Hot starting io-540

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drotto

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drotto
I know this basic topic has been done before, and I have read everyone of them. The io-540 on my PA32 will basically not hot start. I have tried multiple hot start protocols, basically every method I have found. I have had multiple knowledgable people try their methods, but basically nobody can get this engine to hot start reliably. Many times have have needed to let the engine cool 25 to 30 minutes before I can get it going again.

Cold start is immediate. Mags always check out. Engine runs smooth and strong, to the point where other pilots have commented how great the engine sounds and feels. It was an overhualled to zero time engine about 5 years ago, and now has about 300 hours on it.

Any ideas? The best one I have heard (other than the usual try my method), is that there may be a mag issue that is only apparent once the mag is hot. That persons idea is there is an issue with one of the mags that causes spark issues but only at temp, perhaps a bad coil in the core. At low temp it is ok, but when it expands with heat it does not produce enough spark. I am debating either replacing or overhualing the mag, despite the fact it should have many hours left on it.

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what kind of mags to you have? Shower of sparks?....how are your plugs and ignition leads?
 
Checkout_my_Six said:
what kind of mags to you have? Shower of sparks?....how are your plugs and ignition leads?
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Plugs were all noted as like new last annual, and any bad plugs (3 of the 12) were replaced by the shop last May. They have about 35 hrs on the new plugs. Ignitoons leads were in good shape, and were new with engine overhaul 300 hrs ago. Plane is hangered. No shower of sparks. Bendix dual mags dl6n-3000's.

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I'd verify you're getting retarded spark with the impulse couplers. If those aren't engaging it will be hard to hot start. Also fuel flow....with your engine sometimes a flooded hot start is the only option. Warm fuel just doesn't flow right....it takes some flooding to get the hot fuel out and replaced with cool fuel that isn't boiling.
 
Most cases of failure to hot start or fuel vapor lock related. Will it light off then die or not even try to light off?
 
Does not even seem like it wants to catch. No indication of starting. Not even trying to light off. I have tried the flooded start and vapor lock procedures, as well many variations, no luck.

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sounds like an ignition issue....I go in that problem solving direction.

If you could get a cough and a fart then it's a fuel issue....but, lack of those and it sounds like you're not getting a good "timed" spark when cranking.
 
I thought I had a good but costly solution. Istartair claims to have a solution to make starting big bore, hot, fuel injected engines as easy to start as a modern car.

So far, the costly part has worked out. They are still trying to get it adjusted so it starts at all. They are working hard on it, but so far the only thing that works is to try the "Istart" three or four times, then do a normal hot start.

I'll report back if they ever get it working.
 
Just to add the engine has always been hard to hot it start. Even when the engine was " new" with only 30 or 40 hrs on it.

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drotto said:
Just to add the engine has always been hard to hot it start. Even when the engine was " new" with only 30 or 40 hrs on it.

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You’ve probably already tried this but here is my non-POH hot start procedure for my tio-540:
Throttle quarter inch
Fuel off
Crank for two seconds then go full fuel
While still cranking hit the boost pump

It’s the ONLY consistent method I’ve found that works on my engine.
BTW if u shut off the boost too soon it may try to die within about 5 seconds. Just hit the boost again.
This is on a 206.
 
The plane is due for annual this month. Hopefully the shop can sort it out if there is any mechanical issue.

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I've always used the POH method in my Lance (fuel pump off, throttle open 1/2", mixture lean/off then crank, mixture rich when catches). But it takes a loooong time. I have to do a slow count to 10 to make sure I don't give up too soon!
 
Mixture at lean cutoff
Throttle cracked
Run the boost pump for a minimum of 60 seconds, maybe up to 2 minutes.
Cut off boost pump
Crank starter
Mixture to Rich
*maybe* bump the boost pump at the end

Ruby's a straight up ***** to hot start
 
Had the exact same problem. Replaced the mag. Starts easy. Troubleshoot your ignition system with a good mechanic. BTW, a standard mag check does not tell anything about the health of your ignition system.

Also had this problem on an O 360 on a Cardinal. Regular mechanic kept saying I needed to learn how to start it correctly. BS. Changed the mag, problem cured.


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I struggled starting my IO-540 when hot...

After some trial I determine to follow the cold start procedure with one exception and it works great for me every time... I start out with the throttle at normal 1/2” position. As soon as I start cranking I advance throttle... way forward, half or more throttle. When it starts (always does) I somehow manage to pull throttle back to about an inch and advance mixture within a blink of an eye.
 
I shove the throttle full forward and the mixture full forward and turn the boost pump on and watch for the fuel flow to stabilize. When it’s really hot, that may be 20-30 seconds. Then I pull the mixture to idle cut off, leaving the throttle full forward. And then I wait 30 seconds at least. Hit the mags and when the engine catches, I pull the throttle back. There’s plenty of time to move the mixture forward before she dies.

However, if the plane won’t start using the POH method or some variation, then it’s not a problem with the pilot. The problem is with the ignition system.


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I had a CFI I have used tell me the exact same thing. He has used a club Saratoga with the same issue. They replaced a mag and it 100% fixed the problem. Just frustrating that a mag overhauled 300 hrs ago ( was done with the engine according to the paperwork) may never have been 100% right.

I know they suggest 500 hrs overhauls on these mags, but this should be nowhere near the service life. And if true, they have had some sort an issue from almost day one. Would expect better out of freshly redone mags.

I am down to the issue being....

1. Bad mag.
2. Ignition system problem.
3. Timing issue problem.

I know the 540 has a reputation, but this is just stupid. I should not risk burning out the starter or killing a battery to hot start this thing.

Sorry, frustrated. Just looks bad when you pick people up and either you look incompetent or your plane looks like junk, because you can't get it started.

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Talked to the mechanic. He promised me to get it good and hot at annual and then try to replicate the issue. If he can't find a hot start procedure that works, he will track down the issue. He suspects either bad timing on a mag or a mag needing an overhaul. If it is not pilot error.

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Sounds a lot like me, my mechanic and my IO520. We are still trying to figure it out. The only people that keep telling me it is "pilot error" are people that have not tried to start it when hot.
 
Just some ideas:
Sometimes it works to flood the engine, then use full forward throttle (so it gets max air), all the way lean (so it gets no more fuel).

Sometimes releasing the starter as SOON as it coughs (release it early) will allow it to catch and go. Sort of like it only starts when the cranking is slowing down.

Sometimes just normal prime, but as you crank move the throttle ALL THE WAY FORWARD.

I think someone makes a "spray of sparks" magneto that causes spark constantly during startup. Might want to check into that.
 
JOhnH said:
Sounds a lot like me, my mechanic and my IO520. We are still trying to figure it out. The only people that keep telling me it is "pilot error" are people that have not tried to start it when hot.
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A CFI I fly with had the hot start experience with me this weekend. He tried every start method he could think of. The engine just laughed at him, did not even give us a stutter. After about 20 minutes, and 15 various attempts, we gave up. Let the engine sit for about 15 minutes and it decided to start like nothing had happened.

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I had the hot start issue (TSIO-520).....I rebuilt both mags and re timed them, internally. I have a shower of sparks system and I suspect the retard (starting) points in the left mag were not timed correctly. That part of the procedure was not clear and I re-did it to get it right. Mine now starts on the second blade.
 
Amid all this frustration I bet if you left the mags on and went out and pulled the prop through by hand it would fire right up like a wood chipper on steroids.
 
drotto said:
Talked to the mechanic. He promised me to get it good and hot at annual and then try to replicate the issue. If he can't find a hot start procedure that works, he will track down the issue. He suspects either bad timing on a mag or a mag needing an overhaul. If it is not pilot error.

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I’m having flashbacks to my starting problem days. Telling the mechanic over and over that the plane wouldn’t start. Being afraid to stop for fuel because I wouldn’t be able to start the engine. Trying every variation of starting available on the web. It’s not pilot error. Our planes can be hard to start, not impossible. Time for a new mechanic. Or fly it down here to Birmingham and I’ll hook you up with a guy that will get it starting correctly.


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drjcustis said:
I’m having flashbacks to my starting problem days. Telling the mechanic over and over that the plane wouldn’t start. Being afraid to stop for fuel because I wouldn’t be able to start the engine. Trying every variation of starting available on the web. It’s not pilot error. Our planes can be hard to start, not impossible. Time for a new mechanic. Or fly it down here to Birmingham and I’ll hook you up with a guy that will get it starting correctly.


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This shop has never worked on this plane. I know them from when I did my PPL .

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Question re: Lycoming FI. Do any of you shut off the fuel valve when shutting down the engine? Maybe close the fuel a little prior to engine off? I'm about to do a first flight in a Lycoming clone with a zero leakdown FI servo and the advice I've received is that with no fuel bypass (like Continental uses) it's a good idea to shut off the fuel valve, particularly to improve hot re-starts. Comments?
 
Stewartb said:
Question re: Lycoming FI. Do any of you shut off the fuel valve when shutting down the engine? Maybe close the fuel a little prior to engine off? I'm about to do a first flight in a Lycoming clone with a zero leakdown FI servo and the advice I've received is that with no fuel bypass (like Continental uses) it's a good idea to shut off the fuel valve, particularly to improve hot re-starts. Comments?
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What would closing off the fuel shutoff accomplish? It's not a gravity system and both the electric and engine mounted fuel pumps are vented, so it looks like the lines are boiling anyways.
upload_2018-5-10_19-35-36.png

I managed to get stranded today with a weak battery and a hot start. Flooded the living crap out of it then proceeded to pooch the flooded start procedures thanks to my lack of patience and lack of battery juice. Took a jump and a heck of a lot of dry cranking to finally get that thing to start popping. Eventually it started firing, but it did so like a radial, slowest onset to smooth running I've ever seen. The boiling of fuel lines is a real thing on these contraptions. Battery is toast (it was on its last legs but it's real toast now). Lesson learned: don't go off station with a weak battery. And if it doesn't fire up with hot start procedures (no prime basically) right away, eff it, just flood it and do the flood start.
 
Reduced fuel in the lines, reduced fuel forced into the cylinders, better ability to pick up cool fuel at restart. Makes sense to me and the guys that gave me the advice during a conversation about purge valves know their stuff about FI.
 
Stewartb said:
Reduced fuel in the lines, reduced fuel forced into the cylinders, better ability to pick up cool fuel at restart. Makes sense to me and the guys that gave me the advice during a conversation about purge valves know their stuff about FI.
Click to expand...

I'll give that a try next time I have a quick turn, and will report back if I see any difference. Anything to avoid getting stranded in a 95F ramp like I did today!
 
Stewartb said:
Question re: Lycoming FI. Do any of you shut off the fuel valve when shutting down the engine? Maybe close the fuel a little prior to engine off? I'm about to do a first flight in a Lycoming clone with a zero leakdown FI servo and the advice I've received is that with no fuel bypass (like Continental uses) it's a good idea to shut off the fuel valve, particularly to improve hot re-starts. Comments?
Click to expand...

If hot starting one Lycoming IO-540 is not fun, try starting two of them. :p

I suspect the best technique varies quite a bit by installation, type of magneto starting system, fuel system configuration, etc.

I never shut off the fuel valves. But that's not to say that couldn't be an effective preventative step on other installations.

My two IO-540s each act EXACTLY the same during hot starts. Took me a while to perfect the technique for my plane. Crack throttle open 1/2 inch, hit the fuel boost pump, open the mixture for a count of 6 (more than that it floods, less than that it'll still be vapor locked), mixture to idle cutoff, fuel pump off, hit the starter and advance the mixture as it catches, set throttle for correct idle speed. Number of turns to start depends on how long it was shut down, but I rarely need more than four or five blades in the worst case.

I have one of those despised-around-these-parts Gill lead acid batteries, so therefor a necessity to have a reliable hot-start technique, apparently. ;)

I have Slick mags with a shower-of-sparks that starts the engines on a separate set of points in the left mag only. I lavish attention on the mags after having the LH engine starting mag leave me stranded at the fuel pump twice in rapid succession. Discovered that not all mag servicings or so-called "overhauls" are what they are made out to be. It's getting more difficult to find experienced veterans that really know how to maintain magnetos properly.
 
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drotto said:
A CFI I fly with had the hot start experience with me this weekend. He tried every start method he could think of. The engine just laughed at him, did not even give us a stutter. After about 20 minutes, and 15 various attempts, we gave up. Let the engine sit for about 15 minutes and it decided to start like nothing had happened.

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Only need three things to make it run: air, fuel, and a spark.
Air is not usually a problem.
If it's fuel preventing a hot start that means vapor in the lines, or its flooded - either way with all the experimenting I believe you would have by now figured out the right technique to deal with it on your airplane.

I am inclined to agree with those above who have posited it may be an ignition/magneto problem. Although one would expect if you have two identical Bendix magnetos, both with impulse couplings, it would be improbable both would let you down at the same time.
 
I would have someone watch the aircraft while you start it, looking for a black puff of exhaust when it fires. That would tell you the mixture is overly rich. The issue, obviously, is that if it won't start, you can't learn anything.

Second, I'd do a thorough check on the impulse coupled mag.
 
GRG55 said:
I am inclined to agree with those above who have posited it may be an ignition/magneto problem. Although one would expect if you have two identical Bendix magnetos, both with impulse couplings, it would be improbable both would let you down at the same time.
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cept both mags typically do not have starting circuits....or retard spark....ie. impulse coupling or SoS.
 
Checkout_my_Six said:
cept both mags typically do not have starting circuits....or retard spark....ie. impulse coupling or SoS.
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How does the heat affect the mags however? Remember this engine starts flawless cold.

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drotto said:
How does the heat affect the mags however? Remember this engine starts flawless cold.

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you said....it isn't firing when hot. That's why.

If your ignition system was working it would cough and fart and not run when hot. Hot boiling fuel makes the fuel air ratio irregular and the engine won't run.
 
Checkout_my_Six said:
cept both mags typically do not have starting circuits....or retard spark....ie. impulse coupling or SoS.
Click to expand...

Yes, I am aware of that.
However, the OP's post #3 and your response in post #4 seem to suggest a pair in this instance. That's what I was keying off.

If there is an impulse coupling or starting points only on the left mag, as is typical, then it's easy to figure out which one needs to be checked.:)
 
GRG55 said:
Yes, I am aware of that.
However, the OP's post #3 and your response in post #4 seem to suggest a pair in this instance. That's what I was keying off.

If there is an impulse coupling or starting points only on the left mag, as is typical, then it's easy to figure out which one needs to be checked.:)
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This is the bendix dual mag setup. I am fairly certain it starts just off the left mag like a traditional setup, but I am not 100% sure.

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