The crank pulley on an R53 takes power from the crank and supplies it to the serpentine belt, in turn feeding the alternator, AC compressor and Supercharger/water pump. It is a rubber-filled damper and this part is known to fail on the R53 around 80-100k miles (or 72k miles in my case). When mine died, I lost AC cooling, then got the battery/charge light on the dash, then overheated the coolant and had it boil over the coolant expansion tank, causing a nasty steam to rise from the cowel vents. Luckily this happened as I was pulling into my driveway, so I didn't even need a tow and my car was off of the road for only 4-5 days while parts were on the way.
What you will need to complete the pulley swap:
- About 2 hours of free time
- A flat-bladed and a Phillips headed screwdriver
- A long-arm 2mm allen wrench
- A new belt if you havent replaced it recently (past year). For my 16% reduction pulley, I use the Gates brand belt (Part K060539) that is slightly shorter than the stock belt. The JCW engine kit has a unique OEM part that will work with the JCW pulley or your local MINI parts desk can provide you with a new belt, should you still have the OEM pulley in place.
- The MINI tensioner tool
- A belt routing diagram (see Figure 3, below)
- A pulley puller - I bought the 3-arm generic puller from my local auto-parts store for $18
- 3 M6x75mm bolts for the puller (it came with several different bolts, but not this size). I got these at Home Depot in the section with drawers of screws/fasteners. It also took a handfull of washers to build out the top of the bolts so that they wouldn't fall through the slots in the puller.
- A new pulley. I chose the ATI SuperDamper from Way Motorworks: http://www.waymotorworks.com/super-damper-crank-pulley-r53.html
- A new crank pulley bolt. You can get this from your parts counter, but since I already had an order in with Way, I had him send me one for $4: http://www.waymotorworks.com/r50-r53-crank-pulley-bolt.html
Start by parking the car with the steering wheel turned all the way to the right. Leave the car in first gear (or in park for you MCSa drivers) and apply the parking brake. Loosen the lug bolts on the front, right wheel by ¼ turn each and lift the car using the factory jack in the boot of your car or a floor jack. Secure the car on a jack stand or use some other means to ensure that the car won’t drop all the way down to the ground should the jack fail. Remove the front, right wheel and gather your tools. If you are doing the work on the side of the road because your belt broke while driving, slide the wheel and tire you just removed under the car to catch it should the jack slip. It’s better to dent a wheel than to get trapped under the car. Safety first!
Figure 1: You will need a Phillips screwdriver, a flat-bladed screwdriver, a long-arm allen wrench (a 2mm worked well for me), the tensioner tool (across the top) and these instructions
Step 2: Use the flat-bladed screwdriver to remove the four plastic ‘rivets’ that hold the front of the plastic wheel well liner in place. Remove the one Phillips head screw that holds the wheel well liner in place, directly over the axel. You also have to remove a Phillips head screw that is just under the front bumper, near the fog light area that holds the front of the liner in place.
Figure 2: Remove the fastners marked by the red arrows. When you peel the large plastic wheel well liner back, be sure not to get tangled up in the brake sensor wire, marked with a blue arrow.
Step 3: Gently pull the front of the wheel well liner away from the body of the car. There is a sensor wire that tends to get in the way, so carefully move it aside (see the blue arrow in Figure #2). The liner has lots of give, so just flex it up so you can see the side of the motor, the belt and the pullies. You can’t see the entire side of the engine because the frame of the car is in the way, but you have an inch or so of space to work in there. It’s tight, but there is just enough room to do the job.
Figure 3: The wheel well liner flexes up and out of the way, giving you access to the supercharger belt and the crank pulley (the black circle hiding just above and to the right of the brake disc)
Note that the belt has grooves on one side of it. These grooves help provide traction to the belt and it is important that your new belt be installed with the grooves facing the same direction. In the diagram, below, the tick marks on the belt show the side with the grooves.
Figure 4: Here’s a close-up of the wheel well area so you can get oriented (see the brake disc in the lower left corner). It’s easy to get lost when installing the new belt, so this diagram will be useful. The tick marks on the belt show the side with the grooves. You can’t see all of the pulleys from this angle, but I’ve marked their approximate positions for you.
Step 4: Look down at the belt from the top of the engine bay (Figure 5). You can see that the upper-most pulley is covered by a metal cover. This is part of the tensioner assembly. There are 2 pins on the tensioner tool that slide into the side of this cover. The cup at the bend of the tensioner tool sits on a large bolt and uses it as a pivot point. Fit the tool onto these points and pull down on the handle of the tool slowly to get an idea of how it works. It slips off very easily, so be careful and take your time. The tensioner spring is very strong and you don’t want to get your fingers caught in there!
Figure 5: Looking down at the passenger side of the motor from the engine bay, you can see the tensioner pulley cover (and the pulley underneath it). You can see the strong spring that keeps the belt tight and the metal strap that runs out the top of it. Locate the large bolt on the front side of the tensioner cover so you know where the cup of the tool will be placed.
Step 5: When you push down on the tool, you will notice a small metal strap at the top of the tensioner assembly. There are 2 holes in the strap that are visible once you pull the tool all the way down. Take the 2mm long-arm Allen wrench and slide it into the second hole. You can now release the pressure on the tensioner tool slowly and the Allen wrench will lock the tensioner safely out of the way. Don’t try to cheat some time by skipping the locking step… one slip and your fingers are crushed!
The first hole is a handy thing to know about. On cars with a healthy supercharger belt, you will see at least ½ of the first hole when the engine is off. On cars with worn or stretched belts, you won’t be able to see this hole at all and you know that it’s about time to do the replacement.
Figure 6: Here is a picture of the Allen wrench inserted into the second hole of the tensioner spring strap, removing the tension from the belt and making it ready for replacement. You can see the first hole above it. That hole should be at least 1/2 visible when your belt is in good shape and under tension. If the spring covers more than ½ of that hole, it’s time to replace your belt.
Hint: I've started taping the allen wrench to a long handled screwdriver. It makes it much easier to guide the wrench into the hole when you have a longer handle to work with.
Step 6: Once you are sure that the tensioner is locked, take one more look at the path and orientation of the old belt and then remove it from down in the wheel well. Replace the old belt with the new one by feeding it up from the wheel well and hanging it over the pulleys.
Figure 7: Get your tools together to pull the pulley. Here you can see the puller tool that I purchased (which works just fine) and the M6x75mm bolts that I got from Home Depot (plus a few washers to make sure the bolts don't fall through the slots in the puller tool).
Step 7: Now we need to get to start working on the pulley. Remove the 15mm bolt from the center of the old crank pulley. When you try and turn the bolt, the crank will turn, making your job difficult. MINI makes a $120 tool that you can attach to the crank to hold it still, but I zapped it with an impact wrench and the bolt came right off. You can also use a bar to brace the wheel hub (see pic below) or have someone press the brake.
Figure 8: Getting the pulley puller ready to go
Step 8: The ATI SuperDamper comes with a long bolt with a hex head. Install it where the old crank pulley bolt was. Tighten it until it hits bottom, then back it out 3 revolutions. If you leave it all the way tight, the crank pulley will hit the bolt head before it has been completely been removed from the crank spindle. If you try to pull the center bolt on the crank puller now, it will tighten the hex head bolt first, before starting to remove the pulley. That's why, in the second pic of Figure 8, you can see that I added a pair of vice grips. The vice grips keep the bolt from tightening as the puller does its job. Once you get the vice grips in place, tighten the center bolt on the puller and remove the stock pulley (an impact gun made this VERY easy).
Step 9: Once the old pulley is off, check the crank spindle for any burs/nicks and clean up with a bit of fine-grain sand paper. blow out the crank bolt hole and degrease the pulley and the crank spindle with solvent.
Step 10: Get all of your tools ready. You will have to work quickly (but carefully) for step 11, so have everything laid out in advance.
Figure 11: Cooking the pulley.
Step 11: The ATI instructions say to pre-heat the pulley on a hot-plate. I put the pulley in a thick-walled iron pot and set it on my stove on low. I warmed it for 5 min, until I could hold the pulley in my hand, but it was warm enough that I wouldn't want to hold it for long.
(edit) On a newer thread on MA, a bit more information came to light. The poster spoke to ATI who said that the pulley should be heated to 250-275 degrees F. He put the pulley in an oven set to 250 for 10-20 minutes and the pulley slid right on to the final installed position by hand... no need for the first bolt and washer in step #12, below. If your pulley does slide on fully, you can go directly to the final crank pulley bolt, tighten and torque as described. (/edit)
Figure 12: Even if you have an impact wrench, you will eventually need to brace the wheel hub so it won't spin. Since I don't have someone to hold the brake pedal for me, I used an ice chopper as an arm, pinned between the wheel studs, to stop the wheel from spinning as I thghtened the crank pulley bolt
Step 12: Mount the new pulley by hand and use the long bolt and washer supplied by ATI to pull the new pulley on to the crank (by hand... this is not the time for the impact gun). When it hits bottom, remove this bolt and washer and use the new MINI crank bolt. Tighten to 85 ft-lbs torque.
Step 13: Replace the belt. I find it easier to start by hooking the belt over top supercharger pulley and working my way down, ending with the smaller idler pulley in the center. It should be a fairly snug fit. If you have a bunch of slack, go back to Figure 4 and check your belt path… I’d bet that you have missed one of the pulleys. Just go back, check the diagram, and try it again.
Step 14: Use the tensioner tool to remove the pressure on the Allen wrench and remove it. Gently lower the tensioner back down onto the belt. You should feel the belt take the pressure and the belt should become taught.
Step 15: Replace the wheel well liner, being careful to return the sensor wire to it’s normal position. Replace the 2 Phillips head screws and the 4 plastic rivets. Remount the wheel and carefully lower the car back down to the ground. Once it is back on all four wheels, be sure to torque the wheel bolts to the correct values for your car.
UPDATE: OK... I wrote this article some 4-5 years ago. Since then I sold my first R53, Jango, because of a move from Dallas to San Francisco. After 3 years in San Francisco, we moved to Charlotte, NC where our automotive and garage situation was such that I adopt Rufus, a 2005 JCW with 83k miles. I'm in the process of updating / refreshing Rufus and I decided to replace the stock crank pulley with an ATI unit as a preventative measure (while also replacing the idler pulley, belt and belt tensioner assembly). A few things I learned doing this job for a second time:
1) An easier and more accurate way to pre-heat the new ATI pulley before install: Bake in your oven at 250 degrees for 20 minutes.
2) Way Motorworks now sells a crank pulley puller. I had given my generic one and the handful of bolts that I bought to someone back in Dallas with the instruction to pass the tool around the local MINI club to help wherever they could. Way's is $69, which is a tad bit expensive, IMHO, but I didn't want to go through the hassle of assembling a tool set to do the job (the one I bought years ago probably cost $25-30), so I paid up. I've got to admit that it made the job very easy. You remove the stock bolt (a pneumatic impact wrench makes this so much easier), thread a stud in to the hole, screw some small bolts into the pulley, through the large plate and then thread a bolt with a ball bearing on the end through the large plate until it contacts the top of the stud. Tighten that center bolt (again, the impact wrench comes in handy) and the stock pulley comes right off.