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1986 Mercury 9.9 zero compression in both cylinders

L

lacina17

New member
recently purchased a 9.9 Mercury outboard. Had 65 PSI in one cylinder and 80 in the other. I installed the Bars Leak High Mileage engine repair.
Let it sit for 2 days, with the plugs out, cleared the cylinders by pulling the flywheel by hand- rope start- then checked compression and has zero in both ! ou got to be kidding me. Took compression check again - yes zero. Have the power head completely apart and do not see any damage in the cylinders. Please help !
 
racerone said:
Why did you use the Bars Leak potion?????
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i was reading that over 100 psi is correct. I was convinced it had a carbon build-up. Ok not the best choice or idea. The why 0 compression in both now? I only found a blown gasket at the exhaust cover near the spark plugs
 
Time to check the gauge.----Gaskets have nothing to do with compression on your motor.--Repeat , gaskets are not your compression issue !-------I suspect dirt in your gauge.-----Where / how did you use the Bars Leak potion ?
 
racerone said:
Time to check the gauge.----Gaskets have nothing to do with compression on your motor.--Repeat , gaskets are not your compression issue !-------I suspect dirt in your gauge.-----Where / how did you use the Bars Leak potion ?
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with the spark plugs removed, tilted engine up, poured solution into cylinders and left it that way for 2 days
 
You may have done a lot of damage to the engine.-----You may have a dirty check valve on your gauge.----No idea why anyone would use this stuff that way !!----Do a compression test on your lawnmower.
 
yes, you are correct. My Snap on guage went to zero and did not hold compression. I tried another end in my kit and it holds. My diagnosis skills are rusty.
now - where to get a gasket kit from, reed valve plate has some rust.
chasing this no start down- has spark, took plugs out and sprayed starting fluid and will not kick over--
 
Remove bypass covers to inspect pistons / rings.----If you poured a watery solution into the engine ( bearings ?) the motor should come apart for complete cleaning.----And reed valves have nothing to do with compression in the cylinders either !
 
racerone said:
Remove bypass covers to inspect pistons / rings.----If you poured a watery solution into the engine ( bearings ?) the motor should come apart for complete cleaning.----And reed valves have nothing to do with compression in the cylinders either !
Click to expand...
i have the engine completely apart
as i said the engine will not start, has spark, starting fluid in cylinders, no start. that is why i was chasing the low compression.
as a auto mechanic- retired- i have not worked on a engine with reed valves, looking for answers to my no start-
Thank You for your time and help.
 
Does spark jump a gap of 3/8" on a test device, yes or no?---Flywheel key sheared ?-----Wires going to the correct coil / cylinder ?
 
yes, i have a spark tester, good strong spark
i have replaced the trigger, stater, spark box, flywheel key is correct. wires correct at coils. kill switches are good connected and disconnected.
 
With all those $$$ new parts.------With compression in the cylinders.----And with good spark.----And with fuel in the cylinders it should bark like a wild dog.----Sounds like you have a WIRES hooked up wrong issue.------But then again I can not see or touch your simple motor.
 
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