Hi.

Have a 98 Disco I.

Using a ScanGuage for the first time, was driving yesterday in fairly cold weather -- about 15, so cold but not crazy cold.

Coolant temp was running very low. (Coolant full, no leaks)

On flat, highway, would hang around 145. Downhill could get as low as 110. Never got above about 155 when driving.

However, idling in the parking lot, would rist to 180 on the nose, and bounce between 179-182, never straying.

My (uninformed) sense is that things are actually working fine, but in really cold weather the radiator is actually working too well??

So, do folks running in cold weather block part of their grill/radiator? (Winter temps here routinely range from -20 to 40)
Do I need to worry about the engine temp being that low?

Thanks for any insight here.

 

Nope, your thermostat is likely stuck open, or partial open. Replace with either 180 or 195, depending on if you are in the frozen waste lands of the north, where your Depends can freeze solid. Don't use one of the "fail safe" thermostats, it will latch open and do what you describe. The stat should be about $10, plus a gasket, plus 1/2 gallon of coolant. Spring end goes in this hole. Little jiggle device or tiny bleed hole goes at 12:00 position. Keeps a steam pocket from forming.

If the thermostat is closed, there should be minimal circulation near the ECT heat sensor and plenty of warm water.

If applying a radiator muff, don't use cardboard or somethng that will get wet and soggy and clog radiator fins.

Seldom are Rover radiators accused of being "too large".

 

OK, that makes sense. Thanks.

Any recommendation on 180 vs 195?

Winter temp range typically -20 to 40 here.
Summer rarely goes above 75, if that.
But will have trips where temps will be higher.

 

195, and Spike won't believe his eyes when he reads this. You need real heat in the winter. Where are you?

 

Leadville, CO.

10,000 feet!

 

OK, so looking at the shop manual (which I should have done first) seems like the viscous fan/clutch could also be malfunctioning.

But manual is a bit slim on guidance on how to see if the fan is working properly.

I guess I would get the rover running, maybe idling while parked, and watch the coolant temp on the scanguage. If I read the manual right, the fan will go on initially at start up; quickly disengage while engine is cool (as clutch fluid spins out); then re-engage as engine gets to proper operating temperature??

Does that sound right? Any other tips for seeing if the fan is working properly?

Thanks for helping out here.

 

That's 9,900 feet above me. Rovers get better mpg downhill....

 

Not quite on the clutch. When it is stone cold the fluid will have pooled to one side, and when you crank up it will have an initial fan "roar" as it is fully coupled (about 80%). As fan slings silicone around inside and warms up, it reduces coupling to about 20%, and roar goes away. The heat from the radiator air flow on the face of the fan causes it to shift back to higher coupling when face plate hits 170 - 200F ish.

Field test is spin and release fan when cold, should feel like peanut butter inside there, coast maybe a 1/4 turn. Repeat when warmed up, May coast more, but not a whole revolution. Freewheeling indicates silcone is mostly lost, time for new clutch crosses over from Chevy 2000 Express 4.3 liter w/o AC. You have to enlarge bolt holes in fan slightly.

If fan clutch has failed full power conection, the roar does not go away, and you would have more cooling.

Certainly coasting downhill at idle, with 50 mph wind chill, and sub zero to begin with, could require a radiator muff. Perhaps it works better on the trip back up the mountain.

 

I had the exact same situation about a month ago. Found out my thermostat was indeed stuck open, just like Savannah said. "Failsafe" stats are crap, didn't know any better when I installed it.

 

Its not your fan, its the t-stat, OEM temp is 192*F.