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#1
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IO520 Hot start
Hi there, I just got my Cessna 340. My right engine is very difficult
to hot start. I have to crank several times. Have done the flooded start procedure which does not work, the only thing that seems to work is to do a normal start, bring up the throttle halfway and if the engine catches a little bit quickly lean out the mixture. But it is a crapshoot and takes too much effort. Any good tips and experiences? |
#2
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When my engine gets hard to start I check the timing. If that is ok, I
replace the plugs. So far that has always done it. I switched to fine wire plugs which last longer and don't seem to collect the lead at the base. Hot starts are a bit problematical. I have heard that people do a special shutdown procedure so they can start it. They flood it at shutdown and cut it off with the key. That way there is fuel in the cylinders for the start. You might try that. |
#3
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Usually when the engine won't hot start it's because of vapor lock or
fuel boiling. You want to get cooler fuel to the engine. Close the throttle, pull the mixture and run the boost pump for about 60 seconds. Won't hurt the pump and will move the fuel around so that the cooler stuff is there. Then do your normal starting procedure. On 26 Mar 2005 17:35:13 -0800, " wrote: Hi there, I just got my Cessna 340. My right engine is very difficult to hot start. I have to crank several times. Have done the flooded start procedure which does not work, the only thing that seems to work is to do a normal start, bring up the throttle halfway and if the engine catches a little bit quickly lean out the mixture. But it is a crapshoot and takes too much effort. Any good tips and experiences? |
#4
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On 26 Mar 2005 17:35:13 -0800, "
wrote: Hi there, I just got my Cessna 340. My right engine is very difficult to hot start. I have to crank several times. Have done the flooded start procedure which does not work, the only thing that seems to work is to do a normal start, bring up the throttle halfway and if the engine catches a little bit quickly lean out the mixture. But it is a crapshoot and takes too much effort. Any good tips and experiences? http://groups-beta.google.com/group/... 454d9144c88f TC |
#5
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wrote in message oups.com... Hi there, I just got my Cessna 340. My right engine is very difficult to hot start. I have to crank several times. Have done the flooded start procedure which does not work, the only thing that seems to work is to do a normal start, bring up the throttle halfway and if the engine catches a little bit quickly lean out the mixture. But it is a crapshoot and takes too much effort. Any good tips and experiences? I had a hard time hot-starting my IO-360 for a long time. As it turns out, I was slightly misreading the flooded start procedure. I *thought* it said to have the throttle full open, and mixture at idle cut off. Then, advance the mixture while cranking until it catches. That NEVER worked. Finally, I re-read it, and it said to crank with mixture at idle cut off UNTIL it catches, then advance the mixture, and pull the throttle. That way works every time. I doubt your problem was as simple as mine, but who knows ;-) Adam N7966L Beech Super III |
#6
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On 2005-03-27, mindenpilot wrote:
crank with mixture at idle cut off [and the throttle full open] UNTIL it catches, then advance the mixture, and pull the throttle. That way works every time. This works every time for me with an IO-540. Hook the pinkie and ring finger around the throttle, position the thumb over the mixture and just twist when it starts to catch. -- Ben Jackson http://www.ben.com/ |
#7
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Our Aztec has the little "spider" fuel distributor on the tops of the
IO540s. The fuel generally gets boiled out of it after shut down, so this is what works for us. 1. All levers forward, throttles, props, mixtures. 2. Master on 3. Fuel pumps on until the fuel flow needles just barely wiggle... and I mean just BARELY, all we want to do is fill up the fuel distributor, the fuel lines, and send maybe a "titch" into the cylinders 4. Fuel pumps immediately off 5. Mixtures to idle cut off 6. Throttles cracked 7. Crank until it fires, mixture forward, add a little throttle, fuel pump on It normally turns over several more times than with a cold start and we can tell when the engines are about to start by watching the blades slow as compression builds, then they will fire. We've tried the "full throttle mixture at idle cutoff, crank until it starts" but it really drains the battery. Aluminum battery cables, 12v battery located in the right side of the nose, just not a good combination for cranking and cranking. Our owners manual even mentions starting the left engine first. This goes back to the days when Aztecs and Apaches only had an single alternator or single generator on the left engine. Barring any other reason, it simply doesn't make sense to start the engine furthest from the battery first if you have alternators on both engines. We start the right engine first and let it provide extra cranking power to the battery when starting the left. What I try to teach people about hot starts is that the fuel/air mixture will ignite best at one ratio and to think about how to obtain that best ratio given the conditions. Just as we have to prime more or run richer mixtures in cold dense air, hot starts and high altitude operations require just the opposite. Less fuel for less air. We know that the engine is hot, so the air in the cylinders is hot and very thin, right? So we don't have to add much gas to obtain our best air/fuel ratio. Your technique of bringing the throttle up halfway creates a leaner mixture by introducing more air into the system, a leaner mixture is what we want but I would rather start by restricting the amount of fuel, and possibly preventing plug fouling. Work from a lean mixture towards a rich mixture rather than working from a rich mixture towards a lean mixture and then back towards a lean mixture. I'd say to take a good look at your fuel system. Learn where the fuel is boiling away and how to purge air and replenish fuel to that area without adding fuel to the cylinders. Jim wrote in message oups.com... Hi there, I just got my Cessna 340. My right engine is very difficult to hot start. I have to crank several times. Have done the flooded start procedure which does not work, the only thing that seems to work is to do a normal start, bring up the throttle halfway and if the engine catches a little bit quickly lean out the mixture. But it is a crapshoot and takes too much effort. Any good tips and experiences? |
#8
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On 2005-03-27, Jim Burns wrote:
We've tried the "full throttle mixture at idle cutoff, crank until it starts" but it really drains the battery. Aluminum battery cables, 12v battery located in the right side of the nose, just not a good combination My battery (Comanche) is in the empennage, but it does have the copper cable mod. My experience with cranking at full throttle (for a hot start) is that the propeller turns much more easily and much faster, presumably due to the fact that the intake cycle can breathe more easily. It probably spins around more times, but starts about as quickly as a cold start. The Comanche does have a roomy cowl and cools so readily that it doesn't even need cowl flaps, so it may be that I've never experienced the joy of a truly hot IO-540 start. -- Ben Jackson http://www.ben.com/ |
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