Hard to Pull Fuel Primer (Primer rebuild or overhaul)

How to keep the Cessna 170 flying and airworthy.

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lowNslow
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Post by lowNslow »

Thanks again Bruce.
Karl
'53 170B N3158B SN:25400
ASW-20BL
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170 Scott
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Post by 170 Scott »

I have a primer which has a threaded nut and plunger shaft instead of the slotted nut and key to keep it in. Is this, I hope, even original, and if so, use the same o-rings. I haven't yet attempted disassembly except for removal of the nut, which does not allow for removal of the plunger. It's on a '50 A-model
Scott Koelbel
Spring, TX
"50 C170A N170DF
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Bruce Fenstermacher
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Post by Bruce Fenstermacher »

Scott I've never seen a primer like you describe. Doesn't mean there aren't any. Are you sure there is no slot for a pin to fit through the nut.
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170 Scott
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Post by 170 Scott »

Bruce, no there's no pin or slot. It's a totally different style. The nut, which is not knurled, it's a hex nut, has internal theads that threads on the shaft screw into. The threads are quite coarse, probably 8 or 10 pitch, though there is only a couple theads, are just below/behind the knob. I'll have to try and figure out how to attach a pic.
Scott Koelbel
Spring, TX
"50 C170A N170DF
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Bruce Fenstermacher
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Post by Bruce Fenstermacher »

Scott if you can figure it out you can send the picture to my email address and I can post it.
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Bruce Fenstermacher
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Post by Bruce Fenstermacher »

Here are the pictures of Scotts primer. Can anyone identify it. how does it come apart and what if any o-rings does it have?

Image
Image
Image
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Dave Clark
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Post by Dave Clark »

Wow, never seen one of those. What holds it closed? I can envision an o-ring or something in the nut part that holds the shaft just below the knob but a normal aviation primer has a needle on the end of the shaft that seats to close off the fuel supply when closed. Is it even for an airplane?
Very interesting.
Dave
N92CP ("Clark's Plane")
1953 C-180
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Bruce Fenstermacher
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Post by Bruce Fenstermacher »

Dave if you look close just behind the knob you'll see the threads Scott mentioned in his previous posts that thread into the chrome nut at the panel.
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Dave Clark
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Post by Dave Clark »

Oh I thought those were rings. Still, pretty weird.
Dave
N92CP ("Clark's Plane")
1953 C-180
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Indopilot
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Post by Indopilot »

If you will cross refererance that An6227-7 to a MS29513-012 you will probably solve a lot of your problem. The An6227 material is for Mil 5606 hyd fluid applications, whereas the MS29513 is for hydrocarbon fuel applications. What is probably happening is those 6227 orings are swelling after a time and binding up your primers. For a dollar or so you could experiment and throw one of each in some 100 LL and observe which one swells the most. If you have a Aviall catalog it gives a list of o-rings and what their application is. Also some of the primers like Bruce pictured have two o-rings on the plunger FWIW Brian
52 170B s/n 20446
56 172 s/n 28162
Echo Weed eater, Jezebeel
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Indopilot
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Post by Indopilot »

:oops: Guess I have a profound grasp of the obvious when it comes to counting o-rings :roll:
52 170B s/n 20446
56 172 s/n 28162
Echo Weed eater, Jezebeel
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Abe
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Post by Abe »

:D It's been awhile, but the weather finally let us go flying yesterday. I earlier had replaced both O-rings and used DC-4 on them. Had some "peanut butter" in the tube, but got it cleaned out. It's like having a new primer in the plane. My primer, like Scott's, had a nut (11/16") too, but with a slot for the locking pin to fit in. Thanks for all the help gentlemen :!:
Bill
'52 170B
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Kyle Wolfe
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Post by Kyle Wolfe »

Ah, it's the little things in life that are the pleasures.

Went out to the hanger over my lunch hour and replaced the 2 O-rings in my primer. It was beyond giving my wife trouble pulling it - even I found it tough.

Now it's soooooo easy to use. Becky will be pleased!

Once again the forum comes through.
Kyle
54 B N1932C
57 BMW Isetta
Best original 170B - Dearborn, MI 2005
Robert Eilers
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Post by Robert Eilers »

My primer gets difficult to pull every now and then. I just follow George's example and apply a little WD-40. Primer works well for months.
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