Johnson 5.5hp water in cylinder

[tbone303]

This motor had been working perfect for almost 2 years, this summer when I took it out it would not idle for trolling. I know when the lower unit was redone that the main power head gasket had not been changed, noticed some oil slowly seaping from this gasket. I am thinking the powerhead gasket is the problem causing water in the cylinder resulting in poor idling, I can't even adjust the low speed needle for the motor to run smooth either. PSI was 75 in the top and bottom was 70PSI when cold, after running the motor for 10 minutes the psi on the top cylinder stayed the same but lower one was 62 PSI. Any thoughts?

 

[Watermann]

Re: Johnson 5.5hp water in cylinder

If the head gasket was leaking bad enough to allow water in the cylinder then there should be some sign of it. When you pulled the spark plugs did they both look the same or was one clean or have a rusty electrode? Sometimes the gasket isn't leaking inward at a water jacket, only outward. I would replace it if your seeing signs the gasket is leaking, no sense in waiting for it to get worse.

Was it last years fuel you were burning? It could just be that the carb needs cleaned, rebuilt and some new hoses. A year is a long time to just sit around, especially for a 58 year old motor.

 

[tbone303]

Re: Johnson 5.5hp water in cylinder

If the head gasket was leaking bad enough to allow water in the cylinder then there should be some sign of it. When you pulled the spark plugs did they both look the same or was one clean or have a rusty electrode? Sometimes the gasket isn't leaking inward at a water jacket, only outward. I would replace it if your seeing signs the gasket is leaking, no sense in waiting for it to get worse.

Was it last years fuel you were burning? It could just be that the carb needs cleaned, rebuilt and some new hoses. A year is a long time to just sit around, especially for a 58 year old motor.

They are new plugs both plugs looked different the top looked like a regular spark plug brown with color and a bit of oil on it, the bottom plug was very clean and looked like water with oil, that milky look. No rust on the plugs. Would it be the gasket allowing water into the cylinder, could it be something else, but my thinking is the main gasket.?

 

[nwcove]

Re: Johnson 5.5hp water in cylinder

sure sounds like a leaky head gasket ( not base gasket), but do a spark test to confirm that the bottom plug is firing with a strong spark.
if you do get a head gasket make sure to lap the head, and follow the proper torque specs and sequence.

 

[Watermann]

Re: Johnson 5.5hp water in cylinder

A steam cleaned plug with milk on it, yeah don't be running her any more until you replace that head gasket. If you can't get to the head gasket job for a while, pull the plugs out and fog the cylinders with lots of oil and roll her over some. That water will start surface rust almost immediately.

 

[tbone303]

Re: Johnson 5.5hp water in cylinder

Do you mean cylinder head gasket 303438? I have a spare. I lapped the head 2 years ago but will check again. I had spark in both plugs when I check a couple day ago, will check again to be 100% sure. Where do I find the spec for torquing the gasket on?

 

[Watermann]

Re: Johnson 5.5hp water in cylinder

http://forums.iboats.com/johnson-ev...cylinder-head-bolts-johnson-5-5-hp-85122.html

and

http://www.marineengine.com/boat-fo...1955-johnson-sea-horse-5-5-hp-cd-12-out-board

 

[nwcove]

Re: Johnson 5.5hp water in cylinder

...and only torque to 40 INCH LBS on the first pass around the bolts, then repeat the pattern to 80 INCH LBS. Then after a few runs on the motor, re-check the bolts.

 

[tbone303]

Re: Johnson 5.5hp water in cylinder

Thanks a lot. I don't have a torque wrench though, am I able to tighten them by hand with a wrench? in the order in the link

 

[nwcove]

Re: Johnson 5.5hp water in cylinder

Thanks a lot. I don't have a torque wrench though, am I able to tighten them by hand with a wrench? in the order in the link

i would not recommend going that route with crucial specs like a head gasket. you can usually borrow one ...with refundable deposit, from most uap napa outlets or other auto parts outlets.

 

[tbone303]

Re: Johnson 5.5hp water in cylinder

Thanks I am going to have to borrow one as they seem pricey.

 

[tbone303]

Re: Johnson 5.5hp water in cylinder

Good news. Started her up with the new head gasket on torqued to specs, and she purrs like a kitten again. Idles right down. No water in the cylinder either the gasket was my problem all along. The compression in both cylinders after running it for 10 minutes increased. Top was 79PSI, and bottom which was 62PSI is now 80PSI. I still have to change that lower main powerhead gasket but atleast I can now use my motor and go fishing again. Thanks all for the help.

 

[nwcove]

Re: Johnson 5.5hp water in cylinder

thats great news tbone!! look after that little motor and it will look after you.