Did I get a Lemon?

[asw20c]

Last year, July 2024 to be precise, I completed building my RV-14A (140313) and had first flight, a project that took me 7 years 9 months to complete. I purchased a Lycoming Thunderbolt engine (YIO-390-EXP) through Van's to power my aircraft. As I write this, I have been flying my RV for about 13 months (when I'm not making repairs to the engine), and in that time I have put about 237 hours on the plane. The airplane is awesome and flies better than anything I have flown previously. I'm very happy with it, however I have been exceptionally disappointed with the engine.

In the short time I have been operating the engine I've had a stuck exhaust valve which trashed my number 2 cylinder, a fuel injector that went bad, a magneto that crapped out, and a serious oil leak from the top case seam that I have been unable to repair. The oil leak is so bad that I only get about 7 hours of operation before having to add a quart of oil.

In fairness, I have spoken and corresponded with Lycoming about these issues (except for the magneto, that was E-Mag and they offered great support) and up to now both companies have covered everything under warranty. As for the oil leak, Lycoming did give me the option of removing the engine from the airplane and shipping it to them for service, but you know how much work that would require and there is no telling how long the plane would be grounded. I wanted to fly so I chose to simply add oil. My complaint is that for such an expensive engine, and because it was brand new, I believe that I should not have experienced ANY of these issues. Particularly because I actually read the Lycoming manual and have operated it as closely to what they prescribe as I have been able.

Lycoming has treated me well during my interactions with them. No complaints about that. Rather my complaint is about what appears to be poor quality control. Their marketing is that Thunderbolts get special care during assembly from their more experienced technicians. Granted I am a datapoint of one, but my experience does not support that claim.

 

[Norman CYYJ]

Last year, July 2024 to be precise, I completed building my RV-14A (140313) and had first flight, a project that took me 7 years 9 months to complete. I purchased a Lycoming Thunderbolt engine (YIO-390-EXP) through Van's to power my aircraft. As I write this, I have been flying my RV for about 13 months (when I'm not making repairs to the engine), and in that time I have put about 237 hours on the plane. The airplane is awesome and flies better than anything I have flown previously. I'm very happy with it, however I have been exceptionally disappointed with the engine.

In the short time I have been operating the engine I've had a stuck exhaust valve which trashed my number 2 cylinder, a fuel injector that went bad, a magneto that crapped out, and a serious oil leak from the top case seam that I have been unable to repair. The oil leak is so bad that I only get about 7 hours of operation before having to add a quart of oil.

In fairness, I have spoken and corresponded with Lycoming about these issues (except for the magneto, that was E-Mag and they offered great support) and up to now both companies have covered everything under warranty. As for the oil leak, Lycoming did give me the option of removing the engine from the airplane and shipping it to them for service, but you know how much work that would require and there is no telling how long the plane would be grounded. I wanted to fly so I chose to simply add oil. My complaint is that for such an expensive engine, and because it was brand new, I believe that I should not have experienced ANY of these issues. Particularly because I actually read the Lycoming manual and have operated it as closely to what they prescribe as I have been able.

Lycoming has treated me well during my interactions with them. No complaints about that. Rather my complaint is about what appears to be poor quality control. Their marketing is that Thunderbolts get special care during assembly from their more experienced technicians. Granted I am a datapoint of one, but my experience does not support that claim.

I know you don't want to give up flying for a period of time but if Lycoming is willing to makes repairs to your engine in my opinion you should take them up on it. Yes it is a lot of work to pull the engine and a pita but you might end up kicking yourself if things get worse especially when it comes out of warranty.

 

[Dan 57]

Yes, it is disappointing to spend dough for what is claimed to be superior, and end up disappointed. Given the poor reliability record of P-Mags, no big surprise here, but the oil leak just shouldn't happen on such an expensive piece of machinery.
There already is a thread, Thunderbolt Engines, giving the engine choice some thought.

Last Winter I grafted a brand new YO-360-EXP314 on the nose of my 20 year old RV-6.9i, and not really impressed either. It is all dry, but the compressions measured surprisingly low (74/75/74/70) for a 100h engine. It also seems to be running hotter than the previous engine, though my slightly reduced cowl outlet area might be accountable for some of this.
The only noticeable improvement over the previous standard O-360 is it's super smooth running, at any RPM. Also thanks to that 3 bladed MT-Prop... but... this prop was overhauled whist the engine was being replaced by a factory approved service center, and is now displaying shake play on all blades, at or close to the maximum limit. Meaning I'll have to ground my steed coming Winter whilst it gets overhauled again... not happy either.

Bon courage

 

[Mark Dickens]

Last year, July 2024 to be precise, I completed building my RV-14A (140313) and had first flight, a project that took me 7 years 9 months to complete. I purchased a Lycoming Thunderbolt engine (YIO-390-EXP) through Van's to power my aircraft. As I write this, I have been flying my RV for about 13 months (when I'm not making repairs to the engine), and in that time I have put about 237 hours on the plane. The airplane is awesome and flies better than anything I have flown previously. I'm very happy with it, however I have been exceptionally disappointed with the engine.

In the short time I have been operating the engine I've had a stuck exhaust valve which trashed my number 2 cylinder, a fuel injector that went bad, a magneto that crapped out, and a serious oil leak from the top case seam that I have been unable to repair. The oil leak is so bad that I only get about 7 hours of operation before having to add a quart of oil.

In fairness, I have spoken and corresponded with Lycoming about these issues (except for the magneto, that was E-Mag and they offered great support) and up to now both companies have covered everything under warranty. As for the oil leak, Lycoming did give me the option of removing the engine from the airplane and shipping it to them for service, but you know how much work that would require and there is no telling how long the plane would be grounded. I wanted to fly so I chose to simply add oil. My complaint is that for such an expensive engine, and because it was brand new, I believe that I should not have experienced ANY of these issues. Particularly because I actually read the Lycoming manual and have operated it as closely to what they prescribe as I have been able.

Lycoming has treated me well during my interactions with them. No complaints about that. Rather my complaint is about what appears to be poor quality control. Their marketing is that Thunderbolts get special care during assembly from their more experienced technicians. Granted I am a datapoint of one, but my experience does not support that claim.

Just grit your teeth and send the whole thing back to Lycoming. I can say from experience that it's not as bad as you think it is, and it doesn't take that long to reinstall everything when you get it back. In my case, it was a Titan engine and my fault, but same deal. They may be aware of other manufacturing issues that need correcting and that they aren't publicizing for obvious reasons.

 

[Dugaru]

I know you don't want to give up flying for a period of time but if Lycoming is willing to makes repairs to your engine in my opinion you should take them up on it. Yes it is a lot of work to pull the engine and a pita but you might end up kicking yourself if things get worse especially when it comes out of warranty.

This. Not a close question.

 

[lr172]

The oil leak is so bad that I only get about 7 hours of operation before having to add a quart of oil.

If you are leaking enough oil through the case seam to noticeably affect the consumption rate, this will become a major annonyance over the years. Best to get this fixed while its free. Major $ to pull a case apart in todays world.

 

[rsr3]

Could not agree more with what everyone has said. Take advantage of the offer to repair. You will only regret not taking it up in years to come.

 

[Bcone1381]

You built your RV-14. You are an experimental aircraft builder. Nothing came easy. Let Lycoming stand by their engine…let them Fix the case leak. That is a no brainer decision, but you gotta make it.

I think you see barriers. And the time it will take is a barrier to wanting to get started so don’t focus on that. Don’t set any time based goal except what you want to do today. Just go into the shop and do one thing and don’t look at the big picture. Start from the outside and work inside. Remove the cowl. Remove the exhaust. Remove each control cable. Each item is achievable. Celebrate Each goal that is achieved. Soon it will be time hoist the engine off the airframe.

 

[Jonnyb]

Winter is coming!

Maybe pull the engine then?

 

[asw20c]

Resurrecting an old thread that I started last year. My RV has been in the paint shop since 1 October 2025. It is 21 Feb 2026 as I write this, and it isn't supposed to be finished until around mid-March so call it 5 1/2 months. Anyway, during that time I wrote to Lycoming telling them of all the difficulties I have had with this Thunderbolt engine, including the awful oil leak from the case seam. Although it is out of warranty, they offered to repair the case seam leak. They were clear that their repair offer does not cover anything else, but that's fine, I've worked through most of my other mechanical issues anyway. So I'm going to take them up on their offer. As soon as my plane comes out of the paint shop, it will be grounded once more to pull the engine and send it off to Lycoming. I'll post again after the repair to report on how that went.

 

[Full Throttle]

You built your RV-14. You are an experimental aircraft builder. Nothing came easy. Let Lycoming stand by their engine…let them Fix the case leak. That is a no brainer decision, but you gotta make it.

I think you see barriers. And the time it will take is a barrier to wanting to get started so don’t focus on that. Don’t set any time based goal except what you want to do today. Just go into the shop and do one thing and don’t look at the big picture. Start from the outside and work inside. Remove the cowl. Remove the exhaust. Remove each control cable. Each item is achievable. Celebrate Each goal that is achieved. Soon it will be time hoist the engine off the airframe.

And..Take lots of pictures of the installation you have now. Sometimes you forget things in the process of reassembly.

 

[dmattmul]

Resurrecting an old thread that I started last year. My RV has been in the paint shop since 1 October 2025. It is 21 Feb 2026 as I write this, and it isn't supposed to be finished until around mid-March so call it 5 1/2 months. Anyway, during that time I wrote to Lycoming telling them of all the difficulties I have had with this Thunderbolt engine, including the awful oil leak from the case seam. Although it is out of warranty, they offered to repair the case seam leak. They were clear that their repair offer does not cover anything else, but that's fine, I've worked through most of my other mechanical issues anyway. So I'm going to take them up on their offer. As soon as my plane comes out of the paint shop, it will be grounded once more to pull the engine and send it off to Lycoming. I'll post again after the repair to report on how that went.

Earlier you mentioned you get 7 hours of operation before adding a qt. I know several IO390 owners who need to add a qt every 5 to 6 hours with no case leaks. You are seeing the case leak in the bottom of your cowling? Or top case leak even worse. That would create a huge mess.

What oil brand and type are you using? (Stuck valve question)

 

[Bavafa]

Earlier you mentioned you get 7 hours of operation before adding a qt. I know several IO390 owners who need to add a qt every 5 to 6 hours with no case leaks. You are seeing the case leak in the bottom of your cowling? That would create a huge mess.

Pretty much all of my 14 driver friends get about 5-6 hour a quart as I have with both of my 390s. But I was also somewhat disappointed with my TB 390-EXP119 as I had a helicoil issue as well as a stock valve on #2 cylinder with not that many hours on the engine.

 

[IO390]

You would need a mahoosive oil leak to make a noticeable difference in your oil usage, not that it’s acceptable for a brand new Lycoming to be leaking oil.

What would make a 390 burn more oil than other engines? My 320 with Lycoming cylinders is about 1qt in 35 hours..

 

[dmattmul]

Pretty much all of my 14 driver friends get about 5-6 hour a quart as I have with both of my 390s. But I was also somewhat disappointed with my TB 390-EXP119 as I had a helicoil issue as well as a stock valve on #2 cylinder with not that many hours on the engine.

Oil brand and type? Seems many are using 66 who have issues. I have been using AeroShell and to date (700 hrs.) no issues but maybe just luck?

 

[Full Throttle]

Oil brand and type? Seems many are using 66 who have issues. I have been using AeroShell and to date (700 hrs.) no issues but maybe just luck?

Are you running a Lycoming IO-390?

 

[dmattmul]

Are you running a Lycoming IO-390?

Yes

 

[Bavafa]

Oil brand and type? Seems many are using 66 who have issues. I have been using AeroShell and to date (700 hrs.) no issues but maybe just luck?

I have been using 66 and some of my issues like the helicoil should not have been as a result of type of oil. But if you mean the oil consumption, some of my friends with the same engine that are using Aeroshell are getting about the same oil usage.
Edit: A few years ago I asked Lycoming folks at Oshkosh if such burn rate is normal for the IO390 since I got much better burn rate with my 360 engine and they said yes.

 

[simpsontl48]

There is no excuse for this. The manufacturers should be ashamed of themselves. They are selling high priced junk. If this continues, there may need to be a class action lawsuit to get their attention to stop the sloppy shoddy workmanship.

 

[dmattmul]

I have been using 66 and some of my issues like the helicoil should not have been as a result of type of oil. But if you mean the oil consumption, some of my friends with the same engine that are using Aeroshell are getting about the same oil usage.
Edit: A few years ago I asked Lycoming folks at Oshkosh if such burn rate is normal for the IO390 since I got much better burn rate with my 360 engine and they said yes.

The issue of sticking valves correlation seems to be the oil type used not oil consumption. Maybe create a poll?

 

[DaveO]

It is frustrating that you are having this problem with a new engine. However, if you ignore the leak now and you decide to sell your aircraft the new prospect will take that into account with the price. Bite the bullet, though not your fault, fix the engine. When all the dust is settled you will be glad you did.

 

[walkman]

You would need a mahoosive oil leak to make a noticeable difference in your oil usage, not that it’s acceptable for a brand new Lycoming to be leaking oil.

What would make a 390 burn more oil than other engines? My 320 with Lycoming cylinders is about 1qt in 35 hours..

Putting too much in ? My oil consumption dropped considerably when I started putting 4 and a bit in rather than 6 and a bit.

 

[asw20c]

I thought I'd close the loop on this thread. Last year I posted that I have had extraordinarily bad luck with my brand new expensive Thunderbolt engine. There is no debate about that, and in fact I have had even more problems since that original post. To summarize, I've experienced a stuck exhaust valve on my number 2 cylinder (which trashed the piston), bad fuel injector, induction leak, massive oil leak from the case seams, bad starter, and as of today THREE bad magnetos and I only have about 275 hours on the plane/engine.

While my plane was in the paint shop between 1 October last year, and mid-March this year I wrote a letter to Lycoming laying out all the problems I've had, and to my pleasant surprise, they agreed to fix the oil leak at their expense despite being out of warranty. Earlier this year they sent me a crate to ship the engine, so the day after the plane came out of the paint shop in March I began pulling the engine. It took about a week to remove it, get it crated, and shipped to Lycoming. They had said that they would fix the oil leak, but if there was anything else I wanted done while it was in their shop that it would be on me. Fair enough. They also said it would take about 8 weeks for the repair. The only thing I asked them to do in addition to the leak was to inspect each exhaust valve guide for clearance and to ream if needed. My intent was to prevent any future stuck valves.

I was disappointed that Lycoming did not provide feedback on what they found as contributing factors to the oil leaks. But that was my only disappointment. In my opinion, Lycoming went well above and beyond what I was expecting. To start, they disassembled and cleaned the engine. They rehoned the cylinders, replaced the pistons and rings, replaced all main bearings and hardware, reamed all 4 exhaust valve guides, and complied with all service bulletins and instructions for this engine. They then sealed the case halves using a loctite product, and even though it wasn't in the paperwork, it sure looks like they repainted the engine too. They didn't zero-time it, but given its low hours it is practically new again.

After receiving the engine back from Lycoming, it took me about 11 days to reinstall, and although painful, it wasn't as bad as I was anticipating. Maybe because after installing, removing, and then reinstalling again I was getting better at it. Because of the new pistons, rings, and rehoned cylinders, I needed to treat this engine like brand new so I followed Lycoming's Service Instruction 1427C to the letter regarding type of oil to use, ground test run, and test flights. I'm currently at 25 hours into the break-in. I've been closely tracking the oil consumption and although I don't think it has fully stabilized yet, it looks like the curve is bending and it will soon. So far my oil consumption is somewhere between 8 and 10 hours of operation per quart. It started at about 1.8 hours of operation per quart, so the change has been swift and dramatic. It looks like it will probably stabilize somewhere around 9-10 hours per quart, which compared to other engines seems high, but per Lycoming and other anecdotal evidence from others here I believe that is consistent with other IO-390's.

In my opinion, my CHTs are too low, even on cylinders that are not yet broken in. I'm mostly seeing about 315-350. I'd like to see somewhere between 350 and 400. My oil temps are way too high, but lower than they were in the first hours. At first, I was seeing oil temps approaching 230 degrees. Now they are about 200 at 2350 rpm, 210 at 2450 rpm, and about 215-225 at 2700 rpm. There are too many variables for me to refine how best to control oil temperature, as OAT, manifold pressure, rpm, and mixture all have a pronounced affect on oil temperature. I'm running much richer to keep temperatures in check than I would normally, and I'm hoping that I will be able to lean further the more the break-in progresses. I also experimented with different ignition advance settings and after finding the point where it was making my oil temps higher, I backed off a degree or so and now it seems to be in a happy place.

So, to cap it off, I think Lycoming successfully addressed the oil leak issue (and believe me, it was BAD before I sent the engine in for repair). I'm currently working my way through the break-in blues, and it looks like I'm going to have replace yet another magneto (my third in 275 hours), but I believe I'm finally going to have a leak-free reliable engine soon. At least I can say that Lycoming did me right. Now if I could just get past all these crappy magnetos!

 

[dmattmul]

“In my opinion, my CHTs are too low, even on cylinders that are not yet broken in. I'm mostly seeing about 315-350. I'd like to see somewhere between 350 and 400. My oil temps are way too high, but lower than they were in the first hours.”

You will need to understand the thermal differences between a parallel valve engine and an angle valve with oil piston squirters. Night and day. Most IO390 users LOP run in the low 300 CHT range LOP and fight to keep oil temps in the low 200’s.

Maybe mentioned earlier but what brand of oil are you using ? Seems a very high % of 390’s are using Phillips 66 20-50 with stuck valves and a very low % using AeroShell 15-50. My 390 800+ hours no issues.

 

[lr172]

I thought I'd close the loop on this thread. Last year I posted that I have had extraordinarily bad luck with my brand new expensive Thunderbolt engine. There is no debate about that, and in fact I have had even more problems since that original post. To summarize, I've experienced a stuck exhaust valve on my number 2 cylinder (which trashed the piston), bad fuel injector, induction leak, massive oil leak from the case seams, bad starter, and as of today THREE bad magnetos and I only have about 275 hours on the plane/engine.

While my plane was in the paint shop between 1 October last year, and mid-March this year I wrote a letter to Lycoming laying out all the problems I've had, and to my pleasant surprise, they agreed to fix the oil leak at their expense despite being out of warranty. Earlier this year they sent me a crate to ship the engine, so the day after the plane came out of the paint shop in March I began pulling the engine. It took about a week to remove it, get it crated, and shipped to Lycoming. They had said that they would fix the oil leak, but if there was anything else I wanted done while it was in their shop that it would be on me. Fair enough. They also said it would take about 8 weeks for the repair. The only thing I asked them to do in addition to the leak was to inspect each exhaust valve guide for clearance and to ream if needed. My intent was to prevent any future stuck valves.

I was disappointed that Lycoming did not provide feedback on what they found as contributing factors to the oil leaks. But that was my only disappointment. In my opinion, Lycoming went well above and beyond what I was expecting. To start, they disassembled and cleaned the engine. They rehoned the cylinders, replaced the pistons and rings, replaced all main bearings and hardware, reamed all 4 exhaust valve guides, and complied with all service bulletins and instructions for this engine. They then sealed the case halves using a loctite product, and even though it wasn't in the paperwork, it sure looks like they repainted the engine too. They didn't zero-time it, but given its low hours it is practically new again.

After receiving the engine back from Lycoming, it took me about 11 days to reinstall, and although painful, it wasn't as bad as I was anticipating. Maybe because after installing, removing, and then reinstalling again I was getting better at it. Because of the new pistons, rings, and rehoned cylinders, I needed to treat this engine like brand new so I followed Lycoming's Service Instruction 1427C to the letter regarding type of oil to use, ground test run, and test flights. I'm currently at 25 hours into the break-in. I've been closely tracking the oil consumption and although I don't think it has fully stabilized yet, it looks like the curve is bending and it will soon. So far my oil consumption is somewhere between 8 and 10 hours of operation per quart. It started at about 1.8 hours of operation per quart, so the change has been swift and dramatic. It looks like it will probably stabilize somewhere around 9-10 hours per quart, which compared to other engines seems high, but per Lycoming and other anecdotal evidence from others here I believe that is consistent with other IO-390's.

In my opinion, my CHTs are too low, even on cylinders that are not yet broken in. I'm mostly seeing about 315-350. I'd like to see somewhere between 350 and 400. My oil temps are way too high, but lower than they were in the first hours. At first, I was seeing oil temps approaching 230 degrees. Now they are about 200 at 2350 rpm, 210 at 2450 rpm, and about 215-225 at 2700 rpm. There are too many variables for me to refine how best to control oil temperature, as OAT, manifold pressure, rpm, and mixture all have a pronounced affect on oil temperature. I'm running much richer to keep temperatures in check than I would normally, and I'm hoping that I will be able to lean further the more the break-in progresses. I also experimented with different ignition advance settings and after finding the point where it was making my oil temps higher, I backed off a degree or so and now it seems to be in a happy place.

So, to cap it off, I think Lycoming successfully addressed the oil leak issue (and believe me, it was BAD before I sent the engine in for repair). I'm currently working my way through the break-in blues, and it looks like I'm going to have replace yet another magneto (my third in 275 hours), but I believe I'm finally going to have a leak-free reliable engine soon. At least I can say that Lycoming did me right. Now if I could just get past all these crappy magnetos!

First, 210-220 on OT is nothing to be concerned about. I would not make chages in how you run your engine to get it lower. The 390’s use squirters, so chts will be lower and OTs higher than what you are used, but that does not mean it is bad and you shouldn’t try to make it replicate what you were used to. 240 is the time to start becoming concerned with oil temp on modern oils. Generally bad things don’t start happening to the oil until around 250-260 and because we change the oil so often, even these temps tend not to cause real damage. Lycoming sets redline at 235 and that is a bit conservative with modern oils. No real benefit to staying any further below 235 than margin. This is not like chts, where additional heat adds to long term wear.

Second, you keep saying you have been through three mags in 270 hours, but early on you mentioned these are pmags. So, better to say you have had three pmags fail, which is not that uncommon.

 

[asw20c]

“In my opinion, my CHTs are too low, even on cylinders that are not yet broken in. I'm mostly seeing about 315-350. I'd like to see somewhere between 350 and 400. My oil temps are way too high, but lower than they were in the first hours.”

You will need to understand the thermal differences between a parallel valve engine and an angle valve with oil piston squirters. Night and day. Most IO390 users LOP run in the low 300 CHT range LOP and fight to keep oil temps in the low 200’s.

Maybe mentioned earlier but what brand of oil are you using ? Seems a very high % of 390’s are using Phillips 66 20-50 with stuck valves and a very low % using AeroShell 15-50. My 390 800+ hours no issues.

For break-in I'm using 66 SAE50 mineral oil. I believe the standard is J1966? That is supposed to be oil without the ashless dispersant. I'm hoping that when I switch to multi-viscosity again (after 50 hours on mineral oil) that that might also offer a couple more degrees of cooling for oil temps.

 

[asw20c]

First, 210-220 on OT is nothing to be concerned about. I would not make chages in how you run your engine to get it lower. The 390’s use squirters, so chts will be lower and OTs higher than what you are used, but that does not mean it is bad and you shouldn’t try to make it replicate what you were used to. 240 is the time to start becoming concerned with oil temp on modern oils. Generally bad things don’t start happening to the oil until around 250-260 and because we change the oil so often, even these temps tend not to cause real damage. Lycoming sets redline at 235 and that is a bit conservative with modern oils. No real benefit to staying any further below 235 than margin. This is not like chts, where additional heat adds to long term wear.

Second, you keep saying you have been through three mags in 270 hours, but early on you mentioned these are pmags. So, better to say you have had three pmags fail, which is not that uncommon.

Yup. Three PMags. Two where the internal alternator crapped out, and now the third one causes the engine to stutter while also creating an erratic rpm signal when testing during run up. All worked fine on ship's power though, so it has never been a safety issue. Only reason I haven't switched to another brand is because of how simple they are to time. Literally takes about a minute. Love that!

 

[lr172]

For break-in I'm using 66 SAE50 mineral oil. I believe the standard is J1966? That is supposed to be oil without the ashless dispersant. I'm hoping that when I switch to multi-viscosity again (after 50 hours on mineral oil) that that might also offer a couple more degrees of cooling for oil temps.

Change to AD oil will not create a temp reduction in and of itself.

 

[Walt]

Cool CHT’s are a good thing, don’t ‘fix’ that!

 

[Snowflake]

Cool CHT’s are a good thing, don’t ‘fix’ that!

And you need an oil temp at or above 212 to boil off the moisture. Don't fix that either.

 

[Toobuilder]

And you need an oil temp at or above 212 to boil off the moisture. Don't fix that either.

This is a piston squirter engine…. No matter what the oil temp gauge says, it’s a sure bet the temps the oil sees when it hits the backsides of the pistons is a lot higher than that.

 

[Toobuilder]

Yup. Three PMags. Two where the internal alternator crapped out, and now the third one causes the engine to stutter while also creating an erratic rpm signal when testing during run up. All worked fine on ship's power though, so it has never been a safety issue. Only reason I haven't switched to another brand is because of how simple they are to time. Literally takes about a minute. Love that!

Acknowledging the thread drift (fine, since the original issue seems to be resolved), and my internal debate about picking at the Pmag scab on this forum (decided: why not? - it’s been a while), please read what you wrote with a critical eye.

In essence, you are “OK” with an ignition that’s widely touted safety feature (internal generation) has failed you twice, and another has failed on runup and you DONT consider it a safety issue? And you are willing to overlook this discrepancy because it’s “…simple to time”? How often do you have to time this thing where that becomes a compelling factor? Is not that a little bit like taking the family on a road trip with bald tires but it’s OK because you have 4 spares strapped to the roof? Wouldn’t it be better to buy good tires?

What if I told you there exists an ignition that only needs to be timed ONCE for the life of the engine, requires zero maintenance for the life of the engine, and is expected to perform without any failure for the life of the engine? It’s out there.

Seems like one of your core issues is resolved - let’s get you the rest of the way with an ignition you can count on.

 

[DanH]

Last year I posted that I have had extraordinarily bad luck with my brand new expensive Thunderbolt engine. There is no debate about that, and in fact I have had even more problems since that original post. To summarize, I've experienced a stuck exhaust valve on my number 2 cylinder (which trashed the piston), bad fuel injector, induction leak, massive oil leak from the case seams, bad starter, and as of today THREE bad magnetos and I only have about 275 hours on the plane/engine.

The stuck valve, the case leak, and the induction leak are Lycoming problems.

Constant flow fuel injectors don't go bad. They are fundamentally just a few precise holes, and they get full of trash. If you're speaking of an EFI injector, it is likely from Bosch.

Starters and P-mags are also brown box items. I'm pretty sure Lycoming is just a frustrated with them as you are. May we note they went to the trouble of certifying their own version of a Surefly? Perhaps it might be a better choice...or at least one where Lycoming actually has some responsibility.

In my opinion, my CHTs are too low, even on cylinders that are not yet broken in. I'm mostly seeing about 315-350.

No, it's just right. Marvelous. Perfect.

The high oil temperature isn't due to a Lycoming choice. Nor does it mean there is anything wrong with your 390. It's typical for the RV-14 oil cooler setup chosen by Vans.

BTW, Lycoming's oil temperature recommendation is 180F.

At least I can say that Lycoming did me right.

There 'ya go.

And you need an oil temp at or above 212 to boil off the moisture. Don't fix that either.

The cockroach of OWT's. Probably going to be around a few hundred years from now, when Starfleet holds history classes. "Yes Spock, we know it violates fundamental physics, but many people believed it back then."

 

[RNB]

For break-in I'm using 66 SAE50 mineral oil. I believe the standard is J1966? That is supposed to be oil without the ashless dispersant. I'm hoping that when I switch to multi-viscosity again (after 50 hours on mineral oil) that that might also offer a couple more degrees of cooling for oil temps.

Why 50 oil?
How full are you keeping the oil?
Might it not be happier lower?

My planes spits out the top two quarts.

 

[airguy]

I'm running an IO360 PV with piston squirters in my 9A - it does indeed dump a lot of heat into the oil, with cooler CHT's. In cruise at altitude in cold air I will typically be running 180-190 oil temps and CHTS in the 295-325 range, and I had to upsize my oil cooler twice from the "recommended" 360 standard.

On the plus side I can do some monstrous full power climbs to altitude at 90 knots, usually reaching cold air before the oil hits 230F and it starts coming back down - without exceeding 400 on the CHT's