The end may be nigh. :-(
1988 OMC 5.0 (502APRGDP)
I need to do a leakdown test on cylinder #7. (Sad story details are below.)
What is best way to check that piston is at top of its travel, while manually rotating engine? I need to do a leakdown test.
Sad Story:
Compression tests in Spring (April 29) looked good. 1-150, 3 -160, 5- 150, 7 - 150, 2 - 160, 4 - 160, 6 - 150, 8 - 160. These were done on a cold engine.
Been enjoying a great boating season.
Then.... Engine started to hesitate for a split second when accelerating. Also stalled 2 times while running close to WOT last weeks. Started researching issue. Did another compression test. Results not so great this time. 1 -150, 3 - 150, 5 - 140, 7 - 85, 2 - 165, 4 - 155, 6 - 155, 8 - 150. Added a little oil into #7. Compression came up to just under 90. Next up is a leakdown test.
No oil seems to be burning. No smoke out exhaust.
What may have happened:
I messed up. Before first time out this season, I crossed the #5 and #7 sparkplug wires. Ran a little rough but still ran ok at low RPM through no wake zone. Once out of no wake zone (20 minutes later), when increased throttle, boat got up on plane but sputtered and misfired a few times. Turned around and went home, at low RPM. Found my mistake and corrected it. After correcting #5 and #7 sparkplug wires, started her up again and she ran smooth. No problems until recently.
Low compression on #7 may not be cause of hesitation and the 2 stalls. So, I am rebuilding carb too.
But, the compression test results are accurate. Doing a leakdown test to better understand issue. Head gasket? Scorched Intake or Exhaust Valve? Piston Ring? Scorched cylinder? Other?
1988 OMC 5.0 (502APRGDP)
I need to do a leakdown test on cylinder #7. (Sad story details are below.)
What is best way to check that piston is at top of its travel, while manually rotating engine? I need to do a leakdown test.
Sad Story:
Compression tests in Spring (April 29) looked good. 1-150, 3 -160, 5- 150, 7 - 150, 2 - 160, 4 - 160, 6 - 150, 8 - 160. These were done on a cold engine.
Been enjoying a great boating season.
Then.... Engine started to hesitate for a split second when accelerating. Also stalled 2 times while running close to WOT last weeks. Started researching issue. Did another compression test. Results not so great this time. 1 -150, 3 - 150, 5 - 140, 7 - 85, 2 - 165, 4 - 155, 6 - 155, 8 - 150. Added a little oil into #7. Compression came up to just under 90. Next up is a leakdown test.
No oil seems to be burning. No smoke out exhaust.
What may have happened:
I messed up. Before first time out this season, I crossed the #5 and #7 sparkplug wires. Ran a little rough but still ran ok at low RPM through no wake zone. Once out of no wake zone (20 minutes later), when increased throttle, boat got up on plane but sputtered and misfired a few times. Turned around and went home, at low RPM. Found my mistake and corrected it. After correcting #5 and #7 sparkplug wires, started her up again and she ran smooth. No problems until recently.
Low compression on #7 may not be cause of hesitation and the 2 stalls. So, I am rebuilding carb too.
But, the compression test results are accurate. Doing a leakdown test to better understand issue. Head gasket? Scorched Intake or Exhaust Valve? Piston Ring? Scorched cylinder? Other?
