> matter.
Well, I was thinking something like this might be happening:
1. engine coolant temperature drops below thermostat threshold, causing
thermostat to start to close (slowly)...
2. as thermostat slowly closes, coolant temperature drops even more...
3. thermostat fully closed -- coolant in block heats up, but coolant in
radiator drops in temperature rapidly...
4. thermostat slowly starts to open, rush of icy coolant from radiator flows
into block...
5. thermostat slowly starts to close as temperature drops even more...
In this scenario the only thing that really gets warm is the front of the
head where the thermostat housing is. I think all thermostats have at least
a tiny by-pass hole that allows some flow even when fully "closed".
And as you note, the icy wind swirling through the engine compartment is
chilling the exposed surfaces of the heater hoses and control valve, among
other things. So even as the inside of the head is at operating temperature,
these exposed surfaces lose heat rapidly.
> The cardboard
> fix is also blocking the cold wind from the engine compartment. Just a
> thought.
That could very well be it.
I am basing my observations on the fact that my B will maintain a constant
temperature reading of 190 degrees (+ or - 5) at highway speeds in ambient
temperatures ranging from 45 to 95 degrees. But below 40 degrees or so it
will indicate a much lower engine temperature, and in these situations the
heater is ineffective (ironically, when one needs it the most).
>
> Bob Donahue (Still stuck in the '50s)
> Email - bobmgtd@insightbb.com
> 52 MGTD - NEMGTR #11470
> 71 MGB - NAMGBR #7-3336
> .
>> Max Heim wrote:
>>
>>> That's exactly what one would expect. A 195 degree thermostat would help
> if
>>> you aren't running one, of course. But the real solution for winter
> driving
>>> is to block off part of the radiator so that it doesn't super-cool the
>>> coolant at highway speeds. It's nothing to do with the heater itself,
> really
>>> (though the valve design could certainly be improved) -- it's the engine
>>> temperature running cool. I used to keep in the trunk a small piece of
>>> cardboard cut to fit neatly in front of the radiator, kind of snapped
>>> between the lip on the top and bottom tanks, with about 50% coverage.
> But it
>>> so very seldom gets that cold around here that I haven't bothered
> lately.
>
--
===============================
Max Heim
mvheim@studiolimage.com
_______________________________
Studio L'Image/West Coast
707 824 4333 : 707 824 5666 fax
_______________________________
Studio L'Image/East Coast
212 242 3366 : 212 242 3399 fax
_______________________________
www.studiolimage.com
///
/// mgs@autox.team.net mailing list
/// or try http://www.team.net/cgi-bin/majorcool
///
|