Compression Readings on a 8hp

[pscrabber59]

I just bought a early 90's Tohatsu 8hp for $25. After getting it home the first thing I did was do a compression test and the readings were pretty low(30psi, 35psi). Does this mean that the motor's powerhead is shot? I unscrewed both plugs and screwed in the tester and pulled hard about 3-4 times and did it two different times. I don't want to re-build the motor because I lack the knowledge&skill to do it.
Thanks for any advice

 

[Sea Rider]

Re: Compression Readings on a 8hp

Warm engine before testing compression, should have 57 PSI, if just 35 way low.

Happy Boating

 

[TOHATSU GURU]

Re: Compression Readings on a 8hp

Chances are you have a low end gauge that is not accurate so the numbers are off. What you look for is that the numbers are relatively even between the cylinders. I would try a different gauge before worrying too much.

 

[JB]

Re: Compression Readings on a 8hp

Does that engine have a head gasket? Sounds like a blown head gasket between cylinders.

 

[Sea Rider]

Re: Compression Readings on a 8hp

Does that engine have a head gasket? Sounds like a blown head gasket between cylinders.

I'm with you JB. Most boaters don't take into acccount that and oldie most of the time needs a new head gasket along a piston decarb to perform excellent, they prefer to beat the bush wasting time checking other things.... Head gaskets are not eternal, it's a important part to have into consideration to achieve perfect internal combustion & engine punch.

Happy Boating

 

[pscrabber59]

Re: Compression Readings on a 8hp

thanks for the replies guys