Our 1.8T running temps

[kaiser]

I would not worry too much about the PRT. I think it is largely a fad.
Tere are a couple of problems with the 4 cylinder engine, and they are:
The thermostat is on the wrong side of the block, and that allows a sudden rush of cold water to stream into the engine, when first opening. And the second problem is if there is no water in the expansion box, the engine WILL overheat. That applies specifically to the MG F/TF versions, but I think also the 1.8K.
I have now twice had immediate and impressive temperature increases, just losing enough water to empty the expansion bottle! I can't recall any other car, where you can have water JUST below the expansion bottle, and then start overheating like this. After all, there is maybe about one liter of water in the plastic expansion bottle, but the difference between running fine and overheating is perhaps the last 100ml or so. And the difference is not gradual, it is like night and day!

So my suggestions is to make a hole in the thermostat, so that there will always be some flow, that will allow a gradual warming from cold, maybe at the cost of a bit of cabin heat in winter, and then fit a warning for low coolant.
With these two modifications, I think you can achieve anything a PRT is supposed to do for you.
If you don't do any of the above, then check your water like a good boy, often, conscientiously, and thoroughly! Again, again and again!!!

[RobPlews]

Originally Posted by kaiser

I would not worry too much about the PRT. I think it is largely a fad.
Tere are a couple of problems with the 4 cylinder engine, and they are:
The thermostat is on the wrong side of the block, and that allows a sudden rush of cold water to stream into the engine, when first opening. And the second problem is if there is no water in the expansion box, the engine WILL overheat. That applies specifically to the MG F/TF versions, but I think also the 1.8K.
I have now twice had immediate and impressive temperature increases, just losing enough water to empty the expansion bottle! I can't recall any other car, where you can have water JUST below the expansion bottle, and then start overheating like this. After all, there is maybe about one liter of water in the plastic expansion bottle, but the difference between running fine and overheating is perhaps the last 100ml or so. And the difference is not gradual, it is like night and day!

So my suggestions is to make a hole in the thermostat, so that there will always be some flow, that will allow a gradual warming from cold, maybe at the cost of a beat of cabin heat in winter, and then fit a warning for low coolant.
With these two modifications, I think you can achieve anything a PRT is supposed to do for you.
If you don't do any of the above, then check your water like a good boy, often, conscientiously, and thoroughly! Again, again and again!!!

I think you’re rather missing the point there - the PRT is designed to solve the problems you describe.

In my experience the PRT made a huge difference.

[RobPlews]

Originally Posted by T-Cut

Hello Rob, what running temperature did the original provide? I guess you felt it was too high and swapped for the 'lower' black one?

Where did you get the black one/Part Number?


The 'latest' thinking seems to favour the grey version, but the one I checked was not what I expected and returned it to the Land Rover outlet.


TC

From DMGRS - I’ve asked what they think.

Previously it was the standard one (92C I believe) and it would sit at about that cruising on a long run.

I was aiming to take that down a bit - but it seems to have gone up a bit!

I’m wondering if it’s the spring not giving relief. It will idle ok in the 90s-low 100s. No huge rush to put the fan on.

Going to swap it back. Best way to find out.

Oh also changed the pump and the plugs... can’t see either of those causing too much trouble.

[SD1too]

Originally Posted by kaiser

The thermostat is on the wrong side of the block, and that allows a sudden rush of cold water to stream into the engine, when first opening.

Hi Kaiser,

Having observed how thermostats open, which I'm sure that you have too, it isn't a "sudden rush". The word which MG Rover uses is "bleed" and the purpose is to stabilise the coolant at between about 92 and 104 degrees C.

Bear in mind also that when the thermostat begins to open, coolant from the radiator is "bled" into coolant at the same temperature as that leaving the cylinder head which itself is a heat engine. It's evident from the digital display of coolant temperature that no dramatic dip takes place when the thermostat begins to open.

Simon

[RobPlews]

Originally Posted by SD1too

Hi Kaiser,

Having observed how thermostats open, which I'm sure that you have too, it isn't a "sudden rush". The word which MG Rover uses is "bleed" and the purpose is to stabilise the coolant at between about 92 and 104 degrees C.

Bear in mind also that when the thermostat begins to open, coolant from the radiator is "bled" into coolant at the same temperature as that leaving the cylinder head which itself is a heat engine. It's evident from the digital display of coolant temperature that no dramatic dip takes place when the thermostat begins to open.

Simon

Yep that’s the one 👍🏽

[T-Cut]

Originally Posted by RobPlews

Previously it was the standard one (92C I believe) and it would sit at about that cruising on a long run.

That's about right for the OEM buff version. The nominal setting is 88C, but that's basically the trip point. The 88C stats will always make the running a few degrees higher in the petrol engines. Note that this particular stat is stamped 82C internally even though the MGR spec was 88C. Confused? You will be if you carry on.

I was aiming to take that down a bit - but it seems to have gone up a bit!

PRTs are a dog's dinner these days. I couldn't guess what the 'colour' is now supposed to tell you. Fifteen years ago, yes, but not now.

I’m wondering if it’s the spring not giving relief. It will idle ok in the 90s-low 100s. No huge rush to put the fan on.

I've regularly commented over the last few years, the 'relief' spring tension now means nothing to anybody - and I suspect that applies to the manufaturers as well.

Going to swap it back. Best way to find out.

Back at square one, at least you know what you've got. If I had any confidence in today's PRT suppliers, I'd suggest looking at what the Lotus K16 people recommend, the grey one. The problem I found, is which grey one?

Have a read through this. It's the closest you'll get to anything sensible. But also consider they've changed their minds a couple of times since the first edition. It's also had a lot of good earlier information deleted.

https://wiki.seloc.org/a/Pressure_Re...ote_Thermostat

TC

[kaiser]

Quote with reference:

"Fixing the Problems

As a 1.8 litre there are, or were, two minor problems, design features of the basic engine which did give rise to problems when the engine was tuned. The first is the positioning of the thermostat in the cooling system, which was not designed for engines frequently put under heavy load. It was first designed as an efficient engine for lightweight front wheel drive cars, typically the Rover Metro and the current Rover 25, with good fuel consumption and requiring low emissions from start-up when the car was likely to see a large number of very short inner city journeys. It was thus designed to give very rapid warm up by placing the thermostat at the coolant inlet to the engine, where the thermostat measures essentially cooled water from the radiator with a very small quantity of heated water from the balancing circuit until the stat opens. This is a very unusual coolant path design, but is effective in its required purpose.

The system does not function well in cooling circuits with a radiator a long way from the engine in the cooling path, or for engines constantly seeing high engine speeds .The problem arises when the engine is put under heavy load, causing high engine temperatures that are not immediately read by the thermostat because cold water in the radiator and hoses has to pass the thermostat first. This can cause enormous thermal gradients across the engine, causing both distortion of the head and block and also gasket failure. "

http://www.sandsmuseum.com/cars/elis...ine/kingk.html

[trikey]

Originally Posted by T-Cut

PRTs are a dog's dinner these days.

I agree.. I had two 'new' PRT;s fitted when I had my 1.8t, temperature was all over the place.

I fitted the land rover version from Rimmer's and had no issues at all after that, reading a constant 88 deg on the hans gauge, rising slightly when in traffic, then straight back down to 88 deg once moving again.

[ricardo65]

Originally Posted by trikey

I agree.. I had two 'new' PRT;s fitted when I had my 1.8t, temperature was all over the place.

I fitted the land rover version from Rimmer's and had no issues at all after that, reading a constant 88 deg on the hans gauge, rising slightly when in traffic, then straight back down to 88 deg once moving again.

yep as above we run three 1.8 with the Land rover PRT fitted all run a constant 88

[RobPlews]

Thanks all.

Looks like I have a duff black on. Seems the grey one is the way forward.

Rob