Engine Failure

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sonerainut

Active Member
Joined
Jun 17, 2007
Messages
29
Hello All,

It has been a long time since I have posted on the Sonerai.net site. I have been checking in from time to time, it appears there are many new builders and the Sonerai series still is a lot of bang for the buck!

Speaking of bangs...

Recently, after an excellent local flight I had an engine failure. After a pass down the runway as I was climbing and turning downwind, I felt a bang followed by a bunch of shaking as the engine came clanking to a halt. I was able to continue my turn and position for an uneventful dead stick downwind landing. I should have stayed in the slip longer, but still had plenty of runway remaining. It was the first time my GP 2180 has let me down.

The engine total time was approx 130 hrs (sadly over a 13 year period - life tends to win out over flying most of the times) Last fall, I had pulled the heads and lapped the valves and looked over things - nothing noted at the time. Tear down this weekend revealed the following - pictures are worth a thousand words...

Coulda, woulda, shoulda, replaced the exhaust valves when i had it apart..... We found pieces of the piston in the combustion chamber of the other cylinders - lots of metal! When the piston pin was banging on the base of the cylinder, it actually bent the rod.

So now I'm needing to build a new engine. I'm thinking GP2276. Any of you with the 2276 have info on what heads and valve sizes you are using? Are you using stainless exhaust valves too? Any input would be appreciated.

Freedom Is Flying....

Lee
 

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Pttim

I thought this would only take a year!
Administrator
Joined
Mar 2, 2008
Messages
1,637
Location
Pennsylvania
OMG! Lee, so glad you were at your field and were able to get back to the ground safely.
 

eschrom

Well-Known Member
Joined
Jan 18, 2006
Messages
775
Location
Harrisburg, PA
Sorry about your misadventure, Lee, but happy that you're able to write about it. My 2276 has Mofoco 041 heads, which I chose because of their small valves, meaning more meat between the intake and exhaust valves. Years ago with a 2180 I threw away the heads (they were 042s if I recall correctly) because they developed cracks between the valves. So far the 041s are holding up well.

Ed
 

Smokyray

www.iamanet.org
Joined
Aug 6, 2015
Messages
232
Location
TX32
Lee, first nicely done!
Right after I purchased 994SP the original GP2180 gave me several warnings I heeded and removed and replaced it. Having built three RV's the weight/powerplant equation was very familiar albeit half of what I was used to. That said I decided a robust, lighter weight blueprinted racing quality engine was what I desired. After a lengthy search I located my Ultimate 1835.. It had nearly 350 hours now I believe with few if any signs of major wear.
Here is the spec sheet:

Great Plains 1835cc Engine Kit (92mm bore X 69mm stroke) 60HP Diehl ACC/Case
Slick #4316 Magneto and Harness
Zenith #1821 Carb with cockpit adjustable mixture control
Forged 69mm VW crankshaft ground to .010" undersize and balanced to 1/100th of a gram by Gene Berg Enterprises
Piston and Rod set matched to closer than 1/10th of a gram
Mahle 92mm Cylinder and Piston set with Teflon wrist pin buttons
Total Seal compression ring on each piston 2nd ring (prevents blow-by, keeps oil cooler and cleaner)
3-Angle valve job and matched valve springs by Fumio Fukaya (Best VW cylinder head man on the planet)
Manley Stainless Steel valves
4130 steel pushrods (each matched for perfect rocker arm geometry) Gene Berg Rocker Shafts (with shims instead of spring clips)
Laser hardened valve adjusting screws
Blueprinted oil pump
Revmaster Fuel Pump Drive Adapter (driven off oil pump)
Full Flow oil filter
Compression set at 7.0-1 (No oil cooler needed/ temps stay at 170 to 190 degrees/ depending on ambient temperature)
Over-Sized engine case nuts and washers (VW racers have found this doubles case life)

I removed unneeded items and combined with the lighter 1835 reduced EW by 65 lbs. Despite less HP my performance actually improved after the changes! .
Some food for thought...
V/R
Smokey
 

kennyw

2nd and current "Caretaker" N994SP
Joined
Aug 27, 2017
Messages
146
Location
Mount Vernon, WA
Sonerainut, if I'm interpreting those pictures correctly, it looks like #4 exhaust valve beat the piston up. Is that right? Any idea what caused it to fail?
 

oahupilot

Well-Known Member
Joined
Aug 2, 2008
Messages
531
Smokyray said:
Laser hardened valve adjusting screws
This sounds a bit like marketing wank, must be all the sales guys I have dealt with at work. In theory you could use a laser to harden metal, but the end result would probably be similar to case hardening. Do you have more info on this and its claims. Is it better than regular case hardening or does it just sound cool in the brochure. My quick google search pulled up nothing in the first page.

Just curious.
 

oahupilot

Well-Known Member
Joined
Aug 2, 2008
Messages
531
OK I finally found something on laser hardening components.

So its much as I expected, it is just case hardening, but the heat source is provided by the laser versus an oven. The interesting bit is the lack of a quench process and selective hardening ability. It seems like the bulk of this process's benefits is for the factory in lower operating cost and higher through put. Interesting, none the less.

https://www.trumpf.com/en_US/applications/surface-treatment/laser-hardening/
 

Smokyray

www.iamanet.org
Joined
Aug 6, 2015
Messages
232
Location
TX32
Pttim said:
OMG! Lee, so glad you were at your field and were able to get back to the ground safely.
Lee,
I sent you a PM for my VW engine guru friend Toms cell#. He heard your plight and volunteered his dos centavos. Give him a call.
V/R
Smokey
 

ChuckerF14

Well-Known Member
Joined
Nov 1, 2013
Messages
698
Location
Prescott Valley, AZ
Lee,

I can't tell from the photo.... Did the valve stem break at the bottom retainer groove?

ATB,
Chucker

Nice job getting her back on deck safely!
 

sonerainut

Active Member
Joined
Jun 17, 2007
Messages
29
Hi All,

Thanks to everyone for the responses - much appreciated and helpful.

Yes #4 exhaust valve failed at the point where the stem flares into the valve. When it let go, it took a few seconds to beat the piston into what you see in the picture. The piston pin, still in the connecting rod without the piston to keep it aligned in the cylinder, proceeded to beat the base of the cylinder so that the cylinder cracked the entire stroke length in three locations. Heads are the original 040 with small non stainless valves sent from Steve with my long block kit back in the day....

I have been thinking about why such a “low” total time (high calendar time) valve could fail. Like all aviation disasters, multiple small things combine to make a bigger problem.

My thoughts/observations:

1) My original box baffle setup and small oil cooler resulted in some high CHTs and possible head damage (nothing visible though). A large oil cooler fixed the temp problems, but temps had to be watched more than desired. Years later, I fabricated plenums to completely solve the temp issues.

2) Since I (sadly) didn’t fly the thing as much as I wanted/should I typically had some level of valve leakage, especially on #4. Running would improve compression and leakage, but #4 was always weaker than others.

3) Yearly valve adjustment was normal with no tight valves - No indications of valve stretch.

4) I pulled the heads last year and lapped the valves. Nothing unusual noted at the time. All was well afterwards and then it was winter and the plane sat - again....

5) Since I built the plane I was fortunate enough to keep the plane in a heated hangar. Last year I moved to a non-heated and very damp T-hangar.

6) When better flying weather came around earlier this year #4 was weak. I thought it was corrosion again and it would improve after running for a while. Two flights later, the valve failed.

So.....

My takeaway is:

1) I may have caused some head/valve damage from overheating on the initial flights.

2) I didn’t help the engine health by letting it sit so much.

3) #4 was talking to me. What I thought was valve seat/face corrosion was actually a valve that had begun to fail. The picture doesn’t show it well, but the stem showed fatigue “beach marks” across half the stem diameter till it completely failed. Each engine run/increase in temperature cracked a little more. The initiation site doesn’t show anything obvious, but I don’t have access to an electron microscope, so I can’t say for sure what is there. I’m thinking corrosion pit or similar. The damp hangar probably didn’t help that either...

4) I should have had the heads rebuilt or at least replaced the valves when I had them off last.


With all of that said, I am sharing my experience and thoughts only and not suggesting there is anything wrong with our VWs or that everyone needs to run out and replace their valves. In my case, hindsight being 20/20ish, I should have dug a deeper into the #4 exhaust valve leakage and may have avoided this whole situation.

My new engine will have SS valves and I will remove the rockers and oil the cylinders for winter. I will also use engine plugs and some sort of desiccant throughout the season. Most of all, I will listen to what the engine is telling me.

I’m looking forward to getting my new engine built, installed and back into the air.

Lee
 

Smokyray

www.iamanet.org
Joined
Aug 6, 2015
Messages
232
Location
TX32
Lee,
A great thread and responses. Also good to hear from you via email.
Tom (the VW guru) was near draconian in his emphasis on dessicant moisture evaporation via a crankcase tube and plugging the exhaust pipes when parked for any extended time periods.
I complied by utilizing an empty coffee container with a tube size hole in the plastic lid sealed with silicone. I filled it with Damp Rid absorbent silica gel purchased at WalMart and placed the can under the S2 when parked with a long plastic tube connected to my breather exit tube. I also plugged the exhaust ports with "super ball" toy rubber balls the grandkids had laying around, perfect size. I poked a small hole thru them, then threaded weed eater line to use as a handle for removal.

As far as a new engine, don't rule out Lone Star engines here in TX. They are doing some nice work including engineering 2 Harley cylinders on a VW case, essentially a 1/2 VW with up to 70HP.
Check it out: https://youtu.be/g7WpHmzZ3wI

V/R
Smokey
 

DeadRinger

Active Member
Joined
Feb 2, 2012
Messages
30
Location
KAPV
Hay Smoky, sure would be nice if Lone Star would make a 4 cylinder with Harley cylinders. I’d buy one of those!!
 

freeinhim

Member
Joined
Mar 12, 2018
Messages
12
Location
Tampa, Fl
Hi All,

Thanks to everyone for the responses - much appreciated and helpful.

Yes #4 exhaust valve failed at the point where the stem flares into the valve. When it let go, it took a few seconds to beat the piston into what you see in the picture. The piston pin, still in the connecting rod without the piston to keep it aligned in the cylinder, proceeded to beat the base of the cylinder so that the cylinder cracked the entire stroke length in three locations. Heads are the original 040 with small non stainless valves sent from Steve with my long block kit back in the day....

I have been thinking about why such a “low†total time (high calendar time) valve could fail. Like all aviation disasters, multiple small things combine to make a bigger problem.

My thoughts/observations:

1) My original box baffle setup and small oil cooler resulted in some high CHTs and possible head damage (nothing visible though). A large oil cooler fixed the temp problems, but temps had to be watched more than desired. Years later, I fabricated plenums to completely solve the temp issues.

2) Since I (sadly) didn’t fly the thing as much as I wanted/should I typically had some level of valve leakage, especially on #4. Running would improve compression and leakage, but #4 was always weaker than others.

3) Yearly valve adjustment was normal with no tight valves - No indications of valve stretch.

4) I pulled the heads last year and lapped the valves. Nothing unusual noted at the time. All was well afterwards and then it was winter and the plane sat - again....

5) Since I built the plane I was fortunate enough to keep the plane in a heated hangar. Last year I moved to a non-heated and very damp T-hangar.

6) When better flying weather came around earlier this year #4 was weak. I thought it was corrosion again and it would improve after running for a while. Two flights later, the valve failed.

So.....

My takeaway is:

1) I may have caused some head/valve damage from overheating on the initial flights.

2) I didn’t help the engine health by letting it sit so much.

3) #4 was talking to me. What I thought was valve seat/face corrosion was actually a valve that had begun to fail. The picture doesn’t show it well, but the stem showed fatigue “beach marks†across half the stem diameter till it completely failed. Each engine run/increase in temperature cracked a little more. The initiation site doesn’t show anything obvious, but I don’t have access to an electron microscope, so I can’t say for sure what is there. I’m thinking corrosion pit or similar. The damp hangar probably didn’t help that either...

4) I should have had the heads rebuilt or at least replaced the valves when I had them off last.


With all of that said, I am sharing my experience and thoughts only and not suggesting there is anything wrong with our VWs or that everyone needs to run out and replace their valves. In my case, hindsight being 20/20ish, I should have dug a deeper into the #4 exhaust valve leakage and may have avoided this whole situation.

My new engine will have SS valves and I will remove the rockers and oil the cylinders for winter. I will also use engine plugs and some sort of desiccant throughout the season. Most of all, I will listen to what the engine is telling me.

I’m looking forward to getting my new engine built, installed and back into the air.

Lee
Hi Lee, sorry about the engine failure. Years ago(literally) I had a VW and had a valve drop. Fortunately I was on the ground. I have a 2L built by Victor Giles from 7/79 to 5/84 (N747VG). His last flight was 2/08 due to health and passed away. The Sonerai has gone thru a couple of hands I purchased it 3/18. It has not flown since. Amazingly Victor flew the AC 5,719 times all logged. This AC is probably the highest time Sonerai flying. The carb was changed to a Zenith by the previous owner but he cut out the cowl way too much and did not reglass to correct the cooling. I was too naïve and relied on a conditional inspection by an A&P and bought it and flew it twice short hops. The rpm was 1650 on the first hop. The previous owner said the prop pitch was too steep and adjusted the ground adjustable prop to where the static rpm was about 1950. He reassured me that was ok. Flew the second time short but CHT temp was too hot (500+). Trail of tears. Heads were cracked. I got hurt in the pocketbook and pride. It is what it is. Now with two brand new heads with SS valves the engine is running. I have to solve the cooling. I purchased a baffle kit and new oil cooler from Sonex to be installed. I was going to change the oil cooler from below the ac to above like Sonex. I hope this is a good decision. I was asking you for some pictures of your plenum set up. Is there any in the forum. I have some pictures of mine there. One other problem is that Victor had an alternator failure. He installed a little alternator belt driven on the front of engine. He had to modify the cowl to do it. I want to go back to the original rear alternator. Does anyone have one? How much? Thank you for any help you can give me. Harry in Tampa 813-610-8226 The AC is for sale at a reasonable price.
 

sonerainut

Active Member
Joined
Jun 17, 2007
Messages
29
Hi Harry,

I’ll dig up some pictures of my plenum setup and put them in my photo gallery. Stand by...

Lee
 
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