9r72 low compression bottom cyl

[crosbyman]

I have a decent looking 9.5 with the top cyl at 60 psi (normal enough it seems for turtles)

the bottom cyl reads 35 psi 🙁

the engine was purchased seized for 60$ but released fairly easy with some deep creep and firm nudging. the cyl walls are fine

looks like I need to peak at the rings to see it they are simply stuck or a lost cause

should I ..

a- proceed with removing the exhaust cover for a look/see (seems to be a pain to access all the cover bolts…any suggestions ??)
b- keep pistons soaked during winter months, with deep creep hoping the deep-creep will work itself down to the rings and loosen them up
c- wait for Spring time fire up the motor and run some Seafoam, Power Tune etc…. and retest compression #’s

I know the 9.5 are problematic with exhaust fumes issues/seals etc… but I had good success reviving several 9.5 incl my own $50 seized kicker
so hopefully this latest "winter project" will cruise some lakes again.

thanks

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[Mumbles]

Since the motor was seized, there might be rust on the cylinders and rings. This rust must be removed as it can cause severe wear to the pistons and cylinder walls when the motor is started. You might consider doing a complete teardown.

[crosbyman]

that my good man may be above my skill level but you are correct …… the bottom cyl did have a small rust stain

as mentionned on the other NUT case … post

i’ll crack open the lower housing to reach the exhaust cover and take a peek

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[fleetwin]

Yeah, I would take some fine emery to those cylinder walls and give it the 50cent hone job….
Would it be easier to pull the intake bypass cover? I realize the darn carb is mounted to it, but this might be a little easier than wrestling with the exhaust cover….I am assuming this is a fresh water engine…
I would center the pistons, then try to make the cylinders as vertical as possible, then fill the cylinders with engine tuner/sea foam/whatever, and let it soak for a few days.. But, do this only if you plan to get the engine running within a few days of the soaking….This stuff is not a lubricant.
I hear what you are saying, probably not worth the time and effort of rebuilding….I’m betting it will be just fine after this treatment and the compression will come up again on the bottom cylinder….
The only other possible issue is if there is some sort of internal water leak that caused the seizure to begin with….I am not that familiar with the 9.5s, but seem to remember they were prone to internal exhaust cover water leaks when used in salt water….

[crosbyman]

Fleetwin,
excellent option to open the inlet side behind the carb versus the exhaust side …… silly me never thought about it 😳

I’ll try this easier route .. I was going to clean up the carb anyway

so far I have only used deep creep and pb blaster on this fresh water engine.

to bad engines don’t have "oiling ports" in line with the crankshaft bearing … one could open them up by unscrewing a simple bolt and spray the innards with oil 💡

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[lloyd]

Heat up the block using HOT water from your sink and keep turning it over with lube in the cylinders. This allows the rings to expand in the bores and potentially free themselves. Has worked for me numerous times in the past and requires no disassembly. Takes a LOT of hot water slowly poured over the block to heat it up, but costs nothing and easy to do.

[crosbyman]

Loyd, thanks also for the suggestion. I’ll keep this in mind as I progress into this winter project

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