I have been trying for the past week not to talk about it because it freaked me out and it really stressed my out! Rewind to the 11th (Saturday) of this month, I was driving my MCS to my mother's house to go see Fastnfurious7 with her and I'm driving on the I5 North and I start to notice steam shooting out of my front right wheel well and also leaking a wet trail on the road behind me.

So I pull over fast and immediately open the hood to see what's going on, I see coolant boiling out of the cap on the reservoir and coolant all over the place squirting out from the pumps mating surface between the block so I turn off my engine real fast like! I took it to MiniWorx and the diagnostic reveals not only was the Graf pump leaking but so was the oil filter housing gasket, but got lucky that the gasket only failed where the two coolant channels are and not the other two oil channels.

I for the life of me don't understand why I didn't get an CEL light on the dash for overheating..? There was no overheat code in the ECU. Has anyone ever have the heat exchanger leak oil or coolant or is it mostly with the oil filter housing gasket?

 

I am wondering... Was the steam you had formed from the spent coolant hitting the hot exhaust manifold and turning to steam..this being what you saw, and that the leak had not caused enough of a loss of coolant to cause the actual engine temp to get high.

This is only speculation, but a possibility.

Motor on!

 

A cell will only be set if the cars sensors shows an overheat...
You had boiling coolant due to it leaking out and hitting something hot...
If you drove much more...coolant would have gone low...and overheated...
Remember....the sensors are more of an idiot system.....it says "hey look at me", often a problem will not set a code unless you ignore it till damage occurs...
Think of low oil....if the leaks happens long enough, the psi drops, low psi light from the leak....
Same situation for a leaking coolant system...in your case it just happened to leak onto something and make steam so you SAW/SMELLED it....but has it been hidden....you would have gone low in volume, resulting in lack of flow, and overheating.
Remember...
Cars are largely mechanical, with a few sensors added to see what is going on.....too few data point to relay on the computers to tell you what is happening.

 

You didn't trigger an overheating light because the car wasn't overheating. Vehicle cooling systems have to be kept pressurized because they often operate at temperatures above that which coolant will boil at. When the leak sprouted the cooling system was no longer pressurized and the coolant started boiling. If you would have driven much longer you would no longer have coolant in the engine and it would have promptly overheated and probably warped the head.

The heat exchanger is bolted to the oil filter housing. Typically all those gaskets are replaced together. It's not an uncommon failure. Neither is the water pump.

 

As others have speculated here, you probably caught it before it actually overheated. You did a good job and weren't oblivious, so your car lives to see many more days!

 

My oil filter/heat exchanger gasket failed, but not on the coolant circuit (yet). It was dribbling down onto the exhaust very slowly leaving a smell and film on the bell housing. I ended up replacing the oil pan gasket (what I first suspected), but that did not fix the issue. The oil filter housing and heat exchanger are in a f*cking terrible location. Below the turbo and next to the cat, it's guaranteed to fail over time in a hot environment like that...my guess is it'll be one of those things you do every 50k mi or so...and replace the turbo oil feed lines at the same time since it's all right there.

When I took my car in to have the engine replaced, the SA was amazed that the plastic OE water pump had never failed on me.

Sounds like you caught it in time, definitely need to change the vital fluids though. Do you run a ScanGauge? Mine was programmed for the Mini, it tells me oil and coolant temps and has been worth every penny.

 

John at Miniworx is installing a Mini brand water pump, the Graf pump seemed like either the gasket and or housing was a few thousands off at the mating surface. It was leaking from where the gasket has a groove for the gasket which is seen externally on the top part of the pump. I feel the urge to perform an oil change just to be safe.

 

Oil temperatures using scan gauge, on a manual? I though that was just with automatics. Can you set an alarm for coolant temps? Is boiling coolant at the same temperature as normal coolant temps?

Does both oil and coolant pass through the heat exchanger?

 

No. Boiling coolant is 212f (that's why it's boiling). The mini cooling system regularly gets up to 220-230f when working properly.

The heat exchanger is bolted on to the oil filter housing. I don't know if the oil goes through the heat exchanger (I bet it does) but both oil and coolant go through the oil filter housing and the o-ring between the oil filter housing and the block is just as likely to fail as the o-ring between the oil filter housing and heat exchanger.

 

I tell everyone that I know that want to or have a MINI that if the gaskets haven't been changed out in the first 50k miles better do it, it shouldn't be optional based on the design of the housing.

 

The heat exchanger is where the oil coolers plug into if you're running one.

It's just crazy not to do it at or before 50k miles, this problem has a good chance of warping your head if not noticed soon enough. If you lose both oil and coolant God help you!

 

Yeah, Motoring Magic in Thousand Oaks showed me a few warped oil filter housings and its pretty wild. He has a shop he sends them out to to resurface them so they can reuse the existing housing because MINI originally were selling the housings for around $250 or so, and then he noticed that MINI started to sell them upwards of $450-500.

 

Well John found silicon sealant that obviously dried before the pump was torqued down, that's what cause the extra gap between the two mating surfaces causing the gasket to allow coolant passed it. So it wasn't a defective pump after all, darn CarMax techs. John even gave me the choice to not replace the Graf pump with the OEM brand. I told him to go ahead and install the Mini brand pump since everything was all apart.

I just towed my Mini to Miniworx at 2 pm yesterday and he's going to have it ready for tomorrow, quick fast competent mechanics! Would have taken CarMax 3 1/2 weeks since they couldn't even diagnose my car for 1 week, their that booked! The last time it took 3 1/2 weeks to replace the pump and thermostat housing with CarMax! That's about 6 hours of work.

 

That's for water, at sea level air pressure. Coolant has more than just water in it, and I think its boiling point is higher--plus the cooling system is sealed and is at higher than 1 atmosphere pressure, so the boiling point is higher.

But if your cooling system is open to the air (e.g., through a large enough leak) then the coolant will boil at normal MINI operating temperatures.

 

Picked up my Mini from Miniworx, now I feel more at ease knowing competent mechanics performed the job this time around. 2-Years unlimited warranty on parts and labor. I couldn't believe the amount of gasket maker in and around the mating surfaces on my older pump, the sealant got under the gasket in the groove!

 

Yeah, good thing that you got a warning with the leak. Like you said, replace the turbo oil lines at the same time (both of them), and both sets of gaskets on the oil filter housing/heat exchanger. Not a fun job, but not difficult either. It just takes a while to get all the heat shields off.

Enjoy your MINI once you get your hands back on it.

have fun,
Mike