1988 Johnson 140

[jgbutler1956]

I just bought a Mako with a Johnson 140 thrown in. I can crank, but doesn't run great. Compression is 80,90,75,90. (top left, bottom left, top right, bottom right) I increased numbers from putting Yamaha ring free in gas. (was lower on all four) Runs for a little while with pee hole running water out, but engine gets hot. (can't touch for 2 long) Was supposed to have been re-built.. I can see someone took of heads and put gaskets and sealant back on. I run it for a little while then shut it off.. I have looked at the plugs and they are still wet with black wet substance. (is this the carbon?)
Do I
1. Replace the impeller
2. Take off head and inspect pistons. Replace gaskets with or without sealant?
3. Get another motor?
I am new to outboards, but am a fast learner. Would appreciate info on where to get the parts and the part numbers.
I have a manual ordered, but not here yet.
Thanks
Beware the lollipop of mediocracy, one lick and you will suck for life

 

[Dhadley]

Re: 1988 Johnson 140

Welcome!!

The first thing I do with any new-to-me motor is clean the carbs, do a decarb job and replace the water pump. After the carbs are clean and the decarb is done, if the compression on the one low one doesn't come up, you may want to pull the head to see what's going on.

 

[jgbutler1956]

Re: 1988 Johnson 140

Thanks, I'll do that. Any ideas about where to get Johnson parts..?

 

[ezeke]

Re: 1988 Johnson 140

All the parts should be available from your local OMC/BRP dealers. To find them, go to the following link and enter the third choice on the pick list and your zip:

http://dealerlocator.evinrude.com/EN/?Rnd=1186089116984

So that we are all on your page, could you check the port transom bracket for your model number? If the plate is gone, look on the powerhead for a quarter-sized convex welch plug with numbers on it.

Edit: I stand corrected.

 

[jgbutler1956]

Re: 1988 Johnson 140

Actually mediocrity might be ok too .... but mediocracy is the government or rule by mediocre person or group.... webster
Just thought it was a funny saying..... huh?

 

[jgbutler1956]

Re: 1988 Johnson 140

Pulled the heads and all pistons were black ... some completely... cleaned up with carb cleaner and ordered gaskets and impeller. Will clean surfaces and check heads to be sure they are not warped and put back together. Will plan on cleaning all carburators and see what I can get as far as compression
Thanks for your help

 

[Dhadley]

Re: 1988 Johnson 140

Change the complete pump, not just the impeller. And make sure to use Champion plugs only.