The International Cessna^® 170 Association

I have the same P/N (531081) on the dipstick (0-300), and it reads about 1.5 quarts below the actual amount of sump oil. Doesn't bother me though as it was basically "calibrated" the first oil change that I did, and it's better than reading too high. But if you wanted to technically narrow it down I suppose you could find out at what S/N the 0-300's were first put into 172's ( If the engine is not original to the airframe). Just a thought.

Cheers, Jody

The "oil gauge rod" out of my O-300A is also P/N 531081. I haven't flown that engine since 2001, but as best as I remember it read within a half quart or so of the actual amount of oil in the sump. This engine IS original to the airframe, but I have no way of knowing that the "oil gauge rod" is original to the engine. All I know is that it is the one that was on the engine when I purchased the airplane in 1982.

Measuring it, the FULL mark, 8 quarts, is exactly 8 inches from the bottom end, but the marks get closer together, as you go up the stick. This makes sense, as the top of the sump is wider than the bottom. I've posted a picture of this rod along side a ruler called "Oil Gauge Rod 531081" at http://briefcase.yahoo.com/cessna170bdriver in the "Overhaul 2006" folder. Perhaps someone can compare this to the "latest and greatest" P/N 628410A1.

Miles

The Service Letter to which I was referring is Cessna SL-170-1 dated 2-3-56 which states the above referenced part number is correct of the 170.
I would differ slightly on the dipstick being an airframe part. IPC's are approved data and whichever OEM's IPC has a part listed is the "owner" of that part. The dipstick is not listed in the Cessna IPC. TCM holds the TC for the engine and would provide a dipstick per the specification requested by the airframe manufacturer. Hence the request for application of the engine when ordering an engine from TCM to ensure the correct dipstick is installed on the engine. I suspect TCM decided to go the cheaper route and issue SIL00-7A in lieu of the extreme effort required to update all IPC's for alternate part numbers based in engine application.
I think I have the correct part number rod. TCM probably has a cross reference somewhere which ties the one listed in the SIL to mine. It sounds like other operators have the same indication variable as I have. I too am willing to just live with it. It was and is a curiosity as to the indication "error". I never have actually verified that today's quart containers actually hold a quart. Not worth the effort to me.

Steve

Steve, the C-170 IPC is not an approved document. I have never seen a 170 IPC with the words "FAA Approved".

JTS wrote: ...I suppose you could find out at what S/N the 0-300's were first put into 172's ( If the engine is not original to the airframe)...

Cheers, Jody

The dipstick/oil guage rod is specific, not to just the engine, but to the engine installation, (i.e. airframe.) So the serial-range of the engine would not necessarily indicate in which airframe the engine was installed (although, I'll bet you are correct to assume that Cessna probably rec'd engines in serial-batches and probably installed them accordingly. But, in 1956, they possibly installed closely-numbered engines in either 170B's OR 172s. Those engines should have differenct dipsticks depending upon model aircraft .)
Steve has said it more better.

Messed up and put this earlier in Lounge Ck'd my stick yesterday & its part # (toward bottom of stick) is #539779. No where close to either the 170 or 172 part number previously discussed. Its anybody's guess as to what this dipstick is supposed to be in. (Maybe that 1953 Case tractor ) It does work, but obviously isn't the correct airframe part number.

Frank,

Per Cessna SL-170-1 dated 2-3-56 p/n 539779 is the correct dipstick for the 172. Also, the handle portion should be painted orange whereas the 170's should be painted yellow.

Steve

Steve, thanks for the reply. I have seen some dipsticks painted orange, but didn't know why one was one color and the next one still another. Now that I think about it I think the oil filler cap may be orange on some aircraft-----maybe 172's. Both on mine are yellow simply because I painted them that color not knowing what was correct and they will likely stay that color. Orange doesn't do much for me! I wonder if part number 628413A1 (172 # previously mentioned) is interchangable with 539779? One number may have superceeded another.

Just did an oil change and noticed I had the 581081 oil rod. Put in 7 quarts and registered right at 6, which is pretty close considering 1 quart for the new oil filter.