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200tdi getting hot


landybehr
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Hi again,

a friend just dropped a 200tdi from a Discovery into a 110" which was fromerly powered by a 2.5D.

He fitted the temp-transmitter from the old engine so the reading should be correct with the present instrument.

The engine came from a salvaged Discovery, mileage was said to be 90.000miles, and a head-gasket job was done. The timing housing was covered with the white remains of anti-freeze, but this was very likely due the hose from water pumpy<> thermostat housing (bypass hose) being split. It´s been renewed and tight.

The temp gauge rises in a, I´d say normal speed, but does not stop at the middle and goes to the very right margin of the white bar. This is quite close to the red mark !. In normal driving it stays there, but in town traffic the engine got too hot.

We could not observe any leaks. There are no bubbles in the coolant reservoir, and we do not feel there escapes any excess of pressure when it is opened. The engine starts fine with just the usual puff of smoke. Just a little black smoke when accelerating. Changing the fan with 2.5D type does not change anything.

Since then:

He has changed the thermostat with no effekt.

He has mounted the cooling shroud of the discovery - it seems that the temp gauge goes slightly less far. There still is a 3-4inch gap between the shroud and the fan. And the fan could be stopped by hand (armed with a glove) at idle. Now this might be due to not enough hot air reaching the fan to let the viscous coupling operate.

????

Do you have any idea what to look for or what to check ??

Should he just optimise the shroud so that the fan is pulling the air as on an original setup ? I can hardly believe that the shroud is THAT MUCH important, is it ??

Many thanks !

Hendrik

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I might add .. the head gasket was changed before the engine arrived over here. No one can tell how much miles the engine covered afterwards.

The water pump is new. Pulleys are new and tight enough.

Any ideas greatly appreciated !!!

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I've recently done the same conversion and I must say that there is something else than the fan not being 100% effective. Mine has a leccy fan with a thermoswitch, but it never starts in normal traffic. Only when going slow in low gear or on steep and long hills.

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Try water temp sender unit PRC8593 correct one for the Defender version & used in my ex-2.5TD 1989 110 with the existing gauge, my gauge needle sits just to left of centre & hardly moves when worked hard in high or low range.

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You shouldn't be able to stop the fan. I prefer the rolled up newspaper method myself! If it chews the paper up, the viscous coupling is ok, if it stops it aint!

Have you tried it on a fast open road? If the motor stays cool, then this will also point to the viscous coupling.

You do need the shroud fitted properly in order to draw the air through efficiently.

HTH

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Hi,

time for an UPDATE !!

The temp-sender is ok. With a new thermostat things were basically the same. There was always some flow through the radiator - it became hot.

Since, the thermostat was removed and the engine is now driven without. That CHANGED things: The engine does not get hot any more and the needle is leaned to the left instead right. But two things are new: 1) bubbles in the expansion tank (could the water pump, which now generated some relatively impressive flow-noise, simulate bubbles OR can it be nothing else than the engine pressing exhaust gases into the cooling system ?) and 2) the coolant changed to a more "rusty" colour.

I´m inclined to think that there was some rust flake that blocked any waterways internally and that was pulled away by the greatly enhanced coolant flow without thermostat (what do you think?). But what about the bubbles ?? Shouldn´t they have been theree with the thermostat in place if there was a head gasket leaking or something ???

:unsure:

(May flushing be a good idea ? If so, probably now, without the thermostat. Would you recommend any special stuff ?? Something like citric acid (what dosage, if sensible?))

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Recently done the same thing. And had similar problems. I flushed the rad out with a hose pip as knew the radiator wasn't too good. Lots of brwon rusty water came out which was good. I am going flush it again back and forth to dislodge stuff.

Jon

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Hi,

time for an UPDATE !!

The temp-sender is ok. With a new thermostat things were basically the same. There was always some flow through the radiator - it became hot.

Since, the thermostat was removed and the engine is now driven without. That CHANGED things: The engine does not get hot any more and the needle is leaned to the left instead right. But two things are new: 1) bubbles in the expansion tank (could the water pump, which now generated some relatively impressive flow-noise, simulate bubbles OR can it be nothing else than the engine pressing exhaust gases into the cooling system ?) and 2) the coolant changed to a more "rusty" colour.

I´m inclined to think that there was some rust flake that blocked any waterways internally and that was pulled away by the greatly enhanced coolant flow without thermostat (what do you think?). But what about the bubbles ?? Shouldn´t they have been theree with the thermostat in place if there was a head gasket leaking or something ???

:unsure:

(May flushing be a good idea ? If so, probably now, without the thermostat. Would you recommend any special stuff ?? Something like citric acid (what dosage, if sensible?))

Sounds like the head gasket has gone.

But you say the temp sender is ok but is it a defender one or the original disco one. As the disco one will not talk to the defender gauge and therefore give a false reading

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Its not something as daft as the two different engines run with different temperature themostats is it???

First question is does it lose any coolant?

Second question, disregarding the gauge, does it actually overheat?

What temperature do the thermostats open at?? I had this on my series years ago having replaced an engine that turned out to have a 74 degree thermostat in it, with one with an 82 degree stat in it. I spent ages trying to work out why it was overheating, before finally twigging that the thermostats opening at different temps would of course give me different readings on the temp gauage!

Jon

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Hi,

the thermostat is correct, at first it´s been the one that came with the engine. But that was changed with a new one, with the correct 82deg type.

You mentioned a good idea. We had checked the Haynes and the Workshopmanual. They stated the same opening temp for the 2.5lD and 2.5TDi.

The temp-sender from the old engine was re-used, so it really should read ok with the instrument it worked with before.

At the moment it looks like my friend needs to flush the cooling system. That´s simple and can easily be done.

Then he´ll have to put in the thermostat again .. and watch.

If it still overheats (which, at the moment without any thermostat it isn´t doing) then probably the head gasket is shot !???

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Is it getting hot? or does it just say its hot on the gauge?

As said above it could just be the engine earth. My 200TDi read hot when I first got it, sounds exactly like you say and it was just the engine earth causing a duff reading.

Will :)

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Oh .. I forgot :

we think the engine really became hot. While on long roads the engine just stayed hot, the needle moved to the "red" bar in town/traffic light conditions. When the car was parked there was a puddle of coolant under the car. On thing that might have "helped" it by pumping out water was that the bypass hose between water pump and thermostat housing was split. This hose was changed now, and since the engine was not allowed to get to the "red bar" again. Well, hard to juge, but I´d say the hose was either split by deterioration, which explained all the dried out, crusty, old" anti-freeze remains on the timing housing. One might say that excessive pressure led to that split !?!?.

I think the gauge reads right. It cannot do else. It read correct in the Ex-mod diesel and should do with it´s new partner. The earth of the engine is allright. And, the gauge reads plausible low - now without the thermostat in place.

(BTW: will there be problems with the starter when the engine-earth was poor ?).

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Just a thought, but he did change the radiator and fit the intercooler from the donor car didn't he?

One other thing to check is the condition of the fins between the core, as these can rot out, typically on the side nearest the fan, so it is not visible from the front of the vehicle.

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.. should have told you: radiator is new. Intercooler is from the old engine, but that item doesn´t matter here.

The heater of course was kept. But that one worked fine all the time.

The fault got to be into the engine itself.

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Hmmm, another update:

my friend will seek an engineer who can do a compression leak test by analysing the coolant (CO2-test). That should tell whether or not the head gasket is shot and if so the head could be inspected for cracks and need of skimming.

Meanwhile we wonder about the thermostats. And maybe Jon provided the answer.

Point is that the workshop-manual and Haynes-book say the thermostat opens at 82deg for the 200tdi and 88deg for the 300tdi. And it seems like if you order the thermostat for the 200tdi you commonly get the 88deg one. So it could be that we are working 5deg´s higher than expected. Why ? Usually our parts supplier is very reliable and well informed. Are there differences between the Defender and Discovery ? In that the Defender works at 82deg and the Disco at 88deg ???

A problem is that the temp-sender of the 2.5D just fitted into the thermostat housing of the new engine, while the Defender-version (PRC... as mentioned above) does not fit.

So next steps are the CO2 test

if bad then go to garage

if not then do a table of resistance (ohms) with the temp sensor with rising temperatures in a) a pot of water and B) in the engine to compare. Need to know which temperature there is in the engine really.

At the moment we keep it like Sokrates ("As for me all I know that I know nothing")

Would be great if someone could bring ligth into the "?" about the different thermostats.

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Defender 200Tdi should have the 88 degree thermostat as should the Discovery version of the same engine, could be your supplier is getting the older Turbo Diesel confused with the 200Tdi, the older engine could have a 82 or 88 degree thermostat depending on it's home country.

fit the 88 degree & go from there. my 200Tdi is 13 years old & has always had the 88 fitted, I did experiment with a 82 for a while but decided to stick with the 88.

both 200Tdi use different lower thermostat housing that the temp sender fits into. that would most likely explain why the defender temp sender won't screw in, must be a different thread.

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Western,

you´re right. The correct thermostat will be put back in (with the 2.5D thermostat temperature was correctly shown) and the thermostat be housing modified to take the Defender-sender. Measuring/comparing the senders showed that the resistance was very close in "cold" and "hot" but was quite different in "warm"-condition - which is where the engine operating temp is. This fooled him at first.

The engineer couldn´t do the leak-CO2 test because he needed bubbles emerging from the coolant - but there weren´t any. So no leak. Infrared-temperature measuring revealed nothing spectacular.

Well then, the engine is allright. Just a bloody problem with the instrument/temp-sender/thermostat in addition it seems like it turned out as crazy as the different thermostat thing (82deg with the 2.5D and 88deg with the Tdi). So Jon is the thread hero ;).

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