Dip Stick

[n3437d]

First the question (please do not laugh at this) -- just received the "The 170 News First Quarter"
Page 9, Dip Stick "Do not substitute a C-172 type oil dip stick for a C-170. This makes sense to me but.....what if the origianl C-145 was replaced with an O-300 from a C-172? Does the horizontal engine position still matter with respect to oil level? Or does this "cancel out" due to the fact the the dip stick and engine match?

Now the comment -- this First Quarter issue will be "bronzed" and be placed on my night stand near the bed to be read and re-read at least once a week. Kudos to all those that contributed very useful information that we all knew and may have forgotten.

[GAHorn]

The "Oil Guage Rod" (dipstick) should have a part number stamped upon it. The correct PN for an O-300 engine installed in a 170 is: 628410A1 .
(The 172 would be: 628413A1 .)

If YOUR dipstick has a different number on it, then we'll need to attempt a cross-reference, because the above numbers superceded the older, original numbers.

Of course, if you perform an oil change, and measure the amount of oil you install,...then it should be "VEWWY VEWWY CROWSE" - Elmer Fudd.

[170C]

George, this dipstick issue brings to mind a question. How much difference, on the dipstick, do you think we would find if we compared an O300 engine in a C-170 that had 6 quarts of oil in the sump vs that same engine in a C-172 with 6 quarts of oil in the sump? I have never checked to see if my "stick" has a part number on it or not---but I will on Sat. I did fill my sump one qt at a time and mark those levels on my dipstick as the orginal markings were virtually unreadable (geeze, I wonder if I violated some FAR by doing so ). I'll bet my dipstick wasn't changed when the tailwheel conversion was done and furthur more I'll bet there are a lot of C-170's out there with O300 engines in them that were orginally in C-172's and still have the 172 dipstick. Technically, is this a violation to not have the correct dipstick in the engine? Again, the main thought is how much difference in actual oil level would it make I guess the same situation would occur if a C-180 owner put an O-470 from a C-182 in their C-180.

[ron74887]

Frank, on the STC for the 0-300-c,d,e engines it (I) requires that the owner keep his original dipstick, mufflers, carb heat box, and baffling. the dipstick to be sure that it reads correct. In your case, your plane may or may not sit at the same angle as the 170 depending on the gear legs you used, therefore, you need to add oil like you did and mark the dipstick-- same thing when one decides to put 180 legs on the 170, it does change the angle and move oil to the rear of the case. Same would be true for the lycoming conversion and any 182 taildragger.

[N170CT]

FWIW..when I purchased my 170B with O300 engine, it had a 172 dipstick (clearly marked with a small metal tag attached to the handle). I, too, reasoned early on that this was not the best situation and so the first time I changed the oil, I added one quart at a time and checked the level on the 172 dipstick. Turns out the 172 stick indicated about one quart higher than the true level according to the graduations on the stick. I also carefully noted the actual level for eight quarts, which was obviously higher than the range of graduations and marked the 172 dipstick with a Sharpie. This was generally acceptable because I usually fly local with 7 quarts (i.e. 8 indicated) due to the engines propensity for blowing the eighth quart overboard. Used 8 quarts on long cross country flights. Have since replaced the 172 dipstick with the proper one purchased from a fellow member of this association. (Which incidently is just one of many reasons I don't mind contributing $45 to the Association.)

One more note offered for consideration: And that is I would not, repeat, not recommend filing a notch in a 172 dipstick to mark the eight quart level. There is a real danger of the dipstick failing due to vibration and fatigue. Having pieces of metal banging around in the crankcase or blocking/obstructing an oil passage could ruin your whole day .

BTW...anybody out there want to buy a perfectly good used 172 dipstick

[GAHorn]

"Well, that's a horse of a different color!" - Gatekeeper of Oz.

Frank, your situation is a bit more complex, of course, since your airplane is actually a 172 converted to a tailwheel. There's no telling which dipstick you have, but I'd suggest you've done the expedient thing by simply re-calibrating/marking it to a known quantity. It'd be a really anal (not to mention "nosey") inspector who'd condition-tag your airplane over it. (In fact, in most of our cases, there's no telling what ANY of us have. It'd be a good idea to check, however. There have been many 170's operated with insufficient oil, evidently. This causes excessive oil temps and excessivce wear.
Ron, that is also a complicating matter, as regards the STC you offer Members thru the association. That's a great STC and it certainly can add years to the life of 170's in the fight against obsolescence, especially as "serviceable" old 8-bolt crankshafts become unobtainable.
But the dipstick instructions in that STC makes it necessary for an owner (who wishes to replace the "172" (PN 628413A1)dipstick with the "170" (PN 628410A1) dipstick) to make an airframe log entry regarding that change. (For convenience's sake, the most useful log entries would be made in BOTH logs, just to keep future owner's of that engine and/or airframe appraised of this issue. At the risk of starting another oddly-challenging and "sprited discussion": The dipstick/Oil Guage Rod is actually considered an AIRFRAME part...not an engine part. It's just like a generator...it's required to be logged onto the airframe, not the engine. Many folks make entries in both logs either because they don't know, or because they are as anal as me and want to cover all their bases.) I believe a "cleaner" STC instruction would have stated that the required dipstick must either be the correct PN for the airframe, or that the existing dipstick must have it's PN obliterated and/or altered and the stick re-calibrated/marked.

[Joe Moilanen]

My 170B has an 0-300 installed with the O-300 dipstick. With 7 qts., it indicates 8.5 qts. on the dipstick. If I were to sell the plane (like that would ever happen) I would probably change sticks, but at least I know what it should read. (1.5 qts. high).

Joe 4518C

[GAHorn]

Ron and I have been having a fun exchange of emails "behind the scenes" in which we are cussin'/discussin' this issue.
He and I are accusing each other of misunderstanding the other one. (I think it's his weird p'litics...he thinks Jamie is husband-challenged, ...he may be right.... er, I mean.. correct, but I won't go there.)
Anyway... If I read all this correctly.... what Ron MEANT to say, when he said to keep the "original dipstick" ... is to keep the original AIRFRAME's dipstick. (I think I hurriedly read his comment and mistook that comment to indicate to keep the engine's dipstick.)
That's the same thing I'm saying...PROVIDED that your original dipstick is the correct one for your AIRFRAME. (Check your PN and it's actual readout during your next oilchange.)
Sorry if I complicated the matter.

[cessna170bdriver]

My 170B has an 0-300 installed with the O-300 dipstick. With 7 qts., it indicates 8.5 qts. on the dipstick. If I were to sell the plane (like that would ever happen) I would probably change sticks, but at least I know what it should read. (1.5 qts. high).

Joe 4518C

Sounds like another C-172 dip st... er.... oil gauge rod (sorry George ). Also sounds like your 170 sits a bit steeper on the ground that does 170CT's.

SIL 00-7A is a 13-page document listing oil gauge rods for each application for each TCM engine. There are 3 applications listed for the O-300A, with a different rod for each:

Cessna 170 B: 628410A1
Cessna 172: 628413A1
Maule: 629664A1

(I had thought the O-300 or C-145 was also offered in the Swift from the factory, but TCM only lists the C-125.)

For the complete SIL, go to http://briefcase.yahoo.com/bc/cessna170bdriver , click on Overhaul 2006, then download SIL00-7A.

Miles

[GAHorn]

The O-300 was only installed in the Swift via STC. The very similar C-125 was a factory option, however.

[cessna170bdriver]

The O-300 was only installed in the Swift via STC. The very similar C-125 was a factory option, however.

Just to stir the pot a little, would you use the "original" C-125 Swift stick in the C-145/O-300?

Miles

[GAHorn]

Just to stir the pot a little, would you use the "original" C-125 Swift stick in the C-145/O-300?

Miles

I don't quite follow the question. The C125 was only similar in physical size. It has numerous differences which result in lower horsepower output, and would not be suitable for a 170, which is already minimally powered except as a two-place airplane, IMHO. Of course, the Swift IS only a two-place airplane.
There have been some cases of C-125 parts installed in C-145/O-300 engines, probably in error or by misunderstanding. It results in less-than-full hp output due to conn-rod length/piston differences resulting in shorter stroke and lesser displacement for the 125, and also due to lower rpm operating range the carb is flow-rated at lower displacement.

[cessna170bdriver]

Just to stir the pot a little, would you use the "original" C-125 Swift stick in the C-145/O-300?

Miles

I don't quite follow the question.

Specifically, on the 145hp Swift STC, would you keep the stick from the 125 that came out of it? My guess would be "yes" since I think the basic difference in the engines is the crankshaft stroke, plus there was never a stick specifically made for the C145/O300 in the Swift.

Miles

[GAHorn]

Yes, the crankshafts are different in "throw" also. What do you mean by the term "stick"?

[cessna170bdriver]

Yes, the crankshafts are different in "throw" also. What do you mean by the term "stick"?

DIPstick. Guess I shouldn't have assumed that you didn't assume I wasn't changing the subject.