The temp gauge is just at the middle sitting right on the wavey lines on the temp sign when at 80c (so just below dead upright). The thermostat would open at above 50c if i put my foot down a few times, otherwise with normal driving it would open about 80c (by checking if bottom rad hose was warm). By inserting the renault 5 thermostat in the top hose, the bottom hose will now only get warm at approx 84c no matter how much i put my foot down, so that led me to thing the original thermostat had a lazy spring and the water pressure from accelerating was pushing past the thermostats seal and allowing coolant to flow through the radiator...
 
It's got a prt! Pressure relief thermostat. It always blends hot and cold together.


Hi There may I ask is the prt thermostat also present in a TD4 I thought they were only on the 1.8 K series :confused: or am as the icon says getting confused Arctic2
 
They've all got em after 2001 I believe. Even my td5s got one

I Think the reason I am getting confused is that the engine on the R75 1.8t K series are as below and I can not see one of these on my Td4 FL 1 and there are two colours cream/black
 

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I Think the reason I am getting confused is that the engine on the R75 1.8t K series are as below and I can not see one of the se on my Td4 FL 1 and there are tow colours cream/black


The bottom ones yours? That is a prt it's got three pipe fittings. A standard stat will only have two
 
The Td4 from memory has a PRT as well built into the thermostat housing on the end of the engine block
 
Done some googling and I think you're right it doesn't have a prt. So it should just be a simple stat that opens up at a preset temp.
 
Ok I started from the beginning :) some of your probs sound like thermostat sticking open. The fan has it's own control unit that gets a signal from the engine ecu which takes a temp reading from the engine. This also supplies the temp gauge. The fan control unit varies the fan speed depending on temp.
What the bottom hose is doing isn't a good indicator because the radiator cools the water so much, especially at this time of year, that it'll probably stay cold even with a scalding top hose. The td4 like most modern diesels doesn't generate much heat. If your temp sensor appears to be correct. The next likely cause is the fan control unit assuming that the AC has been removed from the equation! Hope that helps
 
Done some googling and I think you're right it doesn't have a prt. So it should just be a simple stat that opens up at a preset temp.

I thought it didn't as the R75 with the M47 diesel engine as the same thermostat and seems to always fail open, thus causing the engine to run cool, not allowing the TD4 diesel engine to get to optimum temp which is what you need on a diesel engine.

So rather than undertake the big job of re-fitting an original thermostat some members added the inline stat into the top hose, either directly or used one of these below, with an 89C stat inside
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According to RAVE the Td4 engine is fitted with a PRT which is integral in the plastic housing on the end of the engine.

It is a different PRT setup to the K1.8
 
According to RAVE the Td4 engine is fitted with a PRT which is integral in the plastic housing on the end of the engine.

It is a different PRT setup to the K1.8

Hi
Sorry I do not know your name as I have noticed that a lot of members do not have their names listed I the about me ? on this forum as opposed to the other forums I visit.

I agree in that the TD4 will have a Pressure Relief Thermostat integral in it's housing what I was getting confused with was the fact that mainly the 1.8 K series housing is called the prt , but in theory I think nearly all thermostats are the Pressure Relief Thermostats in most cars and I say think because I am not 100% sure.


We had/have along running thread on diesel thermostats on the R75 forum I was with before owning my now first FL 1

http://www.the75andztclub.co.uk/forum/showthread.php?t=68468&highlight=inline+thermostat

On my R75 M47 diesel engine I had the inline thermostat fitted
http://www.the75andztclub.co.uk/forum/showpost.php?p=788688&postcount=1042

Gates
http://www.rockauto.com/catalog/raframecatalog.php?catalog=294&partnum=TH01489
 
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