Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

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joydivision
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Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by joydivision »

I've been wondering for quite some time now (I own the car about two months now and have done around 2000kms), if the running temperature of my 2.1td xud11 is normal or cool. I've been reading all I can about this (and searching here and other places), and in fact they seem to run cooler than some other diesels engines. But still I'm not sure. I tried to feel the radiator hoses but I'm not sure if I did it well - I'm not even sure if I felt the right hoses, as I only later learned that the thermostat in 2.1td is mounted underneath engine on left side somewhere difficult to access, so I might have to do the experiment again. Here's what I've been observing:

- normal driving (mixed urban and national roads, not pushing much for the engine): takes around 10 minutes to reach 70ºC, then slowly progresses to about 72ºC on a cool morning or 75, maybe 77ºC on a hot day. If A/C is OFF (no fan), it might eventually reach 80ºC after some more time. But with A/C, it only reaches 80ºC on a really hot day.

- city traffic: on a warm day it might reach 90ºC, but normally only if A/C is OFF. Seems the slow mode fan is enough to avoid it reaching 90. This is a nice touch, makes this a safe engine regarding over heating risk under these driving conditions.

- motorway driving at 110-120km/h: stays at 72ºC, sometimes 75ºC, not more, because of the wind, or because of the fan if A/C is on. On a hot day, goes to 80ºC and stays there.

- motorway pushing it a bit at around 130-140 km/h on a hot day: goes easily to 95ºC even with A/C on, or 100ºC with A/C off, I think I've seen it reach close to 105ºC once (and MAYBE heard the fan switch on in fast mode, but wasn't sure). Both fan work fine, the other day I had it idling a bit longer as I was waiting for someone, with A/C on, and it was very hot weather, and temp rose and then fan went to fast mode and cooled it enough.

So, I'm asking if anyone who had (or has) a XUD11 (or even a XUD9, although it has different cooling system, it's the about the same engine design), if these temperatures seem normal or seem to indicate that thermostat might be stuck open or not closing totally. I've noticed that there are thermostats with different opening temperatures for this engine (80 and 82ºC, but no 75 or lower).
I don't think the temp gauge is showing a lower than real value, btw, because it's stable and if A/C is off, the fan doesn't come on before something like 95/97ºC, if it was showing low temp, this would already be temperature for high speed fan, no? Don't have IR temp meter to check this, though.
Ah, heater inside works fine, btw.

Thanks for hints and opinions. Not that this is really worrying me, as the car drives well, has good mpg (has been doing around 6,7 lts/100 km), just have been noticing that on a cold morning, it drives less well when at 72ºC, compared to when at 80ºC on a warm day... it's a small difference, but can be felt. So I wonder if this is not the best operating temp and caused by thermostat open or not closing fully, or if it's simply the XUD which runs really cold and with cold weather (or A/C fan) is unable to gain more heat unless being pushed.

I know the thermostat is a cheap part, but I also learned that unlike the XUD9, in the XUD11 the thermostat is a real "PITA" to change :lol: , you have to jack up the car and apparently it's still a nightmare to access. So I don't want the mechanic to do this, as it would be expensive, but I also don't want to take on such a hard task by myself unless it's really quite sure that the thermostat is not working correctly.

Therefore, some more tips on how to correctly do the "hose feeling" test would be great. If all this ends up inconclusive, I might simply wait for colder weather in a few months and then see how it behaves, I think then it should be more clear.
PeterN
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Re: Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by PeterN »

Even though the thermostat is in the return pipe the top hose should get hot and do this suddenly when the thermostat opens. If the hose slowly warms up the thermostat is probably not closing or not completely anyway. Does the heater get to full output temperature fairly quickly, if not that's another sign of a faulty one.

The cooling system on the 2.1 is very good, a complete redesign from the old XUD. The thermostat being in the return pipe allows the the system to fully vent on refilling preventing the original head gasket or head failure due to lack of proper bleeding. The thermostat is not that difficult to get to although you will need a mirror but having changed several on XM's I could eventually do it by feel. Its at the bottom rear of the block on the drivers side, I think it only has two bolts or maybe three.

The thermostat unit on the C5 X7 which I have now requires a difficult days work to change, the 2.1 is a lot easier!

Peter
joydivision
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Re: Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by joydivision »

Thanks for the helpful insights, Peter.
When I did the "hose feeling" test, I remember that both the upper hose and a lower hose were warming up slowly and gradually. But I wasn't sure if I was feeling the right hoses. I think I'm going to do it again soon, when the car has been standing longer and weather is not so hot as it is right now. Heater worked fine the last time I checked, pretty quick to heat up.

Yes, I know, have been reading about this and I'm glad I got the 2.1. When you say a mirror, you mean it can be done from above or is it just to be able to find it, look at it? I mean, are you saying that even with the car jacked up and secured on axle stands, to be able to loosen the bolts you still need a mirror? I'm glad you're saying it's not that difficult after all. Because the (very little) information I can find made me think that. Haynes only covers the procedure in half a dozen vague words, no photos, nothing. And on the internet, it's almost impossible to find, I can't even find a drawing - in all of the ressources where I can find almost complete technical drawings of the parts, engine, etc., when I get to the part where the thermostat should be shown, usually says "no drawing available" for the 2.1td... seems it was such a new and at the same time unique design at the time, that they didn't even bother updating available ressources? for the 1.9td I find a lot of info...

Yes, when you say drivers side you're referring to RHD car, right? I mean, as mine is LHD, it's actually on the passenger side. So, it's closer to the actual bottom rear end of the engine block than to the water pump, correct? As I found some sources saying something like "look somewhere below the water pump on the left side of the block". I'll have another look with a good light and maybe I can get my hands on a mirror.
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Doggy
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Re: Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by Doggy »

2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
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2007 BMW E91 325i touring (slower smoother quieter)
joydivision
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Re: Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by joydivision »

That's really helpful, thank you very much! I was unable to find that diagram, on the sites I looked, it was always "unavailable", all the other parts were available, except the part with the thermostat...

So, it's very close to the water pump afterall, part of the water pump assembly group, on the rear end.
I think with all this, it should not be too hard to do the job. But first I'll repeat the hose feeling test - as from the drawing it seems there's a thermostat version of 80ºC, not 82º as I had seen, average temperature of mine does get close to that... I guess it would be possible for the gauge to show 5ºC low without me noticing anything relevant regarding tripping point of the fans (the gauge isn't that precise, anyway), so before I decide to take on this adventure, I'd rather be sure that there's something wrong with the thermostat... The hose feeling test is still the best way, right?
PeterN
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Re: Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by PeterN »

Sorry I forgot about LHD, its the cambelt end. You do have to do it from underneath I'm afraid but if you have a good look at it with a mirror or a camera device would be even better, you will see where the bolts are and should be able to undo them by feel. If you cant see the thermostat just follow the bottom hose it ends at the thermostat housing.

Peter
joydivision
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Re: Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by joydivision »

Thanks. I'm starting to feel that the task might not be that hard after all :D. But first I really have to repeat the hose feel test and be more certain that it needs replacing.
PeterN
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Re: Are these normal operating temperatures for xud 2.1td? or is thermostat stuck open?

Post by PeterN »

Feel the large hoses at the top and bottom radiator connections.

Peter
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