Am I just being a bit thick? 1.8T cooling system

[__chris__]

I really am having a bit of trouble fully understanding what is going on with my car at the moment so am posting this up fully expecting to be shouted at !!

The car has a PRT fitted. (and I've checked there's not an additional one in the dummy housing)
Am I right in thinking that this only opens up when both (a) the temperature gets high enough AND (b) the pressure is sufficient i.e. the engine is doing 2500-3000 rpm?

If this is right, what is supposed to happen if I'm stuck in a traffic jam? Just doing stop/start/crawling along.
The stat will never open as the rpm is insufficient and the auxilliary fan that cuts in at around 110 degrees is worthless as that only blows onto the radiator, and there's no hot water in the radiatior to cool down as the stat hasn't opened to allow the water to flow through.

If I rev the car hard at start up when its sitting on the drive, then the stat will open and the radiator gets nice and hot, but otherwise despite having had the head skimmed and the MLS gasket fitted, flushed the system, and replaced the pump and stat, the temperature keeps heading up to 120 when I'm doing the school run and it seems as if I'm running out of options. Have tried both the original and the new stat with the same result.
Mechanic has drained & refilled the system at least 4 or 5 times and so I'm pretty sure there's no airlock.

Am I missing something really obvious? I do hope so.....

[kaiser]

YES!

It is not both and, but either or, or both.
If you sit in traffic, the thermostat should open because the temperature increases.

Provided you have enough water in the system, (that means, check it) I would replace the thermostat, as it looks as if the temperature part of the equation is not working.

[T-Cut]

Originally Posted by __chris__

- - - the auxilliary fan that cuts in at around 110 degrees - - -

Something's wrong if that's an accurate temperature (?). The slow speed should trip on at 104C. The emergency/heat soak high speed will start at around 112C. I'd do the standard Demist test to check if the slow speed is working as it should. PRTs are usually pretty reliable but anything mechanical can fail. The pressure valve on the standard PRT starts opening at about 2000rpm once it's closed by the primary valve at 88C plus.

TC

[__chris__]

Thanks Gents.

Rimmerbros lists PEM101020 as the right one to get, but doesn't have any in stock.
There's also one that is listed as PEM100990 which I understand is the one for the NA version rather than the turbo, so I'm not going to get that.

I previously ordered www.eurocarparts.com/ecp/c/Rover_75_1.8_2005/p/car-parts/car-cooling-parts-and-car-heating/cooling/car-thermostat/?209750030 from EuroCarParts but have no way of knowing whether they've sent one suitable for a Turbo rather than a NA.

Question is, with none in stock at Rimmerbros, where can I get a new one from?

PS.
I've also seen elsewhere that PEL500110 is a suitable alternative as it's listed on http://www.auto-essentials.co.uk/eco...20-p-3247.html
What do you guys think?
Is there anyone who will know for sure?

[kaiser]

I'm sure you will get one, somewhere!

But, more to the point. Since it seems as if you have replaced this item, why don't you take it out, plunk it into a pot full of water, boil it and see if it opens??

Brand new ones can fail, but it is rather rare.

[VMax1000]

Question is, with none in stock at Rimmerbros, where can I get a new one from

Have a look here

http://www.mgroverpartfinder.co.uk/p...20%26browse%3d

[SD1too]

Originally Posted by T-Cut

I'd do the standard Demist test to check if the slow speed is working as it should.

Chris,

That is your first step, which we have already recommended to you in one of your earlier threads here.

Please report back with the result of the test.

Simon

[kaiser]

Originally Posted by SD1too

Chris,

That is your first step, which we have already recommended to you in one of your earlier threads here.

Please report back with the result of the test.

Simon

This is not quite correct, Simon. The chap states his radiator stays cold if he does not rev the engine. He does not say his fan does not work.
Sure, do the test, if you doubt the fan.
But his problem is a thermostat not opening to heat, but to revs, as he has stated it.
So if we follow your logic, switch on the IPK temperature display and note where the fan starts, to ascertain if all speeds work

[__chris__]

Originally Posted by kaiser

... why don't you take it out, plunk it into a pot full of water, boil it and see if it opens??

Have been driving with the original in situ as I knew that was definitely the right version; have just done this with the new one (which previoously hadn't made any difference). After a while in the pot, the air bubbled out and the stat opened. Kept it in for a while, simmering away and it produced a decent amount of white wax in the water. Perhaps it had been sticking/reluctant to open before and now it's been "seasoned" I'm going to try and fit it tomorrow in the reassuring knowledge that it works.

Originally Posted by SD1too

... please report back

Demist test:
Can't hear anything obvious when I put the demist on from cold.
How long should it take for it to cut in Simon ?

When I had the radiator changed, would the mechanic have had to disconnect the fan? I'm wondering whether there was anything that may not have been put back together correctly, but as the high speed / heatsink fan cuts in, I'd assumed that there weren't any issues with that.

[kaiser]

There should be no wax in the water!
Check and see if anything is leaking.

The fan should come on when the A/C is switched on.
It is to cool the evaporator.