Logo

Johnson 88 SPL ID by Freeze Plug Number

Based on your pictures and the guessing that I do , it can only be a 1996 / 97 / 98 model.------Was this thing submerged ?----One thing for sure is the roller in that curved slot needs attention.----Plus a few more things I am sure.
 
Last edited:
Would 96/97/98 have interchangeable parts, it is on a 1996 Crest Pontoon boat but the previous owner was unsure if it was original to the boat. Hasn't been submerged that I know of, I recently purchased it. It runs reliably but is down on power both electrically and horsepower. Voltage sits at 12.6 (external volt meter) and top speed on the 25' pontoon is about 8 mph. Trying to get all the bugs worked out, any suggestions highly appreciated!
 
The trouble shooting on these motors always , always starts with a compression test.---Post your numbers.-----Then test for spark that jumps a gap of at least 3/8" or more.----Post the results of that testing !----Those years I believe are identical for all parts.
 
I did a compression test Bottom Left 101, Top Left 110, Bottom Right 105, Top Right 88. Not great I know... I also cleaned the screen on the fuel pump filter and put some seafoam in the gas tank. Went for a ride afterwards and the boat was intermittently coming to life. The RPM would jump to about 5500 and i would have a lot more power, I got up to 18 mph in very rough water and dirty pontoons. As I drove the lack of power became less and less intermittent. If i lost it I could trim the motor down and "bump" it at its limit and the power would return. Very weird, like a loose connection or something. Thoughts?
 
Well ---A new head hasket can be found for $20 on this site.----Do yourself a huge favour and inspect the piston / cylinder with 88 PSI.-----Hopefully a blown head gasket is the only issue.
 
How involved of a job is that? I'm fairly handy and generally handle my own automotive maintenance but I have never had a cylinder head off before. Will I need more than just the head gasket assuming everything else looks good once the head is off?
 
I think 10 bolts and the cylinder head is off.---Easy on a fresh water motor.----So easy I think I could coach the 10 year old grandson to do the job.
 
You will look for scored cylinder wall.----Perhaps evidence of broken bits of piston rings hammering the top of the piston and the cylinder head.-----Or lucky you if it is a blown head gasket.----Posting of pictures helps here.----Compare one piston to the other one you will see.
 
I pulled the head. The cylinder with low compression looks brand new. The other cylinder is nasty and there are gouges on the head.. check the pics out and help!
 
The picture to me is abundantly clear that this motor needs to be rebuilt NOW.------There is no other fix.----Broken piston rings.----Every one of these motors will suffer the same fate !!!
 
Back
Top