Didn't think it would work. Reason being is eliminating the connection to the heater core will likely cause strange issues.

 

Would it work better with a 1/8 hole in the flange?

 

I still don't get why people are going to all this trouble. The temps people are seeing with the 180 degree thermostats and clean cooling systems seem fine to me. My engine temps are 190 to 197. Does the engine need to run cooler? There are plenty of high-mileage D2's out there running just great with a 190 degree thermostat in them so the 180 is probably just a little extra insurance. I agree that the stock cooling system is arranged in a pretty creative way, but when everything is in good shape, it functions pretty well. The biggest problem seems to be engines running hot due to restricted radiators, blocked heater cores and worn out water pumps. Most of the D2's owned by people on this forum have probably had their cooling systems neglected by some former owner and between that and DexCool they're left with a mess.

 

Well said, I've taken this approach as well - especially since there's no clear alternative anyways. The inline system is flawed since it redirects high pressure water through the heater core when the tstat is closed but engine is at high rpm.

The best idea is to simply replace with the motorrad unit since it's not only 10deg cooler but the sensing holes are larger (2x large instead of 4x small) I've changed the OE tstat twice on my rover and each time one of the 4 holes was blocked. This WILL cause high idle temps when the bypass spring isn't released.

Cold ambient temps will always cause idle to be hot due to the bypass system and tstat sensing return coolant from radiator being freezing - since it's only flowing what goes through the sensing holes in the tstat; cold water return temps = closed tstat, even though the hot coolant is still passing through the heater core.

Simply revving your engine releases spring and gets accurate temps to tstat and boom, instant opening / good temps. It's only a problem at idle (if blocked) or at idle (if cold outside) however even RAVE says LR allows for a ~50 deg variance at idle in extreme cold conditions.

I say just switch to traditional coolant (green) go with the 180 motorrad tstat, and leave it at that.

 

I'll take an opposite side of the bench. Stat operation should not be determined by constant water flow in the heater core - in older Rovers and early Discos there was a valve and heated water was not inside the core at all times, nor was there always flow. My D1 has stat in block, is a 97, with water moving always in the heater core, and revved up or idle the core gets warm, tsat works like it should, and core does not blow apart.

 

I take the stance that it is a poor design from the start. If it was any good we would not have to have a sticky about changing head gaskets or a million posts on the subject of people having to replace them around 100,000 miles. There are plenty of cars out there from different makers that have coolant systems in just as poor condition with higher miles which are ignored that still cool the cars sufficiently enough due to the tstat is working correctly. Having the tstat in the block is likely what supports them well enough from causing similar issues. Our poor design coupled with an all alluminum engine increases the problem 10 fold IMO.

 

Yep on the design. I hope RMT is able to do a few more experiments before that Rover has to go back to the owners. I was thinking a small hole (like we did old school) would have a little hot water always passing the thermal element of the stat, and make it open more smoothly. Of course, once it is open that hole is no longer an issue. But he is correct, you don't want big swings in temp. Of course, the location of the coolant temp sensor might be closer to that stat than a D1, turbulence, etc. But a D1 is pretty close. Perhaps the D2 ECT is being thrown off by the flow around the new stat. The D1 ECT is over to the side, the D2 is more "axial".

 

The inside diameter of the pipe is only 1 1/4" so I had to use a small toyota thermo. The problem with the thermo is not the flow, or the temp, but how far the thermo has to open to regulate idle temp. It has to open all the way at idle, so when I rev the motor a little, all the hot coolant leaves the motor before the thermo can close, causing the temp to drop like a rock. This phenomenon stops once the radiator warms up, and it was also 30* ambient at the time. But when cruising it was a rock solid 182*. The coolant flows into the heater core from a pipe directly above the thermo I put in.

Why am I going through all this trouble? Because the number one problem with these cars is the thermostat. If the Block and heads weren't constantly swelling and shrinking from an easily corrected cooling system issue due to bad engineering, we wouldn't have all these head gasket and dropped sleeve issues. The fact is these engines will let go of the sleeves if the block gets too hot. "Too hot" is arguable. Too hot to me is over 200*. I have coaxed a clanging motor into not letting its sleeves move around by lowering the temp to 180*, saved the guy from selling the car at a huge loss. So you can stick your heads in the sand and say there is nothing wrong with the cooling system, But i'm telling you, get rid of that stock thermo system and bypass it before you get the awesome sound of clang clang clang clang clang.

 

Redirects high pressure water through the heatercore? You mean like so you have heat in the cabin? Well that's a side effect I like! lol the whole system is under 10lbs of pressure, the water pumps added pressure is negligible.
No clear alternative? That's what this thread is about.

The best idea is def not a motorad thermostat. Its one step up from complete fail, that's not good enough for me. Real world temps are like 5* cooler with that stat in.

I don't get the explanation about the thermo acting different in cold temps. Cold water returning from the radiator? Are you justifying its crappy operation?

I like how you say its only a problem at idle, lol, "It's ok that my cooling system sucks, cause it only sucks at idle." I dont really care what land rover says I don't like 50* variances in coolant temps.

 

Negative.

The discovery I had a normal thermostats, with same issues