You may recall about 15 months ago I destroyed my stock crank damper (harmonic balancer) at the track. Well, a few weeks ago my pulley tensioner failed. Fortunately, the Alta Tensioner Stop did its job preventing a total mess and allowed me to safely pull off the interstate. The Tensioner Stop is designed to prevent collateral damage when a belt fails by limiting the range of motion of the tensioner. In this case, the failure was not the belt, but rather the tensioner arm itself which ended up machining itself into the ATI Super Damper (see photo at the top of the post) even as the engine continued to run on half a belt.
So for those of you who missed it the first time, here’s a revised DIY for replacing the crank damper (aka, harmonic balancer.) The good news is that it takes about half the time to do it a second time; the bad news is that I’m having to do it for a second time.
Give yourself two hours for this task, more if you’re replacing the original damper (and still more if you’ve never done this before.) This isn’t rocket surgery, but does require a bit more physical effort than most projects. Be sure to have all of the right parts before you begin: New damper; correctly sized Belt; and a new damper bolt. You will need a Serpentine Belt Removal Tool as well as a Crank Damper Puller which you can probably borrow from your local autoparts store if you don’t want to purchase one. Check the size of the bolts that come with your Puller kit. The stock damper has bolt holes that are deeply recessed in the damper so you’ll probably want some longer bolts. You’ll also want to pick up an additional M12 bolt that’s about an inch longer than the stock crank pulley bolt. That will help with both removal and installation as I’ll show below. Consider replacing the crank seal at the same time.
To get started, you will need to first place the front of the vehicle on jack-stands and remove the left road wheel. Remove the left wheel liner and remove the underbody panel from the front of the car. You do not have to remove the bumper cover, just remove the three bolts and two screws that holds the panel and it will slip out. Lock the pulley tensioner into position with a sturdy pin and remove the serpentine belt. If you plan to reuse the belt (belts should be changed every 2 years/30,000 miles) then mark the direction of travel on the belt so it can be put back in the same direction.
You should now have a clear view of your crank damper. If this is the first time removing it, spray some PB blaster or WD-40 and let it soak in a few minutes before you begin. This photo shows a stock damper. What you cannot tell from this view is that the half that spins the belt is no longer attached to the half that bolts to the crank.
Put the transmission in 6th gear (or Park) and wedge something between the seat cushion and brake pedal to lock the front wheels. (You may find that you need to put a couple of bolts in the holes and use a pry-bar for counter-leverage as you try to remove the bolt.) Use a long breaker bear with a 15mm socket and back out the crank damper bolt about half an inch. Now it’s time to attach the removal tool.
Center the removal tool on the crank damper bolt and attach in three locations using the stock holes or in the case of the ATI Super Damper below, remove three of the torx screws and attach there.
Ensure the tool is centered on the crank pulley bolt and evenly tightened to the three bolts. Tighten the center bolt and slowly remove the damper from the crank. Once you make contact with the head of the crank damper bolt, loosen the tool and back the bolt out another half an inch. Re-tighten the tool and back it out some more. If the damper does not slide off the shaft, remove the tool and remove the crank pulley bolt. Use the longer M12 bolt we told you to pick up earlier, screw it in at least half an inch, and reattach the puller tool. The damper should come free of the crank. Remove the tool, remove the bolt and inspect the shaft.
Check the crank seal for leakage and replace if needed. If you have a higher mileage car and don’t know if the seal has ever been replaced, consider doing it now anyway as preventive maintenance. Carefully poke a hole in the old seal, and use a probe to pull it out. Simply press the new seal into place or use a small wooden block and a hammer if you need a little more leverage.
Since you don’t want to come back to this part of the engine any time soon, check the idler pulley while you’re here. If there’s play in the pulley or if you’re approaching 100,000 miles, consider replacing it as well. It only costs about $50 and is an easy swap with a 13mm socket. Torque to 33 ft lbs.
The instructions that come with the new damper say to heat it in boiling water then fit it to the crank. I haven’t had a problem getting the damper on the crank in the past, so I usually skip that step. I do end up putting two bolts into the open holes and using a breaker bar for leverage so I don’t spin the engine when I torque it down. If doing it cold, you may need to use the longer bolt to get it started and then switch to the (new) stock bolt. People who have boiled the damper report that it slips part of the way on, and they can use the stock bolt only. Either way, torque the bolt to 85 ft lbs.
If everything is lined up, start the new belt at the crank damper and work it into place leaving the idler pulley as the last bit to fit. Have your helper pull the pin from the tensioner arm spring once you’ve relieved the pressure and slowly let the tensioner return to normal position. Start the engine and ensure everything is functioning properly. Shut the engine off and replace the underbody panel and wheel liner. Reattach the roadwheel, lower the car off of jack-stands, and torque the lug bolts to 87 ft. lbs.
Some parting thoughts: If you need a new crank damper, you do have a couple of choices to make. If you have a 2002-2004 model year MINI, just replacing your stock damper with the revised one from the 2005-2006 model year cars will save you a couple of pounds and spin up a little faster as well. If you track your car often, consider upgrading to an ATI Super Damper which is more robust than the stock damper while still offering harmonic balancing. The ATI damper is slightly lighter than the stock 05-06 damper which may help the engine rev faster. Light weight crank pulleys may make your engine spin up faster, but are not a good idea if value the longevity of your engine (though we have been using one on our trackcar for years). Read up on secondary imbalance before you decide if a light weight pulley is right for you.
