Distributor Bearing
 

In 2008 I bought a used 1993 Civic DX with 185k miles on it. Inside the distributor cap was what Honda enthusiasts call "the red dust of death." This is a slightly oily film of rust-colored dust adhering to the inside of the distributor cap, and it is from the distributor bearing. The red dust indicates bearing failure is near. The popular and reliable fix is to replace the distributor housing. Doing so gets you a new bearing, shaft, three sensors mounted inside the housing and on the shaft, and the wire harness. All of these can age and so not work well. The OEM distributor housing costs $100 and up and may be worth it to get better performance from your old Honda. On the other hand, many on the net attest to replacing just the bearing, the shaft oil seal, and the o-ring, and then cleaning the inside of the housing. I did the latter. Steps follow.
  1. Two electrical connectors (8-pin and 2-pin) attach to the distributor. Disconnect them. Removing the brackets on which the connectors sit helps. Note that Honda's electrical connectors are often persnickety. Sometimes just figuring out how to unfasten them is the most annoying part of a repair. I think the connectors often stick due to vacuum, too. I almost always use a tiny screwdriver to probe and nudge the connectors apart.
  2. Disconnect the ignition wires and remove the distributor cap.
  3. Write down the position of the rotor as 5 o'clock, 7 o'clock, or whatever it is. This is an important step to help in re-assembly later. Remove the rotor. This may require a little prying with a screwdriver. Try not to mar the plastic finish of the rotor.
  4. Remove the three distributor housing hold-down bolts. They require a 12 mm socket.
  5. Gently pull the distributor straight out towards the passenger side. It should disengage from the camshaft fairly easily. Set it on a workbench.

  6. For the next steps, use a vise where you feel it will help. The photo below of the outboard side will help you identify parts. (Thanks to "an2ny888" of honda-tech.com for the first draft of the photo below.)
  7. On the outboard side of the distributor, remove the following:
    • the ignition coil (two electrical connector screws and two screws attaching the coil directly to the housing, all phillips head)
    • the CYP sensor coil (two phillips head screws)
    • the igniter (four electrical connections and two phillips head screws)
  8. Remove the CYP sensor rotor. This is also known as the CYP sensor reluctor. It is a non-symmetrical steel piece mounted near the outboard end (= ignition wire end) of the distributor shaft. See the drawings and photo on this page. The easiest technique for removal is to use two screwdrivers as shown in the drawing below (CYL is the same as CYP here). The drawing below is from a Honda factory service manual, so presumably this is a Honda-accepted method. I wrapped the screwdriver heads in cloth so I would not mar the mounting plate. Do not pry against either the CYP coil, the igniter or any wires. A drop of the penetrating oil "PB Blaster" applied to where the reluctor mates with the shaft may help, but do not get oil on other parts.


  9. Look at the inboard end of the distributor, and refer to the drawing below. Sketch and save the orientation of the coupling relative to the housing. The coupling can go on two ways. You want to get it on the right way when re-assembling. Use a small thin bladed screwdriver or two to pry off the retaining ring (a.k.a. "pin retainer") on the coupling. Push the pin out of the coupling with a small diameter rod or similar. Remove the coupling. Do not lose the two thrust washers.

  10. At the outboard end of the distributor, remove the three phillips head screws holding the mounting plate fixed to the housing. The photo under step 5 shows one of the screws.
  11. Pull the distributor shaft out of its housing by hand. At this point only a little adhesion from the oil seal should be holding the shaft in place, so at most a light tap with a small hammer on the inboard end of the distributor shaft should free the shaft. The shaft will now have mounted on it in order from outboard end to inboard end: Mounting plate, bearing, bearing retainer (three screws), CKP reluctor (a.k.a. crank rotor, a gear shaped piece of steel), and TDC reluctor (a.k.a. TDC rotor, a symmetrical shapped piece of steel).
  12. Measure and record the location of the mounting plate on the shaft relative to one end of the shaft. This is important for re-assembly. It will locate the new bearing correctly.
  13. Turn the distributor shaft so the inboard end is down. Set the distributor shaft on (not in) a vise so the mounting plate sits on the vise and supports the shaft assembly. Use a piece of wood to protect the top end of the shaft, and tap on the outboard end until you see the mounting plate (with bearing and bearing retainer) free up. The mounting plate, bearing, and bearing retainer should slide off after a few more taps.
  14. Remove the three jeweler's size phillips head screws from the bearing retainer, and remove the retainer and then the old bearing.
  15. Wipe off all parts. Compressed air may help to get dust out of the housing. Replace the old bearing, oil seal, and o-ring. Assembly is the reverse of removal. Use sockets and/or scrap pipes or other scraps to tap parts into place. Make sure the mounting plate and new bearing are in the position recorded in step 11. For the CYP, CKP, and TDC sensors, check that the reluctors all align with their respective coil magnets. Before re-coupling the distributor shaft to the camshaft, make sure the coupling and rotor are in the positions recorded in steps 3 and 8.


FAQ

Where can I buy the bearing in 2008?
The old bearing had "6001/12.46 PX1" stamped on its side. As other web sites note, this means my Civic needs a bearing with a 12.46 mm bore. I checked local bearing shops, Napa, and a number of online companies suggested on the net in years past. The only place I found that carries this oddball bore is http://www.cbrbearing.com. The salesperson there was very helpful. CBRbearing charges about $20 for the bearing and "a few bucks" for shipping. The alternative is to go to the junkyard and roll the dice on a bearing you get from a secondhand distributor there.

Where can I buy the oil seal in 2008?
The cbrbearing.com salesperson thought they'd have the oil seal, too. He said it would also run "a few bucks." Alternatively, several online sites sell the seal. See for example http://www.bestautojobs.com/shop/ignitionbesthonda and http://market.autopartsfair.com/honda-engine_parts . Both of these wanted about $9+ shipping cost.

How careful do I have to be when I tap or pound on the distributor shaft and reluctors?
The reluctors (also known as sensor rotors) are the three metal pieces mounted on the distributor shaft, aligning with the coils of the CYP, CKP, and TDC sensors. I practiced on a few shafts at the junkyard before attempting my Civic's. The practice helped a lot, so I did not have to pound so much on my own Civic's dizzy shaft and reluctors. But I did pound a bit. I also used a gear puller to assist in removing and moving sensors when I was, uh, exploring the distributor's construction. But if you are only replacing the bearing, oil seal and o-ring and cleaning things up, then you should not have to move the CKP and TDC reluctors. My Civic's CYP and CKP sensors' reluctors in particular have a number of little dents in them now, but they are working fine.

Do the reluctors have to be located on the shaft in their exact same original position?
Yes, with some qualifications. On my first attempt, I did not understand very well how everything came apart. Nor did I understand how the three sensors worked. By mistake, l moved all the reluctors when I took the shaft apart . I was using gear pullers and pounding a bit. (This turns out not to be necessary. A little tapping here and there should get the bearing off and on. The CYP reluctor likewise requires only a little tapping to re-install.) Despite trying to return the reluctors to their original positions, I was ham-handed, and when I finished the first time, the reluctors did not align well with their respective coils. I knew they were off but was not sure how to fix it easily or whether it would be "good enough." I went ahead and started the car. The engine sounded okay, but the Check Engine Light (a.k.a. MIL) lit. The computer threw a Code 9, CYP sensor. I checked the UK site's manuals and found directions for doing a cursory check of the sensors. They passed. I scratched my head, researched the meaning of "reluctor," and figured the reluctors maybe could not send a strong enough signal if they were not near perfectly aligned with their coils. This was indeed the problem. I took the dizzy apart again and moved the reluctors and the bearing, this time using all the shortcuts I had now acquired. Within 1.5 hours, all was well. The code went away.

Where can I buy a gear puller suitable for gentle nudging of the bearing?
I used the intermediate gear puller in the three puller set Harbor Freight sold for under $20 in 2008. All the pullers in this set are three-jaw.

Must I get a 12.46 mm bore bearing? Or will a 12 mm bore do?
I do not know. I do wonder whether one could get away with a 12 mm bore bearing instead of the 12.46 mm bore bearing. Worst case, it seems to me that the 12 mm one would not slide as far down the shaft, but one then might be able to reposition the reluctors and the shaft relative to the housing, slightly, to deal with this. On my first attempt, at least one of the reluctors was incorrectly positioned by around 1/8-inch, and the shaft itself was about 1/8-inch off from where it should have been relative to the housing, yet the car still ran. Still, I do not have a good understanding of bearing clearances and tolerances, so I could be wrong.

Why not just buy a new OEM housing?
Sure, the housings are plenty cheap costing around $100 to $250. This repair is a project for the hobbyist or the person on a budget. One will understand the distributor's internals much better after it. Getting the distributor apart was not very hard, especially after practicing on a few in a junkyard. Various DIY online sites, the UK site's free online manuals, and various Honda OEM parts sites all helped a lot.

Do the sensors degrade over time?
I think so. From reports on the internet, failures of the three sensors do occur but not often. I wonder whether the distributor can go on indefinitely by just periodically replacing the bearing, oil seal, and O-ring and cleaning dust and oil out of the housing. Or do the sensor coils wear down over time, from heat fatigue, say? Or maybe the insulation on the wiring to the sensors degrades with all the heat, oil, and dust applied to it? The sensor reluctors are just machined hunks of steel, and it seems to me they might last forever. I think replacing the distributor housing every 10 years/150k miles (whichever comes first) is good practice, if only to get all new sensors and housing wiring.

Are aftermarket distributors any good?
First, as  noted above some Civics' OEM distributor housings were running only about $100 in 2008. If I wanted my Honda back on the road as soon as possible, and I had a Civic whose new OEM housing ran only $100, then I would just buy a new OEM housing. If your Honda has one of the more expensive housings, then consider Ebay's Distributor King. One can buy three full distributors from Distributor King for the price of one new OEM distributor. Distributor King's distributors have received mostly favorable (though not perfect) reports by users at wwww.honda-tech.com.

What are some other resources for this job, preferably with photos and drawings?

  1. http://www.e-hatch.com/forum/viewtopic.php?t=110 , though I do not agree with the step where the bearing is actually removed. You should be able to leave the jeweler's screws in place and tap the mounting plate, bearing and bearing retainer from the shaft, all as one assembly.
  2. http://www.angelfire.com/ca/DrOhm/distributorRepair.html
  3. http://techauto.awardspace.com/content/distributorexploded.php
  4. How the CYP, CKP, and TDC sensors work: http://www.megamanual.com/ms2/pickups.htm