Johnson 55

[kevman]

Hello,

I just aquired a boat with a 55hp Johnson. I was told it had low compression in one cylinder. I know there are many variables but any idea what it would cost to fix this. I also could use help identifying the year of it.

 

[HighTrim]

Re: Johnson 55

I could guess by the cowl, but would only be a guess. Post the model number and we can pinpoint a year for you.

What kind of compression reading are you getting? May not know until you open her up and inspect.

 

[kevman]

Re: Johnson 55

I am not sure but the p.o. told me the compression was half of what it should be. I guess I will have to open it up and check it myself. I will try and get the model number and post it on here. Thanks.

Kevin

 

[HighTrim]

Re: Johnson 55

I would not personally take anyones word.

Get a compression tester and find out for yourself. Let us know what you find

 

[kevman]

Re: Johnson 55

Here is the Model # 55EL76E Serial is E4475190

 

[HighTrim]

Re: Johnson 55

Well thats a 76 then.

I have the same motor in Evinrude dress.

 

[boobie]

Re: Johnson 55

Do the compression test before you do anything else.

 

[kevman]

Re: Johnson 55

Thanks for the help.

 

[kevman]

Re: Johnson 55

Hello again,

I am going to get a compression tester this weekend. I believe the compression should be 150 per each cylinder. Am I correct?

 

[ezmobee]

Re: Johnson 55

It will be more important that the numbers are close to each other than what they actually are. The testers are consistent but not notably accurate.

 

[boobie]

Re: Johnson 55

You can have 3 compression testers and get 3 different readings on the same cylinder. The trick is to check the difference between all the cyls with 1 gauge. I should know, I've got 5 of them.

 

[steelespike]

Re: Johnson 55

If your really lucky a decarb treatment with something like sea foam might solve your problem if its just stuck rings.

 

[1946Zephyr]

Re: Johnson 55

Well, fortunately it's the 55hp twin versus the 55hp tripple. Now those are a fun one to work on. The ignition malfuntions on those will drive you nuts. The twin here is just one of the upgraded 50's from the early 70's and are pretty decent motors. Like steelspike says, do a decarb on it, once you get it running and things may improve on the comression. If the compression stays the same after the decarb and running it, then it's pretty safe to say that you have a little bit of piston scoring and a stuck ring, or possibly a head gasket issue.
How long has it been since it ran?

 

[kevman]

Re: Johnson 55

The P.O. said it ran last year. He said he replaced plugs, wires, and solenoid and they look new. I have an inboard and this is the first outboard I have owned. I am in the process of hooking up all the wiring. Its pretty simple but I am not sure where the battery wiring goes. I think the positive goes to the solenoid and I think the neg just goes to ground. I sure would like to see a picture of one that is connected properly. I am going to try and do the compression test over the weekend but I am wondering what the cost would be if the head had to be pulled and I had to re ring it or replace a head gasket. Thanks for all the help so far.

Kevin

 

[1946Zephyr]

Re: Johnson 55

Well, it may not be all that bad. I would do the decarb and compression test on it and see what happens.