Originally Posted by KingKoopa

For what it's worth, my coolant Temps have been terrific with the factory system. New hoses, 180 gray thermo, green coolant, and my Temps never exceed 198 while sitting at idle. Usually they don't even get past 194. Moving at anything over 30mph yields Temps between 183 and 189. Summer heat will be the real test but barring anything over 205 in 100 degree weather I'll call it a success. if you replace the plastic T fitting and keep the rest of your system in good shape I can't see the benefit of varying from the factory design. My heater works quickly in cold weather, my truck runs relatively smooth (still fighting 1172 and 1175 codes) and Im always going to watch my Temps like a hawk anyway so changing to an inline thermo is never going to give me any more piece of mind.

Originally Posted by EstorilM

The best thing you can do is to go through the entire cooling system and double-check anything that's at-risk for failure. I'd say replace all your hoses first, rad and heater core, even the small ones to/from the tstat housing etc.

Next just replace with the motorrad unit.

I've been through different setups with all the temp readings and I've recorded a ton of info. I've also done research on the original LR unit and design.

YOU CAN NOT JUST SLAP AN INLINE TSTAT INTO A FACTORY LR DII SETUP!

People get so carried away with mods, cutting/hacking, electronics, tuners etc it's totally ridiculous to me. LR engineers spend millions in R&D to develop these basic core designs, and people thing a couple google searches will net a better result.

Anyone who is competent enough to totally redesign the core functionality of their rovers cooling system is surely diligent enough to have at least read the entire service manual and such right? Lolz apparently not.

There's a specific section which outlines the desc. / operation and explains why the bypass system has a pressure-operated spring.

When the vehicle is cold (ie. tstat closed) and engine speed (ie. waterpump flow rate) is over a certain RPM, I believe 1800 - the pressure generated through the heater core loops is too great, which overcomes the spring and allows pressure to dump through the main radiator loop.

So what do you do? Rip out the entire bypass system and run it "like a regular old car" except it ISN'T! You're missing that bypass feed and just shoving the entire flow through the heater core!!!

I mean LR does the bypass to protect a vehicle in STOCK NEW config. You all are skipping this entirely on 15 year old vehicles with old components and ZERO pressure bypass.

Sure it should work fine in theory, till you blow a heater core and your car smells like coolant for the next few years.

Why not just figure out the actual problem and resolve it? The OE bypass design relies on a series of four sensing holes in the tstat housing which allow a constant flow of "actual engine temp" coolant to hit the tstat element. That flow is the only way the tstat knows what temp the engine is at, unlike most vehicles where the tstat is near the head/intake manifold.

If one hole is blocked, it reduces the flow by 25% and the tstat opens at a proportionally-later rate. I've removed multiple OE tstats with blocked sensing ports. Two cuts flow by 50%. This is further exaggerated by the fact that the flow must travel through the radiator, and in a static or nearly-static state, the water can become ICE COLD by the time it hits the tstat - which will just close it further. THIS IS WHY the LR manual specifically warns that vehicles in arctic / siberian contentions may experience engine coolant temperatures up to 20+ degrees above normal!

Yeah totally the opposite of what you'd think right? But it makes sense if you understand how the bypass loop works. Colder temps actually increase engine coolant temps - if your sensing ports are blocked.

I've been using the cooler motorrad unit with TWO larger ports instead of four smaller ones, and I've never had another issue. Previously my electric fan would turn on when it was 25 degrees out and I was in park! Explain that? Oh wait, my tstat was shut off completely because flow was so reduced that it was ice cold by the time it registered - but my engine was at ~220+ degrees! The fan sensor is in the intake manifold / normal spot sensing actual temps, triggering fan.

The ENTIRE SYSTEM doesn't need to be re-engineered, why not just address the actual issues?

Besides, you then retain the almost-immediate heat in the winter, quicker engine warmup times, AND no risk of heater core damage / rupture.

Originally Posted by EstorilM

The best thing you can do is to go through the entire cooling system and double-check anything that's at-risk for failure. I'd say replace all your hoses first, rad and heater core, even the small ones to/from the tstat housing etc.

Next just replace with the motorrad unit.

I've been through different setups with all the temp readings and I've recorded a ton of info. I've also done research on the original LR unit and design.

YOU CAN NOT JUST SLAP AN INLINE TSTAT INTO A FACTORY LR DII SETUP!

People get so carried away with mods, cutting/hacking, electronics, tuners etc it's totally ridiculous to me. LR engineers spend millions in R&D to develop these basic core designs, and people thing a couple google searches will net a better result.

Anyone who is competent enough to totally redesign the core functionality of their rovers cooling system is surely diligent enough to have at least read the entire service manual and such right? Lolz apparently not.

There's a specific section which outlines the desc. / operation and explains why the bypass system has a pressure-operated spring.

When the vehicle is cold (ie. tstat closed) and engine speed (ie. waterpump flow rate) is over a certain RPM, I believe 1800 - the pressure generated through the heater core loops is too great, which overcomes the spring and allows pressure to dump through the main radiator loop.

So what do you do? Rip out the entire bypass system and run it "like a regular old car" except it ISN'T! You're missing that bypass feed and just shoving the entire flow through the heater core!!!

I mean LR does the bypass to protect a vehicle in STOCK NEW config. You all are skipping this entirely on 15 year old vehicles with old components and ZERO pressure bypass.

Sure it should work fine in theory, till you blow a heater core and your car smells like coolant for the next few years.

Why not just figure out the actual problem and resolve it? The OE bypass design relies on a series of four sensing holes in the tstat housing which allow a constant flow of "actual engine temp" coolant to hit the tstat element. That flow is the only way the tstat knows what temp the engine is at, unlike most vehicles where the tstat is near the head/intake manifold.

If one hole is blocked, it reduces the flow by 25% and the tstat opens at a proportionally-later rate. I've removed multiple OE tstats with blocked sensing ports. Two cuts flow by 50%. This is further exaggerated by the fact that the flow must travel through the radiator, and in a static or nearly-static state, the water can become ICE COLD by the time it hits the tstat - which will just close it further. THIS IS WHY the LR manual specifically warns that vehicles in arctic / siberian contentions may experience engine coolant temperatures up to 20+ degrees above normal!

Yeah totally the opposite of what you'd think right? But it makes sense if you understand how the bypass loop works. Colder temps actually increase engine coolant temps - if your sensing ports are blocked.

I've been using the cooler motorrad unit with TWO larger ports instead of four smaller ones, and I've never had another issue. Previously my electric fan would turn on when it was 25 degrees out and I was in park! Explain that? Oh wait, my tstat was shut off completely because flow was so reduced that it was ice cold by the time it registered - but my engine was at ~220+ degrees! The fan sensor is in the intake manifold / normal spot sensing actual temps, triggering fan.

The ENTIRE SYSTEM doesn't need to be re-engineered, why not just address the actual issues?

Besides, you then retain the almost-immediate heat in the winter, quicker engine warmup times, AND no risk of heater core damage / rupture.

Originally Posted by KingKoopa

I would not call 10 degress a large fluctuation, and the quick warm up a lot easier on bearing surfaces, not just an emisions/passenger comfort design

Originally Posted by KingKoopa

And the water pump is both pushing and pulling. Take off your upper hose and start the motor and tell me that the water pump doesn't push water.