Start issues on PA 30B

[Randy Johnson]

Had an interesting experience while starting right engine. After successful left engine start and while starting right engine the prop turned... but very slowly. Starter solenoid heated up. But starter wasn't hot after a few attempts.

Ultimately got it started by "bumping" the starter button a few times and then starting it normally. Flew her for three hours and it started normally after refueling.

Aircraft had been idle for about three weeks. Any thoughts?

[Charles Schefer]

Do you have the original Bendix Equipped Prestolite starters? If so you may have a Bendix going bad. I have 2 on the shelf (1 good) since I just upgraded to Sky-Tec 149-NL starters.

On the PA-30 the Starter Solenoids are in the nose compartment to the right of the nose gear. Wondering how you knew they were hot...

- Charles

[Timothy Poole]

Charles the starter solenoids in my '65 PA-30 are under the rear bench seat, not out in the nose.

Tim

[Randy Johnson]

My starter solenoids are in the nose. We pulled the nose cowling to check the wiring from the battery..also in the nose...Charles I do have the original starters.

[Charles Schefer]

Tim - That's interesting! Maybe that was a design change with later models. Mine is a '68 "B".

Randy - If the solenoid is getting hot perhaps there is a lot of resistance and enough power isn't making it thru to the starter...? I determined my starter was the problem by connecting a volt meter to the starter and measuring the voltage during start. Since I had full voltage reaching the starter and my DOM could see the bendix drive no popping forward during start, we knew it was the starter. I've since (2 months ago) put in all new copper (Bogert) and new starters (Sky-Tec 149-NL) and am very happy with the set-up. I'd start by seeing how much voltage is making it to the starter during start and if you aren't getting 14v (or close) I'd look into wiring / solenoids. If you are getting 14v then I'd look into starters. Do you have the original aluminum wiring? The original starter wires will be in a fiberglass looking weave and will have "AL-1" stamped in the sheathing whcih I believe stands for Aluminum 1 guage wire. Over time they may develop higher resistane due to galling where the Aluminum meets the copper terminal and that could add resistance. Your comment about hot solenoids concerns me but truthfully I've never thought to feel and see how hot mine get.

- Charles

[Randy Johnson]

Thanks Charles..great info. Have passed your info along to my A&P.

[William Hughes]

A hot solenoid *coil* is due to several attempts to start in short succession. The inrush current when the starter switch is engaged causes resistive heating in the coil and inductive heating of the metal near the coil. Do it several times in short succession and the solenoid gets hot. Do it way too often and the coil might get hot enough to break down the insulation, causing a short, and then a dead solenoid. Sounds like a normal effect of what you have described during the start up attempt.

If the solenoid *points* are hot (the bits that actually make or break the circuit for the starter motor) then that could be a very serious problem involving too much arcing. But you probably would not be able to do it twice as the points would melt and fuse together, and then shortly thereafter cease to exist.

Dirty solenoid points would induce resistance in the starter motor circuit and prevent it from generating full current. Along with all the other items in the above. Usual suspects that are easy to check are the battery connections, however.