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primer problems

 
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6785



Posts: 6
Location: Markham ON

PostPosted: Sun Nov 07, 2010 3:07 pm    Post subject: primer problems Reply with quote

Cannot get my engine started, 85hp primer feels funny,seems like pressure is not there when pushed in
Are they repairable?
Aircraft Spruce wants $170.00 for a new one.
Any suggestions?
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Randy Thompson



Posts: 2683
Location: Olinda, California

PostPosted: Sun Nov 07, 2010 3:13 pm    Post subject: Reply with quote

The engine should start without the primer. Close the throttle all of the way and crank. It may take a while but if it does not start you might have fuel blockage that keeps the primer from working, too. I am assuming that you have a Stromberg carburetor.
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A&P IA. Holder of STC for O-200A's in 120, 140 & 140A's. Engine overhauls on C-85's ,C-85's with O-200 crankshaft, C-90's and O-200A's
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Ray Hunter



Posts: 815

PostPosted: Sun Nov 07, 2010 3:53 pm    Post subject: Reply with quote

I agree. You shouldn't need the primer. In summer, I handcrank for 8 blades..then get in and it starts up afer 2 blades with the starter. In winter, same thing. Preheat, hand-crank, starts up instantly.
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John C



Posts: 4139
Location: New Hampshire - KLCI

PostPosted: Sun Nov 07, 2010 5:48 pm    Post subject: Reply with quote

To answer your question... Wink
What brand is yours?
Most primers have an o-ring seal that can be replaced. Lukenheimer (sp?) have only a stem packing. They all have inlet and outlet valves, but they generally don't give much trouble, unless some dirt gets in and keeps them from seating.

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www.skyportservices.net
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AmazonJet



Posts: 711
Location: Phoenix AZ

PostPosted: Sun Nov 07, 2010 8:07 pm    Post subject: Reply with quote

I rebuilt mine. It does come completely apart although I had to use a flame to get it to unscrew.

Also, if no fuel is getting to it, it will not have a hydraulic reisitance feel as you push it in.
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skot7ac



Posts: 130

PostPosted: Sun Nov 07, 2010 10:18 pm    Post subject: Reply with quote

Sounds like it might be time for new o rings. It is certainly both easy and pretty inexpensive to do. I "borrowed" this from the 170 page, pretty sure that it's the same primer but I won't hang my hat on it. The links did not work for me, but the info is pretty good.

I ran across the following while browsing Cessna Single-engine service letters and thought it might be a helpful reference to anyone in need of a fuel primer rebuild. Service letter 78-73 says that using NAS1593-012 o-rings "provides smoother primer operation, improved sealing, and longer service life" than the original AN6227-7 o-ring. They recommend replacing them at the next 100 hr. inspection. According to Geniune Aircraft Hardware Co. NAS1593 o-rings are made of Viton. Aircraft Spruce doesn't show the NAS o-ring but does sell MS29513-012 o-rings that "are resistant to fuel and are ideal for applications such as fuel ... primers." I then stumbled on McFarlane's website which seems to have the latest and greatest o-rings ever (for 13 times the price of an MS29513-012): "The MCM83248 series o-rings are 'fuel proof' FAA-PMA replacement o-rings. Only McFarlane has FAA approval to replace the old, less fuel resistant nitrile (MS series) and synthetic rubber (NAS series) o-rings with the latest fuel proof fluorocarbon o-rings! Flurocarbon rubber is commonly known as Viton. It is an advanced rubber that has extremely good fuel and heat resistance and is ideally suited for aircraft fuel system applications." So for the primer the o-ring you need is MCM83248/1-012. Here's a link if you need to order: http://www.mcfarlane-aviation.com/Produ ... 8%2F1-012& Or, if you're willing to risk the FAA checking whether you bought your Viton o-rings from a place that might not have the FAA's blessing to replace the original, you can get them for 36 cents from Sacramento Sky Ranch. (Quite a deal as they are normally priced there at $89 each!) http://www.sacskyranch.com/acatalog/Sac ... s_302.html
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Otterpilot



Posts: 133

PostPosted: Mon Nov 08, 2010 10:21 am    Post subject: Reply with quote

Are there any o-rings that would work in a Lunkenheimer (sp?)?

I don't recall a groove for an o-ring when I opened it up. I rebuilt mine a few years ago with teflon "thread" from the aviation department at Ace Hardware. This worked great for a few months. The original leaking is gone, but there is quite a bit of pumping required to prime the line again before it works. I do still get the occasional drip when I use it though.

Mark
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John C



Posts: 4139
Location: New Hampshire - KLCI

PostPosted: Mon Nov 08, 2010 2:09 pm    Post subject: Reply with quote

The Lukenheimer doesn't need an o-ring. Your issues are due to the packing still leaking. Teflon packing is nearly infinitely compressible. (And you really don't want any if it to get loose in the fuel system!) You need something with more "body". Cotton string impregnated with fuel-lub will work.
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6785



Posts: 6
Location: Markham ON

PostPosted: Mon Nov 08, 2010 8:04 pm    Post subject: primer Reply with quote

I thank you guys for the info you have given me.
Worked on my primer today,found that is has 2 o rings
However there was no fuel to be seen
Question, where does the second line get its fuel from?
2 Lines are going from the primer to the fire wall, one goes to the engine compartment
The other line disappeared to where?
Any info would be greatly appreciated Very Happy
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Randy Thompson



Posts: 2683
Location: Olinda, California

PostPosted: Mon Nov 08, 2010 8:12 pm    Post subject: Reply with quote

The one that gives fuel to the primer is connected to a tee coming out of the gascolator. The other feeds the fuel to a fitting in the intake manifold or spider. Does your engine run?
_________________
A&P IA. Holder of STC for O-200A's in 120, 140 & 140A's. Engine overhauls on C-85's ,C-85's with O-200 crankshaft, C-90's and O-200A's
State Rep for California
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6785



Posts: 6
Location: Markham ON

PostPosted: Tue Nov 09, 2010 2:34 pm    Post subject: primer problems Reply with quote

Got my problem solved guys technically I had NO problem.
Found that my fuel valve was on the OFF setting.
Sorry if I caused any inconvenience to any one. Embarassed
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Otterpilot



Posts: 133

PostPosted: Wed Nov 10, 2010 11:09 am    Post subject: Reply with quote

Well at least it happened before starting, instead of at 30' with no runway in front of you!

I at least got some great info from it. Back a while I read threads on primers and got the teflon idea for the Lunkensphincter (sp?). I like the fuel lube and packing string much better. What came out of it looked similar to that. Just did not have a clue about how to execute it. A buddy has the fuel lube, and all I have to do is find a rugged enough material now.

Mark
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Mike Smith
Forum Moderator


Posts: 1094
Location: Sandy Creek Airpark, Callaway, FL (75FL)

PostPosted: Wed Nov 10, 2010 2:03 pm    Post subject: Reply with quote

Sounds like a checklist is needed and should be followed.
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1950 Cessna 140A, N9688A
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