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Valve guide reaming results

Mconner7

Well Known Member
650 hours since new Millennium cylinders. #3 stuck and bent the pushrod and had witness marks on the piston (pulled and headed to the cylinder shop). 2 and 4 had to be driven into the cylinder with a drift to ream the guides.

Here is what I got out of the guides with a reamer.
 

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170 hours on a IO390. Just reamed #2 exhaust valve guide after experiencing morning sickness. Looks like the same stuff found on reamer and cleaned off the valve stem.
 
170 hours on a IO390. Just reamed #2 exhaust valve guide after experiencing morning sickness. Looks like the same stuff found on reamer and cleaned off the valve stem.

I have read in general the symptoms of morning sickness but specifically to your 390 experience what did you notice? How long did it last? Did you see anything with the EGT's? How did you determine it was #2?
 
170 hours on a IO390. Just reamed #2 exhaust valve guide after experiencing morning sickness. Looks like the same stuff found on reamer and cleaned off the valve stem.

I reamed all 6 and they all needed it. If one is sticking, the others will likely need reaming too.
 
650 hours since new Millennium cylinders.....I reamed all 6 and they all needed it.

IIRC, Superior (specifically Bill Ross) is teaching the cause of guide sticking is not leaning properly, i.e. not operating in cruise with a high enough exhaust gas temperature. Many pilots do in fact shy away from the peak EGT region.

In retrospect, would you agree with Superior's position?
 
IIRC, Superior (specifically Bill Ross) is teaching the cause of guide sticking is not leaning properly, i.e. not operating in cruise with a high enough exhaust gas temperature. Many pilots do in fact shy away from the peak EGT region.

In retrospect, would you agree with Superior's position?

Another poster here. I have a Lycoming YIO-360-M1B (non-Thunderbolt) in my RV-8. I've had a sticking (not stuck) exhaust valve in Cylinder #2 happen twice, the first at 447 Tach Hours and then again at 1020 Tach Hours.

I purchased the RV-8 with about 210 Tach Hours on it. Since I've owned it I've leaned aggressively on the ground, use the Target EGT method for leaning in the climb, and run about 100°F ROP at 72% to 75% power, or 75°F to 100°F ROP at WOT and 2450 RPM at higher altitudes. I do run LOP sometimes, but not extensively. I normally don't run at peak EGT.

The first time the valve was sticking, we reamed all 4 exhaust valve guides, but only Cylinder #2 was crudded up, the other three were clean. The second time, we just reamed Cylinder #2.

My previous RV-8 had a Lycoming IO-360-A1A (PV) with 10:1 HC pistons (modified by LyCon). I ran it much richer in-flight (and never LOP) per LyCon's instructions, to make sure there was adequate detonation margins. In the 1900 hours I flew that airplane, the engine never had a sticky or stuck valve. I know the current owner and the engine now has about 2300 hours on it, with no difficulties.
 
IIRC, Superior (specifically Bill Ross) is teaching the cause of guide sticking is not leaning properly, i.e. not operating in cruise with a high enough exhaust gas temperature. Many pilots do in fact shy away from the peak EGT region.

In retrospect, would you agree with Superior's position?

I am not sure what caused them to carbon up. I seldom run more than 60% power in cruise and always lean as much as I can but without being injected I am limited to around 25 LOP on one or two cylinders, the rest are at or near peak. Mike Bush thinks it’s lead byproducts.
 
Hmm Why #2?

<snip>
The first time the valve was sticking, we reamed all 4 exhaust valve guides, but only Cylinder #2 was crudded up, the other three were clean. The second time, we just reamed Cylinder #2.
<snip>.

Carl, just curious if your baffles have a provision for the lower fin cooling on head #2? Just wondering if that is a variable as well as A/F. My Lyc YIO 360M1B GAMI spread is really small so would not think that would trigger it.
 
IIRC, Superior (specifically Bill Ross) is teaching the cause of guide sticking is not leaning properly, i.e. not operating in cruise with a high enough exhaust gas temperature. Many pilots do in fact shy away from the peak EGT region.

In retrospect, would you agree with Superior's position?

I don't

I have 850 hours on the IO-320 in my 6A. I lean religiously in climb (150 ROP) and cruise (~30-40* LOP) and occassionally even climb LOP. I have also flown about 20% of those hours in winter conditions where CHTS are in the very low 300's. I don' think I have ever cruised at peak EGT. According to this theory, I should be a worse case scenario.

Last summer I built a wobble test rig and checked all Exh guides. All were on the loose side of the range.

I remain convinced that the build up in the guides is coked oil from excessive heat and not lead from too little heat. Just looks at the pics in this post. The debris is jet black, just like Coke, and not grey like lead. Sure, chemical analysis will show some lead, but that is only because the oil was carrying lead particles in suspension before it converted to coke in the guides. Also, lead converts to a gas around 1000* and therefore any lead exposed to the guides above this temp are a non issue. The area of challenge, is idle, where exh temps are below this. We have seen this for decades. Dawdle around at rich idle too long and the plugs foul with lead. What's the answer, run the engine up for a minute an lean it to get EGTs up and it goes away. IMHO, lead is too soft to build up in the guides. It also is a natural lubricant and wont stick to anything, except at VERY thin layers. Look at the plugs. The lead forms little balls that fall right out. No reamer required.

More evidence - This did not happen to auto engines, even in the lead fuel days. Auto engines flow more oil to the rockers and that oil cools the valve stem. Lyc has anemic flow to the rockers due to a poor lifter design (no bypass channel to send oil up the pushrod, like every auto engine has) and therefore stems runs hotter. When / if the stems reach critical temperature, the oil cokes.

Larry
 
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I have 850 hours on the IO-320 in my 6A. I lean religiously in climb (150 ROP) and cruise (~30-40* LOP) and occasionally even climb LOP. I have also flown about 20% of those hours in winter conditions where CHTS are in the very low 300's. I don' think I have ever cruised at peak EGT. According to this theory, I should be a worse case scenario.

Actually I think you would be a model citizen. Pretty sure Bill Ross is talking about folks who are overly cautious with the mixture knob, and tend to fly rich all the time. You, on the other hand, maintain EGT within 150 of peak, or less than 50 the vast majority of run time. I do the same, with no sign of sticking.

Question here is how the sticky valve owners are operating.
 
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I remain convinced that the build up in the guides is coked oil from excessive heat and not lead from too little heat. Just looks at the pics in this post. The debris is jet black, just like Coke, and not grey like lead. Sure, chemical analysis will show some lead, but that is only because the oil was carrying lead particles in suspension before it converted to coke in the guides. Also, lead converts to gas around 1000* and therefore any lead exposed to the guides above this temp are a non issue. The area of challenge, is idle, where temps are below this.

Larry

I run 91 octane alcohol-free mogas at least 50% of the time. I never have any form of lead fouling in spark plugs - in 225 hours of operation our O-360 has produced one tiny ball of lead in one of the massive-electrode plugs and that was early on when I was running 100LL and rich mixtures during break-in.

Last week I completed honing the exhaust valve guides in the engine. Using a ball hone and a lubricant/cutting oil consisting of a 50/50 mixture of ATF and acetone produced measurable results. One guide had approximately 0.004" of buildup in the guide - that valve had to be drifted into the cylinder. The other two guides had less buildup, and the fourth one I'll never know how much buildup it had since the exhaust valve seized, requiring cylinder removal and rework by an engine shop.

Interestingly, the valve guides produced a dark grey slurry on the ball hone - I was surprised by the grey hue as I was expecting (as others have pointed out here) a much darker color to the slurry.

From a technique perspective, I purchased two ball hones - one in 320 grit, one in 240 grit. It was only the one truly bad guide which required the use of the 240 grit hone. The ball hones (1/2" Flex-Hone purchased on Amazon) proved a very easy method of cleaning up the valve guides. I am fortunate in that my valve guides are wearing relatively uniformly, i.e. they remain relatively round.
 
Carl, just curious if your baffles have a provision for the lower fin cooling on head #2? Just wondering if that is a variable as well as A/F. My Lyc YIO 360M1B GAMI spread is really small so would not think that would trigger it.

Bill,

I'll check and see. The CHTs generally run in the very low 300's to the mid 300's in cruise, depending on conditions. Cyl #3 runs the warmest, and Cyl #4 the coolest, with a CHT spread between coolest to warmest cylinders between 12°F to 23°F.

My GAMI spread is small, between 0 to 0.2 GPH.
 
.......Interestingly, the valve guides produced a dark grey slurry on the ball hone - I was surprised by the grey hue as I was expecting (as others have pointed out here) a much darker color to the slurry........

That gray slurry is probably the broken-down abrasive from the ball hone. The abrasive has to break down during use so as to uncover fresh abrasive as it's working.
 
Timely Post

I had #3 exhaust valve completely stick open on friday afternoon. Luckily I was 8,500' and about 8 miles from an airport. It never gave any indication of a problem until it completely failed. Factory Lycoming IO-360M1B from Vans with 930 hrs total. Cylinder is in the shop for a guide replacement and possibly new valve. Bent the pushrod. No piston damage. #3 has always run a little bit leaner that the others and I was in the process of running the Airflow Performance nozzle tuning test when it failed. I typically cruise at 65% power lean of peak. 1, 2, and 4 run about 25 degrees lop and 3 is closer to 80 lop. Engine shop says #3 is much more common to have a stuck valve that the others.
 
SNIP…I typically cruise at 65% power lean of peak. 1, 2, and 4 run about 25 degrees lop and 3 is closer to 80 lop. Engine shop says #3 is much more common to have a stuck valve that the others.

I’m surprised that you could run that large of a GAMI spread and not have the engine running way rough when LOP.

For others - do the GAMI spread at the end of your 40 hours fly off period. It is not hard to get a GAMI spread of 0.1gph or so. Don at AirFlow Performance can recommend replacement nozzles based on the data you send him.

Carl
 
large gami spread

I swapped the left slick mag for a Surefly SIM4 with advance about 50 hrs ago. It allowed for smooth operation at those egt's. With the 2 slick mags it was rough if I leaned that far so I would run closer to peak for smooth operation.
 
Looking for similar data points

For those that have had valve sticking issues, do you use any oil additive such as avblend, MMO etc.

Just wondering if the common thread is coked oil due to excess heat if only engine oil is being used. Then of course the question of what brand of oil is used, fuel type used, leaning operation, carb vs.fuel injected, CHT and EGT norms in cruise, shut down procedures etc.

Perhaps a spreadsheet listing could be put out on the forum for folks having the random sticking values could be accessible to gather a wide and broad set of data ...and potentially some similarities will show up.

Not sure the site could handle a database collection exercise, but maybe a volunteer with extra time on their hands could collect the data? I am sure folks will be glad to submit their data to a central location/individual if they had a sticky valve experience.

Thanks
Paul. RV7A
 
Mystery solved

For those that didn’t follow my entire saga, I had #3 valve stick on my O-540 and bent the pushrod. When I dropped the exhaust valve I found spalling of the guide that is in the first picture.

I reamed the guide but was not happy with the results so I pulled the cylinder and on close inspection found spalled lifters and worn cam lobes. I am sure this is the source of the hard foreign materiel that made its way into the valve guide and stuck the valve.

Time for a tear down with less than 800 SMOH.
 

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For those that didn’t follow my entire saga, I had #3 valve stick on my O-540 and bent the pushrod. When I dropped the exhaust valve I found spalling of the guide that is in the first picture.

I reamed the guide but was not happy with the results so I pulled the cylinder and on close inspection found spalled lifters and worn cam lobes. I am sure this /is the source of the hard foreign materiel that made its way into the valve guide and stuck the valve.

Time for a tear down with less than 800 SMOH.

How were your oil changes/filter exams? Any metal?

-Marc
 
For those that didn’t follow my entire saga, I had #3 valve stick on my O-540 and bent the pushrod. When I dropped the exhaust valve I found spalling of the guide that is in the first picture.

I reamed the guide but was not happy with the results so I pulled the cylinder and on close inspection found spalled lifters and worn cam lobes. I am sure this is the source of the hard foreign materiel that made its way into the valve guide and stuck the valve.

Time for a tear down with less than 800 SMOH.

Thanks for sharing the results you found.
 
That gray slurry is probably the broken-down abrasive from the ball hone. The abrasive has to break down during use so as to uncover fresh abrasive as it's working.

+1

It is also being thinned and mixed with the ATF in your case, which will bring it more towards gray. No need for reamers with lead. It doesn't really stick to anything.
 
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I had #3 exhaust valve completely stick open on friday afternoon. Luckily I was 8,500' and about 8 miles from an airport. It never gave any indication of a problem until it completely failed. Factory Lycoming IO-360M1B from Vans with 930 hrs total. Cylinder is in the shop for a guide replacement and possibly new valve. Bent the pushrod. No piston damage. #3 has always run a little bit leaner that the others and I was in the process of running the Airflow Performance nozzle tuning test when it failed. I typically cruise at 65% power lean of peak. 1, 2, and 4 run about 25 degrees lop and 3 is closer to 80 lop. Engine shop says #3 is much more common to have a stuck valve that the others.

#3 is where the head is getting less cooling due to the limited fin depth. More evidence that it is too much heat and not too little.

Curious if you took steps to increase airflow behind #3.

Larry
 
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Curious if you took steps to increase airflow behind #3.

Does this apply to the parallel valve motors, or just the angle valve? #3 on my engine runs only a few degrees hotter than the others in climb and about 20 degrees cooler in cruise as it is further lean of peak than the other 3. Never exceeds 400F in climb and cruise is about 340-350F. I was in the process of gathering gami spread data to tune the injector nozzles when the failure occurred.
 
+1

It is also being thinned and mixed with the ATF in your case, which will bring it more towards gray. No need for reamers with lead. It doesn't really stick to anything.

Ummm... from your comment I would suspect you don't shoot very much pistol with lead bullets. Getting the lead removed from chambers, forcing cones and barrels is a tough enough challenge that most experienced shooters might argue the point about the "stickiness" of lead. :D

Add pressure and heat and lead forms a smooth shiny surface that looks like polished steel.

I hadn't thought of the color of the penetrating oil as a factor - thanks for helping to get my thinking pointed in the right direction.
 
Ummm... from your comment I would suspect you don't shoot very much pistol with lead bullets. Getting the lead removed from chambers, forcing cones and barrels is a tough enough challenge that most experienced shooters might argue the point about the "stickiness" of lead. :D

Add pressure and heat and lead forms a smooth shiny surface that looks like polished steel.

I hadn't thought of the color of the penetrating oil as a factor - thanks for helping to get my thinking pointed in the right direction.

You are correct. Very little experience cleaning hand guns. I suspect that some of the challenge is that the rifling grooves create a mechanical bond for the lead. I do know that very thin lead deposits stick well to steel when high heat is a applied. Prior to the mid 70's this is the process used to protect valve faces and seats. Once they took the lead out of gas, new alloys had to be used to prevent wear and many older engines lost compression as the valve parts beat themselves to death without the lead coating.

Larry
 
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That is bad news Mconner7!!

Do you know how many years it has been since overhaul?

Around 10 years since overhaul. It was in Phoenix the first 6 years but my hangar is a stones throw from Tampa Bay.

I am blaming the tappet corrosion on salt air and a couple of 6-8 week down times due to the pandemic. I switched from Aeroshell 100+ to Phillips and Camguard a year ago. I will use Camguard from now on regardless of oil because of the salty air at home.
 
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