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Going back to Concord from Odyssey?

ssokol

Well Known Member
Sponsor
Long time lurker, first time (as an RV owner) poster.

I just purchased an RV-6A with an IO-320 and an Odyssey PC680. LOVE the airplane - having a ton of fun with it. But... The aircraft starts up fine when cold but hot starts are a monumental pain. I've had to have the guys from the FBO come out and jump start me at the pump twice in the past few days. I've tried several different a procedures to clear the vapor lock, but none of them have been a "magic bullet".

The Odyssey (installed last year according to the log book) is only good for 30 - 50 blades before it loses steam and can't turn the engine over. That's not quite enough to clear out either the vapor in the lines (if attempting to start without flooding) or the excess fuel in the cylinders (if trying a flooded start). We're pretty sure it's the battery as it the airplane has no problem starting once the jump pack is hooked up (itself a difficult process - need a ground power plug!).

The battery tray on this airplane is on the firewall, rather than centered inside the cabin. It was obviously built for a 25, rather than the half-sized Odyssey. At some point one of the previous owners switched over and left the full-size tray in place.

I like the size, weight, and cost of the Odyssey but if this airplane needs more juice to start then I'm tempted to eat the 11.5 pounds and go with a Concorde so as not to have to worry about running out of amps at some remote field.

Anyone out there have words of wisdom, warning, or agreement? Am I looking at a complicated W&B issue?

Thanks in advance,

Steve
 
No direct answers for you, but...

You might want to find the root of the problem rather than just try to mask it with a battery. PC680's have a long history of outstanding cranking performance on RV's. It sounds like your real starting problems lay elsewhere.

If you do go with a larger battery, to find out if you'll have a W&B issue, you should be able to do the math pretty easy to figure that out. I'm assuming an W&B came with the aircraft when you bought it? Even if it did, the first thing I would do as a new owner was to get a new W&B anyway, just to be sure it reflects the current configuration of the aircraft, not the configuration when it was first built.

Good luck.
 
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Ditto on the reply above. A PC680 starts my IO-540 just fine, cold and hot.

Hot start procedure is simple: Throttle full, cycle the mixture once (full rich and back to ICO), crank.

Works every time, never more than 10 blades. Of course once it fires you don't want to dilly dally getting the mixture to ~half and the throttle back to idle.

Maybe you do need a new battery, but if so I would just replace it with another PC680.
 
Right on. Everyone will fine tune their own hot start procedure but NO boost pump part throttle full lean and crank. Once it starts (should be right away) go half on the lean and sometimes it might be necessary to turn on the boost pump (half way to the hanger) AFTER start to keep it running. At least I have to in the summer here in AZ. If the battery is good the 680 probably is not the problem. After 2700 hours in 2 different RVs this works for me and many others that I know. Hope this is helpful?
 
W&B

30 to 50 blades should be enough to start any engine. The starting problem is somewhere else.

The W&B issue can be a blessing on an RV4. Mine had a 320, a carbon fiber Prince prop(11 lbs), and a relatively light pilot(170 lbs). Without adding weight to the nose, the biggest passenger I could take was 195 lbs and I had to land before the tanks were half empty.

As others have said, get a new W&B to make an informed decision based on you and your plane.
 
One more for 'not the battery'. I put about 200 hrs on a Swift, 1st with an IO-320, then with an IO-360. No hot start problems because I was taught the technique that worked with that a/c.

Charlie
 
Anytime I make a stop on a trip in my RV7, I open the oil access door to let the heat out of the engine compartment. The fuel is hot due to the flow divider and fuel lines that are on top of an IO engine. I think this will help your starting problem.
 
Thanks to everyone who's responded so far. Sounds like there's a lot of support for the Odyssey, and a pretty strong consensus that there's something wrong with either my starting technique (quite possible) and / or some other aspect of the starting system.

Assuming that there's something off about the starting system, any guess what it could be? I know I've got good spark - one e-mag and one standard, both of which check out fine during run-up. Once it starts it runs well. Full rich fuel flow is higher than I expanded on my experience with an O-320 in a Cherokee, but it doesn't seem to have a negative impact on performance.

Thanks!

-S
 
The Odyssey (installed last year according to the log book) is only good for 30 - 50 blades before it loses steam and can't turn the engine over.

I've flown PC-680's for fifteen years (RV-6, O-320) and 30-50 blades is a healthy 680! As others have stated, hot start routine probably needs to be refined. The hot injected engines I see usually are running in less than a dozen blades unless the start is fumbled.

I would be concerned about cooking the starter if 40-50 blades were spun in a short period of time especially if you have one of the lightweight, high-current starters.
 
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Yep, my mechanic came out and read me the riot act for cranking longer than 10 seconds and not waiting at least 30 seconds between attempts. Lesson learned!

I've always had carbureted engines before- never needed more than 10 blades. New world...
 
Good comments but I would add put a voltmeter on the battery after it has set for at least several hours. If it not 12.8, it's not fully charged and yes that is .2 volts higher than a regular lead acid. If it is down, you need an approved charger to get it right, or a very long flight or two. Regular charger won't go into the saturation mode long enough to top it off. And it's a good chance this is your problem.
These batteries can lose capacity if kept too long at less than full charge, but you can recover them by drawing them off into a headlight or similar, down to 10 volts or so, recharge and repeat until the capacity comes up. Full instructions for that on Odyssey's website.
Tim Andres
 
...I know I've got good spark - one e-mag and one standard, both of which check out fine during run-up. ...

Thanks!

-S
E or P-mag? The company is Emag Ignitions and early on they sold both an E-mag and a P-mag but now only sell the P-mag. The difference is the P-mag has an internal generator and the E-mag does not.

If you have a P-mag and it is prior to version 40 of the firmware, get it in for the upgrade and inspection. One of the things version 40 does is during starting is to fire the plugs at 4 degrees after TDC. Either way, try starting it with the traditional mag grounded (off) so it does not fire before the E/P-mag and then turn on (in-ground) the mag. That may also help you.
 
You might want to check that you don't have a parasitic drain on the battery and you are really beginning with a half-drained battery.

Vic
 
Me too.

You have some very good suggestions above and I too would tell you that the 680 PC will carry the load if in good shape. Two other things that do come to mind here. The older big factory starters don't turn an engine very well and turn them slower than needed for good starts. And if the battery is good and has full load carrying capacity one needs to get as much of that pressure to the starter as one can so the starter can use it. We have seen so many RV's with #4 starter cable on them. Some times this works OK with a new generation starter, but if you want to get all the juice you can from the battery to the starter and not have much of a voltage drop or pressure drop if you like that term. Make your ground and feed cables for the starter circuit from #2 and clean good cable ends and luges so that you can transmit as much of that power to your starter motor as you can. And really old starters will start to drag tell you through twice the amperage on them with a jump supply.
Just a couple of pennies to put in the pot. Yours, R.E.A. III #80888
 
Starting

Steve,

Had some start issues when I first bought my -4. The airplane has an IO-360 with a C/S prop which the builder decided needed the battery in the baggage compartment for weight & balance. Changed the starter wire to a #2 as described above (long way from the battery to the starter). Also changed the 149 LS lightweight starter to a 149 NL high torque starter and swapped out the PC 680 with an Earth X battery. I did all these one at a time and at each step the engine started faster & faster. To compound the problem, somewhere in this process the starter solenoid gave up further complicating the issue.

All those changes spun the prop incredibly fast but my hot start technique was lacking to say the least until someone clued me in (this was first injected engine). Ditto what my cousin Mark says above for a good hot start technique:

"Hot start procedure is simple: Throttle full, cycle the mixture once (full rich and back to ICO), crank."

Oh and did I say NO BOOST PUMP? Each engine behaves differently but Mark's technique describes the most common hot start method.

Oly Olson
 
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Dispair!

Threads like this often make me wonder what you guys are thinking, then I slap myself and remember that the mechanical knowledge of most pilots is Zero!

From what you have said the problem is not the battery. The problem is poor hot starting which causes you to run the battery almost flat. So cure the hot starting problem and your battery will be fine.

Now you say 1 email make sure it is V40 as has been previously suggested. That upgrade prevents a host of othe potential problems

Does the mag have an impulse on it. If so with an email and an impulse you can be fairly sure of a good spark

You mentioned at the outset vapour lock, what have you done to address this and eliminate it as a cause. That is where I would start after ensuring the mesh is V40.


Hope this helps! BTW my 0-320 on a PC 680 with two PMags starts hot or cold second blade. Ok it is carbed but all fuel lines are fire sleeved and insulated from heat sink.
 
My -6 with o-320 was doing the same thing as yours. I replaced the pc680 and it still would not start half the time and when it did, it would barely make it over the compression stroke. I tracked mine down to a burnt starter solenoid. The stock starter solenoids are bad to pit the copper disk inside every time the engine starts. I broke mine open and the face of the contactor looked like the surface of the moon. This does not make a good contact and severely restricts your cranking amps. I would replace the solenoid. They are cheap and easy to change. I also ran a ground cable directly to the starter. This makes it start right up.
 
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Long time lurker, first time (as an RV owner) poster.

Steve, all successful hot start methods base on a simple concept. The engine will fire when supplied a mixture that is within a fairly narrow range. So, the goal is to sweep the mixture through that range during the start process, either by beginning in a lean condition and moving toward rich, or beginning in a rich condition and moving toward lean. Either way, when you hit the sweet spot, it will light.

Sweep lean to rich (from Nigel):

Throttle open ~1/2 inch
Mixture Idle Cut Off
No priming, boost pump Off
Starter engage
Mixture slowly forward ('slowly' is at a rate that would take you from ICO to rich in about 5 seconds) until it starts, which is usually about mid range.
Throttle as required to set idle RPM
Mixture lean
Boost pump as required to keep it from stumbling if the fuel pressure fluctuates.


Sweep rich to lean (from Randy):

Prime
Throttle full open
Mixture full closed
Start.
As soon as it starts:
Throttle back to hi idle quickly
Mixture about 3/4 open (This is different on all planes)
If you have trouble keeping the idle, run the boost pump after it starts.


As a personal preference, I recommend learning the "lean to rich" method, as it does not begin with the throttle at WOT. The "rich to lean" method becomes a backup plan if it doesn't fire sweeping from lean, as it was left in a rich condition.
 
When I first bought my RV8 with IO360 I would run my battery down on hot starts because I didn't understand what my engine needed to start when my fuel system was compromised by boiling fuel. It's really disappointing when that happens.

It was a post like DanH and others that made the difference. Bottom line is you need the right air/fuel mixture, sparks at the right time and a starter system with a good enough battery to turn the crank rapidly enough.

My procedure is lean to rich like described. Almost always works. If that fails (occasionally it does) I go rich to lean. The fuel pump goes on right after start as mine spits as sputters until it does.

I recently upgraded from an Odessey PC680 battery and skytec Light Weight starter to a SJ16 battry (220 CCA) and B&C starter. I'm very impressed with the B&C.
The B&C engages first try, everytime and spins the engine faster with less amperage draw then the permanent magnet starter I was using.
 
Im not criticizing the above hot start techniques; whatever works, right? I do find it odd however that folks are recommending against using the boost pump just prior to starting. I use mine, per the procedure recommended by by AFP. The logic seems sound to me: Circulate cool fuel from the tank through the system with the purge value open to get rid of the vapor while avoiding flooding the engine.

erich
 
I agree on the battery. I use the Odyssey 680 in my -8 with IO-360. The battery is doing fine.

I used to go WOT Full Rich and boost pump to a count of 5 then MCO for a hot start. Bring the mixture forward slowly and it would usually start just fine.

I now do the lean to rich that DanH described and it works 98% of the time with just a few blades of turning. Told a Bonanza guy about it once at the fuel pumps and he now hot starts that way.

BTW I found that procedure on the Mooney Pilot's Association website. There is a lot of good information there.
 
Im not criticizing the above hot start techniques; whatever works, right? I do find it odd however that folks are recommending against using the boost pump just prior to starting. I use mine, per the procedure recommended by by AFP. The logic seems sound to me: Circulate cool fuel from the tank through the system with the purge value open to get rid of the vapor while avoiding flooding the engine.

erich

The starting procedure IS different with the AFP and a purge valve. With the typical Bendix FI you will flood the engine if you use the boost pump on a hot engine and any prime at all.

Vic
 
Im not criticizing the above hot start techniques; whatever works, right? I do find it odd however that folks are recommending against using the boost pump just prior to starting. I use mine, per the procedure recommended by by AFP. The logic seems sound to me: Circulate cool fuel from the tank through the system with the purge value open to get rid of the vapor while avoiding flooding the engine.

I have an AFP with purge valve, and do circulate prior to start, mostly because it runs nice after starting with cool fuel in everything. The Bendix/Precision/Avstar owners don't have a purge valve.

The above procedures work with all constant flow injections. The aux pump can be on or off; the mixture knob controls fuel flow, not the pump.
 
A few notes on the electronic ignition system...

I pulled out the manual and it turns out I have a Light Speed Engineering Plasma CDI (Capacitor Discharge Ignition). The system was installed in 2001 when the aircraft was being finished.

The control unit was sent back to the manufacturer for an overhaul only a few weeks before the aircraft was delivered, and the main board was replaced. The ignition wiring is also new.
 
Ok, I dont see where Steve indicated what type of FI system he has, so if it is AFP, perhaps use of boost pump to circulate cool fuel prior to hot start would be a good idea.

erich
 
I'm afraid I don't know what make / model the FI system is - I can't find any details in the engine log or build log.

Would a purge valve result in the overflow spilling out? I ask because when we tried a flooded start we wound up with fuel dripping out of the bottom of the cowl. I expected to see it coming out of the exhaust...

Please pardon my mechanical ignorance - I'm doing my best to learn as I go.
 
I'm afraid I don't know what make / model the FI system is - I can't find any details in the engine log or build log.

Would a purge valve result in the overflow spilling out? I ask because when we tried a flooded start we wound up with fuel dripping out of the bottom of the cowl. I expected to see it coming out of the exhaust...

Given the airframe age, probably Bendix RSA-5, maybe a Precision Silver Hawk EX-5. If you had an Airflow Performance system, the cockpit would include a rather obvious purge valve control...a knob, or lever, or something.

Again, it doesn't matter. The purge is nice, but not essential; the ability to circulate fuel before start is only a side benefit, not its prime purpose. Actual start procedure is the same for all types.

Re fuel spillage with a flooded start (i.e. sweep rich to lean), yeah, that's normal, in particular given an updraft intake. The fuel is squirted into the intake passage in the cylinder head, just outboard of the intake valves (most of which are closed), so it runs down the intake tubes and drips from the throttle body into the air filter housing, out a drain hole, down the inside of your cowl, and onto the ground. Another good reason to use the "lean to rich" method.;)
 
I'm afraid I don't know what make / model the FI system is - I can't find any details in the engine log or build log.

Would a purge valve result in the overflow spilling out? I ask because when we tried a flooded start we wound up with fuel dripping out of the bottom of the cowl. I expected to see it coming out of the exhaust...

Please pardon my mechanical ignorance - I'm doing my best to learn as I go.

Steve,

Fuel dripping out sounds like a recipe for a fire. Please be careful. This might be an occasion when you want to learn before you go any further.

Here's a little info to read about on the Airflow Performance Purge Value.

http://airflowperformance.com/wp-content/uploads/2016/11/Purge-Valve-Manual-8-28-07.pdf

https://www.youtube.com/watch?v=vLC0gryo9oU

Notice in the video the control cable that actuates the purge valve.
 
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Steve,

Fuel dripping out sounds like a recipe for a fire. Please be careful. This might be an occasion when you want to learn before you go any further.

I totally agree!

The fuel servo on the FI system on my airplane does not have the purge valve and return pictured in the Air Flow Performance info. That appears to be a much more sophisticated system than I have.
 
I totally agree!

The fuel servo on the FI system on my airplane does not have the purge valve and return pictured in the Air Flow Performance info. That appears to be a much more sophisticated system than I have.


Nor does mine. Like DanH said, "The purge is nice, but not essential"

If you haven't done it already, consider making a copy of what was said early for inclusion into your checklist, specifically;

Steve, all successful hot start methods base on a simple concept. The engine will fire when supplied a mixture that is within a fairly narrow range. So, the goal is to sweep the mixture through that range during the start process, either by beginning in a lean condition and moving toward rich, or beginning in a rich condition and moving toward lean. Either way, when you hit the sweet spot, it will light.

Sweep lean to rich (from Nigel):

Throttle open ~1/2 inch
Mixture Idle Cut Off
No priming, boost pump Off
Starter engage
Mixture slowly forward ('slowly' is at a rate that would take you from ICO to rich in about 5 seconds) until it starts, which is usually about mid range.
Throttle as required to set idle RPM
Mixture lean
Boost pump as required to keep it from stumbling if the fuel pressure fluctuates.


Sweep rich to lean (from Randy):

Prime
Throttle full open
Mixture full closed
Start.
As soon as it starts:
Throttle back to hi idle quickly
Mixture about 3/4 open (This is different on all planes)
If you have trouble keeping the idle, run the boost pump after it starts.


As a personal preference, I recommend learning the "lean to rich" method, as it does not begin with the throttle at WOT. The "rich to lean" method becomes a backup plan if it doesn't fire sweeping from lean, as it was left in a rich condition.

Please report back your results.
 
Results

So last night happened to be the monthly meeting for my EAA chapter, and I was on deck for the show and tell. I decided to make it an opportunity to work on my hot start procedure with a group that included at least half a dozen mechanics...

After talking through the options everyone here has provided, I used the lean-to-rich method without boost pump and found that it worked flawlessly. Here's what's now in my checklist under Hot Start Procedure:

1) Mixture to ICO
2) Throttle full open
3) NO boost pump on initial attempt
4) Master on
5) Electronic Ignition On
6) Start, gradually enriching mixture

To test it out I got the engine up to temp, then parked it for 20 minutes or so to let the fuel in the divider and lines boil. I followed the procedure and the engine started on 5 - 6 blades. I shut down, gave it another few minutes and tried it again with the same result.

I think I must have been flooding it before, as I was trying to start with the mixture rich and the throttle cracked - the same basic procedure I used on carbureted engines previously.

I'm going to do some more testing this afternoon - it's supposed to be about 95 here today so it should be a pretty good opportunity to see if I've got it down.

Many thanks to everyone who responded with suggestions. Looks like VAF just saved me the cost of a new battery!
 
That's very similar to the technique I was taught in the Swift. We'd begin with throttle wide open, mixture at idle cutoff, and as soon as the engine fired, 'swap the levers'.

Amazing what we put up with to have 'aircraft quality', ain't it? You're kinda cheating, with that electronic ignition.

Charlie
 
Hot start

I have a optima red top battery, you can taxi on
The starter if you want too, little heavier than a
"Aircraft" battery but after 4years still cranks
Forever
 
Bad Battery

I switched from my tried and true Wal-Mart lawn tractor battery last year to the PC680. Well it just died after 1.5 years. Never had a problem with my Wal-Mart batteries so lesson learned. I'm back to replacing the lawn tractor battery every 2 years for $30.

The removed battery goes to my Snapper lawn mower so no starting problem there either!
 
PC680 capacity

I've been running a PC680 most of the life of my plane, three or four of them in the last 14 years or so.

I have FI, so the hot starts do take some care as others have written earlier. That said, every couple years I'll botch one (two types of FI users - those that have and those who will botch a hot start...). The 680 can burn down a starter if you let it - they have an absurd amount of cranking power. Charging voltage, battery age, starter condition, cable condition, solenoid condition and connection conditions all contribute to performance.
 
I kind of like my ECI mechanical fuel injection (FI) with return fuel lines to the feeding tank (i.e. Continental Mechanical FI).

Hot starts for this setup are:
  1. Turn on electric boost pump for a count of 10, then turn it off.
  2. Set mixture full rich and crack throttle 1/8 in (normal starting procedure)
  3. Engage starter.
  4. Engine starts.
  5. Set mixture as appropriate for the specific environmental conditions.
  6. Go fly.
With the return fuel lines the boost pump moves hot fuel out of the fuel lines and replaces it with cool fuel from the fuel tank. No more vapor lock. No more hot start problems.
 
Two more data points

In 2011 I installed a PC680 in my RV-8 in the aft location behind the baggage compartment floor. 7 years and 550 hours later I decided to move the battery to the firewall to improve the cg with two people and low fuel plus to improve accessibility. Having the battery behind the baggage floor, even with an access door, is a pain.

I bought an EarthX battery box and new master contactor, made some new cables, installed a spare PC680 that had sat on the shelf for 5 years on the front, and pulled the old PC680 out of the back. I charged up the firewall battery and it cranked the engine fine the first time (disregarding a faulty starter ground issue). Several trips later it was still turning the IO-360 over fine.

Last week I got to thinking that maybe after I went to all the trouble of moving the battery location to the firewall I should have sprung for a new PC680 for on the firewall so I took both old batteries first to Autozone for a load test and then to Batteries Plus. Both places said both batteries had a bad cell.

Now it seems to me that a bad cell would have dropped battery voltage a noticeable amount, but maybe not. I gave them both bad batteries and bought a new one for the firewall. Yes, maybe I should have kept one for a spare but with a new battery under warranty and a bad cell in the old one what's the point?

Summary - my experience with PC680 batteries bought in 2011 and 2013, one in service all this time, one left on the shelf, both with bad cells but both turning over the 360 just fine! I think they've proven to me they can do the job and hold up. Perhaps the new one will fail tomorrow but for right now I am happy with the (now 3) PC680's I have bought.
 
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