Compression on 1979 Johnson 175

[blackhawkdc]

Hey guys, I'm looking at buying a boat with a 1979 Johnson 175 horse V6 outboard on it. He had a shop look at it and was told that it had 130psi compression in 5 cylinders and #1 cylinder had 105psi. What is the spec for this motor? Thanks!

Seth Petro

 

[R.Johnson]

Re: Compression on 1979 Johnson 175

You don't want more than 10-15 lbs. I would want a look at that low cylinder.

 

[Jayboid]

Re: Compression on 1979 Johnson 175

I agree. If you haven't bought this motor yet, you should probably look elsewhere.

 

[blackhawkdc]

Re: Compression on 1979 Johnson 175

thanks, I offered the guy $375 for the motor, trashed boat, and a trailer that needs work. Expect I'd have to rebuild the engine, but that's no problem for me. I'm an auto mechanic by trade and have built several motors in the past.
See if he bites on my offer or if he cusses me out.

Thanks again,

Seth Petro

 

[tashasdaddy]

Re: Compression on 1979 Johnson 175

i would try a decarb before tearing it down. could just be carboned up rings sticking.

 

[Jayboid]

Re: Compression on 1979 Johnson 175

I agree. If you haven't bought this motor yet, you should probably look elsewhere.

Oh, for $375 and you're a mechanic.....I've changed my mind. Go for it.

 

[jonesg]

Re: Compression on 1979 Johnson 175

Trashed 175's around Boston sell for $600+.

If he goes for $375 offer him $900 for his house.

 

[blackhawkdc]

Re: Compression on 1979 Johnson 175

yeah, I'd be willing to offer him more for the motor, except for the fact that I'd have a big chunk of fiberglass (the boat) that I would end up having to demo and dispose of. Probably take me a pretty good day to get through a 19 foot deck boat.

 

[emdsapmgr]

Re: Compression on 1979 Johnson 175

A stock 175 with the stock 456/457 heads should be around 108-110 lbs compression. If someone had added the 235 heads, that could bump it up another 10 lbs or so. Were you there when the compression testing was done? If not, I'd ask to witness a retest.