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Date:         Mon, 20 Jul 2009 16:38:41 -0700
Reply-To:     Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Subject:      What not to do when rebuilting a starter.
Content-Type: text/plain; charset=us-ascii

Executive summary:

Don't put too much grease on the rear bushing in the starter. A 27mm socket is of great help to slide the brush assembly onto the commutator.

Full story:

While the other Canadian's in Edmonton were suffering from the 30C heat and sunshine this Sat I spent some quality time in the pleasant shade under the bus. Runup to this was that cranking rpm were low, and the Diesel would barely start. What could be the problem? The new 100Ah battery not delivering the juice? My starter rebuild gone bad in only one year? (My previous rebuild lasted 10 years) Good old Joe at the autoelectric's tab welds of the new brushes gone bad? Brush holder broken again? (caused the death of my two previous starters. Luckily Joe found another used one for me.)

A quick check of cranking voltage showed 8V up front. This time I measured across the courtesy light; previoulsy have caused numerous shorts by stickingt he probes into the cig lighter socket. Time to go get another battery? Wait... BTDT before, wasn't the battery that last time. Get wife out to crank while I measure the battery terminals in the back. 9V over battery. Still not a stellar voltage. But the more important question is where is the missing volt going? A quick check of voltage across the ground wire shows 0.6V. I double it and cranking improves, but only marginally. Given the gauge and length of the wire I calculated the current to 2000A. Now that is a bit high even for a Diesel!

So out comes the starter. At least that is now a fairly quick procedure. Practice makes perfect. Loosen the stay that holds the clutch slave cylinder. Unbolt the two big (19mm) bolts holding the starter. Forgot something? How about taking off the electrical wires? (Luckily at least I had disconnected the negative battery wire.) With wiring disconnected the starter can be manouvered out by pulling down on the (now loose) clutch slave cylinder, and by twisting the starter around its axle and pivoting it upwards. Takes a bit of fiddling, but works well. Seems like I have forgotten how heavy a Diesel starter is. Good thing it didn't fall down on my face.

Quick disassembly of starter. (In driveway this time; last time wife was unhappy about marring the kitchen table...) An inspection of starter shows that bushings are still good; they ought to be after just one year. But what is that yucky looking stuff on the commutator? Looks like grease! Not good for conductivity. Off with the brush assembly; clean up grease with some naphta, and smooth brushes and commutator with emory cloth.

Now, I've always had trouble getting the brush assembly back on the commutator. Though I have five fingers and there are only four brushes I seem not to be able to hold all the brushes in and at the same time sliding it on. Bosch supplies a little plastic tube with the complete brush and brush holder assemblys. This does a good job, but I'm both to cheap to buy the whole assembly when only brushes will do, and I would lose the plastic tube before next repair anyway. So what to do? In the past I tried to keep the brushes spread with everything from toilet paper rolls (too weak) to can lids (don't come in correct diameter). Now on my third rebuild sitting in front of my tools, thinking what is a suitable cylindrical object with the rigth diameter? How about sockets? Yes, right there in front of me are numerous perfect cylinders from 10mm to 36mm in steps of 1 or 2mm! Turns out a 27mm was the perfect size. Just barely larger OD than the ID of the commutator, yet fits inside the brush holder. Made a 2min job of what used to take me 20 min.

Reassembly of starter. Only small dab of grease in rear bushing housing this time. (Last time I probably packed it full thinking more is better. Then when heated; those long crankings when I had a fuel leak maybe... the grease probably expanded past the bushing and onto the commutator). Test starter outside. Now spins up quickly. Back under bus and reverse procedure to install. Good weight training to lift kg's of starter in one hand while pulling against the clutch hydraulic cylinder with the other. Always a bit more fiddling to get it in than to take it out. Bolt on battery plus and exitedly crawl out to try. Turn ingition key. No cranking. Not even solenoid clunk. Doh, forgot the wire from the ignition switch. Back in the shade on the cheapskate creeper (cardboards).

Finally wwrrrrrrr, dunk, dunk, dunk, du.... It's like the starter cranks it faster than the Diesel idle. (or maybe it was just my imagination in the exited state of finally having it working)

Martin (and 1.9TD Westy "Poppie")

Here's more rebuilding steps from my post a year ago if someone is interested:

Starter: Bosch: SR28X

068-911-023JX Diesel Vans 83-Mid 85 To VIN 25-F-065628 068-911-023MX Diesel Vans Mid 85-on Fr VIN 25-F-065628 Replacement for 83-Mid 85

Bosch starter do-it-yourself rebuild

I just rebuilt the starter for my '82 Diesel Westy. Last time I did it was in '99, I think, so the previous rebuild lasted about 8 years.

Bosch rebuilt starters can run near $200 nowdays, but rebuilding it yourself is not hard. Here are some tips:

First check that the problem is really the starter. Measure the voltage over the starter itself while cranking, ie from the positive iput terminal on the starter to the starter housing. If it's 8-10V and the starter still is cranking slowly the starter is most likely bad. If battery voltage is ok but voltage at starter is low check voltage drop in the positive and negative circuit. When I measured I had .2V drop in the neg circuit and .9V in the positive. Of the .9V .7V was over the solenoid and .2V in ther actual cable.

If it is not starting at all, no noise, no click, despite having 12V at both starter and solenoid, check connections to the solenoid, and then between solenoid and starter. This time I found that the metal tab running from the outside of the soloid terminal and connecting the solenoid winding was sheared off. I soldered on a flat piece of copper (from a water pipe ground strap) to fix it.

If your starter motor runs strongly, but the starter gear quickly disengages from the flywheel (hence not cranking motor more than a fraction of a turn), the culprit is often that the starter bushings are worn unevenly, allowing the starter motor shaft to wobble and the starter gear out of engagement with the flywheel.

This symptom is particularly noticeable for Diesel owners here in the north, since the starter torque needed to crank a Diesel in the cold is very high, hence even a slight shaft misalignment will push the gear out.

I think it always pays to change at least front and rear bushings even if these look ok. Middle bushing I think plays less of a role. (and even new ones are quite loose. I suspect they are there more to center the middle plate on assembly of the starter, than to have any function when the starter runs.)

So you determined that its the starter. All Bosch starters, gas or diesel have the same basic design, but the sizes and housings are different between different models. Get the right parts!

Wear parts are basically:

1/ Bushings: 3 total. One in each end, and one in the middle. The latter I don't think carries much load. Cost: about $1 each from the Bosch distributor.

2/ Brushes: 4 in total. You can buy either a brush assembly for $45 with the 4 brushes already mounted, or 4 loose brushes for about $15 total. If you get loose brushes get ones with small u-shaped metal ends welded to the copper braid. They are much easier to solder to your brushholder.

The above is Bosch prices VW dealer prices are about twice as much.

Rebuild procedure:

1. Unscrew the two small screws on the commutator housing (back) this releases the brush holder.

2. Unbolt the two studs in the back. Now the commutator end comes off after removing a circlip on the end of the shaft, and the stator is loose, but don't pull it off yet.

3. Loosen the 3 screws holding the solenoid to the front housing

4. Between the solenoid and the starter motor is a small rubber piece. See if you can loosen it. Carefully wiggle and separate the front housing.

5. Solenoid and starter can be separated at the solenoid end. Take off the solenoid. (To prevent binding wipe off any dirt or corrosion on the solenoid plunger before reassembly)

6. Determine shape of bushings. The gear end bushing is in the bellhousing on starters for transverse engine models, and in the front housing on longitudinal engines. Replace front and rear bushings if worn.

7. To get at the middle bushing remove the ring and c-clip in front of the gear. Mine has a c-ring inside covered by another ring outside. Tapped off the outer ring with a 1/2" deep socket, and took off inner c-clip with pliers. Slide off gear assembly. Take out plate holding middle bushing. Replace if worn.

8. Check brushes. New brushes have about 8mm between the tip and the copper braid. I'd replace them if they are more than half worn. Also if the bushings were really bad the starter shaft has been riding out of center, and the brushes have been wearing irregularly and need replacement.

9. Snip off the braided copper holding the old brushes. Don't lose the springs! File off any remains from the brush holder. Solder on new brushes. Make sure they are soldered well. Each brush will pass 100's of amps at startup!

10. Inspect the commutator. If pitted (from arcing) file down until clean copper. If out of round use a lathe.

11. Assemble the parts. Grease bushings and gears lightly. You don't want grease on the commutator or so that it can spatter on the clutch.

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