What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

intermittant oil usage

W

Wiley

Active Member
I now have 165 hrsTTSN in 2 years on a Mattituck xio-360-M1B. Temps have always been consistent and in the appropriate range. Compressions normal and consistent. Break in was done per factory recommendations. Bore scope looks good and verified with my mechanic. Aero splat separator installed.

Concern has always been from oil on the belly and oil usage of 1 qt/5 hours. Ever since it was new, it can blow out a little oil from the exhaust on startup, sometimes enough to discolor the grass under the plane. No smoke noted on initial taxiing. The more stop and go flying with short hops, the more it loss is noted. On a long 9 hour cross country last week, only used one quart.

At times, I can taxi and idle long enough to switch passengers and get a pretty significant smoking on increasing the throttle to taxi again. Once in burns off, no more smoke.

I hate to start digging into it when it is working and running fine. Any thoughts on the cause?

Could it be pulling oil around the valve stem on closed throttle operations at low rpm? If it is an oil ring, why is it not burning large amounts on cross country?

I think it is cyl #3 as there is some oil backing up into the MP line and a little oil in the cyl on scope.

Any engine guru insight would be appreciated.

PS. See you at oshkosh
 
First of all, 1qt/5hr is well within the accepted range. I can't speak to the cause, but I would not take extreme measures to change it. If something simple, no problem.
 
What level do you run your oil at in the sump? In other words, at what dipstick reading do you add a quart?
 
Your symptoms point to oil leakage past a valve. My belief is that most oil consumption in Lycomings is due to the oil rings and their interface with cylinder. This type of oil consumption really only shows symptoms like oil on the belly and excess carbon build up on pistons/heads.

When you blow smoke on startup, you have oil getting into the combustion chamber after shutdown. This larger than normal collection of oil burns at startup, causing the smoke and liquid oil coming out exhaust. This can also happen at idle, when it won't burn as well and vacuum is higher. Hit the throttle and you get smoke. This could also be an over-shot from your accel pump with the smoke being due to over-rich condition.

Lycomings don't have seals on the valves like cars do. The prevent oil intrusion past the valve, in part by a tight clearance and by not sending much oil to the rocker box. If you do anything to upset this balance, there is no seal to prevent the oil intrusion.

First check should be for a blocked oil return on one of the rocker boxes. Oil collecting in the box allows oil to get near the valve guide and it will leak down the valve stem. If this check out, you'll want to look for a worn valve guide (wobble test).

The fact that you get smoke on accleration leads me to believe you have a plugged oil return.

Larry
 
Last edited:
Thank you for the replies.

I run about 7 quarts. I assumed it wasn't blow by loss as it did not change after the separator was added.

I looked under the valve cover. No evidence of retained oil. Couldn't detect any wobble, but didn't take the valve springs off. Given only 165hrs on a new engine, I wouldn't expect such a worn guide. I guess it could be a manufacturing issue.

Other than the uncertainty and oil on the belly, is there any reason to Not continue flying as is?
 
Wiley said:
Thank you for the replies.

I run about 7 quarts. I assumed it wasn't blow by loss as it did not change after the separator was added.

I looked under the valve cover. No evidence of retained oil. Couldn't detect any wobble, but didn't take the valve springs off. Given only 165hrs on a new engine, I wouldn't expect such a worn guide. I guess it could be a manufacturing issue.

Other than the uncertainty and oil on the belly, is there any reason to Not continue flying as is?
Click to expand...

7 qts is too much. it seems each has a different stabilized level, but I would expect yours to be around 6 quarts or less. I would expect some of your oil less is induced by running too high of a level.

Oil burning is technically un-related to blow-by. Yes, the same root issues usually causes both. Excess blow-by is from the compression rings not providing an optimium seating on the walls. Oil consumption due to burning is caused by an improper oil ring seating with the wall (and others, such as valve stems); often caused by the same thing that caused the improper compression ring seating. Did you notice a defined cross-hatch pattern on the cylinder walls during your inspection?

When looking at oil consumption, you are looking at either/both oil loss due to blow-by (oil leaves engine as mist in crankcase vapor-often indicated by oil on belly) and oil consumption due to burning in the chamber due to poor oil control by the oil rings or leakage past a valve (usually leaves excess carbon deposits).

The fact that your separator made no impact on belly oil only means that you are overrunning it. That could be due to excess blow-by or by an ineffective separator. My ACS separator was very ineffective. When I replaced it with an Anti-splat, oil on belly disappeared.

The fact you get oil coming out on startup indicates that you have excess oil getting into the chamber. Ineffective oil rings/seating, leaving too much oil the walls, will allows that excess oil to pool in the chamber and burn on startup.

Your engine should not be spitting raw oil out on startup. Excess oil is getting into the chamber somehow. Valve and poor oil ring interface are the most likely points of entry.

I am with Jesse that 5hr/qt is not a safety issue.

Larry
 
Last edited:
You might find 7 QTS to be a bit high. Try running it with no more than 6 QTS and you might find a reduction in the usage. Typically LYC 4-cyl engines will vent off anything above 6 QTS rather quickly. At the factory we run them below 6 QTS with no issues...
 
Doing a leak down test on all the cylinders could narrow your search. Remove the dipstick and open up the throttle when doing the tests. While you have the cylinder pressurized, and the prop held tight, have someone put their ear up the to the oil filler, the exhaust and the intake. If the pressure is leaking past the rings or valves you'll hear it. If so that's where your problem is. Checking the valve guides, where oil will seep past if they are bad, is not as easy but can be done without removing the cylinder. Check the return lines. Note that the higher the power settings the more oil will go thru the motor.
 
Joe Blank said:
You might find 7 QTS to be a bit high. Try running it with no more than 6 QTS and you might find a reduction in the usage. Typically LYC 4-cyl engines will vent off anything above 6 QTS rather quickly. At the factory we run them below 6 QTS with no issues...
Click to expand...

Exactly where I was going with that question. Thanks, Joe.

My guess is you're dumping most of your lost oil out the breather and onto the belly of the plane. Run it at 6qt for 10 hours and report back.
 
Ditto: too and also

There are some good things highlighted in most of these posts. To chime in on this one seams almost pointless. So I will only comment on a couple three things. We run our IO-360 with an "M" sump at 6 quarts for just the reasons stated above. We only put 7 or 8 quarts in if we know we are going over bad terrain for a long flight, because we know that the top one, one and a half or two quarts will blow off from crankcase vent pressures and flow. There is one thing that stud out about. One of the cylinders has standing oil in the bore often. This may be a sing or indication that that cylinder will need a ring and hone at some point, "BUT" the oil use rate at this point even with the fact that the sump is being filled above 6 quarts is well within the normal use per hour rates. My impression is that you have a watch and keep track kind of thing going here. This is just me, but I would lower my fill levels to 6 for the around town flights and then track your use of oil. Then watch that cylinder that is making a little oil and if it get worse over the next couple of years, you may wish to pull hone and re-ring it if you want to become a rounder at some point in the next five years or so.
Hope this make you feel better about your position, but it is hard sometimes to see through the Kristal ball. Yours as always. R.E.A. III #80888
 
follow-up

Couldn't stand it any more. Had a larger than normal burp of oil on the grass a couple of weeks ago and decided to do something about it. On bore scope, #3 cylinder still oily. Pulled the cylinder. Oil ring looked OK, 1st ring had 2-3mm of chrome flake off on the surface. Valves were tight with no play.

On pulling the intake tube from the sump(horiz intake), there is oil/fuel flowing from the sump. Not much, but sitting against the #3#4 tubes with the tail down.

New rings placed and cylinder de glazed.

On initial use, minimal amount of oil on belly on startup. After 4-5 hours and 5-6 shutdowns, oil noticed again on startup this evening. Frustrating.

1# would a sniffle valve be helpful?
2# could it be slowly building up in the sump with flight in the level position and collecting in the rear of the sump with sitting, causing a bolus of oil on startup?
3# should I check the other cylinder rings even though the compression are fine and looks good on scope?
 
Oil pooling in a cylinder isn't likely coming from the walls. Unless all of your rings are broken, you can't get enough oil on the walls to pool. The likely source is the valves. My first check would be for a plugged oil return line from one of the rocker boxes. If the oil can't drain, it pools near the valve/guide and leaks through to the other side. Once through, the oil gets sucked in chamber and burned or blown out the exhaust and deposited on the belly with the engine running. With the engine off, this oil goes with gravity to the intake runner and/or exhaust pipe (likely both). It is this oil likely getting blown out on startup.

Easy test. Run the engine for 30 minutes and quickly pull each rocker box. If oil pours out, you found your problem.

Larry
 
Last edited:
further follow-up

Thank you for your time.

Flew for 30 min then immediately disconnected the drain tubes at the cylinder. No drainage from all four. Tubes and cylinders all open on inspection.

Intake plenum plug removed and had several drops of oil. Raised the tail to level and got a 1/4 cup of oil.

I picture the plenum collecting oil on taxiing and after shutdown, then falling to the back of the plenum to be picked up at startup the next time and blown out.

Other than adding a sniffle valve, any thoughts.
 
when you pulled the intake tubes, what did the top of the intake valves look like? excessive oil leaking past the intake valve guides will have a large deposit on top the intake valve (stem side), like mentioned above did you remove the valve spring and check for obvious excessive play in valve to guide clearance?
 
Wiley said:
Couldn't stand it any more. Had a larger than normal burp of oil on the grass a couple of weeks ago and decided to do something about it. On bore scope, #3 cylinder still oily. Pulled the cylinder. Oil ring looked OK, 1st ring had 2-3mm of chrome flake off on the surface. Valves were tight with no play.

On pulling the intake tube from the sump(horiz intake), there is oil/fuel flowing from the sump. Not much, but sitting against the #3#4 tubes with the tail down.

New rings placed and cylinder de glazed.

On initial use, minimal amount of oil on belly on startup. After 4-5 hours and 5-6 shutdowns, oil noticed again on startup this evening. Frustrating.

1# would a sniffle valve be helpful?
2# could it be slowly building up in the sump with flight in the level position and collecting in the rear of the sump with sitting, causing a bolus of oil on startup?
3# should I check the other cylinder rings even though the compression are fine and looks good on scope?
Click to expand...
I have had a mixture of oil and fuel come out of my sniffle valve from day one and have had a number of discussion with Lycoming which they claim it is OK.
I believe you are experiencing the same thing and a sniffle valve would help your situation as this seems to be collecting in the sump.
 
Wiley said:
Thank you for your time.

Flew for 30 min then immediately disconnected the drain tubes at the cylinder. No drainage from all four. Tubes and cylinders all open on inspection.

Intake plenum plug removed and had several drops of oil. Raised the tail to level and got a 1/4 cup of oil.

I picture the plenum collecting oil on taxiing and after shutdown, then falling to the back of the plenum to be picked up at startup the next time and blown out.

Other than adding a sniffle valve, any thoughts.
Click to expand...

1/4 cup of oil cannot be normal. You can expect some leakage past the valve guides, but it should only be enough to coat things and not enough to belch oil out on start up or collect a cup of oil.

Only two things come to my mind. One would be a really loose intake guide. I just don' know if the Lyc's throw enough oil on the intake valve to put a 1/4 cup of oil in your sump. My guess is No, but don't have the experience to say. The other is a crack in the intake plenun inside the sump. If you think this is the case, you could pull the intake tubes, and shine a flashlight into the sump, maybe through the dipstick hole and look for light. You could also block all but one of five entrances to the sump and put compressed air in the fifth. Air through the crankcase breather would prove a leak/crack.

Larry
 
Last edited:
Wiley said:
Thank you for your time.

Flew for 30 min then immediately disconnected the drain tubes at the cylinder. No drainage from all four. Tubes and cylinders all open on inspection.
Click to expand...

Just to be sure. did you poke into the AN fitting on the head to be sure the rocker box wasn't full of oil? If the blockage is inside the rocker box, pulling the drain tube wan't show that. A blockage inside the rocker box would still produce the results you found. Your engine wouldn't be the first if you found a portion of a shop towel or paper towel in there plugging things up. I would expect a partial flow, but full blockage is not outside the realm of possibility.

Larry
 
problem found

When I first had a cylinder off 1 week ago,I inspected the sump... no crack. After all the other round of contemplation, I looked again today. With a bore scope from the front L intake, you can see a small crack at the top on the back wall. About a 1/4" long. Just under the area of the screen plug. Now to take it off.

Any recommendations on repair/replacement?

Mattituck TMXIO-360


Frustrating as this is a new engine. Bought new in 2007 by someone else and kept pickled until I bought it and mounted it 2 years ago.
 
Last edited:
Wiley said:
When I first had a cylinder off 1 week ago,I inspected the sump... no crack. After all the other round of contemplation, I looked again today. With a bore scope from the front L intake, you can see a small crack at the top on the back wall. About a 1/4" long. Just under the area of the screen plug. Now to take it off.

Any recommendations on repair/replacement?

Mattituck TMXIO-360


Frustrating as this is a new engine. Bought new in 2007 by someone else and kept pickled until I bought it and mounted it 2 years ago.
Click to expand...

A welding professional should be able to easily repair it via Tig welding.

Larry
 
Weasel said:
Crack in sump? Crack in cyl head letting oil into the intake?
Click to expand...

We have a winner!

Wiley said:
. . . After all the other round of contemplation, I looked again today. With a bore scope from the front L intake, you can see a small crack at the top on the back wall. About a 1/4" long. Just under the area of the screen plug. Now to take it off. . . .
Click to expand...

Excellent diagnostics and persistence! Any chance of discussion with Mattituck? It would likely be a casting issue and not the first they have seen. TIG on a cast oil pan can be challenge. Maybe a trichlor soak and oven baking?
 
I understand Teledyne Mattituck Services closed down a couple of years ago. Is Teledyne Continental supporting their exp class engines?

Divco was recommended to me as a place to have it repaired. I'll try to get in touch with them.

I assumed it is manufacturing defect. It seems as if welding would be acceptable as it does not appear to be a stressed part. I will however try to source a new/salvaged part.

It is finally cooler here. Good timing as the teardown begins..... now.
 
Jesse said:
Mattituck moved to Mobile. They didn't shut down.
Click to expand...

Close enough, on the eastern shore.

H.L. Sonny Callahan Airport, KCQF

8600 Highway 32

Fairhope, Alabama 36532-5073

251.990.5080
 
Last edited:
Sending it to DIVCO for repair. If it were in the case or a cylinder, I would be less likely to have it welded. Since it appears to be in a low stress area and more likely a casting defect, I think welding should be OK (although I have no data to support this assumption). They estimated $200-250 on the phone. Boxed and ready to go.

My as well get a 2 month head start on the condition inspection while waiting.
 
all fixed

Kudos to DIVCO. Welding and shipping for $210. Back together today and running great.(and dry).
 
was this a casting flaw or.... the engine may have hit the ground at some point during shipment type of crack?
 
I assume a casting defect. No history of blow to the case or resting on the sump. In an area of three walls coming together. Fairly thick material around the area.
 
You must log in or register to reply here.
Back
Top