1963 40HP Johnson Compression

[doomanmxz99]

Hey guys going to do a compression check on the above motor and was wondering what I should be looking for as far as numbers go???? Crank dry or turn on gas and go that way??? Thanks for the info guys.

 

[tashasdaddy]

Re: 1963 40HP Johnson Compression

remove the plugs, you can do a dry crank, turn the motor over till the guage quits rising, you are hoping for at least 100psi, but more important that they are within 10% of each other. guages are different and read differently. post your finding here afterward.

 

[doomanmxz99]

Re: 1963 40HP Johnson Compression

I got 68 in the upper cyl and 75 in the lower and that was a dry crank. It has not been run in just about 3 years. Not 100 so what should I look for to get this up to par. I looked down the holes and I cant see any scoring or anything bad????

 

[tashasdaddy]

Re: 1963 40HP Johnson Compression

tilt the motor has high as you can. or lay it on the floor with the plug hole up. put some marvel mystery oil in each cylinder, and leave it a couple of days. then drain the oil, turn it over a very times to blow out excess oil, and then recheck. hopefully it will free up the rings.

 

[doomanmxz99]

Re: 1963 40HP Johnson Compression

Ok I will do that and post back here in a couple days to let you know if anything has changed. Thanks

 

[doomanmxz99]

Re: 1963 40HP Johnson Compression

I have been putting in some Sea Foam and Marvel but shortly after I put it in it runs out the bottom. I know not all is running out but should it coming out????

 

[Chris1956]

Re: 1963 40HP Johnson Compression

If the exhaust port is open the oil will run out. You can turn the flywheel a bit to close it.

 

[doomanmxz99]

Re: 1963 40HP Johnson Compression

I will give that a shot. Now another question the upper cyl piston is all black on top but the bottom one looks pretty clean can I take some carb cleaner and get all the junk out??? Also was reading in another post about some cover to remove to look at the cyl?? Not sure which cover??? Thanks

 

[Chris1956]

Re: 1963 40HP Johnson Compression

There should be a smaller transfer cover on one side of the block, on that crossflow motor. The larger cover is the exhaust cover. Remove the transfer cover and you can see the rings.

BTW - the clean cylinder could have a water leak, which is why it is clean.

 

[doomanmxz99]

Re: 1963 40HP Johnson Compression

I dont think it had a water leak because when I pulled the plug on the other hole the gap was 0 mashed to electrode so not firing to well on that one so I am sure that is why its dirty than the other hole does that make sense to you? Thanks for the info about the covers.

 

[doomanmxz99]

Re: 1963 40HP Johnson Compression

Pulled the covers and I need rings. Does anybody know where I can get them or have an OMC number for them and the head gasket??? The pistons look good and so does the hole but when I do this should I run a hone in the cyl just to clean it up??? Thanks