Valve Guides and Lycoming Engines

[mongo]

One thing I have learned in racing, if Exon-Mobil makes an oil for whatever application you have , use it you will not regret it, hell even when we are sponsored buy another oil company we just switched the oil in the bottles.

Every engine builder I have ever had in my time in Indycar, NASCAR, and endurance racing have always used Mobil 1.

Cosworth
HPD
ROUSH
PENSKE
COMPTECH
ECR
BILL DAVIS
TRD
BRAYTON
PORSCHE
Lotus
AER
Illmor
Hendrick


The list goes on.



Sent from my Transformer Prime TF201 using Tapatalk 2

 

[Darrel Starr]

Talked to Darrell Bolduc today about SJs engine, Darrell arguably runs the best engine shop in the Midwest, at Anoka County Airport. He said that they run the wobble test on both Robinson 22 and 44 helicopters every 400 hrs. Those helicopter run high cylinder head temps and that then leads to worn guides -- so the recurring problems in that case is related to high CHTs. But he has seen cases of misaligned valve seats and guides. He occasionally comes across an exhaust valve burned in just one spot with the seat eroded away and a worn guide - hard to tell if the worn guide led to the burned valve or the other way around. He has seen more problems with Continentals than Lycomings with parts sometimes just flat made poorly or with machining operations or metallurgy out of control.

 

[8GCBC]

Any data? ;-)

 

[Steve Pierce]

Well we replaced all of the exhaust valve guides, and dressed all the valves and seats. Put her back together with new rings and bumped up the oil pressure. All compressions were 78/80 after flying her hard for a few hours. No oil leaks and not getting the blow by we were prior to all this work. Tal delivered the airplane to Kansas City in 3 hours. Wish our work contributed to his 165 mph ground speeds but I think that was the tailwind he had. Hoping not have to do anything to this engine again but clean plugs, adjust timing and change the oil in the future.

 

[sj]

Steve, feel free to share the info you received about over-lean operations on takeoff being the culprit. I'm not convinced fully that was the situation here, but certainly will be watching takeoff egt very closely in the future.

One of the great things about having Pierce work on your planes is he can't sleep at night until he gets to the bottom of "why" something happened. Since he has two teenage daughters, you can imagine he has a lot of sleepless nights.



sj

 

[OLDCROWE]

I'm just glad it's fixed which really means it's out of the way of far more important projects

 

[Steve Pierce]

I spoke with Ken Tunnel at LyCon yesterday and he when I asked him if they had seen any problems with the exhaust valve guides in recent years he said when they had seen this it was due to lean mixture on take-off. This engine seems to run rich all the time so not sure that this applies here. Keeping our fingers crossed.

 

[btracy]

Steve, Have you flown 9CC enough to know how much your oil consumption has improved, or do I need to ask Dana. I just had to have the guides replaced in mine with pretty much the same symptoms. With 20 hours I no longer have the oil dripping from the struts or the gear. Curious if my blow by was a sign that I should of been looking at the wobble test before it failed the compression test

 

[sj]

Bill,

We did not really have any oil consumption problems before hand and there don't seem to be any now. It settles in just under 6qts and stays there for a long time. Given what Pierce found, I would have expected more blow by, but there wasn't.

sj

 

[P.o.P]

I know the thread is somewhat stale but I thought I would comment.

An earlier post refers to O-200 guide wear.

Looked @ one yesterday & Rockers do not line up well with the valves.

Seen this before but nothing can be done in the field.

The oil samples noted higher copper .

Slightly opening the valve & attempting to move

revealed some wobble.

The Sky Ranch Engineering Manual addresses.

It seems to imply the guide alignment is incorrect

& will side load the valve whicj in turn causes guide wear.

 

[G44]

Although this thread is 7 or 8 years old, has anyone seen anything like this since?

Kurt

 

[DENNY]

I had to have all 4 exhaust valve guides on my factory 0320 at about 500 hours. The wobble would cause a exhaust valve to improperly seat for about 5 seconds then it would reseat. Intermittent problem with loss of power not just running rough. Took a bit to find the problem but once I did I went on a crusade to get my CHT's down. It is interesting to see the Lycoming acceptable valve guide wear/time policy. I will see if I can find it again.
https://www.youtube.com/watch?v=x6OyfoV1Z2I
DENNY

 

[BC12D-4-85]

But....when heated to running temps couldn't the parts experience a closer fit due to thermally induced expansion?

Gary

 

[DENNY]

Yes they do and that is what initial valve guide to stem clearance accounts for. However, accelerated valve guide wear will cause too much play in the guide. Excessive CHT's with subsequent exhaust valve issues is why Lycoming came out with the modification to squirt oil on the exhaust valve guides.
DENNY

 

[astjp2]

So I am wondering if an excessive amounts of starts and stops would cause issues, say if the engine was started and ran 10-30 minutes, flew, landed, stopped, shut down, and repeated in 15 minutes for another start...like 15-20 times in a day over several days cause excessive buildup on the exhaust valve leading to stuck valve? Say like a Young Eagles day or students for short hops?

 

[DENNY]

The valve/valve guide issue is truly the work of the Devil!! On one side they get full of crud and stick and on the other side they are so loose ya can throw a cat through the space. Some run fine for over 2,000 hours others show problems at 200-500 with no real consistency. I think keeping the guide cool will help with wear. The guy that made Camguard has a nice writeup on how leaded fuel transforms as it burns, over my head but a good read. Does anyone use TCP in the fuel?
DENNY

 

[hotrod180]

In my experience, Continentals have more of a valve guide issue than Lycomings,
but then I have way more time behind Continentals so maybe that accounts for it.
I had to ream 3 out of 6 exhaust guides on first run ECI cylinders on my C170,
1 at 783 SMOH & 2 more at 973 SMOH.
They were so tight the valves had to be driven out with a brass punch.
The other 3 were fine.
Almost always ran 75% mogas / 25% avgas blend, or else 100% mogas,
so I wouldn't think lead was the issue.

 

[BC12D-4-85]

I have a question for the old timers that's been a challenge to answer...has valve sticking always been an issue with aircraft engines? Like post WWII civilian use mainly. Anyone here know or hear something years ago that says it's always been a problem? Or something else?

Gary

 

[astjp2]

In my experience, Continentals have more of a valve guide issue than Lycomings,
but then I have way more time behind Continentals so maybe that accounts for it.
I had to ream 3 out of 6 exhaust guides on first run ECI cylinders on my C170,
1 at 783 SMOH & 2 more at 973 SMOH.
They were so tight the valves had to be driven out with a brass punch.
The other 3 were fine.
Almost always ran 75% mogas / 25% avgas blend, or else 100% mogas,
so I wouldn't think lead was the issue.

Did the ECI's have exhaust rotators? That was an STC for thier jugs for a while...