Help Identifying Primer Type

[SomethingScrewy]

I never use the primer on my 1940 BC-65, but when testing it during the annual inspection, I found it to be inoperable. It is the kind where the knob pulls out under spring tension, and it springs back in upon release. I assume the squirt is supposed to happen on the way back in. It does not seem to be drawing fuel into itself. I have yet to check the lines are clear, but we will do that first.

Can anyone identify the make/model of this primer assembly and give me an idea what to expect when we disassemble it? Is this style typically serviceable? Does it contain o-rings that can be replaced?

Thanks,

Lance

[kevinbrooker]

Our BC12-D still has that primer in the panel. Yes, pulling the plunger loads the primer with gas and releasing it allows the spring to push the gas into the engine. The one in our plane is installed in a sub panel just below the main panel. This location is set about 1/2" deeper than the main panel and also contains every other engine control. The rub is the spring is pretty stout and its hard to get any more than fingertips behind the knob. I added a short look of shoelace girth hitched behind the know so I can get a finger through the look to give it a pull. Super helpful in the winter when a single shot of primer get the engine to fire. T

The primer takes one pull to prime the actual primer. The first tug feels a lot easier than subsequent yanks. The loop also helps me hold the plunger out so the chamber can fill with fuel.

At one annual we overhauled the primer. There is a leather wrapped section for the plunger which was all dried out. A bit of linseed oil rejuvenated the wrap and we coated it in silicone before reinserting it. The ball bearing check valve and seats were all cleaned up too. at each annual we take it apart and re-grease it with the silicone.

[SomethingScrewy]

Excellent, thanks for the response. I know we are talking about the same primer, because you are exactly right - the spring is very tight on the way out. If the primer does not draw in fuel and you accidentally release it, it snaps back to the panel quite violently.

Armed with this info about the internals, I will have my A&P disassemble it during the annual.

Regards,

Lance

[Hank Jarrett]

Some of the "Old Time" hardware stores carry leather cup seals to repair those primers (might try Tractor Supply or a farm supply too). That primer was originally used on old tractors.

Hank