On my ride into work yesterday morning, my '03 MCS decided that I needed a little excitement in my life, and began cycling through overheating and returning to a normal temperature...over and over again. While the car was overheating, I had no heat blowing, then when the temperature returned to normal, heat would blow hot. This immediately had me thinking heater core or water pump, possibly the thermostat.

After limping her home last night, I popped the bonnet to find that the expansion tank appears to have failed...as there was coolant dripping off the bottom of the tank, and the heat shield directly below the tank, and pretty much everything below/behind the heat shield, was covered in coolant. This was good news to me, as it's a much cheaper & easier part to replace. It just accelerated my timetable for doing some work on the car I had planned to do next month.

So when I replace the expansion tank this weekend, I am also going to replace the radiator fan, as the resistor for the low-speed fan has failed. This is where I start getting into a lot of the "I'll be in there, so I might-as-well do" projects...

• Remove Intercooler & Clean, Replace I/C couplings
• Remove Supercharger & Clean/Change S/C Oil
• Replace Water Pump - I am assuming the water pump is fine (based on the expansion tank failure), but I cannot definitively rule it out as being bad.
• Replace Thermostat - Original, so I should probably do it as preventative maintenance.
• Replace Radiator Hoses - Original, they look okay, but if I'm draining coolant, this is my chance to replace them.
• Radiator - Original. The radiator seems fine, so I'm debating whether I do it or not, but if I'm in there...

I am definitely making a bit of work for myself, but like I said...I'm in there, so I feel like might-as-well do these things as preventative maintenance. So, I guess my question is, is there anything there (aside from the Intercooler/Supercharger maintance...that is being done) that seems over-the top or unnecessary? Or I guess, anything that I am missing?

Thanks,
Steve

 

You MIGHT have a failed headgasket from your description....
And after multiple overheats, it would be expected, just like head and deck warpage...
Overheating is death to a motor....think you need to fix the issue that caused the overheating....then fix the dammage from the overheating....then "overhaul" it to restore capacity...
since the overheat resulting in loss of heat...i am guessing the issue is a head/gasket issue.

 

From what you have here I'm not so sure it's an expansion tank issue. If the system did over heat it sounds like the coolant tank cap did it's job and released the ever increasing system pressure venting coolant as needed. So may point back to thermostat (common) or water pump (less common). Please keep us posted!

 

Good point. I'll take a closer look at the expansion tank. That the bottom of the expansion tank was covered in coolant, and the top was clean leads me to believe the tank failed though. Regardless, for $65 I'll replace it, along with the water pump, thermostat, and my cooling fan with failed low-speed fan, along with a few other maintenance items.

It'll be a weekend of turning wrenches

 

That's always a good time! I will be flushing my coolant system this weekend and get to use my new Uview Airlift to fill it so I have that to look forward to this weekend.

Good luck with your repairs.

Cheers

 

Well, it's been a fun week, unfortunately, I am not quite done with my overhaul. This has turned into a pretty big project...not that it's difficult, just time consuming. I ended up ordering some additional parts to do some additional work while I had the front clip of the car taken apart, and I am awaiting the arrival of those parts, but hopefully, but this weekend, I should have my MINI back on the road...and running nice and cool .

So here's what I've got going...

I found that the original coolant expansion tank was leaking, since coolant had spilled out all over the heat shielding above the exhaust headers. Nothing like that lovely sticky-sweet smell of coolant all over the engine bay . So I replaced the expansion tank with a new OEM unit...$60 from the dealer.

I also replaced the thermostat ($30 from the dealer), and checked the thermostat housing to verify it was not warped, cracked or anything like that. It looked very good, so I cleaned up the housing, and got that all put back together.

Since the coolant hoses were original, and the ends had gotten quite brittle, I am replacing them for a set of Venair silicone hoses from OutMotoring...and for pretty much the same price as a set of replacement OEM hoses. I have 3 of the 4 hoses hooked up now, the hose attached to the water pump will be the last to go on.

While I had the airbox out (in order to access all these items), I also took the opportunity to clean up the intake hoses and the airbox itself. It's amazing how much debris accumulates in there.

All that was done by Saturday morning. Now I am waiting on my belt tensioner tool, a CravenSpeed 15% pulley, a S/C pulley puller, and an ALTA tensioner stop. Since I'll have the supercharger off to replace the water pump, and re-oil the supercharger again, I figured I might as well do that pulley upgrade I've been talking about for years.

I also threw in an ALTA pulley tensioner stop to add since I'm right in there. Some peace-of-mind so that when that part fails, it doesn't grenade other components. Once I have the supercharger re-oiled, re-pulley'd, and the water pump replaced, I can reinstall the supercharger, replacing the profile gasket, add the new drive belt, and I can start re-assembly!

A new JYC radiator cooling fan ($80 from RockAuto...I could not justify $300+ for a part that WILL fail again), since the resistor on my original fan died. Although, I ended up having to swap the JYC fan, into the original fan shroud as I snapped off one of the mounting brackets on the JYC shroud. Then a new Mishimoto radiator will sit in front of that fan.

Once everything is hooked up, I add new coolant, verify everything is running smoothly, and finish getting her buttoned up.

Like I said, this turned out to be a bigger project than I was planning, but it's always enjoyable turning wrenches. I'll even try to post some photos...although I think all of these projects have been covered ad-nauseum here at NAM. Even so, maybe it'll help someone in the future.

With all this, I even found my next project...replacing the crank-case/valve-cover gasket. I found that had been the source of an oil leak I've been chasing down since I replace my control arm bushings a few months ago. I think that one will go down later this summer though...with my next oil change. I'll just be checking my oil level a bit more frequently until I can do that repair. The list never ends...

 

 

All this without checking head gasket? Check for signs of mayo in your oil before you button everything back up. And oh, if you haven't changed your stock harmonic damper, an ATI or PRW should be part of "while-you're-in-there" work.

 

Head gasket is fine...no coolant in the oil, or oil in the coolant. I've checked...repeatedly.

Yeah, a harmonic damper, lightened crank pulley...lots of stuff would be nice o do while I'm in there. Unfortunately, I have to draw a line somewhere, as that money tree I planted isn't yet sprouting $100 bills.

 

Just sharing from experience. Helped a friend replace his dead pulley, an '05 w/ just 20+k mi. I pushed my luck on postponing the damper upgrade til it failed on me on the road, too @ 40+k mi......regrets always come late. And, go for a dampened one.

 

Yeah, such is the price of car ownership. Stuff breaks, and we get to fix it. It would be nice if we could do everything we wanted, whenever we wanted to...I gave up that option when I decided to get married and have two kids though.

 

Totally can relate as we've 4 ourselves.
Feel blessed to have been an OCD mech engineer's son, having been exposed to all his ingenious backyard machine shop projects growing up. Rubbed on me the value of overbuilding & preventive maintenance. The limited knowledge learnt has been quite useful for our cars' DIYs. Imagine if we had to rely on the dealership for everything......
Glad you don't have the head gasket issue. Your plans are sound. Hope you get everything done soon w/o hitches!

 

Well, after about 20-odd hours worth of work, I have a new coolant expansion tank, new thermostat, new silicon radiator hoses, new water pump, a supercharger with fresh oil and a CravenSpeed 15% reduction pulley, an ALTA tensioner stop, some new ALTA silicon intercooler couplers, a new Gates drive belt, a new radiator fan, a new Mishimoto aluminum radiator, and of course fresh coolant running thru her veins.

But most importantly my MINI is running cool as a cucumber again, with a nice little bump in power...and that supercharger whine!

All-in-all, it wasn't necessarily difficult work...the most difficult thing was getting the new radiator hoses and hose clamps fitted, then getting the supercharger and water pump re-installed as one unit. I had to remove the intake duct between the supercharger and the throttle body to get them re-installed as a unit (after unsuccessfully trying to re-install them separately). But I can certainly understand why a dealer would charge so much to replace the water pump and thermostat...it's all the labor. But for what the dealer would have charged me to do just the water pump & thermostat, I as able to everything above...and have the satisfaction of doing it myself.

Everyone I've showed photos, tells me how crazy I am for doing it myself. Maybe I am, and this was definitely the most extensive DIY automotive repairs/upgrades I've ever tackled myself, but it looked a whole lot scarier than it really was. And I saved myself a butt-load of money.

I'll post some of the photos I took during the process later today, when I have some time.