Johnson 18 HP engines

[cbourbeau32]

I'm going this next weekend (weather permitting) to look and hopefully purchase one of two engines I've found on CL. My question is this: what compression pressure range should I be looking for on the upper and lower cylinders on the engines. One is a 1966 and one is a 1958.

Thank you, Charlie

 

[bonz_d]

Re: Johnson 18 HP engines

Most importantly you want to see an even ready between the 2. Rope start engines will usually be lower than an electric start model. Rope start, 50-70 psi is not uncommon because they are not turned over as fast as one with a starter..

If a rope start I would give it 3 or 4 good pulls and then repeat it a few times and take an average of all the readings.

 

[kfa4303]

Re: Johnson 18 HP engines

Hi c. Those are both great motors your going to look at. I have a '66 myself. I just fired her up yesterday for the first time all winter, third pull and she was purring like a kitten 1966 was the first year Johnson made the 18hp into 20hp. However, the two motors are still virtually identical, although I especially love the paint job on the '58 models. Assuming the compression is good on both motors, (+90psi with the cylnders reading within 10% of each other), all the rest can be fixed with ease. You can get any routine pats you may need right here at iboats for about $20 each. Here are some handy links.

Maintaining Johnson E & FD Serie
http://www.*****************/parts/...ntage-evinrude-johnson/381415/38141500001.htm
http://www.*****************/parts/johnson-evinrude-parts.php?year=1958&hp=18&model=FDE-12

 

[nwcove]

Re: Johnson 18 HP engines

Most importantly you want to see an even ready between the 2. Rope start engines will usually be lower than an electric start model. Rope start, 50-70 psi is not uncommon because they are not turned over as fast as one with a starter..

If a rope start I would give it 3 or 4 good pulls and then repeat it a few times and take an average of all the readings.

50-70 psi is way to low for for either of those motors. look for numbers above 90, and preferrably over 100 psi and within 10% of each other. when testing.....pull it like ya hate it !

 

[HighTrim]

Re: Johnson 18 HP engines

Yeah 50 to 70!? yikes WAY too low for an 18hp.

My low hours, 18hp motors in my collection are pushing 140 to 145psi. Those are low hours motors though. I also have many in the 100 to 125psi range that all run well and idle down good. The 18s should all easily be over 100psi, on a known good gauge. I have never seen one over 145 psi.

The 10hp QDs are in the 90 to 125 psi range for a good non worn powerhead.

 

[bonz_d]

Re: Johnson 18 HP engines

My mistake, just looked back at an old thread for the 18hp I had. Best I could get for numbers on it was 85 lbs on both cylinders. At first it was only 70+ until I was able to run it a few time. But even at 85 lbs this engine ran very strong and was able to push a 14' Lund s14 that weighed 300 lbs dry and was able to plane it with 2 people in it. Yes the gauge I was using may have been off some but not 20lbs worth.

 

[cbourbeau32]

Re: Johnson 18 HP engines

I should have mentioned in my original post a little about each engine and asked for opinions on which one to buy so I'll do it now.

I can get the 1966 (running last summer) for $200 it's electric start but has a cracked steering bracket which I think I can remove and repair fairly easily.

I can get the 1958 for $275 (gone completely through by mechanic (including carb rebuild) 4 years ago and then stored). It's a pull start.

Which one in the opinion of the folks here would be the better deal? Assuming of course that both have good compression.

Thanks, Charlie

 

[nwcove]

Re: Johnson 18 HP engines

if it were me, and electric start was not needed, the 1958 would be the hands down winner if it was in equal condition with the 1966. but thats just me....the 58 is much more pleasing to the eye!!!

 

[HighTrim]

Re: Johnson 18 HP engines

I agree. I don't even give the 60s OMCS a sideways glance. Not even close cosmetically to the 1958 model. Buy the 58, put a new water pump in it and new gear oil and enjoy the water.

 

[cbourbeau32]

Re: Johnson 18 HP engines

@ Chris, it's just cosmetic though and not quality correct?

Thanks, Charlie

 

[HighTrim]

Re: Johnson 18 HP engines

@ Chris, it's just cosmetic though and not quality correct?

Thanks, Charlie

Yes, the cosmetic appeal is just not there for me, no offense to the guys that like the 60s vintage, just my 2 cents. Same rugged, dependable motor. The 18s are pound for pound, best motor period!

 

[cbourbeau32]

Re: Johnson 18 HP engines

Thanks Chris, I do like the looks of the 50's model way better. I saw a picture of one on here the other day that had been restored and it looked incredible.

Charlie

 

[kfa4303]

Re: Johnson 18 HP engines

Yeah, can't beat that reverse two-tone of the '58. I have one of the old, ugly, white "wedding cake" 60s models. Runs great all the same. Plus, it matches my ugly white boat The '58 would be too pretty on my old beater.

 

[cbourbeau32]

Re: Johnson 18 HP engines

KFA, your thought process is about like mine. I'm putting this motor on a boat that a friend gave me that has been sitting in his pasture for 20+ years so she ain't too pretty but they should make a good match.

Thanks, Charlie

 

[kfa4303]

Re: Johnson 18 HP engines

yeah, I kinda like the "understated" (aka I'm too lazy to paint my boat and motor) look I keep saying I'm going to give everything a nice coat of paint one day, but I never seem to get around to it :/ Besides, I'm sure I'd scrape it all up on an oyster bar on the first trip out. As long as she gets me there and back again, I'm happy. I actually fired the ole' girl up yesterday for the first time in months and she started right up on the third pull It's supposed to be almost 80F down here (FL) this weekend, so I might actually be able to hit the water!

 

[tjandrews]

Re: Johnson 18 HP engines

The "understated" look isn't so bad... This is my '56 15HP on my old 14FT boat. The boat is painted light blue because it used to be Mom's and that's the color she wanted it to be. But if you ask me, what's left of the OEM paint job looks halfway decent next to the light blue of the hull. Plus, I don't have more than $200 in the whole outfit!

 

[cbourbeau32]

Re: Johnson 18 HP engines

Nice looking fishing rig TJ. Thanks

 

[kfa4303]

Re: Johnson 18 HP engines

Sweet little rig. I actually like the way paint ages on an old tin boat. They seem to get better looking with age like blue jeans, whereas the glassers are nice and shiny for a year, or two then hit the wall hard. Plus, you can always bring a tinny back to life with a good $100 rattle can paint job, not wacky chemicals, grinders, or respirators required.

 

[cbourbeau32]

Re: Johnson 18 HP engines

Well I'm going next Saturday to look at (and buy if the compression is good) the 1966 model. I'm pretty excited to get it home and get it ready for some late winter/early spring fishing. I appreciate all the advice on this great site.

Thanks again, Charlie

 

[kfa4303]

Re: Johnson 18 HP engines

I like my little '66 20hp. She runs great and pushes me along at about 20mph with a light load.