I guess I need to order the lighter spring thermostat. Truck hit 215.6f on the ultraguage today. It cooled down to 212, but stayed there till I got off the highway. One on the regular road it was back to 198f. Why does it get so hot on the highway (driving 65)?

 

It is not the thermostat. It is not the fan clutch. It is not the AC electric fan. Your radiator cannot transfer the heat from the coolant to the air quickly enough, even though you have a 60 mph breeze going thru there. Most likely radiator sludged up, and if it is this bad a flush is not going to fix it. Will show up as cooler on bottom rows, because sludge won't let enough water thru those rows. I had my copper/brass radiator rodded out, with a 180 stat (in the block on a D1) I run 180 - 183 at freeway speed. high 80's - low 90's. You may be able to flush it and get some improvement.

 

Well it's a new radiator, head gasket, peak coolnt with water wetter added. I dont see a new a new thermostat on the old invoice. So I was thinking the other thermostat might help.

 

Sounds like a T-stat issue. The trucks usually run hotter on the back roads with less breeze through the rad, and lower on the higher. If reversed, sounds to me like the stat isn't opening right. I had put in a new stat that was bad from the factory and that was the issue I had for the short drive (heated up on the highway). All the wind through the rad won't do anything if the stat is sticking. BTW, the soft spring lowered my temps 15 degrees. If you didn't have cooling issues before, a regular one should be fine but I suppose no issue running the lower temp one.

 

I just finished my PEL500110 (soft spring Land Rover Thermostat) install.

Well my temps dropped 10-15 degrees across the board. I am very happy with this mod and would recommend it to anyone.

I got mine from Rimmer Brothers - Triumph Car Parts, MG Rover Car Parts, and Land Rover Car Parts and Spares

Just thought I would share my experiences.

 

is it possible i received a bad radiator?

discovery4life - thanks for the link. the one you bought there, is it different than the motrad from Amazon for $45?

 

No, a radiator is a metal box full of tubes. Did not know you had a new one. If tubes are squeezed off, by physical crushing or full of calcium and sludge, water won't make it through all of the radiator. You can eval the radiator when warmed up with an infrared thermometer, heat from top to bottom of the fins, with engine off, should be within 10 degrees on a fresh one. Of course, there is always the chance for packing material to be inside from poor shipping practice. Or marbles slipped in as a shop prank.

As for the stat, with all the work that was done, the metering holes on the top inlet could be gunked up with trash floating around. Those tiny holes send hot water into the stat to mke it open. If clogged, it takes longer to open. It is important to see that the measuring point (coolant temp sensor) is some distance from the actual thermostat. There will be some lag time. The 82 C soft spring stat is the best thing since sliced bread.

So now that the rad is not part of the picture the stat can be number 1 suspect.

 

And for reference, here is the flow chart for the D2 cooling system, sample water comes from the T into the top of the stat housing. When cold, if engine revved above idle, WP produces enough pressure and the bypass disk (with metering holes) descends, allows water pressure to bypass the heater core. When warm, the main stat opening forces bypass disk closed, reducing flow from above to the metering holes.

 

Good advice from the others on the radiator issues, also when disconnected check the flow of water through the radiator. Also try back-flushing using a garden hose (low pressure is all that should be required to push water back and forth through the radiator. By going both forwards and backwards it should ensure that any foreign material is cleared.

As for the thermostat, the pel500110 is different from the motorad. The motorad has the same opening temp but the pel500110 has a softer bypass spring which allows better coolant flow at idle. Also the Pel is genuine Land Rover.

Btw I have heard that the pel500110 stat is also available through Lucky8 and BPutah.

 

Savannah thanks for the info. Today it was the same temp out and it didnt top 204.6f. Not sure why it was so hot yesterday. The shop that did my head gasket needs to re-replace the cam seal since it started to weep a little (appt in 2weeks). When's it there I will ask them to pop the soft spring thermostat so I don't have to deal with it, yes I know it is easy. But since it will be there anyways..