1975 Johnson 85hp Compression Check???????

[springer9861]

Hi All,<br /> I went and looked at a used 16 boat tonight and I also took a compression check on the motor. The motor is a 1975 Johnson 85hp, it had #110 on all four cyclinders. Is this good for this old of a motor? The guy selling the boat said that the motor had been rebuilt in 1995 because his friend tried to adj. the carbs and that burnt a hole in one of the pistons. The rest of the boat looked good, it's a 92 yar-craft and he wants $3000.00 for it.... Thanks for any and all info!!!!!!!!!!!!! Larry

 

[Fouled Plug]

Re: 1975 Johnson 85hp Compression Check???????

Can't really say on the boat, but the compression on the motor isn't too shabby. I would try decarbing it if you decide to buy and see if you don't get a few more #'s of pressure. How was the lower unit oil? Did you get a test drive of the boat yet?

 

[springer9861]

Re: 1975 Johnson 85hp Compression Check???????

Fouled Plug,<br /> I didn't check the lower unit oil. What do I need to look for? The guy selling the boat said we could take it out anytime I wanted to. Thanks for the reply...... Larry

 

[Fouled Plug]

Re: 1975 Johnson 85hp Compression Check???????

Look for metal shavings, water in lube. New lube is sometimes added just before sale to mask seal probs or other nasties. A test run should last a while and cover all ranges of RPM's and several stop/start cycles. Check the lube again after the run.