0470 overheating and running rough

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AlaskanOutdoorsman
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0470 overheating and running rough

Post by AlaskanOutdoorsman » Sun Sep 02, 2018 2:38 am

Boat is running fine for 5 or 10 minutes then the temp starts increasing and the engine starts running rough as if it's either not getting fuel or is fouling plugs. (Which it doesnt). Engine loses power so I limp at 2000 RPM to the bank to let oil temp cool down from 250 degrees. Oil pressure never goes over 60 or under 50. After a few minutes it runs fine and starts all over again only to repeat the process.

Other than an oil change I changed my plugs recently and upgraded my Champion's to D21's. Curious to anyones thoughts: is it a spark issue, to hot a plug, air leaks or a fuel issue? I've had no issues with this boat otherwise and aircraft ships are all closed for the extended Labor Day weekend.

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Re: 0470 overheating and running rough

Post by John Fenner » Sun Sep 02, 2018 9:15 am

Sounds like a lean condition to me, d 18 is all you need, d21 for oil burners in bottom plug holes. What carb?
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Sun Sep 02, 2018 10:04 am

Aircraft carb located below the engine.

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Re: 0470 overheating and running rough

Post by John Fenner » Sun Sep 02, 2018 11:34 am

Make sure lean and rich lever is at full rich, make sure fuel tank vent is clear of obstructions.
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Sun Sep 02, 2018 10:08 pm

No go; neither were the issue. Found two small airleaks kn the manifold booties; going to attempt to resolve and try again. The overheating makes me wonder if it's two issues but one step at a time. Need to spend time with the manual tonight to see if anything stands out.

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Re: 0470 overheating and running rough

Post by Gary S » Mon Sep 03, 2018 6:35 am

Air leaks will make it run lean. They don't have to be big leaks to do it.

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Re: 0470 overheating and running rough

Post by Slidin Gator » Mon Sep 03, 2018 6:49 pm

Gary S wrote:Air leaks will make it run lean. They don't have to be big leaks to do it.
And running lean will make it run hot, which explains both issues. You will torch the exhaust valves if that is the issue. It sounds like time for new rubber on the intake system.
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Re: 0470 overheating and running rough

Post by rowdy1 » Mon Sep 03, 2018 8:07 pm

My 520 is doing the same thing, I have resealed all of the intakes and re clamped all of the boots. I can not find the leak. Look for a black oil like substance in the intake. Im told that is a sure sign of an intake leak.

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Re: 0470 overheating and running rough

Post by John Fenner » Mon Sep 03, 2018 8:49 pm

Non chlorinated brakeclean spray will find your leak.
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Tue Sep 04, 2018 5:36 pm

After a leak test it appears I have a bunch of air leaks around the rubber sleeves. Hopefully that was the only problem. Hope to know more tonight.

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Re: 0470 overheating and running rough

Post by Rich Andrews » Tue Sep 04, 2018 6:10 pm

better make sure that carb is right as well or risk a whole lot of $$$$$
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Sat Sep 15, 2018 1:02 am

Update:

Been swamped with work so just got the boat. Ran it today after I ordered/installed new wires on both mags. Fixed all the air leaks on the engine. Installed a new carb heat cable, P-nut on the carb heat 'foot' and adjusted the carb throttle rigging per a mechanics instructions.

Checked torque on prop. Started engine and it initially ran great. Smooth with a lower idle than before at 800 RPM. It used to be 1000 RPM. Wondering if it's the new plug wires but so far I'm a happy camper..

5 minutes run time on trailer with new prop at 2700 RPM. Smooth.. no issues. This is where it acted up before on the river so I wanted to see if it would duplicate on the trailer.

Oil pressure running 50-60 PSI steady. Normal.

Temp started to climb (expected). At about 180 on gauge and five minutes run time it started slowly losing power. When RPM fell to 2500 the power continued to drop but it started immediately running rough then I shut it down. Grayish white smoke coming from the exhaust.

Back to the drawing board.

Have not done a compression test or drop leak test. Don't have the tools for it. Aircraft shops are a minimum of three weeks out to look at it.

I'm going to pull the plugs, look at them then go back to D16's like I originally had. I don't expect a hot plug could be the issue but I may be wrong.

Could this be a stuck valve? Broken spring? Bad rocker? I don't have any exhaust obstruction. Carb works fine.

Moose season has another week for the area I have a permit in. Any suggestions would be helpful.

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Re: 0470 overheating and running rough

Post by John Fenner » Sat Sep 15, 2018 8:17 am

Ok, you obviously have a timing issue here, pull #1 plug, get to compression stroke tdc and back up crankshaft to 22° btdc if it is a true o470 there are degree marks on bottom edge of flange to align with split line of case to determine the degrees, pull sight plugs from mags and point covers, the gear in sight window should be on a beveled tooth dead center of said sight window, if not then timing is likely too high, if it is in center of both, proceed to check that both sets of points are just barely beginning to break open, be sure that the tungsten contacts are not pitted, and still crowned and thick.
If all the above checks out good, you may have some bad fuel, assuming you are running 100ll avgas.
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Sat Sep 15, 2018 3:18 pm

Im trying to sort through your suggestions. A bit over my familiarity.

This boat has only ran premium pump fuel. Would hotter plugs throw off timing? I noticed it as after the change or is it just coincidence?

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Re: 0470 overheating and running rough

Post by John Fenner » Sun Sep 16, 2018 7:57 am

There lies the problem, it is detonating, you need to back off timing for 1, or go run some av gas through it 2 being you noticed a difference with the plug heat change, you need the d15 plugs back in it. Connies are very temperamental with timing and detonation you will have cracked cylinder heads and hammered ring lands as well as rod bearings if this continues.
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Re: 0470 overheating and running rough

Post by Striker543 » Sun Sep 16, 2018 10:37 am

Another option is using a real octane booster. I ran ACES IV from bnd automotive in my continental e 185 with pump gas. It’s not cheap, but it works very well. You also have to call directly the first time you order as they do not have an online store (they don’t want people purchasing the wrong product), but you can order via email after that.

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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Mon Sep 17, 2018 3:33 pm

Tonight I'm swapping the plugs and going back to the original D16's like it originally had. I'll gap them at .020. This much I can do on my own.

I'll report back later tonight after the engine run. Thanks!

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Re: 0470 overheating and running rough

Post by mojoe » Tue Sep 18, 2018 7:29 am

One of the great things about this site is the wealth of knowledge available. The trick is identifying it when it is given. You should follow John Fenners advice.

Running avgas and making sure timing is right is cheap and simple compared to the damage detonation causes.

Avgas not only has higher octane to burn slower. It has lead to lubricate the valves. Also is more tolerant of sitting in a tank for extended periods of time. I don’t know all of the differences, but there are 3 reasons it is better for your motor. Not to mention the obvious: you motor was designed for it.
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Wed Sep 19, 2018 4:39 am

Agreed mojoe. I've not done the timing on these 0470's before, going to have to learn how. After the advice here and speaking with a few mechanics (the river version of a friend of a friend telephone troubleshooting) the list of what it 'could be' has grown to include:

air leaks.. (resolved- fixed leaks)
bad cables.. (resolved- installed new cables)
hot plugs/timing issue..
carb ice/lack of carb heat..
weak or wandering magneto..
carb issues..
bad cylinder(s)..

Tonight's run up didn't provide any answers so the boat's on it's way to an aircraft mechanic's shop tomorrow. Hoping to have some solid answers in the next 24-48 hrs.

Fingers crossed I can get her running and install the new set of blades in my garage before the end of moose season.

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Re: 0470 overheating and running rough

Post by John Fenner » Thu Sep 20, 2018 9:06 am

Mags do not wander unless impulse coupler springs are weak or broken.
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Fri Sep 21, 2018 6:35 pm

Mechanic update:

No top end; all cyl are low pressure and she's burning aluminum.

Compression test results: cyl #1 30/80, #2 0/80, # 3 10/80, #4 42/80, #5 13/80 and #6 49/80.

Borescope results: cyl #2 has a burnt piston with a hole in it. Cyl #4 and #5 have oil leaks where head screws to bore

Mag's were at 24 degrees; should be at 22 degrees.

No idea on the lower end. Mechanic didn't want to dig further and said the motor was 'junk'.

Clearly a full top end with chrome cyl's wasn't done 50 hours before I bought the boat as I was told. I wonder what performance level this engine was running at during my time with it.

In any event my mechanic will only rebuild to aviation standards ($32,000) so it's either scrap this engine, pallet it up and ship to the lower 48 for airboat rebuilding (if it's affordable), or start searching for another engine and/or upgrade to a reliable I0-520 that will bolt right onto the engine stand. My new prop hasn't even been unboxed yet.

Anyway.. time to search for an affordable/reliable engine rebuilder or a source for another engine. LOL.. Anything out there that is more affordable than Barnstormers and trade-a-plane?
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Re: 0470 overheating and running rough

Post by Slidin Gator » Fri Sep 21, 2018 11:08 pm

Bummer! It should have been blowing white smoke with a hole in #2, but no question that explains the high oil temps.

Given the following:
- Motor has been running too much advance for AV Gas
- Motor has been running pump gas
- Motor had intake leaks, so it was also lean

It is very likely that the motor has been knocking for some time and it has probably done a number on the bearings. Personally, I would measure the piston wrist pin bearings for out of roundness and diameter as an indication of damage to the rest of the bearings to help with deciding between a top end or full rebuild.

For consideration, rebuilt jugs with new piston and rings (chrome or 0.010" over) are going to run around $600-$650 each. Used serviceable with a valve job and new rings can be had for around $400. So somewhere in the $2,500-$4,000 (+ ship & tax) range for a set of 6, you install. A full rebuild is in the $9-$10K range. The extra $22K is to pay for the FAA inspectors, paperwork and insurance in case it falls out of the sky, not needed here.

You should keep your eyes out for an out of hours aviation run out for less than a rebuild, that's where the boat motors come from. If you settle on an IO-520, you can also plan to swap that narrow blade for a full width Whisper tip. You also need to find an aviation mechanic that does boats on the side.

Good luck!
I grew up thinking I-10 was the Mason Dixon line.
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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Fri Sep 21, 2018 11:35 pm

Well said. I just upgraded and bought the full Whispertip to try but the engine blew so they are in an unopened box.

I've been looking for a few weeks and only found a few out of time engines in Alaska. A swamped 0470-R recently sold for $2000 with no log book. Another had a cracked case, no book again. No 0520s at all but I'll keep looking. I'm not sure which engine is best at this point. My first aircraft engine has me a bit frustrated. Dont want to blow another up.

I'm going to weigh a number of options, including shipping out to have a rebuild or just change to a crated marine auto ebgine/gearbox.

Pump gas and 300 hp would be nice but will be about 14k.

Thanks

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Re: 0470 overheating and running rough

Post by Slidin Gator » Sat Sep 22, 2018 9:37 am

A CAR MOTOR! Just because your first date turned out to be a real bch, did you switch to guys? :stirpot:

There are lot's of blown up car motors out there too, and 300 Hp is no where near enough for the weight you are going to add, unless you go Eco, yah, those are simple (not).

A swap entails more than just buying the motor and gear. At a minimum you will need new rigging and prop and realistically you probably need a wider hull to handle the prop torque. If you really want to go to the dark side, you are better off selling what you have and buying a CM boat.

AV motors are basically overgrown VW engines that are simple to work on yourself, once you know how. Find an old hippie with a badd azz micro bus to help. These things are rabbit holes either way. It is possible to tune an AV motor for pump gas if you know what you are doing. In fact, you guys in AK have the advantage of cool air, custom made for air cooled engines. Striker had a good suggestion earlier.
Striker543 wrote:Another option is using a real octane booster. I ran ACES IV from bnd automotive in my continental e 185 with pump gas. It’s not cheap, but it works very well. You also have to call directly the first time you order as they do not have an online store (they don’t want people purchasing the wrong product), but you can order via email after that.
Good luck with what ever you choose. Expect several posts from the CM guys telling you their farts smell like roses.
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

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Re: 0470 overheating and running rough

Post by AlaskanOutdoorsman » Sat Sep 22, 2018 4:59 pm

Gator your funny as hell, thanks for the laugh. In the end I have no idea what I'm going to do but the fact that no-one knows ac engines on the river presents a challenge when you break down.

Alaska air boating is different than you guys down south. My boat will with the 220 HP, as was, would easily haul two grown men, camp, extra fuel and a moose or three caribou with no issues. Would it run ground? No, but I didn't need it to. Most ground running I'd do would be running out of water and sliding over various size patches of gravel/tundra from water spot to the next in the swamp or on the river. My buddy has a CM and extra 110HP with his gearbox but his Alaska Airboat style hull is 1000lbs heavier. Ran with him and never had any issues on the river or in the swamps. I just wasn't as fast but we burned the same fuel over the trip and I was in the elements with no cab. My boat can haul a hell of a load, it's just more of a tractor. I'll get there.. just not as fast as some.

Most airboats up here run CM's due to the boat being so big and heavy, having an enclosed, heated cab, and wanting to haul a load of meat and run dry ground. Avgas isn't available on the rivers and gearbox's on aircraft engines are rare so your limited to HP/Torque. We also have some serious silt and mud and even with poly it isn't forgiving and will bring you to a screeching stop. Got stuck on it myself this year.

My only issue with this AC engine is knowing what to do and not do. Never messed with them other than this boat and while I did what I was told, Im a bit worried I added to the engine failure by not knowing the engine. My boat previously had a big block on it with a huge enclosed cab so changing to a CM is just a matter of $3K for an engine mount and new cage. That said, I have no idea at this point and have to decide if a rebuild on this engine is worth it or not. Worse case I would rebuild it and sell, upgrading to a new boat all together.

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