Hi all, I have been experiencing overheating issue, on and off and need some help on what to try next.
Here is where I am at.





If I start car from cold it takes very long time to get to operating temp, I had to take if for a drive to get there, then within a few kms the temps will spike with yellow then red warning lights then drop off rapidly to normal, then spike again.. recently the spike would not drop right away so I shutdown. Checking under the hood, I could see the coolant level was almost to the top of the expansion tank.

• Car threw code for coolant temp sensor so I replaced that. No other codes currently.
• Expansion tank cap blew coolant so I thought it was not holding pressure so I replaced that.
• No leaks, no coolant in oil or oil in coolant..whew!
• Lower coolant hose under rad is not getting hot?

So I am down to Water pump or Thermostat.? How can I figure out which one it is?
I understand I should do both of these but I would prefer to tackle these one at a time as I am going to do the work myself and these do not really overlap except for the coolant drain/fill.



Thoughts?


Thanks!

 

The engine control module (ECM) (DME) controls and monitors operation of the thermostat. Controlling the thermostat function according to a map allows the engine management system (DME) to raise engine operating temperature quickly and precisely to the optimal range and to maintain it there for maximum efficiency and minimum emissions. Besides the obvious CEL code that points to a thermostat issue, other symptoms of a faulty thermostat are engine overheating, slow to warm up and lack of heat.

When a water pump begins to fail, you'll notice that the car tends to overheat at low engine speed, such as sitting at a stoplight. When you accelerate, the engine temperature will drop. Now, this is not always indicative of a coolant pump failure, but a good starting point. You may also want to try squeezing the top radiator hose with the engine warmed up and running. You should feel pressure build up on the back of the hose and surge once it is released. If you feel no pressure, it's a fair bet that the coolant pump is failing. The most common problem with the electric coolant pumps is a fault code for coolant pump volume.

You have a few options. We have the Genuine thermostat HERE in stock and ready to ship (a lot of these thermostats are on back-order at other distributors right now). Other option, since you said you may want to do your water pump as well, is our water pump super kits HERE, which include the thermostat. These kits give you everything you should need to replace in your cooling system while you're in there to do the job. We also have DIY tech articles that contain all the above information and a step by step process to replace these components. It's on our site under MINI > tech info tab at the top. Let me know if you have any questions.

 

You PM me and I got it . Let me know how it goes , if you need anything eles let me know.

 

Ok so I started on the thermostat replacement, got the old one out, but am concerned about the residue I found in it, is this normal, thoughts?
This milky residue does not show up anywhere else, dip stick, oil cap, expansion tank, etc.

Thanks!

 

Could have been form an oil cooler / oil housing gasket leak and fix and the residue from the oil leaking into the coolant ( was no flushed all the way ) or you have a leak in that section ?

Has its been changed.

https://www.northamericanmotoring.co...placement.html


Responded to all your PM's I am glad to help.

 

Finished thermostat.. still overheating..so I moved on to the water pump.. got it unbolted. .how do you get it out of there? I don't have enough space in any direction.
Any tips?

Thx

 

Go to our site. Under MINI > Tech Info (tab at top) > R56 Articles > Cooling System - 5th article down under that is the water pump one. It will help you a lot as you will have to slightly lower the engine to access the water pump, which is attached by five 10mm water pump fasteners (red arrows below) This info and image is all from that article. Let me know if you have any questions.

 

I have it raised.. not lowered, will try that tonight.


Also what is the best way to test the friction wheel assembly?


Thx.

 

3 bolts and then pull the tab

https://www.northamericanmotoring.co...-r56-help.html





http://www.realoem.com/bmw/enUS/show...diagId=11_3917



on the water pump there can be a tick to it : I have done it myself.

https://www.northamericanmotoring.co...acement-3.html

 

The friction wheel (HERE) can fail a few different ways. The pulley or the pulley bearing can become noisy, causing a high pitched squeal or scraping sound when the engine is running. The friction wheel internal tension spring can also fail, causing reduced pressure on the water pump pulley. This can cause slipping and engine overheating.

To check for a weak internal tension spring, pull the friction wheel away from the crankshaft pulley (green arrow). If you can move it and create even the smallest gap (red arrow) it is faulty. This and more info can be found in our DIY for its replacement.

 

Ok took the friction wheel assembly out, which helped get the pump out..whew.

I think my problem might have been this all along as I can freely move the pressure wheel arm with little resistance. My wheel is smooth metal with what looks like burn marks..is that normal?




Also found this video.. Mine behaves the same.


Appericate all the replys.

Thanks!

 

Is it makes noise and rattles , i would replace it while you are there. Is the drive wheel on the water pump pulley damaged ?

https://www.northamericanmotoring.co...e-to-time.html

 

It will over time, due to heat, cold and the rigors of operating multiple pulleys, develop signs of wear: cracks, fraying, glazing or missing chunks. In addition, the tensioner and its pulley may develop defects. Bearings in these pulleys are lifetime lubricated. The lubrication eventually dries up or wears out and may cause noises. Since you have it out and have determined this may be your issue, replace it. We have them HERE. In that video, he shows the pulley, check the condition of yours as well. We have them HERE.

 

Water pump pulley is in good shape, I will replace the friction\tension wheel for sure.

Thanks

 

You are welcome. Let me know if you need anything else. Its a tight fit in there so watch your fingers against the side firewall, Did this before many times.

 

UPDATE:
Still overheating...

So I have replaced the thermostat, water pump, and friction wheel.
I have done many heat up cool down cycles and bleed system via bleed screw each time when hot, every time more air sometimes waiting 10-30sec for coolant to come out.


I also have discovered a correlation with temp coming out of the vents and coolant temps. I can go down the road for a few mins..temps normal, very hot heat out of the vents.. then it will start blowing luke warm and the coolant temp will spike, within 10-30sec..heat will come back out vents and coolant temps drop rapidly.


I am thinking multiple air locks in heater core?.. clogged or most clogged heater core? causing coolant flow blockage?


If I keep bleeding and keep getting more air ( which locks heater core) then head gasket? Although I do not have any symptoms of that.


:(


Suggestions?

 

You need to have your cooling system bleed properly, shops use a pressurized system to get all the air out of the cooling system. Air can get trapped in the heater core, I have seen some have insane difficultly getting all the air trapped out.

 

Make sure the heater core valves are open all the way, Have your heat on high in temp inside the car, you might have air getting trapped due to clogging.

 

+1

You're sure there are no other leaks in the system correct?

 

I pulled the heater core, it was spotless inside flushed it without issue. Now I need new seals for the heater core pipes?..they are one time use?..cant get them to seal properly.
Heat was always at max during all bleeding attempts. Not sure what you mean by "heater core valves"?


Thanks.

 

Once I get the heater core pipes to seal, I will refill and double check for any leaks and at this point as you and Systemlord said I probably have it towed into dealership for pressure test and fill.


Thanks

 

Meant the heater core open , flap open all the way to tell if you are getting full heat in no air. So used to saying valves on the BMW side.

Heater core install clips and seal. You have to watch on removal , I would get the clips set, most people reuse the double tubes , but you have to watch not to damage the seal on them. Drain the coolant first to get most of it out.

https://www.northamericanmotoring.co...p-removal.html


Install DIY :

 

I was having overheating issues for a while, I was pretty sure it was air trapped in the cooling system. I eventually learned my head gasket was failing, once I got it replaced, coolant system bled the air out with no problems and the over heating stopped.

Might be a long shot, and hopefully not the issue your having, but check your coolant for any exhaust or oil contaminants and maybe even do a compression test.

 

Any updates on this?
I'm having the exact same overheating symptoms.
Just replaced the Timing chain, Thermostat, and Water pump. Have what seems like a milky residue. No leaks, bleeding via the bleed on top of the thermostat housing - get a lot of steam after a drive around the block. But coolant levels don't change and after driving around the block the temp gets to about 121C. That's when the temp light turns on.
'09 R55S 39,800 miles.

 

Have read a bunch on this. To recap current findings:
Getting tons of hot air from heater turned on max.
Coolant level doesn't move (unless I let out some from the thermostat bleeder).
Car temp at idle never gets too hot.
Car temp driving around the block reaches 120c. (Then the overheating light ((yellow)) appears.)
Fans both seem to run nice and loud. All fuses look fine.

Could this be from air still trapped somewhere?

Just keep bleeding?