Is overhaul worth it?

[colslick]

I have a 74 Johnson 50hp,ran good up till two yrs ago,been in garage since,wasn't preserved. Will turn over but won't start.Have no experience overhauling but want to try. Is this a mistake or turn it over to a pro or forget it? Any opinions would be appreciated!

 

[JACK-NJ]

Re: Is overhaul worth it?

What happens to old outboards that causes them to be difficult to start: <br />1. The fuel pump (diaphragm) works off of crankcase pressure. When the motor is allowed to sit the crankcase seals become brittle and leak and crankcase pressure is lost. Hose down your engine with some dishsoap and water and look for pressure escaping form the upper and lower seals as you crank. Also look around the crankcase seals etc. Fix as needed and you probably will have solved the problem. (This assumes you have decent primary compression and spark)<br />2. The piston rings get gunked up with carbon to the point where compression falls to a level where starting becomes difficult without some creative carb tuning. (which will eventually make matters worse) Use an OmC or Seafoam type cleaner for de-gunking your motor and hope for the best. <br />Good luck -Jack

 

[JB]

Re: Is overhaul worth it?

Hi, colslik. I think that is the 2 cyl. looper. That engine was 20 years ahead of the industry, so it is worth making it run. If it was running well when stored, it probably doesn't need a full overhaul. Jack is right about fuel pumps and seals shrinking. Carb gaskets also dry out, but I don't think seals and carb gaskets would prevent it from starting. Lack of fuel would, stuck rings would, and lack of spark would. <br />Quickie fuel pump test.<br />Disconnect one fuel line from the pump at a carb. Stick it in a bottle or can and spin her over. If it pumps fuel into the bottle or can the pump is working. Put the line back on. Do this outdoors with no flame or spark nearby.<br /><br />Quickie compression test.<br />Pull both spark plugs. If you have no compression guage, stick a finger in to block the hole. Spin it over. If it blows your finger out, you have compression. If you have a guage, you should get at least 100lb of compression and the two cylinders should be within 15 lb of one another. Finally, check that the spark plugs are slightly wet after trying to start it. If they are dry, you are not getting fuel from the carb(s).<br /><br />Quickie spark test.<br />Pull one spark plug. reconnect it to the plug wire. Put on a pair of her nib's rubber dishwashing gloves and hold the base of the plug against the block while turning her over. Repeated sparks should be visible.<br /><br />If it fails any of the above tests you know where the trouble lies. A fuel pump kit is an easy, do-it-yourself project. If you don't have compression, squirt about 1 tsp of oil into the bad cylinder(s) and try it again. If compression improves but stays weak, you have stuck rings. If that CD ignition has failed you will need more specific instructions . . .I have the Clymer book on that engine and can guide you through troubleshooting the ignition, or if you are not inclined, take it to a pro. If both carbs are failing (fuel pump okay, plugs not wet), same thing. If it passes all tests and still refuses to pop I was wrong about leaky seals. Take it to a pro.<br /><br />Hope this helps. Happy boating.

<br />JB

 

[colslick]

Re: Is overhaul worth it?

Thanks for the great advice,this is better than what I normally pay $60 an hour for. You have inspired me and my son to take on the project, we love the finger compression test! Personal for JB, I went through Army flight school a few miles west of Cool in the late 60's. Spent many a wonderful evening fishing and camping on the Brazos, first time I flew over Possum Kingdom I thought it was the Pacific Ocean. Truly Gods'<br />country Regards, Bob Davis

 

[JB]

Re: Is overhaul worth it?

Thanks for your comments about God's country, Bob. I forgot one important item not related to getting your motor running: replace the impeller in your water pump. This is a routine, preventive maintenance item that should be done every two or three years even in regular use. After sitting up for several years the rubber gets brittle. Get the dealer where you get the inexpensive kit to explain, and show you, how to do it.<br /><br />Ft. Wolters doesn't look much like it did in 1970, but the Brazos is still a great fishing hole. So is PK; it is now one of the premier striper lakes in Texas.<br /><br />Good Luck. <br />JB