Hey there, I have a 99 Disco II,

My temp gauge started rising from nowhere, then leveling out about 3/4 way up. After a while more it would finally start rising again, and I would have to turn on the Defrost to HI to get the engine temp back down. I was at a constant RMP and load

I have changed the water pump and Thermostat

I have flushed the coolant system with water also

I have bled the system according to rave, water level stays good.

When I start the engine, I can wait about 10 minutes and I hear the viscous coupling kick in.

So...why am I still having cooling issues and they are not constant cooling performance? I am in maine, ambient has been no higher than 80 MAX, still happens when 60degrees out.

Has anyone seen where the Viscous Fan coupling kicks out when it's hot?

I bought this vehicle in November with 167K, I now have 175K on it, not sure when Viscous Fan was done last. It's a pretty expensive piece though...

Thoughts are appreciated, thank you!

 

So this is when sitting still?

If so, does it overheat while you're moving.... specifically highway driving? If it does, that will rule out the viscous coupling and fan.

Did you check your thermostat before installing to see if it opens properly? Have you check if your radiator hoses are both hot and check for cold spots in the radiator (an IR thermometer is good for this).

 

Send me your number and quit driving it till we can talk so you don't cause any more damage.

 

I do have an IR thermometer.

Mike if you want to e-mail me your number I'll call. ben@harbordigitalsystems.com

The issues happened before the thermostat changeout, so with the new unit it is doing the same thing.

 

...and yes...it still starts to creep up while driving on highways.

 

Ahh..OK. So that will tend to eliminate the fan/clutch, because at highway speeds the fan pretty much doesn't matter.

I'd check to see if you have a clogged radiator with your IR thermometer. Of course, the center should be a bit cooler since that's where the bulk of the airflow is sitting still, but if the top and bottom is significantly different or you can find areas that are significantly cooler, you can be pretty sure it's gunked up in there.

 

I just ordered a Radiator, I'll install it this weekend. I'll test drive and reply afterwards!
Thank you!

 

Disco 2002 just overheated this morning for the first time. Mechanic says it's a freeze plug. I think it's the thermo stat-looks dark brown.

Should I start with the thermostat?

 

Edit: new thread started, never mind.

 

Bet your mechanic saw you coming, have you verified it's a freeze plug, do you know they hardly ever fail on a Rover, have you lost all you coolant, which a freeze plug will cause? If not find an honest mechanic or send me your number and I'll walk you thru what to do.