Issue with heating 3.0Si

S

stupot1397

Member
 Lincolnshire
2008 3.0Si

Hi all

I'm having an issue with the heating - in the fact I currently don't have any!

From what I've read this could be many things but I'm just trying to narrow it down before I start replacing any parts

I'm struggling to work out what the hell is going on - as some things aren't making any sense at all.

1. The car is not overheating - the gauge goes up to temp and the car runs fine
2. The pipes at the heater matrix are stone cold - so I think this is the cause but why they are cold I'm not sure.
3. The pipe are cold all the way back the the expansion tank where they are connected.
4. I have tried to do the bleeding procedure for the N52 with the throttle to the floor for 10 seconds, but at no point does the pump start or kick in to do the procedure.
5. If I run a pump actuation test from diagnostics, (the 50% and 95% options) this works and the pump works and pumps water.
6. If I drive it down the road, and rev up the engine the heating does come alive, until it goes back to idle and then goes cold again


I am currently assuming some sort of airlock or thermostat problem? . The coolant level hasn't changed so not sure where the air is getting in., if it is that.

I have now had the pipes off to the heater and back filled and there didn't appear to be any sort of blockage - in fact the water that came out was quite clear after flushing. The state of the the thermostat and water pump are unknown as regards replacements - expansion tank is the original one from late 2007!

I would have though if the water pump was failing it would show up as overheating but I haven't had that at all.

No fault codes related to water pump.

Any help is appreciated.
 
Have you tried running the engine with the heater pipes off? I've had that issue on an M54 engine. Nothing was coming through the pipes at all. Ran it for nearly five minutes and suddenly water started flowing out of one of the pipes: pushed it back on and after another minute or so water started flowing back out of the matrix: pushed the other pipe on and all worked normally.
Obviously be careful not to scald yourself.

I would also suggest you get a code reader on it and look for water pump codes within the DME.
 
stupot1397 said:
4. I have tried to do the bleeding procedure for the N52 with the throttle to the floor for 10 seconds, but at no point does the pump start or kick in to do the procedure.
Click to expand...

Then you must be doing it wrong. It'll run the sequence as many times as you like - there's no "I'm fully bled, I shan't bother" about it. But, unless you've had the system apart, there's no reason for the water to vacate the heater matrix.

stupot1397 said:
6. If I drive it down the road, and rev up the engine the heating does come alive, until it goes back to idle and then goes cold again
Click to expand...

Sounds like the thermostat is stuck open.
 
enuff_zed said:
Have you tried running the engine with the heater pipes off? I've had that issue on an M54 engine. Nothing was coming through the pipes at all. Ran it for nearly five minutes and suddenly water started flowing out of one of the pipes: pushed it back on and after another minute or so water started flowing back out of the matrix: pushed the other pipe on and all worked normally.
Obviously be careful not to scald yourself.

I would also suggest you get a code reader on it and look for water pump codes within the DME.
Click to expand...
Worth a try, like you say I'll try not to end up in A&E !

There are no codes for the water pump at all, I've already scanned it
 
smorris_12 said:
Then you must be doing it wrong. It'll run the sequence as many times as you like - there's no "I'm fully bled, I shan't bother" about it. But, unless you've had the system apart, there's no reason for the water to vacate the heater matrix.



Sounds like the thermostat is stuck open.
Click to expand...
If I'm doing it wrong, can you tell me what the correct procedure is - I'll probably agree but I've read about how to do it so many times and it will not do it at all. ignition on, heater on full, blower on 1st speed, foot flat to the floor for 10 seconds - but nothing. Also tried it with headlights on and off but again - the pump does not start.
 
Not sure if it is the same for the 3.0si but for my 2005 2.5 it really helps to have the front of the car up in the air to aid bleeding. I know this car doesn't have an electric pump procedure but it definitely helps get all the air out, because they are a bit of a pig to be honest.
 
stupot1397 said:
If I'm doing it wrong, can you tell me what the correct procedure is - I'll probably agree but I've read about how to do it so many times and it will not do it at all. ignition on, heater on full, blower on 1st speed, foot flat to the floor for 10 seconds - but nothing. Also tried it with headlights on and off but again - the pump does not start.
Click to expand...
If you are doing the process correctly but it doesn't start bleeding then there is a pump issue or at least a signal to the pump issue.
I usually start the process with the expansion tank cap off so I can see the jet of coolant firing into the top, signifying a pump running.
The pump runs very quietly and tbh you can sometimes only hear coolant circulating rather than pump noise itself.
So, starting from cold, fire up the engine with the expansion cap off and see if there's any coolant movement.

I am not certain of the electrical side of things, but maybe if there is a thermostat fault it affects the pump as well?
 
stupot1397 said:
If I'm doing it wrong, can you tell me what the correct procedure is - I'll probably agree but I've read about how to do it so many times and it will not do it at all. ignition on, heater on full, blower on 1st speed, foot flat to the floor for 10 seconds - but nothing. Also tried it with headlights on and off but again - the pump does not start.
Click to expand...

Sorry, I was in a bit of a hurry with that post. I was meaning that, if the sequence is right and it doesn't run, then the pump must be dead, which would explain lack of noise as well as no heat. But then I would have expected some engine overheating if you've driven for any distance. Which sort of rules out the pump. Very circular.

One possibility is that the thermostat is stuck open as well as the pump being dead so the excess cooling is balancing out the excess heating.
 
smorris_12 said:
Sorry, I was in a bit of a hurry with that post. I was meaning that, if the sequence is right and it doesn't run, then the pump must be dead, which would explain lack of noise as well as no heat. But then I would have expected some engine overheating if you've driven for any distance. Which sort of rules out the pump. Very circular.

One possibility is that the thermostat is stuck open as well as the pump being dead so the excess cooling is balancing out the excess heating.
Click to expand...
No worries. I’ve got no codes for the pump, in diagnostics I can run the pump at 50% or 95% and that works. Just not the bleed procedure.

As suggested earlier, I’ve found at startup the pump doesn’t seem to run either. Can’t see a jet of coolant at the expansion tank. But not sure if that’s normal at idle engine speed.

I can drive the car and it doesn’t overheat at all.
 
Just an update to this, did a pressure test on the system and ended up with a problem being detected around the expansion tank. Air was hissing out of this once under pressure. Got it removed and there is indeed a pin hole in it, which I would suggest has been causing the airlock over time.

So waiting for a replacement now (it was the original from 2007) then a coolant flush and hopefully that will be it.

I still don’t understand yet why the water pump bleed procedure doesn’t work but we will see once the new parts are fitted.
 
I had an issue with the coupe this week

I couldn’t start the bleed process via the manual process

However with inpa it worked perfectly
 
My E86 has also been like this - doesn't start from the throttle pedal, but starts perfectly from inpa.
 
So, expansion tank replaced - along with the bracket it mounts to as they wouldn't come apart with damaging both.

Pressure tested - all OK now - no leaks or pressure drops after 30 minutes.

So good to go, or so I thought - refilled the cooling system with a vacuum filler - all seemed to go OK and filled it back up to the correct level.

Started it up, went for a drive, exactly the same! Nothing coming to the heaters, also started getting a temp fluctuation up and down so clearly an airlock still in there - RARRGH.......

Even though it was Vacuum filled - As mentioned before, the pedal method just doesn't work for me.

I have a Launch X431 reader and it cannot start the process for the pump, it tells you to do the pedal method and it can read the speed but it always said zero.

So having had an old E90 330D in the past I still had INPA kicking around, bought a new cable and managed to connect it up.

Managed to find the part in INPA for doing the bleeding - and it worked. After the 1st run I needed another litre of coolant, then did a second run and it needed another 0.5L. After the 3rd time the level did not change, so at this point I was ready to test again.

Low and behold, within a couple of minutes warm air started to come through the vents, and then after about 10 minutes of driving it was like a furnace! Got back to base, left it overnight and checked the level again and still correct.

Since then I've used it a few times and it has been absolutely fine with no issues or coolant loss. So at this stage I can say that the cooling system bleed appears to be absolutely essential to make sure these cars work 100%

I'm still not sure why the pedal test doesn't work - but clearly from INPA and driving it the water pump is working perfectly.

Just thought I'd leave my experience here in case anyone else has the problem.

IMG_2842.JPEG
 
I wonder if it's a problem with the throttle pedal not reaching or reporting full travel. IIRC there's a section in INPA that will give you a 0-100% reading on it.
 
smorris_12 said:
I wonder if it's a problem with the throttle pedal not reaching or reporting full travel. IIRC there's a section in INPA that will give you a 0-100% reading on it.
Click to expand...
Mine does the same as OP - I checked this too and it hit 100%, just never started the bleed cycle.

Very bizarre indeed
 
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