What is difference between IO360-A3B6D and IO360-A3B6?

[PT20J]

1 hour ago, jaylw314 said:

Wow, so Lycoming actually is still selling A3B6D rebuilds, I never realized that.  I thought they were in the business of selling only A3B6's so they wouldn't have to rebuild the TCM/Bendix dual mag.

I discussed this at length with my Lycoming rep when I purchased my factory rebuilt A3B6 to replace the A3B6D. He told me that they would overhaul or rebuild a D. It would come with an overhauled mag (Lycoming generally supplies new accessories) because new dual mags are not available. He told me that the A3B6D was designed at the request of several airframe manufacturers but in the end it was used primarily by Mooney and Cessna for the Cardinal. It has fewer components in common with the other IO-360 variants. He said that Lycoming would always support it, but over time due to the lesser numbers produced and attrition, they might become more expensive to maintain than the A3B6. Normally, Lycoming upcharges for a rebuilt with a dissimilar core exchange, but I got a discount for turning in an A3B6D core in exchange for a rebuilt A3B6. This signified to me that Lycoming would really like them to just fade into the sunset.

By the way, my rebuilt A3B6 is doing great. A bit over 200 hours on it and it's getting 12-13 hours per quart of Phillips 20W50 starts immediately hot or cold on the supplied Champion massive spark plugs, and has a GAMI spread on the stock injector nozzles of 0.3-0.4. Even well LOP it's very smooth for a 4-cyl engine. I was never concerned about the reliability of the dual mag, but I am very happy to have roller lifters.

Skip

[jaylw314]

17 hours ago, PT20J said:

I discussed this at length with my Lycoming rep when I purchased my factory rebuilt A3B6 to replace the A3B6D. He told me that they would overhaul or rebuild a D. It would come with an overhauled mag (Lycoming generally supplies new accessories) because new dual mags are not available. He told me that the A3B6D was designed at the request of several airframe manufacturers but in the end it was used primarily by Mooney and Cessna for the Cardinal. It has fewer components in common with the other IO-360 variants. He said that Lycoming would always support it, but over time due to the lesser numbers produced and attrition, they might become more expensive to maintain than the A3B6. Normally, Lycoming upcharges for a rebuilt with a dissimilar core exchange, but I got a discount for turning in an A3B6D core in exchange for a rebuilt A3B6. This signified to me that Lycoming would really like them to just fade into the sunset.

By the way, my rebuilt A3B6 is doing great. A bit over 200 hours on it and it's getting 12-13 hours per quart of Phillips 20W50 starts immediately hot or cold on the supplied Champion massive spark plugs, and has a GAMI spread on the stock injector nozzles of 0.3-0.4. Even well LOP it's very smooth for a 4-cyl engine. I was never concerned about the reliability of the dual mag, but I am very happy to have roller lifters.

Skip

Thanks for the info!

You know, I never thought to ask this, but does Lycoming still recommend the Lycoming additive for the roller lifter motors?  I've always used it, but maybe its overkill

Edit: checked the SB, yes, it applies to all Lycoming motors

Edited December 24, 2020 by jaylw314

[PT20J]

I think "recommend" is perhaps a little strong.

LW-16702 is required by AD for certain engines with smaller faced tappets.

Lycoming "approves" the use in all it's engines. (SI 1409C)

Aeroshell and now Phillips make oil with the additive in it approved by the FAA as meeting the AD so you don't have to mix it if you have an engine that requires it.

 

[bmcconnaha]

Thanks for the info!
You know, I never thought to ask this, but does Lycoming still recommend the Lycoming additive for the roller lifter motors?  I've always used it, but maybe its overkill
Edit: checked the SB, yes, it applies to all Lycoming motors

Can you point me in the direction of the SB that’s recommended it in all lycomings? All I have is this one, and it doesn’t include IO360 from what I can tell. I’d rather use cam guard than the lycoming additive anyways.

https://www.lycoming.com/sites/default/files/The%20Use%20of%20Lycoming%20LW-16702%20Oil%20Additive.pdf


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[jaylw314]

On 12/24/2020 at 4:17 PM, bmcconnaha said:

Can you point me in the direction of the SB that’s recommended it in all lycomings? All I have is this one, and it doesn’t include IO360 from what I can tell. I’d rather use cam guard than the lycoming additive anyways.

https://www.lycoming.com/sites/default/files/The%20Use%20of%20Lycoming%20LW-16702%20Oil%20Additive.pdf


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My bad, it was a Service Instruction, not an SB

https://www.lycoming.com/sites/default/files/Lycoming Engine PN LW-16702%2C Oil Additive.pdf

[bmcconnaha]

On 12/26/2020 at 9:37 AM, jaylw314 said:

My bad, it was a Service Instruction, not an SB

https://www.lycoming.com/sites/default/files/Lycoming Engine PN LW-16702%2C Oil Additive.pdf

thanks!

[rotorman]

In the 1990's, I flew a 1978 M20J for a short time. The owner decided that he wanted to fly the airplane from Connecticut across the Atlantic via Greenland and back. So he installed a extra fuel tank and completed his adventure. Shortly after, it was time for him to inspect is D3000 mag. He found that the common gear that drives both mags had a missing tooth. The gear is made of some kind of plastic or nylon not metal.

I made the conversion to A3B6 when overhaul time came.

[201Steve]

On 12/23/2020 at 8:07 PM, PT20J said:

I discussed this at length with my Lycoming rep when I purchased my factory rebuilt A3B6 to replace the A3B6D. He told me that they would overhaul or rebuild a D. It would come with an overhauled mag (Lycoming generally supplies new accessories) because new dual mags are not available. He told me that the A3B6D was designed at the request of several airframe manufacturers but in the end it was used primarily by Mooney and Cessna for the Cardinal. It has fewer components in common with the other IO-360 variants. He said that Lycoming would always support it, but over time due to the lesser numbers produced and attrition, they might become more expensive to maintain than the A3B6. Normally, Lycoming upcharges for a rebuilt with a dissimilar core exchange, but I got a discount for turning in an A3B6D core in exchange for a rebuilt A3B6. This signified to me that Lycoming would really like them to just fade into the sunset.

By the way, my rebuilt A3B6 is doing great. A bit over 200 hours on it and it's getting 12-13 hours per quart of Phillips 20W50 starts immediately hot or cold on the supplied Champion massive spark plugs, and has a GAMI spread on the stock injector nozzles of 0.3-0.4. Even well LOP it's very smooth for a 4-cyl engine. I was never concerned about the reliability of the dual mag, but I am very happy to have roller lifters.

Skip

Skip,

What are the hidden surprises in this conversion? Hoses, connectors, etc. Did everything line up pretty well or were there some extra money to spend re-hanging the new variant?

[PT20J]

17 minutes ago, 201Steve said:

Skip,

What are the hidden surprises in this conversion? Hoses, connectors, etc. Did everything line up pretty well or were there some extra money to spend re-hanging the new variant?

Everything went smoothly. All the important stuff is in this thread. My summary is near the end.

Skip

[EricJ]

3 hours ago, rotorman said:

In the 1990's, I flew a 1978 M20J for a short time. The owner decided that he wanted to fly the airplane from Connecticut across the Atlantic via Greenland and back. So he installed a extra fuel tank and completed his adventure. Shortly after, it was time for him to inspect is D3000 mag. He found that the common gear that drives both mags had a missing tooth. The gear is made of some kind of plastic or nylon not metal.

I made the conversion to A3B6 when overhaul time came.

FWIW, most gear-driven case accessories have plastic or non-metallic drive components, so that if the accessory fails or seizes the weaker drive in the accessory fails and does not present a shock or drag load on the internal case gears or train.   This is true of essentially all magnetos, vacuum pumps, etc.  The dual mag main spur gear is metal and the separate distributor gears for each side are plastic, like most mags.   There's not much difference that way.

[N201MKTurbo]

So, the last time I had my dual mag repaired, one side quit working. It turns out that it was the distributor gear on the side that failed. The metal hub had rotated in the plastic gear so the distributor wasn’t hitting the right post.

Aaron said he has seen a lot of these. Not a design problem, a quality problem.