Had an exhaust valve hang a couple weeks ago on the 470 with only 150 hours on the cylinder (edit: checked logs, it was just under 200 hours on cylinder). Interested to hear some thoughts/experience from others on here.

The valve hung and hit the piston, trashing valve, valve guide, pushrod, and piston. All was warrantied and replaced with all new parts. (edit: Nothing was warrantied, Texas Skyways did not stand behind their paperwork nor verbal warranty).

The reason I am asking y'all is cause i like as many opinions as i can get, but also cause the cylinder shop that everything was sent to originally said piston n valve guides were fine, which we balked at. Then said maybe reports got screwed up??? I was about to just buy a new cylinder to get my plane back in the air, but Texas Skyways beat me to it and did just that (edit: no they didn't, I got stuck with the bill). I was not privy to the exchanges between them and the cylinder shop, but we do not know what failed verifiably at this point.

The mechanic who did warranty work (Texas Skyways did not warranty) and all my other mechanic buddies were of the opinion that the modified rocker arm had a defect and the oil that squirts there was not being distributed properly, causing the valve to hang almost completely wide open. There was valve guide shavings in the rocker box cover also, none in the oil filter and oil is sent out for analysis. (oil analysis came back: abnormal valve guide wear from day one, mechanics think either improper bore of valve guide or modified rocker arm defect)

Here is pictures of the piston and bent pushrod.





Got the new cylinder and all replaced yesterday then flew for an hour and half. It ran rough at low power settings and I was bummin. However, this morning mechanic checked everything and said an induction clamp was completely loose on the side we had just taken apart. They tightened it and said it ran super smooth on the ground and temps were all perfect and even. Sure hope so, gonna get back this evening and fly it.

If anyone has any advice or input I welcome it. Never had to replace a jug but it was bound to happen someday. Sure screwed up my plans to make it to the High Sierra Fly-in...

So they think the oil coked the stem and guide????. You need to get that prickly pear juice fermenting and run some cooler burning, cleaner fuel.

Marty, the modified rocker arm injects oil directly into the valve guide, as far as I understand, and that either there was a defect/malfunction with that or the valve guide wasn't right from the get go. It is possible that carbon deposits could have made their way into valve guide, but on such a low time and age cylinder (installed and overhauled mid July) is unlikely?

Yeah the 100LL compromise sucks. Hoping to have the home ethanol production (legally) thing figured out sooner than later since I can run it with the STC for this motor. Would be really nice to never clean plugs and if I get weathered out pour a shot of homebrew from the fuel sump

A friend of mine did that to an O470 a long time ago. He's pretty sure it happened when he tried starting it early on a frosty morning without a preheat.

CAVU

That sucks! At least it's fixed now, and the price wasn't too bad right?

There was no signs of buildup on the exhaust valve stem or guide where they are exposed to the exhaust gases?

Where do you normally set your mixture in cruise?

Batson, yup it sucked but as you said atleast the price was right. Gotta say Texas Skyways stood behind their warranty n got me back in the air as quickly as they could. (Edit: Actually I got screwed by TS, and told the warranty doesn't mean squat and even though I have the oil analysis from day one showing abnormal valve guide wear from first oil sample, and all JPI data to prove I never ran the engine hot, I am stuck with the bill. There is more to the story I will update below)

We don't know what actually happened to the cylinder...the shop that the cylinder came from originally is who it got sent back to. I've heard these people do great work from others, and won't say who, but this time around it was not great customer service. They told me the piston was fine, pictured in previous post with gaping dent from where it slapped valve, and that the valve guides were fine, I have a baggy with valve guide shavings I found in rocker box cover? Then they said the valve was burnt, it wasn't, and then said maybe they got reports mixed up. At that point I quite calling and let Skyways figure it out.

Skyways ended up just buying another cylinder, pushrod, piston etc. to get me back in the air. According to the mechanic doing warranty work it should have been a 1-2 day turnaround on the cylinder repair and it ended up being 9 business days and just getting the new one??? (Edit again: Skyways didn't buy squat they lied to me and I had to foot the bill)

After cylinder R&R, there was a bad vibration at low power setting and idol, found an induction leak from install and that fixed it. However winds were in the 20knot range during my test flights and the prop was making too much noise from that to be confident. Finally had a calm morning the other day as I was heading back west and it was really smooth. Barnstormer dropped in and said it sounded great from the ground.

Had the perfect day yesterday, light rain and calm winds, ran beautifully at all power settings. Got 9 hours on it now...Man that was a long two weeks

Comin back home

Yesterday

Looks lonely out there. Looks like you could use some company in that god forsaken land. Poor guy.
You've had a few people's fair share of problems over the last 6 months in the motor department!
Hope she's runnin good now for good!

I'm surprised nobody has beaten me to it yet. Have you tried Marvel oil in the fuel and oil? One of the things I have learned from the older and more experienced mechanics is that MMO helps the valve guides stay lubed. I have used this stuff on the smaller Continentals, but I've never had an O-470. I can say that I fully believe it works well on the 65 through O-300 Continentals, and I continue to spend money on it in the gas and oil.

I do not have any experience with the 470 series motor, so there may be some good reason not to use it.

And of course, valve guide lubrication may or may not be the root cause of your problem.

Flight - I use MMO at every oil change on my airplane(s) works very well in oil . In fuel when I use autofuel - lubricates fuel system components against nasty alcohol's bad effects . Stuck valves are more common on lycomings .

EZ, yup I am a fan of MMO and ran it in my old L motor in both fuel and oil. On this motor have used it in the fuel but not the oil. Been running camguard with Phillips 20W50 XC.

The motor has been running good with new cylinder and was just finally breathing a sigh of relief...until we were on our way to town yesterday and all the sudden the engine started stumbling and running rough. #1 cylinder EGT went up 150 degrees and I couldn't even lean anywhere near peak without roughness/sputtering. Luckily, we were real close to the airport and landed shortly thereafter.

Figured it was a fouled plug but thought how? It had only only been 9.5 hours since cleaned n gapped plugs. Well I have been following their directions for break in to a T and running extra rich...100-200 ROP at mostly high power settings.

Here's what running nice n rich did for me anyways...plug from #1


I had a mechanic buddy tell me to run seafoam in the oil every once in awhile to help clean up carbon/lead deposits. Used it with automotive/marine engines but never airplane. Anyone ever tried it in aircraft engines? Pretty similar to what MMO claims to do.

We had valve and fouled plug problems with pipeline patrol Cessnas using 100LL to a much greater extent than using either 80-87 or auto gas. A Pawnee will go 100 hours without cleaning the bottom plugs using auto gas. Cessnas, especially C-152, will require the bottom plugs to be cleaned every 50 hours or less using 100LL. 100LL has enough lead for the large piston engines that drank 100-120 in the past. It has too much lead for small piston engines.

Update:

Wanted to give plenty of time before I posted this to see if Texas Skyways would come around. I've updated all my posts where I said they did good and stood behind their warranty. Ultimately, this is a long story and I will skip most of the details, the end of the story is I got stuck with the bill and 4 weeks of downtime playing along with Texas Skyways BS. The first cylinder they did "warranty" was supposed to be mine that was repaired, it wasn't mine but was a used cylinder that cracked in less than 30 hours from a bad weld. After it cracked and was removed, I had to wait while they reviewed all my JPI data (oil analysis; they never even wanted to look at oil analysis but it was made available to them) and then just told me I got it hot, beyond redline hot in the 500 deg plus zone??? Very strange when they had all the engine data from my JPI proving the cylinder never went above 385 degrees at any time (they insisted they needed the JPI data and I was out of town and had to pay an IA to retrieve the data)…….the weld on the cylinder had an air bubble in it, and that is where it cracked from (see pictures below).

Sorry if this comes across as me trying to bash a business online. The goal here is to give a first hand account of the customer service experience I had with Texas Skyways. From the $2600 that magically appeared on the bill the day I went to pick up the engine, to the raw deal I got forced into on the prop I "had to buy" from Texas Skyways, to this absurd experience with cylinder swapping and causing 4 weeks of downtime and me footing the bill on something that was warrantied in black and white, as well as verbally warrantied with my father and 2 friends witnessing as the owner of TS shook my hand and told me 6 months from installation on the top end full warranty parts and labor. If not for the oil analysis showing abnormal valve guide wear from day one, and the JPI data that proves I never operated the engine anywhere near above 400 deg fahrenheit, I would probably keep my mouth shut.

I'd received multiple PM's from people who had negative experiences with TS prior to my purchase, but the good seemed to outweigh the bad and I went through with the purchase. Since then, I have come across many individuals locally in my region (TX) who have had the same customer service experiences with Texas Skyways, and the same magical increase in the bill by thousands of dollars at the last minute, so I decided it best to put the this information out there...

Here is a pic of the cylinder that was supposedly mine that was repaired, it was a completely different cylinder, mine had no welds among other differences...the crack sprang from the air bubble in the weld. The oil spots between crack and spark plug appear to be cracks but are not. The crack ran bout 5 inches down side, thankfully found this on the ground.

Whats the history of these cylinders? Did you start out with these as new or overhauled? Just seems like some reused cylinders that go passed as good enough but probably have lots of hours on them. 470's are not prone to having cylinder problems.

Been my experience that re-run cylinders are a bad investment.

Sorry TS stuffed you. Way too small of an industry to be doing that to people.

First of all, only the #5 cylinder had problems. Other than this issue the motor is great and I am happy with the performance. The motor is a Continental Reman and Texas Skyways doesn't really do anything but send stuff off to other people and then put it back together with their nifty oil pan etc.

The scoop on the cylinders is they where originally new continental cylinders that had 145.2 hours on them at the time of TS overhaul to "new tolerances" with new pistons, pins, valves/guides, etc. Texas Skyways overhauled the Factory Reman motor that had 269.5 TT, originally built in 2008. They used new lifters, new carb, new oil cooler, and added the "seventh stud." Their STC allows the 470-U to be operated at higher RPM to achieve 250HP, the dyno reports they have show 263HP at 2600RPM for whatever that's worth. The 470-U has high compression cylinders and a phase III case, same as 0-520.

When I bought the engine they had the cylinders nickeled/overhauled. So yes they were technically overhauled cylinders, but not unknown jugs, these had very low time before they got sent off to be nickeled.

I'll post pics of the logs below; there was a cylinder recall from continental and this motor got 6 new cylinders, that is why there was less time on the cylinders than the motor.

Note #6 R&R all cylinders


This is the warranty, Jack told me over and over when trying to get him to stand behind his warranty that he does not warranty cylinders. This even after he warrantied it the first time, albeit with some random POS cylinder that was not the new tolerances cylinder I bought. Anyways, see what y'all think about the warranty. Seems pretty straight forward to me......

Looks like one would expect a full warranty for six months then after that you're on your own for cylinders and the other major components are pro-rated.

There was an early TS conversion here in a c180. It was a beautiful airplane. It was on an air taxi ship. They could not make it run right, died at idle no matter what. The story was that TS told them to use a larger jet in the carb, however they could not produce sufficient paperwork to that effect to satisfy the FAA inspector at the time. The company pulled the engine, sold it for pennies on the dollar (to bad I was broke) and put in a brand spanking new factory O470.

Yeah GB, it was 5 months in when the valve hung. The warranty not only says six months every things covered, the owner shook my hand and said the top end specifically was covered for 6 months in front of 3 witnesses, 2 who are on here.

It's not even about the money at all, it's about standing behind you word. A cylinder swap is not a huge deal and had they just done right and given me a new one (like I bought) this could have all been over with in a couple days, instead it put me outta business for an entire month total time down. I use my plane dang near everyday for work and if we hadn't just bought a cub I'd have been screwed. Without the cub the amount of money/time it would have cost me for not being able to use an aircraft makes the dang cylinder cost laughable

In the aviation industry I've been fortunate enough to deal with some incredible people/businesses, like Alaskan Bushwheels, and just as the guys that do their best deserve a lot of credit, the one's that will kick you when your down deserve a little notoriety too.