Ant CB

Ant CB

Member
I just had all the jugs off for re-honing and new rings. I also have the guides checked and 3 exhaust guides replaced.

Should I expect the plugs be more susceptible to oil fouling initially? On the first flight after the engine work the plugs were fouling, I was able to clear them at high power but it re-occured. I'm runnning REM37BYs.

I previously had oil coming out of the intake manifold drain after shutdown, I thought that honing cylinders and re-ringing the pistons would resolve this, but after the first flight it still does it.

I got a puffs of blue smoke when I applied power for run ups, it's always done it but once again I thought this would go away with the cylinder work that was done.

Any ideas?

Cheers
 
Oil or fuel?

Are you sure it's not fuel mixed with sluge that is draining? Is it fuel injected? If so it may just be fuel pushing out after shutdown, which is somewhat normal.
Tim
 
From the little I know unless the rings or intake valve have been installed correctly the oil burn off should be short lived.

Perhaps you can identify the plug that is giving you problems - watch the EGT drop during the miss and if it is the left or right mag - pull the plug - confirm that it is indeed fouled. Also test the plug for high impedance and if so replace it. A faulty plug may flashover around the insulation preventing the plug from firing.
 
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What model engine? What did you do fro ground runs before the first flight?
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
Its and angle valve 360 with high compression pistons and fixed pitch prop.

On the first run, I ran it at 1000rpm until it was warm, then 1500rpm for a few minutes then full power for 5 seconds. Then pulled the cowl and had a look around to check for leaks etc...

Then taxied out and ran up normally, then by the time I got to the runway I was getting fouling again. It cleared okay but I didn't think it should foul that quickly. I do lean for taxi.

After shutdown, about a teaspoon worth of oil ran out of the manifold drain over a few minutes.
 
Are the plugs new? If not clean and properly gap them. That may help with the fouling. 37 BY?s would be the least likely of the massive electrode plugs to foul easily.
What was the piston skirt clearance? Very important to keep that below .011.
Is there a lot of oil in the induction system? remove the intake pipes and inspect them. Is any one pipe way wetter than the others?
Also inspect the intake plenum. It is possible for a pin hole or porosity hole in the roof of the intake plenum to allow oil from the sump into the intake system. Maybe try washing it out and drying it and then let it sit overnight and see if any oil appears.
A drip or two of oil out the sniffle valve in the first couple of hours after a re-ring isn't abnormal but it should clear up within a few hours use. Within 4-5 hours of use or sooner.
If the lack of ring break in is the cause, the oil should discolor fairly rapidly to black and consumption should be very high like a quart an hour or something like that.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
The plugs are less that 10 hours old but I did clean them and check them when I did the jugs.

I have cold air induction so the intake and oil sump are physically separate units.

I'll keep an eye on it and hope it clears up, neither my engine builder or mechanic can figure out why it does it but both say keep running it and see if it clears up.
 
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