[wdas]

Hello, I've noticed that my 2005 320d e90 (163hp) keeps low temperature, so I am going to order new original BMW thermostats to replace, I've seen few videos so I know to to remove it and assembly it back up.
My main questions are about draining and bleeding the system.
1. If I understand correctly, my engine is m47n2 which has a drain plug on the driver side that should be unscrewed to drain the coolant?
2.Once the coolant is out I should disassemble the parts and replace the small and big thermostats, plug in the drain screw, and start filling the system with the draining screws open?
3.How do I find out if my car has electrical pump or mechanical? Since I read that if it has electrical I should follow the procedure that you have to press the gas pedal for 10 seconds to start the pump for 12 minutes to bleed the air out,and if it's mechanical I have to fill up to the top, close bleed screws and filler cup, start the car, wait few minutes to heat up, open the cap and add coolant if necessary as the car has self-bleeding ?

[bimmerfan1972]

I don't now that engine, I would start here. Look up your VIN on www.realoem.com, enter your VIN last 7, click browse parts. You should be able to find the part number of the water pump. If it is electric, I assume it is, then yes there is an automated bleeding procedure.

[bimmerfan1972]

Actually it looks like it is mechanical. Here is a video showing the replacement.

[wdas]

https://www.realoem.com/bmw/enUS/sho...diagId=11_3324

It says mechanical?

Edit:Yes I've seen this video too, was wondering why he did not drain the coolant from the bottom of the car and drained it straight from the hose? That's why I decided to ask here since I got confused which one is correct and how to find out.

[bimmerfan1972]

Originally Posted by wdas

https://www.realoem.com/bmw/enUS/sho...diagId=11_3324

It says mechanical?

Edit:Yes I've seen this video too, was wondering why he did not drain the coolant from the bottom of the car and drained it straight from the hose? That's why I decided to ask here since I got confused which one is correct and how to find out.

The water pump is above the reservoir, so probably doesn't lose much coolant. I would go the extra step and flush the radiator at the same time.

[bimmerfan1972]

Yeah, you can see there is a pulley that the accessory belt turns, so that would be mechanical. I usually shop on FCPEURO and ECSTUNING, but I do not see your part on either site. I'm sure it's out there somewhere, but I believe this is what you are looking for. Of course, make sure you verify it is the right part before you buy. https://www.ebay.com/itm/19163879876...evt=1&mkcid=28

[wdas]

So If I understand correctly, I should start with drain screw at the radiator, then remove the thermostats, change, install, put the radiator plug on, loose the bleeding screws, top up coolant (don't close the cap or bleeding screws), start engine, wait for coolant to come out of all bleeding screws and close them, let engine idle for few minutes and watch the coolant level?

[bimmerfan1972]

Oops, just re-read your post and you are doing thermostat only. I have the electric, but that procedure looks logical. I'm sure you've found this article too, but this guy has a method:

https://abetterbmw.com/how-to-bleed-...oolant-system/

[wdas]

Great, thanks. Also wanted to ask how much coolant does that engine require, since I am thinking of buying genuine bmw concentrate, so wanted to make sure how much of that I need? Or If I don't get the bmw coolant, can you at leasttell me which color is good ? I've read that bmw recommends blue ?

[bimmerfan1972]

Originally Posted by wdas

Great, thanks. Also wanted to ask how much coolant does that engine require, since I am thinking of buying genuine bmw concentrate, so wanted to make sure how much of that I need? Or If I don't get the bmw coolant, can you at leasttell me which color is good ? I've read that bmw recommends blue ?

I'm not sure how much it takes, but I've read many places to use the BMW coolant and use a 50/50 coolant to distilled water mixture so that's what I do.

[wdas]

I did change the thermostats and the temperature now is 87-88 steady. My question now is, the bleeding was slow and one thing that I don't like is that there is a small back coolant flow that returns the coolant into the tank, it is supposed to be a straight line of coolant, however on my car is barely leaking.

I've read somewhere that there might be a pocket of air stuck somewhere in the engine, and even though you see good temps it might create a bad area that is not cooled properly. So my questions is, since I have tried to unscrew the bleeding screws and coolant leaks from all of them, should I be worried about the stream of coolant that is not returning much coolant into the tank?
The coolant level (after few long drives) measured in the morning is between min/max, the temp is steady and warms up in around 15 mins in cold weather.

[wdas]

Any suggestions?

[ptpending]

Originally Posted by wdas

I did change the thermostats and the temperature now is 87-88 steady. My question now is, the bleeding was slow and one thing that I don't like is that there is a small back coolant flow that returns the coolant into the tank, it is supposed to be a straight line of coolant, however on my car is barely leaking.

I've read somewhere that there might be a pocket of air stuck somewhere in the engine, and even though you see good temps it might create a bad area that is not cooled properly. So my questions is, since I have tried to unscrew the bleeding screws and coolant leaks from all of them, should I be worried about the stream of coolant that is not returning much coolant into the tank?
The coolant level (after few long drives) measured in the morning is between min/max, the temp is steady and warms up in around 15 mins in cold weather.

you did all correct, you should have additional electric pump which helps when engine is idle
this pump usually dead on many unserviced m47 cars, it is easily repairable, you need to replace brushes which are torn up
another measure for successful bleeding with mechanical pump is to lift up front of the car a little
also you can ask someone to increase engine revs and to see if the stream of the coolant is bigger

[wdas]

Yes the coolant stream does increase when revving up, but shouldn't it be like that without revving ?

[wdas]

Up

[ptpending]

m47 and m57 have mechanical water pump, driven by belt
so they have different performance on different RPMS
and thats why they have additional water pump to assist on low RPMS

[wdas]

So if I understand correcly it's okay, and the stream is low because the additional pump has most likely failed?

[RealPreshaanB]

Originally Posted by wdas

https://www.realoem.com/bmw/enUS/sho...diagId=11_3324

It says mechanical?

Edit:Yes I've seen this video too, was wondering why he did not drain the coolant from the bottom of the car and drained it straight from the hose? That's why I decided to ask here since I got confused which one is correct and how to find out.

For those needing a reason, it is much easier to drain the coolant from the EGR thermostat as I've done in the video since the job does not require a complete radiator flush. it is also possible to complete a radiator flush using this method as no contaminants will enter the block of the motor itself and you have a lesser chance of stripping a plastic fitting or breaking the plastic hose fittings.

The bleeding process I've been using and had zero issues with all replacements I've done is the "cold bleeding" process. Open all bleeding screws and fill up until all the air has escaped from the cooling system, starting with the main distribution pipe, then the EGR Thermostat (If still on the vehicle), then finally the expansion tank itself

it is advisable to replace the bleeder screws whenever attempting a repair like this as they aren't very expensive and do run the risk of breaking or the head stripping due to the amount of heat cycles they go through

i hope this clears any confusion

thank you