Powerhead ID

[RickK]

How do I tell for sure what size johnson powerhead I have on my 170?  Decals say 115 but I've been told by someone who worked on it that it was a 90.
It is a rebuild I bought and it is a 60 degree engine and we figure that it is a 96 or later. I see no serial number plate on the bracket.  I do see a number stamped in the freeze plug on the starboard side of the engine. G4242955

[akbridge]

Pictures please.  We will figure it out.  Why not put a nice etec on there?

[RickK]

What should I put pics up of?
I want to rebuild this one (has 137 hours since last one - which I didn't do) and that way I know what I have and it'll outlast me.

[seabob4]

Rick,
You may want to contact seahorse over on THT (PM him).  Dude knows everything about OMCs...

[RickK]

Thanks Bob  

[saltfly]

Rick if you can find out yourself, go to ishopmarine.com then pick on parts list then Johnson. Then pick on the year then 115hp, then pick any of the model numbers. You will see a difference in part numbers between the 90’s and the 115’s. Try and find any part numbers you can find on your motor. Then match you part numbers with their parts list. The serial number on your fre. plug, really doesn’t do you any good. You need the model number to know your hp. Or if you know some one with a dyneo, or if you take one of the carbs. off and measure the jets. A 90 uses #26, 115 uses #25. You can use a #26 and #25 drill size to do the measurements. But I do wonder why some one would remove the Model and serial number plate.

[fitz73222]

Some of these engines within a certain "family" are virtually identical with the only exception being jet size as mentioned and port size.  The intake and exhaust ports on a 90 will be smaller than a 115 and that's really the only difference. Since most blocks in the last 15 years are cast without removable transfer port covers you can go in through the exhaust cover plate and measure the exhaust port diameter. Of course then you need to find out what the stock port sizes were which maybe interesting to research. I doubt there is a piston bore change between the 90 and 115 but look at the stock piston diameters and see if there is any difference.  I've never been able to make heads or tails of the number stamped on the welch plug and I always figured it was something internal to OMC for identification but you never know; sometimes one letter or number change differentiates what the engine is. A good OMC guru may know or have access to data that could help.

[RickK]

Thanks guys.  I'm going to take another look and see if I missed the plate somewhere - only place I didn't look is in the front under the hydraulic steering cylinder.

[seabob4]

Thanks guys.  I'm going to take another look and see if I missed the plate somewhere - only place I didn't look is in the front under the hydraulic steering cylinder.

No Rick, not under the cylinder.  Should be on the starboard side of the engine mounting bracket/plate.  If it's not there, or on the port side...it just ain't there!

[saltfly]

Rick Bob is right, OMC only put those plates on the mounting bracket.

[RickK]

It ain't there then.  :cry:
Wonder how the mechanic could tell it was a 90 then    I was hoping I might be able to call or email OMC and ask about that number on the plug.
Bob, I PM'd seahorse over on THT.

[saltfly]

Rick the number on the freeze plug, on OMC’s was always the serial number. They always had the serial number in two places. So you could always tell if the block  had been changed, or if the motor was stolen and the bracket plate removed.   How he is saying its a 90 on a 60 degree V, has got me. It can’t be seen in the serial number. Now on 90 degree V, that’s a different story. Some of the later 90 Degree V’s 115’s  used the pot bellied water-jacket and the 90’s use the flat, between the heads. But not the 60 degree motors. So your guess is as good as mine.

[RickK]

So hopefully OMC will be able to tell from that # then  

[saltfly]

Johnson is still making parts. So they may have kept the paper work on all of their motors. You can try and contact them and see if they have a cross reference.

[seabob4]

So hopefully OMC will be able to tell from that # then  

BRP now, my friend...and seahorse knows his doo-doo ca-ca...