1993 3cyl 60hp Johnson designe defect?

[edbrown]

I own '93 Johnson 3 cyl. 60hp engine. Experienced noticible lose of power climbing up on top<br />of the water. Once on plane, rpm and top end speed satisfactory. Took engine to dealer to <br />check for power loss on hole shot. Dealer said power loss result of loss of compression, loss of <br />compression due to scored cyl wall. Dealer said this vintage of 3 cyl Johnson (50 - 60 - 70 hp)<br />notorious for needing rebuilding because of scored cyl wall. I looked at cyl wall, ... didn't see <br />much, but did notice some minute verticle lines on one side of cyl wall. Dealer said scored cyl <br />wall caused by designe flaw in water cooling circulation between #1 & #2 cyl. Can this be right? <br />If so should I rebuild or get rid of it? Engine has preformed well, have I just been lucky? Dealer <br />estimates $2000 to $2400 worth of work needed. I ran it last weekend, ... same problem but <br />usable. Am I on borrowed time with this engine? Ed

 

[ob]

Re: 1993 3cyl 60hp Johnson designe defect?

edbrown,First thing you need to do is perform a compression test on all three cylinders.This will take the guess work out of a scored cylinder wall as a possible culprit in your performance issue.Look for numbers around 120 psi or so but most importantly that all three are within 10%.If compression looks good I would look for idle mix being too lean or restriction in low speed circuit.Also the carb link and synch needs to be set properly.Do the compression test and we can go from there.Don't let the same mechanic that gave you the rebuild estimate perform the test.He may be seeing dollar signs.

 

[Dhadley]

Re: 1993 3cyl 60hp Johnson designe defect?

Welcome!<br /><br />To be a design flaw a great majority of that design have to fail in exactly the same fashion. They have to be set up correctly and have no outside influnces that caused the failure. <br /><br />Some motors have a certian reaction to things like lugging, wrong spark plugs, stale fuel, clogged jets, poor water pressure etc.<br /><br />Tell us more about your set up -- top rpm with average load, water pressure, spark plug brand and number, what octane fuel, how fresh, what oil etc.<br /><br />Thats a very good designed motor. There are things to do to help it live a long life. There were some service updates. Did you do them?

 

[edbrown]

Re: 1993 3cyl 60hp Johnson designe defect?

The dealer told me that he should have a nickle for every 3 cyl engine of that size and ventage <br />he has had to rebuild. He told me that some mechanic (somewhere) learned how to correct the problem by drilling three holes in the engine in a specific spot to allow better water circulation. He said the problem is precipitated by the fact that the lack of cooling water caused by the design causes a "hot spot" between cyl 1 and 2 which leads to the cyl scoring and loss of compression. My spark plugs are those recommended by the book on the engine. I don't have that with me at the moment but will look when I get home tonight. I have probably missed the "service updates" in that I have had virtually trouble free fishing with that engine. I have been religious about servicing/winterizing/etc. I burn 87 octane most of the time, but have used 93. I have seen no diference in preformance (87/93 octane). I have used nothing but factory recommended oil in the fuel. If I am in the boat by myself on a calm lake I can top out at about 5200 - 5300 rpm and GPS says I am going about 36 - 37 mph. Same as when it was new. The boat is alum/dbl console/wood floor/fish tanks, etc probably weighs in about 1600 lbs with the motor. What sort of service updates? Where can I read about them?

 

[ob]

Re: 1993 3cyl 60hp Johnson designe defect?

Your engine should be propped to turn between 5800 -6000 at WOT with a light load.I think you have been overpropped from get go.Also insure that the engine is mounted at an optimal height on transom as to reduce engine load and exhaust back pressure.(X demension)<br /><br />Your engine may also be in the year era of a TSB on the waterpump,t/stat,and overboard tell/tale restrictor.The old pump design was updated from a three flute impeller to a six flute impeller,the spring load on the T/stat assy was changed,and the tell/tale restrictor was removed and just the hose from the powerhead is used with grommet provided in upgrade kit.<br /><br />Has the engine always had low speed throttle -up issues?<br /><br />I am not aware of any water jacket design issues.

 

[Dhadley]

Re: 1993 3cyl 60hp Johnson designe defect?

Your dealer will have them all. Mr Clanton has them in real good order here. Do a search on this subject and you will see where he has listed them before. <br /><br />Dont run the 93 octane, its not needed and can add to combustion heat. At that rpm you are lugging the motor which will coke up the rings pretty quickly. Especially with 93 octane. If you are running something other than Champion plugs that may contribute to its demise also.<br /><br />There are some cooling holes that are pretty small and we have opened them up a tad if the motor was run in grassy waters or around shallow muddy water. <br /><br />There are some carb jetting changes that we have found that really help in certian cases. Right now I'd suggest that you determine if you are going to rebuild the motor and if so, I would get the rpms up to where the motor is running "happier" throughout the entire rpm range.<br /><br />Good luck!

 

[rodbolt]

Re: 1993 3cyl 60hp Johnson designe defect?

hello <br /> I am with all the rest. the 3 cyl omc is a workhorse that rarely failed. if you want to know how bad the scrathes are the do a leak down test. it is more accurate than compression and can pinpoint minor flaws.<br />I have never heard of any flaws with the cooling system other than some bullitens moving the tattle tale pick up and the waterpump/restrictor upgrade on the pump.<br /> good luck and keep us posted

 

[clanton]

Re: 1993 3cyl 60hp Johnson designe defect?

DH how did I get to be Mr.Clanton, hey you will be fine. If I come to Port Charlotte, how can I find you?

 

[Dhadley]

Re: 1993 3cyl 60hp Johnson designe defect?

Let me know when youre coming and we'll meet up for lunch. dhadley50@aol.com

 

[Mark R Groves]

Re: 1993 3cyl 60hp Johnson designe defect?

I don't mean to deviate too far from the original posting. However, the mention of the 3 blade impeller concerns me as I have one on my '89 Evinrude 40hp. Is this pump design truly problematic? Mine seems to pump quite effectively. Should I be looking into changing/upgrading it?

 

[ob]

Re: 1993 3cyl 60hp Johnson designe defect?

McG,Contact your local John/Rude dealer and see if the waterpump change affects your particular engine.My 96' 70 Rude seemed to pump well also before the change affected it from the three to six flute pump.The six flute changes the pumps capacity which is why T/stat and waterpump indicator(tell tale) are part of the change.In my case without changing the spring load of the T/stat relief and revising the overboard indicator would result in backpressuring the cooling system which could have led to premature head gasket failure.