C-145 Crankshaft

[rarjc]

The crank in the C-145 on my 1952 170B needs to be replaced. Having a hard time locating one but one outfit suggested using an O-300 crank.They said it is a direct replacement except that I would need a propeller adapter because of a difference in the prop flanges. Have any info on this? If what they say is correct, can I solve my problem by also changing the prop instead of fooling with adapters?
Bob Raber

[GAHorn]

Bob, the O-300 engine is essentially the same as the C-145, largely only a difference in nomenclature... but be aware that there are differences within the engine-family. A C-145-2 is essentially a O-300-A engine, and they both use the same propeller and are both legal on the Cessna 170 aircraft. They use the same crankshaft, which has an 8-bolt prop-flange.

Subsequent models of the O=300 (such as the O-300-C and O-300-D) use a different crankshaft which has a 6-bolt prop-flange and therefore uses a different prop. (There is NO ADAPTOR of which I am aware....the use of the 6-bolt crank requires a different, 6-bolt prop.)

Installing a O300-C or D crank in your engine will essentially convert it to an O-300-C or D engine and require you to use a different prop...the most common being a McCauley 1C172-EM7655, which was also used on many of the early 172 aircraft.

Our association, (The Int'l Cessna 170 Association) owns the STC which approves the installation of that engine and prop combination into a 170 or 172 aircraft. If you are a bona fide member of our association, you can purchase it very inexpensively to make your engine/prop installation legal....after you have converted your engine in accordance with TCM Service Bulletin M75-6R1 (which is what allows you to convert your engine.)

Hope this helps.

[Mark Harwood]

Bob,
I just did a quick search and found this site with a c-145 crank for sale. Might be worth a look. http://www.grannybot.org/~macjava/aircraft.html

[blueldr]

Apparently the engine manufacturer, Continental, uses an IO-360 crankshaft as a replacement when they do an O-300 that requires a replacement crank.
Member Richard Pulley should know more about this.
As you may or may not know, the IO-360 engine requires the replacement of an "AIR MELT" type crank if the engine case is split. The same holds true for the Continental IO-520. It is my understanding that the AD requiring this replacement of "AIR MELT" cranks applies only to those engines. I've been told that there is no restriction on the use of these removed crankshafts in either the O-300 or O-470 continental engines. If this is true, I would expect that an "AIR MELT" crank from an IO-360 could possibly be acquired rather inexpensively since it would have no value for an IO-360.
It would be interesting to see if this really is a possibility. As a general rule, serviceable O-300 cranks are difficult to locate.

[hilltop170]

If you buy a new crank from Continental it will be an IO-360 crank and will be priced accordingly. Plus it will have an un-safetied plug in the oil bushing inside the crank that is likely, no, highly likely to unscrew itself while flying and come out. When that happens you have about 10 minutes to get on the ground before the plug comes completely out and you have a 3/8" stream of pressurized oil coming out the end of the crank into the spinner. It has happened THREE TIMES on my plane. Continental will not do anything about it and has told me there is no problem, just put it back in. I have reminded Continental there is no problem until somebody gets hurt.

Bluldr's idea about the airmelt cranks being useable in the O-300 is worth checking out. It could potentially save big bucks. The engine shops I've talked to tell me there have been just as many VAR crank failures as there were airmelt. I have an airmelt crank in my O-520 on my C-180 and will not be happy to junk it at overhaul. All of the IO-360 cranks whether VAR or airmelt still have the oil bushing that has to be plugged for use with a fixed pitch prop so that problem is still there.

[ron74887]

Bob, I have 2 0-300-C/D cranks that I can send off and get certified. They would require you to use a 6 bolt prop and the STC from the association. You could convert your engine to an angle drive starter at that time since you are splitting the case. It requires a different starter pinion( in the case--pinion for lack of better term) and thevacuum pump bolts to the angle drive. Not sure exactly how to price them. I am in the directory. Ron

[rarjc]

From Bob Raber-thanks to all for your responses. Based on your input and what else I could find, we are likely to go the conversion route to an O-300 C or D and get a new prop. We don't need a vacuum pump (venturi is fine) so we should not have to make any other changes if I understood your input. If you have part numbers for the crankshafts and standard props it would save me time. If I misunderstood anything, give a shout, I hope to get with our mechanic tomorrow for his agreement to the plan and will get the club STC.

[flyingjunebugs]

Hi Bob,
Would be interested in the 8 hole propeller if you want to sell it. Wish you luck getting back into the air. Thanks Bruce in AK 907-952-2584