Temperature Question - Can it be too cool?

Knightspirit

Well-known member
Sep 22, 2019
251
84
Mount Shasta, CA
I am wondering what is going on with my temperature - '99 Disco 1. I noticed when I got it that it never really warmed all the way up - so I bought a new temp sensor and got one of those blue tooth OBD plugs so I can monitor it exactly. I just drove for over an hour in 30º F outside temps at about 75 mph and I never got above 140º on the gauge.

I am thinking that either the thermostat was removed or the one in there is stuck open. I have seen reference to 180º thermostats - but the ones for sale at Atlantic British are all 190º. Any problem with running too cool? I figure I will just buy a new thermostat and install it and see if that changes anything.

Anyone have a link to a 180º thermostat - or is that something I can just buy at the local auto parts store? Thanks!
 

p m

Administrator
Staff member
Apr 19, 2004
15,617
837
58
La Jolla, CA
www.3rj.org
To answer your first question: yes, the engine can be too cool.
Running the engine with colder-than-factory thermostat (or none at all) is not good for the engine for several reasons.

That said, my D1 and Classic have 160F thermostats, and tend to run at about 170-180F. The purpose of that was not the engine longevity, but maintaining lower pressure in the cooling system.
 

Knightspirit

Well-known member
Sep 22, 2019
251
84
Mount Shasta, CA
To answer your first question: yes, the engine can be too cool.
Running the engine with colder-than-factory thermostat (or none at all) is not good for the engine for several reasons.

That said, my D1 and Classic have 160F thermostats, and tend to run at about 170-180F. The purpose of that was not the engine longevity, but maintaining lower pressure in the cooling system.
I am worried about head gaskets - so a 160º sounds good - where did you get that?
 

WaltNYC

Well-known member
Mar 3, 2010
707
135
NYC
Knightspirit, I'd use a 180 if I were in Northern California. PM is (I think) in So Cal where temp spikes are more prevalent.
 

p m

Administrator
Staff member
Apr 19, 2004
15,617
837
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La Jolla, CA
www.3rj.org
You should be fine with 180-195F thermostat.
It is better for the engine to run constantly between 190 and 200F than to bounce between 160 and 200. The upper limit is not controlled by thermostat - it is whatever the radiator/fan clutch/fan/water pump can dissipate.
 

cositsworthit

New member
Apr 28, 2014
3
0
austin texas
1. Yes an engine can be too cold

2. Even with no thermostat, this engine is not going to be damaged as long as it still reaches normal operating temp...190 I think (see rave)

3. I'm in Texas and running an inline mod with a 180 thermo in it.

If you live where it snows, you will probably want to keep your throttle body heater. I bypassed mine