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- Nov 5, 2015
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I have started to have starting issues, and rough mag checks with out very heavy leaning when not at full power. Have about 150 hr's on the mag's after @flyguydon rebuilt them.... when I first installed the rebuilt mags, it started on the 2nd blade, and ran really great. Now the left mag struggles to get the engine started... I did have the switch set to the right mag last week and it started on the first blade... that was a surprise until I saw that the switch was not set to the left mag.
I pulled the plugs yesterday, and they actually look good, no lead fouling, good color, (tan,) and only Cyl #2 lower with any oil.... that one was expected. I have added an engine monitor so now in flight lean to 1420 EGT and 350 CHT on Cyl #3, Cyl #1 and #4 are about 1390 EGT and 320 CHT... #2 is the lowest at 1300 EGT and 285 - 300 CHT. The monitor doesn't record the data... Cyl #2 had a low Compression last year at annual, because the plane had not flown for 3 to 4 months.... was 65/80 and blowing past the rings.
I have flown 40 hr since August, having not flown since February due to a knee replacement and other health issues.... Will test the compression again after cleaning the plugs. Turning the prop there is the impulse click, and will be checking the timing when we do the compression.... We did do the MMO "treatment" to flush the rings and that did improve the temperatures that the cylinder runs at.... Interested in seeing what the compression numbers are at now.
So, with all that background, what to look for regarding the left mag??.. what other items need to be reviewed to look for issues??... Looking for ideas about what to look at that I have not yet accomplished.... will check the intake hose clamps, and look for other leaks but the temperature imbalance doesn't seam to be caused by air leaks.
If everything shows no known issues, will return the mag to Don to have another look at it.... Don does a great job on these but a 50+ year old item may just need some more love.... Not ready to spend the $$$$ for the electronic mag system.
EDIT: O-360-A4A, Bendix S-2 mags, post flight mag check is good with the same drop on both mags, pre flight mag check will be 150 to 200 RPM drop on the left, 50 on the right.... will be closer tot he same after running at heavy lean, full throttle to get more heat in the heads.
I pulled the plugs yesterday, and they actually look good, no lead fouling, good color, (tan,) and only Cyl #2 lower with any oil.... that one was expected. I have added an engine monitor so now in flight lean to 1420 EGT and 350 CHT on Cyl #3, Cyl #1 and #4 are about 1390 EGT and 320 CHT... #2 is the lowest at 1300 EGT and 285 - 300 CHT. The monitor doesn't record the data... Cyl #2 had a low Compression last year at annual, because the plane had not flown for 3 to 4 months.... was 65/80 and blowing past the rings.
I have flown 40 hr since August, having not flown since February due to a knee replacement and other health issues.... Will test the compression again after cleaning the plugs. Turning the prop there is the impulse click, and will be checking the timing when we do the compression.... We did do the MMO "treatment" to flush the rings and that did improve the temperatures that the cylinder runs at.... Interested in seeing what the compression numbers are at now.
So, with all that background, what to look for regarding the left mag??.. what other items need to be reviewed to look for issues??... Looking for ideas about what to look at that I have not yet accomplished.... will check the intake hose clamps, and look for other leaks but the temperature imbalance doesn't seam to be caused by air leaks.
If everything shows no known issues, will return the mag to Don to have another look at it.... Don does a great job on these but a 50+ year old item may just need some more love.... Not ready to spend the $$$$ for the electronic mag system.
EDIT: O-360-A4A, Bendix S-2 mags, post flight mag check is good with the same drop on both mags, pre flight mag check will be 150 to 200 RPM drop on the left, 50 on the right.... will be closer tot he same after running at heavy lean, full throttle to get more heat in the heads.
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