Overheating - no cooling fan?

Thank you again.

I am about to drop the car off. (At a garage, not a cliff yet)

I know you can't remove the actual thermostat from the housing to test it as I broke the old one trying! The 2 miniature wires, which must be the supplementary electrical heating wires referred to earlier, broke. I guess this is the reason why these thermostats seem only to come with the housing.

It would be possible to remove the spring and valve from the housing to achieve the same effect as a constantly open thermostat though without destroying it.

I am actually moving my money off the thermostat being the issue now, but on to what I am not sure.

Anyone reckon this will actually get diagnosed? I think it will be a good test for the garage and they did seem keen to get to the bottom of it. Up to now I have been impressed with all the work they have done for me - if they sort this they will get more of my work.
 
For a garage, especially a BMW indy, this should be an EASY diagnosis.

It does sounds like a stat issue to me, but I have a good friend who's a better mechanic than I, and if you don't get a fix today just post up and let me know, I'll forward this onto him and he'll come back with an answer I'd trust.
 
Did you check the link on the N52 special bleed procedure i posted above? If it's an airlock, not bleeding correctly may be the cause...
 
INPA clearly shows a problem with the ECT sensor, implausible value means it's sending completely bollocks readings out, that don't fit into anything, well, plausible...

That can't help with engine operating temp and fan operation.

Clear the codes and then in INPA go to the sensor readouts and watch the ECT value (engine coolant temp)...

See what temp it's actually getting up to and ignore the gauge as it's clearly a gauge that just reads not so useful info.

I'm looking into remapping these cars ECU's soon, I really want to fix things like this. Ie, make the gauge actually sweep linearly with temperature. It'd be interesting to even try get the readouts coming in to the mpg/average speed/time display area too... hmmm...

Dave
 
That's interesting. I assumed (with my absolute zero INPA knowledge) that ECT had got invalid readings as a result of the original overheat ie I interpreted it as meaning the coolant temp went out of a possible working range. Do you mean that this print out might have been telling me all along what was wrong? Doh! I can really be a bit slow sometimes.

My bro did clear the codes, so I had better let the garage know about this error code - they didn't get to the car today. I guess they know I have a few "fun" cars so I am the first customer to get put back when they have a problem at their end.

I also found it very interesting to read that the dash temp' gauge will sit dead centre "normal" anywhere between 75 and 113 deg C. It bugged me that the temp could be "perfect" so much of the time - ie it never goes below the mid once warmed and also spends a lot of the time sitting exactly in this place. It was this sitting at the mid in fact that made me think that the coolant temp sensor must be working correctly because, without thinking about it to hard, I had assumed this was correctly reading a much more exact temperature. Now this has started to make really good sense to me and I could believe that the overheat that destroyed the head gasket may also have duffed up this sensor so that it breaks away too early.

It's not like I have spent a lot of time thinking about these things but since the problem I had started to wonder how so many cars are so good at keeping their temp perfectly constant whatever the load, speed etc. A wide normal range makes that much more understandable.

Maybe there is nothing really wrong with the car?!!!
 
From what I made of the link the reason for the temp gauge reading centre normal through such a wide range that the ECU regulates the thermostat to achieve a temp that is ideal for the engine load mostly for emissions. So having a true reading gauge would be pointless unless you can second guess the ideal temp for the load and conditions. It might be better for BMW to have fitted a cold / normal / overheating! readout?

I'm still not sure yours should be reading 3/4 then dropping back, I don't think my 2.5 has ever moved above the normal centre mark. Having read how hard these are to bleed I'de guess it's air locks, but that can of course be down to a micro leak which are a real devil to find as they don't actually get wet, just evap' as the fluid comes out.
 
The gauge is just a digital readout based on the sensor, so if the sensor is giving erroneous readings the gauge is useless.

Implausible fault readings in error codes will usually mean the voltage or resistance, or whatever method is used (probably resistance here) is simply not possible. Ie, it'd be the equivalent of something way out of the calibrated range, so maybe over 200degC, or under -50degC or something bizarre like that.

Or maybe it suddenly changed value and then returned to normal (I've seen other cars dip to -50 then back to say 75degC for an instant via OBD logging which is clearly not right), and the BMW ECU may be flagging that as a fault... and could also be a sign of a senile sensor basically hehe.

I'd deffo put INPA on the car, go to the real-time value readouts, and start the car and watch the ECT value as it goes up... it should ideally go from ambient air temp > 80degC ish...

Also worth then watching expansion tank water temp (dip a probe in) as the car warms up, you should see it get hot when the thermostat opens up, and then sit around the same temp as the ECT temp... this is making sure the sensor is correctly linearised vs the calibrated temperature...


My 2p, for the £20 or so it costs, maybe worth just getting a new sensor too. It's a critical element, it's given fault codes in the past, AND it's the only thing you haven't changed yet!




As per the wires to the thermostat housing, I assume that is the waxy variable thermostat thingy?! I then assume that means it has a finite lifetime? Or can the wax stuff cycle indefinitely?

Cheers

Dave
 
YESSSSSSSSSSSSSSSSSSSSSSSSSSSSS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The garage called me early this morning and asked "did you say you put a new thermostat on the car?"

They were reading 110deg at the top pipe and 75deg beside the thermostat. They said that if they knew nothing of the car or the work I had done to it they would have been telling me to replace the thermostat. I decided that the evidence against the NEW one I had put in was getting too strong and to go for it. My new one had been an ebay one. The garage was very busy so they couldn't really do it there and then but they ordered me one in and at lunchtime I picked the car and the new thermostat up, took it home and fitted it, myself.

This meant I had to go through all the bleeding again. I did this with the engine on tick over and after a while I suddenly heard a whirring sound like a squeaking belt. This was the new thermostat opening for the first time. I had never heard any sounds from the old one and this alone put a big smile on my face!

Well 20 miles later with a mix of booting it and sitting idling in traffic and it won't budge from normal. Now all I need to do is learn to drive without one eye permanently on that guage! Oh, and deal with the catalogue of other problems that the car seems to have:-

Occasional intermittent misfire which I am putting down to the coil pack on number 4, alarm going off for no reason, right door speaker going on and off with cds but not the radio............

So a very big thank you to everybody who took the trouble to help me on here and to the good mechanics at Fegusson's garage in Sutton who took the time to diagnose the fault and a genuine interest in it being fixed. 10/10 for them to date.
 
Mr Whippy said:
As per the wires to the thermostat housing, I assume that is the waxy variable thermostat thingy?! I then assume that means it has a finite lifetime? Or can the wax stuff cycle indefinitely?
Click to expand...
You know as much as I do about this now, but I love to speculate. I'm certain the wires are for the heating element that melts the wax. As for the expected lifespan of the wax, it's anyone's guess. I'm pretty sure BMW will claim it is a lifetime part, just like their coolant and gear oil. Which we all know is just hype. I personally believe it is as reliable as the bi-metal springs we typically see in thermostats, which isn't saying much. The exact same bi-metal devices seem to vary wildly in longevity. A particular thermostat can fail in a few years, while it's identical sibling will last decades. I expect no different from these wax capsule devices.
 
CarmadJames said:
YESSSSSSSSSSSSSSSSSSSSSSSSSSSSS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The garage called me early this morning and asked "did you say you put a new thermostat on the car?"

They were reading 110deg at the top pipe and 75deg beside the thermostat. They said that if they knew nothing of the car or the work I had done to it they would have been telling me to replace the thermostat. I decided that the evidence against the NEW one I had put in was getting too strong and to go for it. My new one had been an ebay one. The garage was very busy so they couldn't really do it there and then but they ordered me one in and at lunchtime I picked the car and the new thermostat up, took it home and fitted it, myself.

This meant I had to go through all the bleeding again. I did this with the engine on tick over and after a while I suddenly heard a whirring sound like a squeaking belt. This was the new thermostat opening for the first time. I had never heard any sounds from the old one and this alone put a big smile on my face!

Well 20 miles later with a mix of booting it and sitting idling in traffic and it won't budge from normal. Now all I need to do is learn to drive without one eye permanently on that guage! Oh, and deal with the catalogue of other problems that the car seems to have:-

Occasional intermittent misfire which I am putting down to the coil pack on number 4, alarm going off for no reason, right door speaker going on and off with cds but not the radio............

So a very big thank you to everybody who took the trouble to help me on here and to the good mechanics at Fegusson's garage in Sutton who took the time to diagnose the fault and a genuine interest in it being fixed. 10/10 for them to date.
Click to expand...

Well done ..you got there in the end, just shows you, a friggin new thermostat caused you a lot of trouble, and I'm sure you changed it just to be safe ! It will take you a few weeks to stop looking at the gauge I'm sure :driving:
 
Well this just goes to show that new parts are not always equal, or any good!

I've generally found over the years that non-OEM bits are usually cheap for a reason.

Even stuff like brake discs/pads can be iffy... but at least they are not complex parts like a thermostat!


Great news any way. Glad it's fixed!

Dave
 
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