e39 not heating up OR changing up!
Discussion
Over the past few weeks the temp guage has started to play up, or so I thought! It seems to have a life all of it's own! It heats up to the first white mark on the guage and sometimes goes no higher and then at the weekend decided it didn't want to go that far! Then it decided on the motorway that it didn't want to change up into 5th, it's an auto (and it's the first time it's done that trick!). Then tonight, it's 2 degrees out, it barely rose above the blue mark for 4 miles and I had to change up manually!
Any ideas anyone....please!
Any ideas anyone....please!
Thermostat could be stuck shut, I will assume you have checked the coolant levels.
As for not changing up, my current car is a tiptronic, and the 840 is auto aswell, what I find in the cold is that the change takes longer, as silly as it sounds it could be related, in my Mitsi (I know not a bimma) when its really cold the gearbox takes forever to change up in auto, until it's warm with hot air coming out the vents, not sure why it does it, but the 840 also does similar.
Mind you could not be that, when was the fluid in the box last changed? What fluid was used? Was it fully flushed or just dropped and refilled?
Only reason being is ATF fluid is very important in an autobox hence why they usually have filters on them and a cooler for the oil in the radiator, gearbox oil could be breaking down or due changing, the gearbox in the 840 needed flushing as it was getting old.
My first port of call really would be checking the fluid level of the box, and check the TC seal isnt dripping, I would have a good look at the oil, most of the time ATF is bright red so if its dulled or going brown probably wants changing, but make sure it gets a full flush, as an autobox has a billion oilways, so you will drain about 5 litres of fluid out the sump and the gearbox will hold 11 litres of fluid, if you drain and refill it still has manky old oil which will mix together and defeat the object, so get a full system flush using the correct oil for the box as some of the autoboxes made can die from wrong oil.
Heater wise I would go with stuck thermostat
I would like to point out that I could be drastically wrong on the gearbox side of things so wait for someone who actually has more of a clue than I do about the BMW gearbox, as I haven't worked on a BMW mechanically speaking so really don't know, get better advice of someone else.
As for not changing up, my current car is a tiptronic, and the 840 is auto aswell, what I find in the cold is that the change takes longer, as silly as it sounds it could be related, in my Mitsi (I know not a bimma) when its really cold the gearbox takes forever to change up in auto, until it's warm with hot air coming out the vents, not sure why it does it, but the 840 also does similar.
Mind you could not be that, when was the fluid in the box last changed? What fluid was used? Was it fully flushed or just dropped and refilled?
Only reason being is ATF fluid is very important in an autobox hence why they usually have filters on them and a cooler for the oil in the radiator, gearbox oil could be breaking down or due changing, the gearbox in the 840 needed flushing as it was getting old.
My first port of call really would be checking the fluid level of the box, and check the TC seal isnt dripping, I would have a good look at the oil, most of the time ATF is bright red so if its dulled or going brown probably wants changing, but make sure it gets a full flush, as an autobox has a billion oilways, so you will drain about 5 litres of fluid out the sump and the gearbox will hold 11 litres of fluid, if you drain and refill it still has manky old oil which will mix together and defeat the object, so get a full system flush using the correct oil for the box as some of the autoboxes made can die from wrong oil.
Heater wise I would go with stuck thermostat
I would like to point out that I could be drastically wrong on the gearbox side of things so wait for someone who actually has more of a clue than I do about the BMW gearbox, as I haven't worked on a BMW mechanically speaking so really don't know, get better advice of someone else.
Thanks for that.It confirms what I thought!
Was trawling the internet last night and the thermostat appears to be the first port of call. The other thing it is doing is drinking petrol at an unusual rate. I suspect that the thermostat is stuck open, the car isn't getting hot, the car thinks it's still cold so is keeping the choke on (as it were) and maybe the car is hanging on to gears in an attempt to warm up!
That, of course, may be totally illogical!
Was trawling the internet last night and the thermostat appears to be the first port of call. The other thing it is doing is drinking petrol at an unusual rate. I suspect that the thermostat is stuck open, the car isn't getting hot, the car thinks it's still cold so is keeping the choke on (as it were) and maybe the car is hanging on to gears in an attempt to warm up!
That, of course, may be totally illogical!
It could be your temperature sender/sensor, the gearbox ECU will be needing this info too as it assists in getting the gearbox up to temperature as quick as possible but as the correct rate. And thats probably why your gearbox is late changing gear as its seeing the temp too cold to change it to its normal temperature mode.
Thanks,any idea where it is and if I can check it Phumy, or should I just change the thermostat and see if that solves it?
When the car does get to operating temperature the gearbox seems ok but when cold I am driving it tiptronically so still using it. Also understand that if the thermostat is stuck open I am not damaging the engine, as opposed to it it was stuck shut.....when presumably the car would overheat and go bang!
When the car does get to operating temperature the gearbox seems ok but when cold I am driving it tiptronically so still using it. Also understand that if the thermostat is stuck open I am not damaging the engine, as opposed to it it was stuck shut.....when presumably the car would overheat and go bang!
Edited by Scamp's Walker on Thursday 17th December 09:13
I'm not too sure they use the same sensor for the gauge and the ecu, older cars had 2 different ones, but these days you might be right.
There is a another more complex dimension to this though.
The V8 e39s had an ecu controlled radiator. The same classic 2twin loop cooling system is used, one loop for the heater matrix, and when hot the thermostat opens and closes to control the coolant flow into the radiator.
A point to make just in case people didn't realise, which many don't, is that the engine doesn't get to temp and opens the 'stat, it's actually moving all the time to keep the temp level. On a fast motorway cruise, most cars can easily overcool themselves is the stat is open, so it will open and close on the go to maintain the temp.
You'll often see taxis with rad blankets as they have an immense cooling system designed for sitting in traffic on hot day, but they'll also need to hold temperatures in when cold.
BMW added a small electric heater into the thermostat housing which is controlled by the ecu. This way, the ecu can over-ride the mechanical stat by heating the element and forcing it to open.
I know these stat heaters fail quite often, it's a very popular error code, but usually it stops heating.
This means that if the heater lead is shorted, or there is an ecu problem, it can also hold the stat open and overcool the engine.
Make sure you get the error codes read, as the stat might not be at fault despite the problem being a stat stuck open!
There is a another more complex dimension to this though.
The V8 e39s had an ecu controlled radiator. The same classic 2twin loop cooling system is used, one loop for the heater matrix, and when hot the thermostat opens and closes to control the coolant flow into the radiator.
A point to make just in case people didn't realise, which many don't, is that the engine doesn't get to temp and opens the 'stat, it's actually moving all the time to keep the temp level. On a fast motorway cruise, most cars can easily overcool themselves is the stat is open, so it will open and close on the go to maintain the temp.
You'll often see taxis with rad blankets as they have an immense cooling system designed for sitting in traffic on hot day, but they'll also need to hold temperatures in when cold.
BMW added a small electric heater into the thermostat housing which is controlled by the ecu. This way, the ecu can over-ride the mechanical stat by heating the element and forcing it to open.
I know these stat heaters fail quite often, it's a very popular error code, but usually it stops heating.
This means that if the heater lead is shorted, or there is an ecu problem, it can also hold the stat open and overcool the engine.
Make sure you get the error codes read, as the stat might not be at fault despite the problem being a stat stuck open!
Miniman, despite there being a blizzard here, I have been out and checked and as far as I can see it looks quite complcated! Doesn't all the rad cowl, fan etc have to come off, or is there a short cut way? Funnily enough my garage reckon an hours work as well. My grage also mentioned possibly having to replace the plastic housing as well, does that make sense?
You need to replace the housing piece (kind of a bent tube that the thermostat fits in the middle of), I think it cost me about £25 for the whole kit including the stat. I think the "official" way involves removing the radiator but it can be done without. From memory, you do need to remove the fan cowl though.
Not sure that mine has the little heater thingy as there are no wires running to the "flange housing". Presumably as I don't that the heater bit I just need to replace the thermostat and not the whole "flange housing" as was suggested in an earlier post? So it's just cowl off, fan off, undo bolts, remove old stat, replace gaskets and bolt back up. Sounds simple I guess, but it's freezing so may leave to to my favourite indy to do next week!
As you've got a 6cyl, you won't have this heater, so that 1 less thing to check.
The thermostat housing is made of this horrible fragile black bakelite type plastic, and they crack very easy.
They aren't expensive, so to make sure you don't get stuck with a cracked one, is best to have one waiting in the wings just in case.
It can be a DIY job.
http://www.pelicanparts.com/BMW/techarticles/E36-T...
Yes, thats for an e36, but it'll be the same sort of thing on your engine.
The thermostat housing is made of this horrible fragile black bakelite type plastic, and they crack very easy.
They aren't expensive, so to make sure you don't get stuck with a cracked one, is best to have one waiting in the wings just in case.
It can be a DIY job.
http://www.pelicanparts.com/BMW/techarticles/E36-T...
Yes, thats for an e36, but it'll be the same sort of thing on your engine.
Scamp's Walker said:
Any ideas anyone....please!
Despite appearances the temperature gauge is not analogue! - it rises to the first white mark as the coolant warms and then goes to vertical as soon as it reaches the operating temperature range and stays there unless it gets too hot or cold at which point it moves to the appropriate quarter mark where analogue style behaviour is resumed...The gearbox works differently when cold, moving all the shiftpoints up the rev range...
Either the thermostat is stuck open or the temp sensor is goosed, or both.
Not sure about the M52 but it's as well to change the water-pump when you do the thermostat with the V8s
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