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Mini Cooper, Time For A Refresh

Since getting the Mini, I have been using it a lot, but it needs a good servicing and to fix the coolant leak. I got around to doing it the past couple of days.

After topping up the coolant and unblocking the overflow bottle the car has been very reliable. It hasn’t overheated, even in the 30c heat the other day, but it has been slowly losing coolant.

The coolant was leaking from the stupid little plastic joiner for the heat hoses, with the bleeder screw on it. It was old, plastic and isn’t aging well.

Typical BMW stuff. The other issue was that the bleed screw kept seizing and the cross was stripping out. Every time the screw was tightened, the two parts of the coupling (which are joined together by a thin, hollow, plastic piece that allows air transfer between the two pipes) twists and it was breaking the plastic.

The first step to fix this is to get the car in the garage, and in the air. This is the first car I have managed to get up onto the ramps without them shooting halfway across the garage.

This is the little beasts engine. Not much power, but a lot of fun.

The plan was to drain the “coolant” in the system, refill, add radiator flush, run it for a bit and then drain it.

To drain the coolant, you need to remove the little plastic cover under the bumper so you can access the lower radiator hose.

The R50 doesn’t have the extra under covers like the R53 does. This cover is held on with a captive Phillips head screw on each side

And then three or four 10mm bolts under the front edge of the bumper. You don’t need to remove the Phillips screws, just the bolts.

Then you have access to the radiator hose. The Mini doesn’t have a drain plug, so prepare to get messy.

Undo the hose clamp, pull the hose off and with a big gush, coolant goes everywhere except your drain pan. Good thing I got that big drip tray, it’s a shame that when it’s full of liquid, and you try to lift it and tip it into the drain pan, the liquid will literally go EVERYWHERE but the pan. Rolling around in smelly brown muck isn’t fun.

This is the muck that came out. I suspect looking at it, that it’s not coolant at all, but bloody stop leak. Someone knew it was leaking coolant and tried to fix it with crap in a bottle. Obviously it didnt work.

I refilled the system with water and radiator flush, ran the engine for as long as I could with it still leaking (in hindsight I should have replaced the broken part first, and then flushed it) and then dumped it out again. It was getting cleaner, but still gross and brown.

With the system drained, it was time to tackle the coupling. Here it is, in its glory. You can see the coolant that has leaked out of it

This is where I got pissed off. BMW/Mini uses these stupid “constant tension” hose clamps that you can see above. They are a spring clamp with tiny little tabs that need to be pressed together to open the clamp.

I tried every single pair of pliers I own in an effort to release the part, but they just didn’t cut it. A couple of them could open the clamp but couldn’t move it without slipping off the tabs.

I spent two hours trying to find a pair of the correct hose clamp pliers. Everywhere from mainstream parts shops, to engineering trade shops, and no one had them in stock. I ended up ordering this pair for about $70 from Supercheap

Seriously. This was a revelation, having dealt with stupid hose clamp things using just pliers in the past, these pliers make it so easy. The one on the right is what I used for the Mini hose clamps. I’m not sure what the ones on the left are for, but I’m sure I will work out an alternate use some time in the future.

Within minutes of opening the package, the hose clamps were off. They ratchet to hold the clamp open, and don’t slip off.

These clamps were the easy part. Whoever designed the hose clamp placement on this was a sadist. The top clamps were OK, they point upwards. The clamps on the bottom hoses, were completely upside down so you cant get the pliers onto the tabs.

To make enough room to work this issue out, I removed the battery and its mounting box. Its pretty easy to remove. Remove the battery, and lift the DME (commonly called an ECU if you aren’t working on a German car) out from its slot next to the battery. There is a tab on either end of the DME that needs to be moved so you can lift it out, and then remove the plugs. With that out, the box is held in with three 10mm bolts inside the box, and one 10mm bolt on the outside of the box between it and the air filter housing

With the box out, we have space

I removed the top hose from the thermostat to give me more room, and then to remove the lower hose clamps I removed the hose from the fitting on the head (circled). This allowed me to twist the whole lot sideways so I could access the clamps.

And then refitting was a matter of just carefully slamming it all back into place. One thing I changed was to align the lower hose clamps so they can be accessed from the side. The battery box may need to be removed to access them, but at least it will be easier.

This is the old crusty rubbish

With the coupling in place, and all the clamps sorted, it was time to fill the system up again for one more flush. I just used plain water this time, and it came out mostly clean.

Since I ran the engine, the water in the system was pretty warm now, so whilst I waited for that to cool down so I could drain it safely, I chose to drain the engine oil. I picked up a new sump plug the other day, as they have an integrated rubber seal, instead of a replaceable washer like a normal car.

The old sump plug (which is 1/2″, weirdly) had been reused a couple of times and almost all the rubber was gone from it. It was also stupidly tight.

Whilst that was draining, I set about opening the oil filter housing. The housing is tucked away behind the exhaust manifold.

How tight should an oil filter housing cap NOT be? This tight. A massive 34mm socket, a 1/2″ breaker bar and my jack handle. Even then I still had to lean hard on it.

Big socket

If you wind the cap off most of the way, but don’t remove it, the oil in the housing will mostly drain back down into the sump, and out the still open drain hole into your pan. Makes far less mess this way. One warning though, being tucked up under the exhaust manifold the oil filter cap gets bloody hot, and takes some jiggling to get it out. It made my hands tingle for sure.

The old filter was pretty black, but otherwise looked good. I pulled it out of the cap and gave the cap a clean. Take note of the cage in the middle of the cap. It was stuck in the filter for me, so I removed it and seated it over the big spring. It clips in place, and it MUST be refitted to the cap or you will not have oil pressure.

In went the new filter, and on went the new O-Ring. The filter has a bigger hole at one end, this is the one that pops over the cage.

Remember to lube up the O-Ring, and then refit the filter and cap. It should only be torqued to 18ft-lbs which isn’t much, so no idea why it was so hard to remove.

The engine takes about 4.5L of oil, so I picked up some trusty Valvoline Synpower full synthetic 5W40. It comes in a handy 5L pack, so in went about 4L

I fired up the engine, the oil light went out quickly and everything sounded good. The oil level was a little on the low side, so I added another 500ml to bring it to full.

Success, now for the next part. I checked the spark plugs the other day and noted that they were genuine BMW, so probably pretty old, and looked very worn. They are this weird type where the center electrode barely pokes above the ceramic, even when new

I did some digging, as I didn’t want to pay $25 a spark plug, just for some fancy pants long life platinum things. The spark plugs on the Mini are SUPER easy to access, so replacing them every 20,000km or so isn’t an issue, and it’s hardly a high performance engine. I did some digging and found that NGK lists the BKR6E spark plug as an alternative. I checked all the relevant details like length, thread, reach etc, and they all worked out the same as the genuine plugs, so picked up a set. About $8 each, far more reasonable.

It turns out the Mini was running two different types of genuine plugs. Two Bosch and two NGK. Not ideal

In went the new plugs, gapped to around 0.8mm as per spec, and then it was time to get serious with the coolant.

First the coolant bottle got a quick scrub with a rag and screwdriver to clean out any residual gunk. It came up really well considering.

Everyone wanks on about using “genuine BMW coolant”, but at the end of the day there are plenty of compatible coolants out there. The cooling system in this isn’t made of magic, its plastic, rubber and aluminium. Just like most other engines.

Because I wasn’t 100% sure what was in the system to start with, I wanted to be sure that I could mix with it. The only important thing with coolants is to not mix types. I picked this Prestone coolant up because it can mix with all types, without issue. It’s also friendly with modern engines.

I drained the water, buttoned the system back up again, and opened the bleed valves. I mixed up a bottle of 50:50 coolant and poured it slowly in. It’s a weird yellowy green.

There are three bleed valves. The one at the back that I just replaced, one in the front right corner of the engine, and one stupid tiny little one tucked up under the inlet manifold

The third one gets everyone. It’s almost impossible to see unless you know what you are looking for, and it isn’t like the other bleeders. This one is a little 8mm bolt. The stupid thing is that unlike the other bleeders which have a slot in the thread to vent the air, this is a normal screw and needs to be completely removed to vent. If you drop it, you better hope you have a magnet stick nearby to go fishing. I did it twice. If you’re lucky, you can stick the screw carefully to the magnet stick and use it to screw it in a couple of threads. In the end I used a long extension with a socket on it so loosen the screw right off, and carefully wiggle it to let it vent before screwing it back in.

This is where it is. In front of the engine, to the right of the dip stick

With the bleed valves open, the coolant going in will push the air out. Keep pouring it in until the coolant starts to flow out. Then I ran the engine for a bit to bleed more air out.

I ran it up to temperature, and opened the valves a couple more times to burp more air.

I’ll check the coolant and bleed valves again tomorrow, but we should be good to go. A quick drive shows the engine feels a bit punchier, and runs nice and smooth. Its also quieter at idle. According to the sticker it’s been around 10,000km and 12 months since the last “service”.

Before I wrapped the work up for the night I gave the engine bay a quick wipe down with some 303.

Its’ come up pretty good. The whole car needs a clean, but that will have to happen after British Car Day now, as the Rovers need my time.


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