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525i Engine/coolant temp low and little to no heat
Hi all, Got an issue on 2005 525i M sport.
First off, had radiator replaced after it was found leaking, before this, I know that the engine temperature was at the last two bars on the rev limit on dash. Here's where the problems start... Picked up the car from shop, drove normally for 10mins and then noticed heating wasn't working/slowly dying as I was turning it up on the drive home. Thought it was just new coolant and radiator so all was just cold? Next morning, for 50km drive had no heating and engine temperature was really low (ie. lots of bars on the dash meter). That week I drove 500km and had no heat but same low engine temperature. Took it back to shop next week and got thermostat replaced. Picked it up today and had heat for drive home (thermostat was faulty so replacement was necessary regardless) later on in the day, very little heat, and engine temperature is maxing at 70*C (on hidden menu coolant sensor temp reading)... Sorry it's long, I like to be as detailed as possible, Any ideas on what's going on here? would a faulty temperature sensor cause the low engine temp and almost no heat inside the cabin? Water valve? Would like some info before I take it back and they just replace parts randomly :angry: |
Not sure I have any spot on advice. A bad water pump might cause less heat to be available for the climate control, but the car would also overheat and you'd get a message about that. Is the shop a BMW shop? There is a specific coolant air bleeding procedure. If that isn't done, you can end up with air pockets in the system and maybe that could manifest as you are seeing??
I'm pretty sure there is some kind of water value for the climate control heating system. |
I've got my fingers crossed hoping it's not the water pump, but as you say it has got to be water related. The shop is a Euro specialist, and the guy working on my car is an ex BMW tech, so I've got some credibility in these guys. I went back the next day to get the bleeding procedure done again, and I checked their method which was all to specification.
The other thing is, no error codes show up, hence why we ruled out the water pump. So no error, and no overheating (quite the opposite is happening instead), and erratic heat responses :nono: I suspect a sensor, water valve or heat exchanger? :think: |
Go to Realoem.com and find your car. There is a valve in the climate control heat circuit. You should find that valve under the hood and test it out. I've had two other cars in my lifetime that had a faulty valve there and it prevented the heater from blowing hot.
Not sure this is your exact model or not: RealOEM.com Diagram Selection |
Originally Posted by Pistratoaie
(Post 1545494)
Hi all, Got an issue on 2005 525i M sport.
First off, had radiator replaced after it was found leaking, before this, I know that the engine temperature was at the last two bars on the rev limit on dash. Here's where the problems start... Picked up the car from shop, drove normally for 10mins and then noticed heating wasn't working/slowly dying as I was turning it up on the drive home. Thought it was just new coolant and radiator so all was just cold? Next morning, for 50km drive had no heating and engine temperature was really low (ie. lots of bars on the dash meter). That week I drove 500km and had no heat but same low engine temperature. Took it back to shop next week and got thermostat replaced. Picked it up today and had heat for drive home (thermostat was faulty so replacement was necessary regardless) later on in the day, very little heat, and engine temperature is maxing at 70*C (on hidden menu coolant sensor temp reading)... Sorry it's long, I like to be as detailed as possible, Any ideas on what's going on here? would a faulty temperature sensor cause the low engine temp and almost no heat inside the cabin? Water valve? Would like some info before I take it back and they just replace parts randomly :angry: |
Originally Posted by twh
(Post 1545555)
Go to Realoem.com and find your car. There is a valve in the climate control heat circuit. You should find that valve under the hood and test it out. I've had two other cars in my lifetime that had a faulty valve there and it prevented the heater from blowing hot.
Not sure this is your exact model or not: RealOEM.com * Diagram Selection
Originally Posted by Quarta2six
(Post 1545561)
If Im not mistaken I think a Thermostat stuck in the open position will cause low temp and little to no heat. I would think an CEL would be thrown though
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Update, been a hectic few weeks where I've been with the car away and couldn't take it in for necessary works. I've got the thermostat and water valve (heater tap) replaced.
Now, I get heat quicker when starting up in the mornings so that's a relief, however the heat drops off and blows slightly warm when I'm exceeding speeds above 70kph :huh: Still no error codes, what is going on??? I'm pushing for a thermostat change again by mechanic to see if the new part is faulty... |
Have you enabled the coolant temperature display on the dash to make sure that the coolant is actually getting up to the correct temp? If it is, then your thermostat is obviously fine and you're looking at another issue.
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On the cluster? Yes I've checked the KTMP temp throughout a 2hr drive, and it was at 72-77 almost the whole time. There were some times when it would reach 88 and one time 98, but then it'd drop back to the mid 70's. I do have a new sensor/fan switch to test that out on Monday 29th when it goes in for full day testing and checks at mechanic. So... still the stat sounding like the main cause?
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Yes, definitely sounds like the main stat. When the temp got higher i'm betting you were in slow moving traffic, or stationary. Then as soon as you speed up the temp drops again dje to the stat being stuck open. Did the heaters work ok when the temp was 90+?
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Yes, definitely sounds like the main stat. When the temp got higher i'm betting you were in slow moving traffic, or stationary. Then as soon as you speed up the temp drops again due to the stat being stuck open. Did the heaters work ok when the temp was 90+?
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Well now I turn the heaters off once I exceed 70kph. But I did try turn the heat up when temp rose, so long as I'm at low speeds or stationary (as you mentioned) heat was fine, speed up = no heat regardless of coolant temp. I'm going to have to wait for next week to get into this. Thanks for the help, good to have more people's input to put my mind at ease :thumbsup:
I'll keep you posted |
How many bars is it supposed to show normally after warm? How do you access the hidden menu to see coolant temp? What is the right temp it should be when warm?
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Bars on rev counter should be down to only 2-3 visible (for petrol, not sure on diesel). Here's a link on how to access the hidden menu:
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I got the opposite problem..
Hi, my N52 is running on low coolant temp. Changed thermostat twice but no change. Its in the 76-85 deg with one exeption, in speeds > 95 km/h it heats up to 100-108 degC and seems to operate according to the N52 heat management design.
On throttle it cools down to 80 as per design to protect the cylinder heads. Why on earth is it running on 80 deg in low speeds?? Can oil cooler be malfunction? Some other thermostat.... Thanks in advance Torgny Sweden |
Hi Torgny, I'm having the same issues you are but mine doesn't heat up above 95kph... I would've thought it would run hotter at low speeds? I know mine does at the moment. From what I've searched most of them run too hot when thermostat goes bad, so ours are special cases :whistle:
are you referring to the oil cooler stat on the right of the radiator? I asked about that at the mechanic and he didn't think that would be related :hmm: Unless you've got a diesel, which has an EGR thermostat (and some petrol 8 cylinder cars, I think), there aren't anymore thermostats. I would try changing the coolant temperature sensor (referred to as fan switch in some cases) it's cheap. As soon as I've got news on any changes to mine I'll let you know:) |
Many Thanks, yes it is driving me crazy. Its a BMW E61 Touring 2006 (N52 engine)
I logg ECU coolant via OBDII and app TorquePro. Yes its the engine oil cooler that Ive heard have thermostats. Its a bit disturbing that the BMW tech dont seems to know the heat management on this engine, it all started with fault code P0597 (thermostat bypass valve open) but it ran on quit good 95 degC, changed TS and it got "cold", changed again on complaints... same story still..cold. Do you have any more specification on the coolant temp sensor (fan switch), art nr, link? Thanks again I appreciate all help! |
Chart engine coolant
1 Attachment(s)
See attachment! Engine Coolant driving on highway and city..between the "peaks, highway > 95 km/h" I stopped shortly and it heats up a little bit, then starting city driving gives the fluctuation 74-84 degC.
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I recorded (via phone camera) sensor reading on dash today to show the fluctuations to my mechanic on Monday. I'm getting relatively the same readings you are, except above 95k there's no change still. When I stop, it's usually stable at 92.
Between the cars, they don't sound too far off in difference, mine's year older, N52 engine though so resolve one, resolve the others... I know what you mean about not getting down to the bottom of it all even with BMW technician, change one part and all these other issues show up, nightmare :( Since you say changing thermostat twice didn't resolve the issue, I'm thinking I should hold off pushing my mechanic for doing replacement and look for the cause elsewhere, really need Monday to hurry up so I can get some news, hopefully! Part number for coolant temp sensor (fan switch) I got, 13621433077, no. 3 here: http://www.realoem.com/bmw/showparts...26&hg=17&fg=30 This is going in Monday as well. |
have you changed the thermostat and/or checked the electrical connections to it (if it has them)? Petrols should run around 100C+ while doing 60mph , diesels 88C. The only way to check your thermostats are working is by checking what temp it holds while doing 50mph+
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100+ sounds high, I was looking more towards 90-100. by my dash reading in hidden menu, above 50mph it is between 72-78. Much too low, I have changed the thermostat hoping to fix this issue after a radiator replacement. But there was no change, I'm not too knowledgeable on electrical, without full research that is.
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if yours is an auto, there is a thermostat in the oil cooler which could have failed.
Diesels with a new thermostat run at 90C on the highway (even if it's -5 outside, I've checked!) - petrols I know for a fact run higher than this, and last time I asked a petrol owner they said 100C or 105, can't remember but it sounds about right for a petrol. |
Yes it's an auto, when I first started having these issues, I considered thermostat, coolant sensor and oil cooler to be the culprits. Oil cooler being the last and remaining one to check off, it seems to be coming down to that.
I would be happy to reach anywhere above 90 at this stage, haven't seen mine go above 100 at all, and it is a petrol... weather here is never below 0, so should reach temps pretty easily; but it's not :mellow: Ahh, back to looking at oil coolers I guess |
It will be realy interesting to see if the fan switch replacement works for you, Ive located mine and it does not seem that hard to get to. I have in the past sprayed some electrical cleaner on everything but no result and also inspect visualy and by hand checking for bad cables but no... Thanks for the link btw.
When im doing 60 mph (80.47 km/h) its pending 76-84 degC..... I noticed today that when just starting it up and idle towards operation temp it will like go up to 92 degC and then, what I belive, the stat just open and drops it to 80s.... Oil cooler I been reading about in some other forum..well at least its the most easy part to get to...wonder if open it and clean it could resolve the problem. If the stats are on the oil side perhaaps they can stick as the vanos for example... This is like taking too much energy from me.. hehe..but I never give up! |
Hehe, I'm like you, I've been told to just live with it since it's not a big deal, but I'm not happy until I know it's all working properly! btw 60mph is 90kmh.
Yeah oil cooler is luckily easy to do, I'm just not sure why that affects reading by coolant sensor... so maybe replacing that sensor might resolve it. Have to wait and see. |
Yes it should have been 90 ofcours.
I shall try to find a used oil heat exchanger cheap and make a test... What I understand the oil cooler stuck open let hot water enter the top of the radiator and make the fan switch believe stat needs to open...it does but not for the correct reason.... I do not know.....dam |
So after Monday and Tuesday testing by mechanic, found one sensor to be giving different reading to coolant sensor. So we've replaced that sensor (I don't know anything about it), thermostat again with another BEHR one, and fan switch I believe.
So the temperature readings are confirmed to be accurate, but still no change in circumstances. Engine climbs to 92 when stopped in traffic and thereabouts in slow traffic. accelerating and cruising above 40ish (km/h), temperature plummets to 75 and remains there... Of course, cabin heat drops above 70km, which might make sense since engine temperature is at 75 at this speed. Heat runs properly when stopped because engine temp rises to optimal range. Well I'm out of ideas now, anybody got any ideas/recommendations? |
Just throwing out some thoughts...
Have you found anything from BMW that shows what the cooling profile is? Like at idle, cruising, allowable temperature ranges, etc. (1) Have you checked to make sure the water pump is not running all the time? That is, could it be that there is a permanent signal telling the water pump to run? (2) If not (1), perhaps the engine computer is telling the water pump to run constantly or more than necessary while you are in motion. Checking this would require tapping into the water pump wiring harness someplace. |
I'm looking at the Bentley manual...
(3) The thermostat is also controlled by the engine computer. Quoting from Bentley, "the engine control module activates the thermostat to maintain the engine coolant temperature within a narrow range. If the electronics fail, the mechanical function of the thermostat acts as a fail-safe". So, it could also be possible the thermostat is somehow being held open as my (1) and (2) above. That is, a permanent short in the control to the thermostat or some erroneous signal while the car is moving. |
Thanks for the input twh. I'll be checking on those things at the end of the week with tech. Plus getting software updated as another step to try out. I'm wondering whether your 3 point is closest to plausible; but what really doesn't match is that there would surely be an error code if water pump wasn't working properly... right? Thanks again, will post back
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Hey, working too much no time for problem solving but met a guy on the train the other day, diesel expert but have forwarded our problem to a BMW expert, will keep yo posted
T |
Update Everyone, I went back to check for software update, turns out it was already updated to latest version. So by now I was going to start replacing oil cooler and then heat exchanger in hope of good news.
As I did my usual 2+hr drive early on Monday morning, car started as usual; heat came on quickly when stationary. Above 80Km/h heat dropped off and engine temp was low 70's. Over an hour into the drive I decided to check sensor temperature... 95 :huh: turned on heat and lo and behold IT WAS AL WORKING PERFECTLY!!! :clap: Been driving all morning and has still been working like it should. Conclusion? some serious blockage in the coolant system that was resolved after about 2 months of driving? but the headaches it gave me :nono: Torgny could this be the same for you? maybe some blockage that's just driving us up the wall :angry: Thanks everyone for your help and input. Lets hope it stays resolved at this stage :) |
Hi, oh that great its seems to have been solved but Im not sure its the status for me, mine is running 76-84 when stationary and up to approx 95 km/h ...then...the stat (I belive) closes and it operates on 100-108 degC. Speeding down or hit the clutch ...instant drop to like 80 degC...
Blockage...perhaps but how on earth shall I locate this?? I have a laser temp meter and will measure on the cooling hose from oil cooler and compare this to another similar car..same engine...to make sure the oil cooler isnt dumping hot water all the time to the top of radiator.....probably a long shoot... Thinking that if your is running on 95 degC ...are you sure its not running with stat bypass open? I had that and fault code P0597... Im very confused and BMW dealer work shop still says no fault on my car... Yeah thanks everybody for hopefully taking me closer a solution on my "#¤%¤& car! |
I would agree that the oil cooler seems to be the blame.
I drove mine today to see how things are going, and it's again not running properly :doh: I may have jinxed myself earlier, clearly spoke too soon. But this has brought up the possibility of a blockage in the pipes. Since you've got a laser temp meter that would be excellent to test each pipe after a drive then compare to see what's different. I'm going to try do the same technique and see if there is any change. Still no fault code, just can't explain why it was working fine on the one random day :| |
Did you replace the water pump and thermostat already?
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Thermostat has been changed twice, water pump hasn't. It hasn't given a fault and it works, so don't think its that. There has been the suggestion that the pump is getting wrong signals and not running as it should, so that's something I'm planning to look into.
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I made a couple of bleeding of the EWP but ofcourse no change,anyway could hear the EWP running in sequence and different revs sooo it seems to have its function....
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Made a test on my friendes Car of the exact same model, same behavior as mine!
What am I missing...is my car as design?? I will try to read my display for cooling temp from ECU. Anyone knows how that is done? Torgny |
whoa, hold on, so your friends car is running the same issues :o surely that's not to design specs... :( Can't remember if you mentioned already, did you change the radiator sometime before or when things weren't running properly? Because now I'm trying to get a salvaged one just to test if rad could be the cause, clutching at straws now.
The mechanic has a workshop computer which stays plugged into the OBD while driving to access all the readings, that's how he read cooling temp from sensors, ECU, and what the ECU was telling the pump to do. You might be able to do the same thing with personal pc, I haven't tried it though. |
I have 06 530i with n52 engine. I think I have the same problem. Most of the time its around 80C sometimes goes up to 100C but no often. Changed thermostat once. When I was at my mechanic he had someone elses 525 for an oil changed and we checked that car behaved exactly the same. I was thinking about changing my thermostat again, but I'm not sure I should do it anymore. What I noticed is if i have heat/ac on when the car is cold is doesnt even warm up much. I have to click the off button and wait for engine to warm up. I've talked to alot of people and read alot of forums on the internet and no one seems to have any clue.
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