In a message dated 2/3/2008 7:19:16 PM Eastern Standard Time, [EMAIL PROTECTED] writes:
I have a 1966 Alon with a C90 engine. While doing the annual we were hand-turning the prop to check compression and notice that the starter seemed to be engaged when we turned the prop in reverse, but not when turned in the proper direction. Is this normal? tullypp, No, this is not normal. The starter should be disengaged at all times unless you are starting the engine. If you have an original equipment Delco-Remy pull-type starter, the proper sequence of operation is that when you pull the starter handle, the first amount of travel engages the starter clutch gear into the crankshaft gear inside the accessory housing, and the last bit of travel depresses the switch button on the starter, which causes the starter to energize. The starter drive clutch assembly allows the crankshaft gear to "overrun" the starter gear when the engine finally starts. You said that the starter appeared to be engaged while turning the prop backwards, but not when turning it forward. If the starter clutch gear is engaged with the crankshaft gear, then when you turn the prop backwards, the starter clutch locks up, and causes the crankshaft gear to turn the starter. When you turn the prop in the forward direction, the starter gear is probably still engaged to the crankshaft gear, but the clutch is now doing it's job and allowing the crankshaft gear to overrun the starter gear. In other words, the clutch is slipping like it is designed to do when the crankshaft gear is turning faster than the starter gear. This is a potentially catastrophic situation if you should run the engine in this condition. The reason that I say this is that these gears are not designed to be engaged while the engine is running at high RPM. In all probability, the teeth of the gears are just barely engaged, and if run this way, the tips of the teeth could wear or break. In addition, if the clutch should overheat and seize internally, you'll end up breaking the clutch housing and possibly dropping metal pieces into the engine. The two most likely causes that I can think of for the starter remaining engaged are: 1. The starter linkage is not adjusted properly, and it is mechanically holding the starter gear in. This can be fixed by following the adjustment procedure in the engine overhaul manual. The manual gives the exact dimensions and clearances for adjusting the starter pivot arm that engages the gears and energizes the starter. As a quick check, look at where the pivot arm contacts the end of clutch shaft. There should be a minimum of 1/16 inch air gap between these two points. (Ref: Continental Engine Overhaul Manual) 2. The spring that pushes the starter clutch assembly back from the crankshaft gear may be broken or seized. I'm a bit fuzzy on this, but I think that spring is located inside the shaft of the starter clutch assembly. I suggest that you get to the bottom of this problem and get it properly fixed before running the engine. The starter clutch, and the whole design of the starter system on these engines is the engine's Achilles heel in my opinion. The reason that I say this is that the starter clutch is designed such that if the engine kicks back on starting when the clutch is engaged, then something is probably going to get broken, and it's probably going to be the starter clutch, or worse yet, the teeth on the crankshaft gear. On the Lycoming engines, when the starter clutch or drive gears break, the pieces fall into the cowling, or at worst, into the starter drive housing, which is all external to the engine. On these little Continental engines, the broken parts fall right through all of the gears in the back of the engine and into the oil sump. Just a bad design in my opinion. In fact, a kickback on starting one of these engines warrants pulling the starter off the engine and looking for a broken clutch or broken teeth on gears. Again, just my opinion. (I formed that opinion when I pulled a chunk of crankshaft gear tooth out of my oil sump with a magnet after the engine kicked back several times.) Based on my experiences with these starters, I recommend getting rid of the original starter altogether and installing a B&C starter. It's lighter, turns the engine over much faster, eliminates the critical adjustments on the starter pivot arm, and has a much better clutch design that can't, or is much less likely, to shed metal into the accessory section. Let us know what you find out. Best Regards, Wayne DelRossi Alon N5618F Hours logged since restoration: 362.0 "Nobody has ever scientifically proven that life is supposed to be serious." **************Biggest Grammy Award surprises of all time on AOL Music. (http://music.aol.com/grammys/pictures/never-won-a-grammy?NCID=aolcmp003000000025 48)
