MCS 2013. 70,500 miles.

I heard a bump driving my car about a week ago. It is like the sound you would hear with run flats going over a 4inch pipe at 30mph. I changed my battery about a week ago so I figured the battery hadn't seated and it fell into place.

Well when I got home I notices about a half cup of coolant on the ground around where the Thermostat sits. My experience with coolant problems is they give you signs and if you ignore them, on a long hot trip, something major gives. What could have been that sounds related to the cooling system? It seed more on the water pump side but I don't see anything leaking there. The last time I looked at the process for doing the water pump it was major work.

 

My thermostat temp sensor died at ~32k (2012 S) so I replaced the water pump with a metal unit, and the plastic water pipe connecting pump and thermostat "since I was in there". I wouldn't call the work "major" if you've wrenched before, but it was tedious getting the metal clip back in on the water pipe to thermostat side. I'm at over 70k now and haven't had to go back in (yet).

Not sure what that noise was, running over a 4 inch pipe doesn't sound like fun!

 

How did you know it was bad though. I think the typical failure points on these engines is the plastic vanes on the water pump fatigue and fall apart. Which could have been what I heard. Or, the thermostat plastic housing develops a crack which I'm sure usually starts out small when warm and gets bigger and the water pressure begins to open it up more and more.

I have watched the pictures of people trying to remove the water pump without the belt tensioner and it looks maddening. I would hate to get myself in that bind and can't get it out. Getting directly underneath to that back pipe also doesn't look easy. After all that work, for $50, I probably would change all the water pipes as well.

The engine light just came on. So I ran a diagnostic and the only thing I am seeing is cylinder 3 is misfiring for some reason. I just replaced the plugs and coils so I am guessing it is carbon buildup.

 

To make sure it goes as smoothly as possible have all the specialty tools on hand. They will cost more than DIY methods but might save you the madness. You can remove the intake manifold to make it easier to access the water pipe as it runs underneath it. If you are cleaning carbon you'll have this off anyway. Trickiest part about the intake manifold is a hidden bolt on the passenger side.

 

What specialty tool are you talking about, the special tool to remove the belt pulley tensioner?

 

It looks like the antifreeze is coming out from the back pipe on the thermostat side. It could be higher and simply dripping out there but I see it splashing against the frame and I see it dripping against the back side of the transmission. If I run the car for a good 20 mins, once I set the car, I see about a 1/3 cup of antifreeze on the driveway until it cools and seals back up.

 

Yup. Might as well change the belt too

 

I'm really disappointed that these german engines use so many plastic parts that are subjected to extreme heat cycling and buried within the engine. Hopefully you'll get another 70k out of yours.

 

Yeah, so what is the total list of work that I'm looking at?

• Waterpump
• Thermostat
• main Rear plastic pipe from WaterPump
• New main Belt.

• "since half the pipes have to come out to do this job". Replace all water piping to prevent any future failures related to cooling system failures.

 

Don't know if the new pump comes with a new pulley, but you don't want to reuse the old one. It's a wear item.

 

Anyone know the total hose coolant count? Is it 9 or 15
https://www.ebay.com/itm/304267338963
https://www.ebay.com/itm/304267338963

 

If you're changing all hoses check out this thread regarding the hose coming from the coolant reservoir
Fix another critical stupid plastic engine part thanks bmw

 

Turbo coolant hoses
realoem is helpful to find exploded diagrams

 

Thanks. I already replaced that part last year.
It looks like in this kit they give you a metal T

https://www.ebay.com/itm/384111727039

Ok, I could have used that article a year ago. I think that replacement part was $60 or so but this PEX connector looks like a 100% Better solution. I actually reinforced mine but it will fail again.

 

Yeah, once you have removed everything to replace the thermostat, the water pump, and the crossover, you may as well put in new hoses at 70K. Then the entire coolant system has been overhauled except for the radiator. Good for another 70K miles. Nothing worse than the coolant system going out on a long trip. Virtually everything else can be "milked" to a garage except for that.

 

We have that T here:

https://www.ecstuning.com/Search/Sit...h/11539845352/

 

I already replaced that part just last year. I am good for at least another 10 oil changes at this point. Also I reinforced my part with JB weld right at that part that has the minor plastic reinforcement, so it should last longer than OEM. Dumbest place to put the oil filter below the coolant tank hands down.

That is not my current problem. My current problem is that it is leaking when warm right where the cross over pipe goes into the thermostat. It's probable just rotted out there. I'm going to overhaul the entire cooling system, less the radiator, expansion tank, and the turbo/expansion tank connector.