If you have an infrared thermometer, like about $30 from hardware store; point at top rows of fins when warmed up, engine off. Then in same vertical line, the lower rows. If more than 10F (bottom cooler) then sludge could be blocking lower rows, and you could have a 50% radiator.

Radiator chemistry is 24/7, just at a different speed when engine heat is present.

180 stat will make things better, but may mask a partial clogged radiator, which will continue to grow mud chiggerz with the help of age, Dexcool, well water, tap water, extra stopz leakz that never found a leak, etc. Most radiators for Rovers are horizontal tubes, so they are all fed in parallel. The Mark I palm reader is not always the best tool to use for hot and hotter.

 

Try the 180 stat first.
Makes a big difference.

Then if rad is shot - replace the rad.

Fan clutch - does not make that much difference unless it is really hot out.

 

At idle when the temp is 212 I can bring it down to 203 by holding the RPM's at 1500-2000, so maybe a new fan clutch would help.

 

Check to see if the radiator has a cold spot dead center. No heat, no fan clutch lock up.

 

Yep, sludge (inside, or mudd chiggersz outside) can build up in enough rows to cut heat in air flow to clutch face, and it will not get hot enough to come back to full power.

 

Seriously, You will be above 210 F with the 190 degree thermostat.
yes, if you run it fast, temps go down - at ldle like you said.

I have been all through this two week ago with mine.

All that made a REAL difference was

REPLACING THE 190 degree WITH A 180 Degree thermostat.

Changing my radiator DID NOT HELP.
Changing my fan clutch DID NOT HELP.

The third thing I did was put in the 180 degree thermostat.

ONLY THEN did my temps stay around 203 at idle - idle meaning 400 RPM
and my AUX fan did not come on after that.

Just saying..
You can throw money at it.
Go ahead.

But, the 180 degree Tstat makes the biggest difference.

DO that first

1) Put in 180 degree stat

still bad

2) Fan clutch

still bad

3) Radiator

still bad

Large vane water pump.

still bad

shoot it.

 

One point that should be made is there is no need to throw parts at it. You can diagnose the radiator for hot/cold spots. You can diagnose the fan clutch. You can confirm electric fan will run and is not blowing fuses.

The 180 soft spring stat is a great upgrade for a D2.

 

After going for a long drive today it was idling at 220 so I used my temp scanner laser gun and only found a 20 to 25 degree differences from top to bottom of the rad, and no cold spot in the middle, I picked up a new fan clutch today for super cheap and will replace it along with the t-stat next weekend, today I changed the diff's t case and transmissions fluid and filter t-case and tranny not the most fun to refill lol

 

Repeat your tests after you make the changes. Your overall temps may be lower, but the higher differential on the radiator may remain.

 

You may want to look into the thermostat mod that eliminates the factory thermostat and uses a gm thermostat and some other hose. I had a mechanic do the mod for me. With a half clogged radiator, but not leaking, I got temps of 185F driving thru 105F desert in august full on A/C for a 2 month road trip. Sometimes at idle the temp would creep up, but hit the gas to rev rpm watch it cool. (ultra gauge) Usually it ran about 183 after the mod... before it ran about 200F.

I just had a new radiator installed and it didn't rise above 183F even at idle for a half hour. new Radiator, fan clutch, thermostat mod, I'm confident I won't see a temp above 195F under almost any condition. 120,000 miles and the engine sounds great, and I am trying to keep it that way.

Thanks Masterrovertech for all the great work.... Chris at 5 Corners Auto Repair in Long Branch, NJ

scott