barn find 2005 Nissan 18hp Fourstroke (NSF18B2).......need advise on what to do

Hey guys,

I recently purchased a 2005 Nissan 18hp fourstroke from a lady who said that her grandfather passed away and she was clearing out . The barn was full of odds and ends and I stumbled across the outboard. It had a couple things that immediately made me question it, but for the $250 I paid for it, I thought I would take the risk. The engine was laid on the side with the cowling was removed and the spark plugs were missing. I pulled on the starter cord and held my finger over the plug holes and it seemed to move freely and make at least some compression. I was on the way home from work when I ran across the barn sell, so I threw the engine in the trunk of my car and drove home. I got home and pulled the cord (freely) a couple more times and now it seems locked up. I have pulled it at least 10-15 times freely before it locked up. I plan on tinkering with it over the next couple days, so I am curious what you guys recommend that I should do to complete testing to see if it is worth my time and money to get it going. I plan to start with the obvious compression test, but what else would you do to give her the once over. Thanks in advance!

First see if you can free it up. Might use some marvel mystery oil in the plug holes. Odds are, since it turned freely before, the starter lock is probably jammed. Once free, you may want a new water pump kit -- not just the impeller, and you may need to clean the carb. Also change oil and LU lube. The 18B2 is cool as there is no choke. It has electrically-operated enrichment when starting.

pvanv said:

First see if you can free it up. Might use some marvel mystery oil in the plug holes. Odds are, since it turned freely before, the starter lock is probably jammed. Once free, you may want a new water pump kit -- not just the impeller, and you may need to clean the carb. Also change oil and LU lube. The 18B2 is cool as there is no choke. It has electrically-operated enrichment when starting.

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Thanks Paul!
I am planning on tinkering with it this evening to see what the deal is. I think I have gotten it freed up, but it might have an issue with compression. I say this because I left penetrating oil In the cylinder over night (laying on its side with the cylinder down) and in the top cylinder the oil quickly left (by the rings presumably). I am hoping that maybe it’s juat a seating issue, but that’s just hopeful thinking. It was probably left laying in the barn with out the spark plugs installed for a reason. Do you know where I can acquire the correct service tech manual? I can’t seem to find one online. Thanks again for your help!!

I have a reprint of the now-out-of-print Factory service manual for $35 plus postage.

pvanv said:

I have a reprint of the now-out-of-print Factory service manual for $35 plus postage.

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How would I need to send you payment?

Also, in your opinion, If I do find more significant issues that would warrant a rebuild......Would it be worth it? Are these motors known for problems or are they typically reliable?

Update after the day of tinkering.
GREAT NEWS!!! after the night of soaking the cylinder was free. I then moved on to the compression tests. It checked out at 92 psi in both cylinders! I think that this is acceptable due to the decompression feature these motors utilize to help with pull starting. This compelled me to move forward and go buy new oil and spark plugs. I arrived home with the new supplies and noticed that the electronic fuel shut off devise on the top of the carb was broken and no longer seated on in top. (I will end up replacing it) but for now it’s ziptied in place. I drained and filled the oil and installed the plugs. It started with ease! It even idled well!! I couldn’t run it but just a moment because the water pump isn’t moving enough water to make it pee, but it ran! I did notice while it was running a “tapping” noise coming from the mid section (near where the oil drain plug is located) but hopefully it’s just because it hasn’t been ran in a LONG time and will quite down after it runs for a bit.

The 18B2 is a special motor. The same as a 9.9/15, but with larger carb and higher lift cam. A good runner. As always, run the carb dry or drain it if sitting for more than a few days.

pvanv said:

The 18B2 is a special motor. The same as a 9.9/15, but with larger carb and higher lift cam. A good runner. As always, run the carb dry or drain it if sitting for more than a few days.

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Thanks for all the advice Paul!
Im still interested in the manual if you don’t mind. I am going to have to put a new water pump, and I have never done this on a Nissan. I’m sure it’s similar to a Johnson/Evinrude I have done in the past, but i always consult the manual!

WP kit is about $39 MSRP.