dead cylinder?

[Ilikesalmon]

I have a 1962 Johnson 5.5 hp outboard. The motor runs rough, smokes alot, doesn't want to idle. The top cylinder spark plug is very sooty, the bottom cylinder spark plug is very clean. I have replaced the coils and the points appear to be ok. I did a spark test and the spark appears good on both plugs. I have re-built the carb and the problem still remains. I have not done a compression test (no tester) but the motor "seems" to run on both cylinders. Any suggestions would be greatly appreciated.:%

 

[funpilot]

Re: dead cylinder?

Very Clean? Like shiny new metal clean?

If it is, you are steam cleaning that plug due to a cylinder head leak allowing water into that cylinder. Probably a blown gasket. Get a new head gasket and see if that takes care of the problem. Follow the manual for torquing instructions and torque in stages.

fp

 

[Paul Moir]

Re: dead cylinder?


Compression testers are very inexpensive and should turn up a head gasket problem. Just make sure you get the type that screws in, not the type that pushes in. Even putting your thumb over the spark plug hole and turning will give you some indication.

Have you replaced the impeller? If so, how did the bottom crankshaft gasket look? Is the fuel pump connected to the top cylinder or the bottom?

 

[VADER8674]

Re: dead cylinder?

you can borrow a compresion tester from auto zon on there loan a tool program

 

[Ilikesalmon]

Re: dead cylinder?

Yes, the lower spark plug is very clean and shiny. I did replace the impeller, but did not check the lower crankcase gasket. The fuel pump is connected to the top cylinder (I believe). I bought a compression test gauge, brought it home , tried to screw it in to the spark plug hole, wrong size!! I bought an automotive tester!! So, you guys have to know, you are not talking to a rocket scientist here!:'(

 

[Paul Moir]

Re: dead cylinder?

Have a look at that compression tester and see if there's an adaptor screwed on to the end of it. Most often compression testers will fit two sized plugs which are used on autos - 14mm and 18mm. Your outboard is 14mm. I've never seen an 18mm only compression tester.

The bottom crankcase gasket ought to have been sitting right on the driveshaft. You have to take it off to get the lower unit off. Is it possible it's missing? You can just see it here in the background sitting on the driveshaft:

 

[Ilikesalmon]

Re: dead cylinder?

Thanks Paul, I'll check my compression tester tonite when I get home. You know, my motor didn't have a crankcase gasket like the photo shows! The last owner (one of many I'm afraid) probably didn't put it back on. I'll look into getting another one and also a new head gasket.d