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

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Originally Posted by stevesav

So does This mean that the primary valve in the PRT is opened from inside the PRT, then the hot water goes into the rad & then down to the bottom hose inlet on the PRT?.

PRT operation is described in Posts 44 to 46.

TC

[stevesav]

I have read those posts loads of times lol, but not being an engineer It doesn't corm across as very clear to me.
What I am trying to get a grip on is that if my rad is not getting hot is this due to the PRT not working correctly & not letting the hot water circulate?.

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When the PRT main valve opens, hot coolant from the head is directed into the top of the radiator. This is upper left as you look at the engine. The left side of the upper hose T-piece connector becomes hot and the top end of the radiator will become hot.

As coolant flows down it's cooled, so the temperature at the bottom will be warm, once it's fully circulating. The complete radiator surface will rarely become hot. On the move, the bottom may be only luke warm.

The easiest way to know whether any thermostat is working properly is to watch the coolant temperature during a typical journey using the Trip Screen Diagnostic routine. It should be running in the 90-100C area depending on the conditions.

TC

[stevesav]

Well just thought I would give an update on my running hot problem.
I fitted the new radiator but that didn't make any difference ( but at least she had a new radiator now).
So Matt from DMGRS said that although I had already fitted a new PRT it was possible that it could be faulty, so I purchased one from him (PEM100990) which turned out to be a different colour from my previous one.
So last Thursday I fitted the new PRT, bled the system & started her up to check everything, well much to my delight after a few mins the radiator started to get warm( this wasn't happening before), the temp was going between 85-89 deg. I took her for a good run & the hottest she got to was 90,
When I got home I let her tick over for about 20 mins & when the temp got to 104 the fan kicked in & bought it down to 89 again, to say I was happy at this stage would be an understatement lol.
I have since driven over 200miles with a beady eye on the temp & it hasn't once gone over 90. Nor have I had any coolant lose.
So would just to thank all those who gave me advice & especially Matt for making an owner feel very very at ease with his car again

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Originally Posted by stevesav

- - - I purchased one from him (PEM100990) which turned out to be a different colour from my previous one.

Thanks for the update. What colour is the stat you have now?

I fitted the new PRT, - - - the temp was going between 85-89 deg. I took her for a good run & the hottest she got to was 90.

That's the range I now get with a back PRT. The original buff one ran about 10 degrees hotter across the range.

Would you repeat the constant speed/variable gears test I described in Post 66? Do you observe a drop in temperature according to engine revs?

Since swapping over to the black stat, I do not observe the temperature fall when the speed test is repeated. That suggests/confirms that the secondary relief spring is stiffer than the one in the buff unit. Indeed reports elsewhere suggest that the black unit has virtually no PRT activity and operates as a basic wax stat. What few tests I've done so far, I think that is probably the case.

TC