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IO-390-EXP fuel injector damage

jsisk

Member
I ordered a factory new Lycoming 390-EXP engine for my 14. In late April, the first engine run was a difficult, rough start, and did not last long. I was surprised to see in the post-run inspection black, sooty liquid coming from the exhaust slip joints and blown all over the white engine mount. It rubbed off with my finger and smelled like fuel and exhaust. I suspected an excessively rich mixture. Our troubleshooting included pulling all the fuel injectors. We found that 3 or the 4 had been over torqued at the factory to the point that top of the nozzle inserts had sheered off and were stuck in the B-nut of the fuel lines. The result was an unregulated flow of fuel into the cylinders.

When we contacted Lycoming, they did not have the replacement fuel lines and injectors. They directed us to Airflow Performance for parts, which we had to purchase outright, despite being under warranty. The subsequent warranty reimbursement has been a nightmare and I still waiting 4.5 months later.

My greatest concern here is this: how does a factory engine, presumably assembled with automated tooling, get over torqued during assembly? and how is the problem not realized during a test run for 30-minutes? The test stand data supplied with the engine is VERY scant, no FF or temp data.

This problem seems to be a assembly process problem, so the odds are that my engine is not the only one that was incorrectly assembled and tested without catching the problem. Obviously, one buys a factory new engine to avoid just this sort of problem. I think there is one, higher torque spec for the injector body, and another lesser spec for the fuel line.

If you are having unexplained fuel, leaning, or significant cylinder-to-cylinder temp differences, you may want to check your fuel injectors for this problem.
 
Jonathan,

I, too, had serious starting issues with my IO390-EXP Thunderbolt engine. I had to have the Lycoming installed Sky-tec starter replaced. Great customer service by Sky-tec, btw. fysa, Lycoming doesn't run the engines with starters they ship to you.

In troubleshooting, I removed the fuel injectors and noted that 3/4 had minor damage, apparently from being overtorqued. I soaked the injectors overnight and found tiny black specs in the acetone. I was able to start the engine after that, but I am still tweaking the idle, timing, and mixture. She is not a happy starter and still seems rough to me.

Jeffrey Turner
 
I am sad to add my name to this list, though my issues have been different and they have been addressed by Lycoming. Mine is a EXP119 TB which I had expected a tad more attention. I have been wondering if QC has been affected by the pandemic and all other mess that has been going on during the past two plus years. Needless to say, my airframe (SB) and wiring has had zero issues.

I have a warranty claim that I have not heard back. I am not sure what is the standard time frame for processing it.
 
Sad to hear, and one reason I prefer small 'custom' builders. It seems every large Co. prefers to hire less qualified folks so they can pay lower wages. I think they miss the big picture (or just don't really care), but if they just paid a better wage, they could hire talented folks and avoid all the warranty repairs.
Corporate bean counters running things rather than folks that know what it takes to do it right.
 
Will check mine

This is not great news as i have a new IO-390 exp setting in the box and I’m a few months away from bolting it on . I will be checking this asap …
 
...
Corporate bean counters running things rather than folks that know what it takes to do it right.
So true. One thing I love about my Mattituck is the clear attention to detail when they built it. The person that built it even signed the engine. Even though they don't exist any more, I'm sure that they raised the bar for the others that still build engines today.
 
This is pretty disturbing, makes you wonder if they can’t torque the injectors properly, what about the connecting rod bolts and cylinder bolts and such? Maybe Lycoming can add a new option to the engine order form…you know, base price $50K, add custom paint color and chrome valve covers (aka Thunderbolt), $60K. And new checkbox for “Assembled by competent person who knows how to use a torque wrench”, $70K. I’ll start saving up for this option for when it’s time to order my VW…er, Lycosaur…here in a few years.
 
Sad to hear, and one reason I prefer small 'custom' builders. It seems every large Co. prefers to hire less qualified folks so they can pay lower wages. I think they miss the big picture (or just don't really care), but if they just paid a better wage, they could hire talented folks and avoid all the warranty repairs.
Corporate bean counters running things rather than folks that know what it takes to do it right.
I should add that I have bought three brand new engine from Lycoming and the first two have been flawless.
 
Updates

Standard Lycoming build, not Thunderbolt.

Have any updates on this problem ?
I too have a exp 390 and doing a efii sys32 and have to remove my injectors , did lycoming populate a list of engines that may have been over torqued ? I’m getting ready to remove mine and I’m a newbie my fear is snapping one off , i may use a torque wrench to measure the torque required
 
Have any updates on this problem ?
I too have a exp 390 and doing a efii sys32 and have to remove my injectors , did lycoming populate a list of engines that may have been over torqued ? I’m getting ready to remove mine and I’m a newbie my fear is snapping one off , i may use a torque wrench to measure the torque required

The OP was reporting over-tightening of the B-nuts, not the brass body into the cylinder head.
 
So true. One thing I love about my Mattituck is the clear attention to detail when they built it. The person that built it even signed the engine. Even though they don't exist any more, I'm sure that they raised the bar for the others that still build engines today.

Your experience with your Mattituck was different then ours. We bought two O-360’s at the same time. A friend and I built two SuperCubs (Smith’s). My friend sold his cub because he lost faith in his and I myself never was satisfied with mine. I now have a Lycoming I0-390 flying since 2016 in my 14 and so far am completely satisfied with it. I’m no longer chasing oil leaks and not concerned that the cylinders might fall off( not a Mattituck issue but an ECI issue that Mattituck got stuck with. Just my opinion, might differ from others and that is OK.
 
Sorry to hear about the problems you experienced. You would think that would show up on the test stand. Any idea what the torque spec should be?
 
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