Thread: American know how.

what part of the US,could it be a water heater

This?
JEGS In-Line Thermostat Housing | JEGS Performance Products

I still have problems working out how they work.

Where does the temperature signal come from to open them?

Is it just the water in the pipe nearer to the head , so that it could be much cooler than the water in the head itself.

IMHO you would need a bleed of hot water into the hose near the thermostat from the water pump.
It was these doubts that led me to pay hundreds to machine the Thor manifold I fitted to a 3.9 to accept a normal thermostat in the accustomed position which worked well..
AFAIK that is one reason you have the complicated bypasses in the factory thermostat.
Regards Philip A

how the cooling system works, basics | Grumpys Performance Garage

Drill a little hole(s) to maintain some flow for sensing

I wrote in a thread the other day that we have been converting the LR cooling system to the inline thermostat setup. The whole point is to eliminate the bypass loop and external thermostat housing. All kinds of benefits.

Originally Posted by Chubbs878

The whole point is to eliminate the bypass loop and external thermostat housing. All kinds of benefits.

we're all listening,,

no pressure

Originally Posted by Chubbs878

I wrote in a thread the other day that we have been converting the LR cooling system to the inline thermostat setup. The whole point is to eliminate the bypass loop and external thermostat housing. All kinds of benefits.

Sorry but I totally disagree. I've been doing a lot of research and testing on these to find the best solution, and I'm a total convert to the Pressure Relief Thermostat (PRT) system.

What I have learned though extensive reading and testing, is that I had totally misunderstood (for years!) how the system works and the benefits it gives.

I have run engines covered in thermocouples to find out what goes on inside it, and it's quite a different story to what you see at the coolant outlet on the manifold.

The PRT bypass port is closed by the thermostat as it opens. What it does do is to stabilise the block temperature, as the water inlet to the pump is blended. Without it, the block temperature goes up and down by several degrees as the thermostat opens and closes. It is far more stable with a PRT, which reduces thermal stress between the block and liners.

In the case of the old thermostat in the top hose (which has served very well for over fifty years), there is also only one place for the water to go when the thermostat is closed. Of course that is the heater, which has to take the full flow. With the PRT there is the bypass circuit as well, which is fully available when the thermostat is closed.

When the thermostat opens, water is blended (hot with cold from the radiator) before being fed back to the engine. Because the bypass is open the flow is much faster through the engine block and head, so the temperature of the water coming down the bypass much more accurately reflects the block temperature.

Originally this system was developed to stabilise the temperature in smaller engines, with Cast Iron Wet Liners seated in Aluminium alloy cylinder blocks. The reason a stable temperature was required was that the rapid increases and drops in the temperature around the cylinder liners would cause them to un-seat from the block, and lead to leaks around the base of the liner seat and early head gasket failure.

I have measured this in some cases with a four cylinder engine, and found that in typical conditions the thermostat outlet temperature drops by 2-3 degrees after the thermostat opens, but it has taken some time for the cold water from the radiator to go through the water pump and all around the block to reach the thermostat. Where the water enters the block, the temperature will vary by 8-12 degrees (Centigrade of course). With a PRT, the temperature is stable throughout within 1-2 Degrees.

Although I cannot find any proof of this, I believe the principle was developed by Honda (I may be very wrong with that), as they were amongst the first to use this type of system. Since then, nearly every modern production car uses this system; partly for emissions, partly for longevity.

PRTs crossed from Honda to Rover (with the introduction of the K-Series engine), and then on to Land Rover. All Land Rover V8s since the arrival of the Disco 2 have used this system, as do Jaguar, BMW, etc.

We all know that car manufacturers are a tight bunch, and won't put anything there unless it's absolutely required. PRTs cost more, so there must be a reason.

As far as I can see, the only challenge with the PRT is the massive lack of choice of opening temperatures. All European Disco 2 and Range Rover P38 V8 motors came with a 92 'stat, which means they run at 95-96 degrees normally.

Whilst there was an 82 Degree hot climate 'stat available for the D2, it has long since been obsolete. This would have given an operating temperature of 85 Degrees, which is pretty much ideal for a road-going V8. I have recently bought loads of different 'stats (many advertised as 82 Degree) to test, but most of them have turned out to be 87 Degree. Nonetheless, that gives an operating temperature of 90 Degrees, which is still better than 95 Degrees. Tomorrow I am testing yet another 82 Degree version, and I have high hopes for this one. Of course I'll let you know what I find.

Out of interest, 95 Degrees is the point at which the Rover V8 starts to lose power. The difference between 95-102 Degrees is around 15 BHP lost. Heat is also a factor in facilitating the dreaded slipped liner.

I'm in the process of converting all my top-thermostat V8s to PRTs, and the results look very good so far.

However, I always have an open mind...

Wow, Mark,, an AULRO exclusive??

as someone whos slipped a liner or two the blended temps sound good,,