David Vance:
Recently I have had a problem getting my plane to start. The starter motor turns, but apparently the bendix isn’t getting the starter gear to engage the gear on the motor. After 8 or 10 attempts, it will finally engage and we’re off… but it’s a little embarrassing sitting on the ramp listening to the whir while the passengers fret over the overall condition of the
plane. This problem has just recently come up and I confess that I have not been flying much, so that part has had little exercise the last 6 months or so. Is there a quick fix for a sticky bendix? Squirt of silicon? Rap with the proper sized mallet?
Steve King:
I’ve had the same problem with my 79 Sundowner (with 2100 hours on the original engine and starter). Sometimes it was so bad it seemed like it would never engage. When that happened, I found that by just getting out and moving the prop by hand a fraction of a revolution it would then engage right away on the next try. I thought we were going to have to buy a new starter or Bendix drive; we didn’t want to do that, because engine overhaul might be in the near future, and some engine overhauls come with a new starter. If just shooting it with WD-40 doesn’ fix yours, you might try my similar but more complex solution. This has really taken care of the problem for us, for a period of around 18 months and well over 200 hours.
On mine, I think the problem is a combination of wear and dust getting into the Bendix drive (since being exposed to a dusty ,windy environment seems to trigger the problem). My solution is to do the following, at 50 hour intervals. Why then? To do this on mine, I need to have the lower cowling off to get at the starter. At every second oil change–the 50 hour interval–I pull the top and bottom cowlings so I can do an engine compartment inspection similar to what would be done during an annual or 100 hour inspection.
1. Using compressed air and a solvent gun, I clean the Bendix by shooting into it from the front. There’s a drain hole to let the solvent out.
2. Then, using an air nozzle and compressed air, I try to dry it out.
3. Let it sit for a while to dry some more.
4. Shoot it with WD-40 or LPS2.
Dan Kirby
Bruce, I’ve used WD40 on starter shafts for years, with nothing but good results. I think its the water that causes most of the problems, and WD stands for water displacement, which is how they named the product. Makes sense to me.
Jay:
I had this problem last winter, but it has not returned this winter. Here is what I found and how I took care of it:
Your starter gear that engages the fly wheel travels on a steel ‘rod’ this ‘rod’ becomes rather dirty or gummed up over the years. A local A&P told me that he is always having to take his starters apart and polish the part. Knowing that I didn’t want to remove the prop and all the work that comes with that on my 66, he gave me a can of WD-40. I was real good about spraying the part down for about 3 weeks, then apparently it was cleaned off enough that it was no
longer necessary. NOTE: I would not use silicone if I was you, I have found that silicone spray eventually traps and attracts dirt.
I may spray it down the next time I fly just as a preventative measure. Maybe the cheapest fix you can have on a plane.
Editor’s note:
I don’t have a scanned reprint of Lycoming SI-1278, that gives lube instructions for the traditional Bendix starter drives. Here is a reference from Sacramento Sky Ranch. Note that there is a big difference between dry silicone lube and conventional spray silicone from the hardware store. People are having good luck with WD40 because it also serves as a light solvent, so it is cleaning each time it is lubricating. If you are having a problem with oil and dirt contamination, due to engine leaks, WD40 is probably your best bet. If your engine stays dry up front, you’ll get longer service from a cleaned and dried Bendix drive shaft, coated with dry silicone.
In my opinion the single greatest advantage of the lightweight starters is the elimination of the Bendix drive, and instead the use of a solenoid linkage for positive engagement (and disengagement). Be careful if you select a new starter; the Electrosystems/Prestolite “lightweight inline” starter still uses a Bendix drive. The Bendix was first used by Chevrolet in 1914.
What is the proper lubricant for the starter Bendix (engagement gear on Lycoming engines)
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Prestolite or Electrosystems starters use a Bendix gear that rides on a shaft. It is important to keep the shaft clean to prevent sticking. Electrosystems and Prestolite recommend a dry silicone lubricant as wet lubricants attract dust and dirt.
Starter Bendix
