Hot Starting

[Tom G]

I had an experience the other day with my plane that has never happened before. It refused to start. It was this past Monday July 5. Here in the New York area there was record heat. I flew from my home base up to Blairstown NJ Airport with a passenger to have lunch. We landed, went into the restaurant and came out about 45 minutes later. We tried for almost an hour to get the plane started and it absolutely refused. Not a pop, a kick back or anything, it was as if the mags were turned off. Now the temperature was about 101 degrees and it had been sitting in the sun the entire time. The heat was the only thing we could attribute it to and it was oppressive! Out of desperation we moved the airplane to the only small piece of shade on the entire airport, it was so small only the nose would fit. We went back inside for 30 minutes, came out and it started on the first blade! I just thought I would pass that on for whatever help it could be to anyone else. Incidentally even full of fuel with a 200 pound passenger on a day this hot we had no problem taking off and getting a good climb rate. Mr. Taylor certainly designed an efficient airframe! But we all know that.

[mohawktipi]

Re: Hot Starting

Here in Texas, we are used to "hot starts." If you find yourself in this situation again, try turning the prop backward four blades. Then go through your normal start routine.

[magman]

Re: Hot Starting

I presume you did not check for spark.

The insulation in magneto coils can deteriorate.

This can show up with hot starting difficulties.

Another thing you might try is to open your cowling while at lunch.

Won't fix coils but might cool the engine more.

[Tom G]

Re: Hot Starting

we pulled it through backwards, which usually works quite well if its flooded. I've been starting this plane for decades so I'm very familiar with its quirks. The mags are excellent, one was completely overhauled by Savage less than two years ago. I chalk this up totally to the excessive heat which was the only non common denominator. Thanks

[dkbringham]

Re: Hot Starting

Ours won't start in any degree of heat, so if we plan on starting soon after shutdown, we always open the cowl for mag cooling.

[fearofpavement]

Re: Hot Starting

Our O-200 equipped BC-12D is terrible to start hot but I found something that works. When we go to shut it down and plan a restart we just turn the mags off with the engine at idle. When time to start, we just make the mags hot and prop it without moving anything in the cockpit. Usually starts on the first or second blade.

[lfries]

Re: Hot Starting

I usually shut down with the mags at 800-900RPM. Depending on my length of time away it may start without doing anything other than turning on the mags. If I have been away too long it will still start easier at 800-900 RPM than at the idle position. Too long is probably in the 20 - 30 minute range.

[Dano"T"]

Re: Hot Starting

I had the same thing....new slick mags fixed the problem for good.

[N95334]

Re: Hot Starting

Tom,

You using Mogas or Avgas? Had the same problem and it was a start of another problem. The engine would quit on landings on the roll out. I was using Mogas with that 10% alcohol. Thought I could get away with it. What a dummy I was. Well in short tore the carb apart and other fuel system parts and found all good. I have since upped the idle 100 rpm and using Avgas and no further problems.

[dalepj]

Re: Hot Starting

It sounds to me like a fuel vapor lock. I had that happen to me one time in my 1939 Stinson HW-75. It sat on a hot ramp for about 2 hours in really hot summer time. Cranked and cranked, not a pop. Allowed it to sit until cooler evening, and it started promptly.

Dale Jewett

[gfortin]

Re: Hot Starting

I had an experience that is similar but different. After flying for an hour around the lakes region of Maine, I landed at Eastern Slopes to gas up. After gassing I started up and began taxiing, after about 100 ft I push the throttle in and the engine stopped. I could not get the engine started. I tried everything I knew and several different scenarios to get it to fire up, Nothing. I pushed it back to the FBO hanger took the cowling off. Found fuel dripping with the fuel off. I gave the carb two gentle taps with a hammer. The fuel stopped. I tried to start it again. It fired up on the first propping. Something like a float or a needle must have been stuck. It sure was a frustrating experience. I had a great flight home to Limington.

[Tom G]

Re: Hot Starting

Dennis, I have never used anything but avgas in it. I really think as Dale mentioned that I had a vapor lock. It went from being absolutely dead with no sign of life at all to starting on the first blade.

[Mark Julicher]

Re: Hot Starting

I'm puzzled.

A vapor lock is common enough when fuel vaporizes in fuel injector lines, but exactly what part of a Taylorcraft fuel system can vapor lock? The intake tubes are supposed to have vapor in them. The carburetor ought to be cool given that the float bowl is a big heat sink. The fuel line from the gascolator to the carburetor could maybe vapor lock if it is too close to the exhaust header, but not seeing your installation I could not know for sure. I suppose you might insulate your fuel lines if that is a suspected issue. Definitely check that the fuel line runs continuously down hill or continuously uphill from the gascolator to the carburetor so there is no way to trap an air bubble in it. That situation could behave like a vapor lock.

Failure to hot start on a little Continental seems to be more often weak coils than anything else. If you could borrow some magnetos and go try to replicate your problem ... that would prove interesting.

[dalepj]

Re: Hot Starting

My vapor lock apparently occurred in the fuel line where there was a "hump" or high spot. After an engine removal and re-install, the FBO had replaced the fuel line and routed the new one with the high spot, and also fairly near the muffler. After re-routing the fuel line to remove the high spot and further away from the muffler, there was no more trouble. Take a careful look at your fuel line routing. The available "pressure head" pressure from the tank to the carb is very slight. Keeping the line continually below the "hydraulic gradient" is essential.

[NY86]

Re: Hot Starting

My vapor lock apparently occurred in the fuel line where there was a "hump" or high spot.

Theoretically, a gravity feed fuel system cannot vapor lock unless it has a high spot (between 2 low spots) to trap the vapor bubble.

OTOH, if you have such a high spot, 100 degrees OAT plus engine heat probably stacks the deck in favor of vapor lock...

A weak coil is likely to show up under these conditions, but, given dual mags, statistically unlikely to cause a no start (assuming you start on both mags), I'd think.