C-145 Dipstick and Oil Fill Cap Seals

How to keep the Cessna 170 flying and airworthy.

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dstates
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C-145 Dipstick and Oil Fill Cap Seals

Post by dstates »

Fellow 170 owners/fans,
I was looking through both the Continental O-300 and 170A parts catalogs and could not find part numbers for a new o-ring for my dipstick or the oil fill cap seal. Does anyone have those part numbers handy?

Thanks,
Doug
N1235D - 1951 170A - SN: 20118
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GAHorn
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by GAHorn »

Pretty sure this is what fits the oil cap without paying Continental prices: https://www.aircraftspruce.com/catalog/ ... ecfer=8981
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by gfeher »

Yes, George is correct. I replaced my oil cap seal with the one in that link that Spruce sells. Fits perfectly.
Gene Feher
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by 170C »

Gene, your correct. As George suggests, those gaskets do fit the oil filler cap. Replaced mine a couple of weeks ago and it fits nice and snug now. The old gasket must have been the one from the factory. Hard!
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by n2582d »

dstates wrote:Fellow 170 owners/fans,
I was looking through both the Continental O-300 and 170A parts catalogs and could not find part numbers for a new o-ring for my dipstick ... . Does anyone have those part numbers handy?

Thanks,
Doug
Doug,
Fig. 1-11 of the O-300 IPC shows p/n 537299 as an oil gauge rod ring. I thought this was the o-ring you are looking for but, as George points out below, it is a metal ring to secure the dipstick.
Oil Gauge Rod Ring.png
Oil Gauge Rod Ring.png (11.61 KiB) Viewed 24055 times
In my IPC fig. 11-14 shows another o-ring. O-ring p/n AN123864 (superseded to p/n AS3570-111) is what to use on dipstick 531081. The later style dipstick, p/n 628410A1, uses p/n AN123860 (superseded to AS3570-010).
Fig. 11
Fig. 11
Click to enlarge
Click to enlarge
Here is a photo of a C-145 dipstick next to an O-300 dipstick which I found in this discussion.
IMG_1845.jpg
Notice the difference in o-ring size.
Last edited by n2582d on Tue Oct 08, 2019 8:05 pm, edited 3 times in total.
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by GAHorn »

Gary, I doubt that the o-ring he’s asking about is the item 14. He’s likely insterested in one at the base of the dipstick (oil gauge rod) handle where it fits in the tube.

Doug, a quick solution is to use an O-ring assortment to select one that is close-fitting. If it’s presently missing then find one that is a snug fit. It’s not a high-pressure area that needs tight sealing. (It better NOT be seeing high pressure!) :wink:
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by n2582d »

Deleted due to misinformation.
Last edited by n2582d on Tue Oct 08, 2019 8:07 pm, edited 4 times in total.
Gary
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by dstates »

Thanks for the lead on the fill cap seal.

I also saw both of the engine parts catalog callouts shown in the previous messages and wasn't sure if the o-ring in fig 11-14 was what I was looking for and just shown in a weird exploded state. George is right that I am looking to replace the one at the base of the dipstick handle. I'm not sure what the ring is (#16 in fig 1-16) because Aircraft Spruce wants $9.75 for one piece of 537299. I sure hope that is not an o-ring price. If so, I'll just go to NAPA.

Doug
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by GAHorn »

dstates wrote:Thanks for the lead on the fill cap seal.

I also saw both of the engine parts catalog callouts shown in the previous messages and wasn't sure if the o-ring in fig 11-14 was what I was looking for and just shown in a weird exploded state. George is right that I am looking to replace the one at the base of the dipstick handle. I'm not sure what the ring is (#16 in fig 1-16) because Aircraft Spruce wants $9.75 for one piece of 537299. I sure hope that is not an o-ring price. If so, I'll just go to NAPA.

Doug
I’m temporarily at a disadvantage since my computers were wrecked in a storm so my PDF version of the TCM/IPC is unavailable to me. I’ll have to find a way to get it downloaded again... but there are at least two different versions of dipsticks (oil gauge rods) and tubes. The one depicted above is the type which has a semi-circular “C-clip” (item 16) which holds the rod securely in the tube. It mates with a “slot” in the receiving-tube. The other type (which I actually have in my O-300-C) only has a rubber O-ring.
'53 B-model N146YS SN:25713
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An originality nut (mostly) for the right reasons. ;)
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by n2582d »

I’ve spent an inordinate amount of time researching these dipstick o-rings. As a result of what I’ve found I’ve edited my previous entries with what should now be correct info. First, the sleeve that the dipstick fits in is press fit into the side of the case; there is no o-ring associated with it. In fig. 11 it appears that the dipstick fits in a hole in the sump. This illustration is incorrect. Here is a photo of my spare O-300A case.
Left case half O-300A
Left case half O-300A
Fig. 11
Fig. 11
Note that the hole in the corner mates to the hole in the sump which Continental incorrectly illustrates to be for the dipstick. This hole connects with the left oil galley in the case.

So to get the correct part number I called Continental Motors “Gasoline Engine Parts” phone number listed at the bottom of their home page. This connects you with Aviall. According to the guy I talked to Continental does not allow them to have parts books. You can’t call them and say “I need an o-ring for dipstick p/n xxxx.” Unbelievable! So I call Continental Technical Support. After numerous calls and them consulting with engineering to pull the prints for dipstick p/n 531081 they tell me I need o-ring AS3570-010. I order that from Spruce and it turns out to be the wrong size. I assume it is what fits on the later style dipstick p/n 628410A1. Here are a couple of dimensions for the two of you who have followed this whole thread.
Dipstick p/n 531081 uses o-ring AN123864 superseded to AS3570-111
Dipstick p/n 531081 uses o-ring AN123864 superseded to AS3570-111
AN123860 superseded to AS3570-010 for dipstick 628410A1
AN123860 superseded to AS3570-010 for dipstick 628410A1
Last edited by n2582d on Wed Oct 23, 2019 1:29 pm, edited 2 times in total.
Gary
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by bgiesbrecht »

gfeher wrote:Yes, George is correct. I replaced my oil cap seal with the one in that link that Spruce sells. Fits perfectly.
Agreed. I just did this over the weekend. Perfect!
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by Karl Towle »

When I faced this problem, I did what George suggested; I found an O-ring assortment and selected the size that fit.

There was a discussion some time back about installing the O-300-C or -D engines. The subject of the "oil gauge rod" came up. It is important to realize there are two very different designs, and the gauge rod/dipstick must be correctly matched with the tube that is pressed into the crankcase. The two pertinent posts start here: http://cessna170.org/forums/viewtopic.p ... 27#p114368 and the one that follows.

I spent some quality time in the C145/O300 parts catalog. On the subject of "Oil Gauge Rod," I found this note:
To order an oil gauge rod assembly, supply engine model, airplane mode! and date airplane was manufactured~ We will determine the correct oil gauge rod upon receipt of this information.
So, Thanks Gary for your research, but I think it should be noted that the 531081 part number you found, would only fit the earlier style "Guide, OIl gauge rod," as Continental calls the dip stick tube. And, I find no way of confirming if that part number is for a 170, or 172 (which should use different part numbers).

Again, the takeaways from all this are: there are two different size O-rings, depending on whether or not you have a spring clip retaining your dipstick, and whatever dipstick you have, it needs to match the design of the tube it slides into. Also, from the post linked to above, you need the spring retainer design if you use 240 deg as your oil temp red-line value.

Hope this helps.
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by dstates »

Who knew it would be this complicated to find an o-ring on a dipstick. Thank you guys for the information. Tons of good info in theses posts and the posts linked in them.

I did get the oil fill cap seal from Aircraft Spruce and it fit great. I’ll throw a picture of my oil gage rod below just for fun. I plan on taking it to an auto parts store and find an o-ring that will fit it well since it doesn’t seem like anyone has narrowed in on a part number.

This place is full of great 170 info and people.
Thanks,
Doug
DEB80BA4-B06F-4A40-AC89-C2A9F7B56750.jpeg
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by n2582d »

The o-ring you need is AS3570-111.
Gary
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Re: C-145 Dipstick and Oil Fill Cap Seals

Post by GAHorn »

I cannot say too often how much a simple O-ring assortment kit in the shop has saved a project around the house and hangar. This $12 kit. https://www.amazon.com/Neiko-50443A-Uni ... B000OMKIDI is also available from Horrible Fright. Inexpensive and has held up well for ten years. I’ve fixed the wife’s vacuum cleaner, washing machine, and the brakes on the 4-wheeler and resealed a hydraulic jack with it ...along with certain other projects with a simple trip to the shop for this kit. (I am not recommending it for aircraft purposes but I do know which one from the kit fits the oil gauge rod.) :wink:

Let me warn you... the $12 kit in the red storage box is a great assortment, but that EXACT SAME KIT is sold by various retailers from $8 all the way to $129 ..!!!! No kidding. There is NO DIFFERENCE in those kits, they are nitrile and work fine for most purposes. O-Reilly’s also sells a smaller kit for about $8 but the one I’ve already recommended is the one I’ve found most useful.

(O rings do have a shelf life however so store them properly in cool, dry, area, preferably In a large zip-lok.)
https://www.amazon.com/s?k=o-ring+assor ... rs6o97g1_e
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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