1973 18 hp Evinrude starts out running great, but slips out of gear

[scuba_redneck]

Hey guys, I have a 1973 18 hp Evinrude outboard that starts out running great but after running at WOT for about 10 minutes in forward, stopping, shifting from forward to neutral, then back to forward it refuses to run at WOT. I can get it to run at midrange but can never get it above that. It feels like the gears are slipping but it puzzles me as to why. When it went into the water it had new oil in the lower unit, but when we got it back out it was milky white. I know I am going to have to replace the seals in it, but was wanting to address the slippage while the foot was off. Would the water intrusion into the foot cause the oil to not provide enough lubrication making the gears slip or is this problem going to be with the clutch dog or shift lever? If anyone has any experience/ pictures of a worn clutch dog vs a new clutch dog that would be very helpful. This is my first outboard to work on and I want to do it right the first time and not have to break it down any more than absolutely necessary.

 

[Will Bark]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Could only be a slipping prop hub; mark the prop hub and the prop with a straight line then run boat and see if the two lines are still together, if not then the hub is slipping and you would need to go to prop shop to get rehubbed. If lines are still toghether then you need to look at possibly a cylinder that's quit firing. Good luck.

 

[1946Zephyr]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

it could also be worn clutch dog and/or shift linkage that is loose or out of adjustment.

 

[steelespike]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

If it thumps like you hit something it's probably the clutch dog.
If it simply revs losing speed it is a spun hub in the prop.Draw a water proof line all the way across the underside of prop
do a test run and check the line.

 

[scuba_redneck]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

It feels like I am hitting something when I try to open the throttle from idle after running. So from what y'all are saying it is not than likely the clutch dog. Does anyone have a picture comparison between a worn clutch dog and a good one? Also does the repair manual have any specifications for adjustment on the shift rod?

 

[steelespike]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

If it sounds like you hit something it is the clutch dog.The very few motors I've done it was nearly impossible to tell the difference.
I believe there may be an adjustment at the shift lever so that the lever is in the neutral detent when the gearcase is in neutral.
There are 2 detent balls in the gearcase that help maintain position these are somewtimes lost in the course of events during repairs. A repair manual is a must if your working on your motor. Reprint factory manuals are available here or on the internet.
After market manuals are fair, factory are best.

 

[scuba_redneck]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Ok, so im 'this' close to getting to the clutch dog, but the skeg is frozen to the lower unit. Anyone have any tips for how to get it off? I have the 6 screws out and it refuses to budge. Ideas?

 

[AlTn]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

soft faced hammer or 2/4 smack it side to side, front to back..if you gain a gap use wooden wedges to free it

 

[scuba_redneck]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Thanks a ton AITn! I am going out right now to try it out to see if it will come free.

 

[kbait]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

DON"T forget to unscrew the phillips headed shift yoke pivot screw from the skeg before hammering away!

 

[1946Zephyr]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Hahahaha the one time someone says to remove the phillips screw. After all the times we say not to.

While you have that motor all apart now, make sure there is absolutely NO slop in the upper portion of the shift rod. Through the obround access hole, take ahold of the shift rod with your long nose pliers and check for any up and down slop. There should be none at all. If there is, you'll need to pull the powerhead and check the connections at the shifter bellcrank. Three issues work hand in hand, when your motor pops out of gear and all need to be addressed, when you fix it. Out of adjustments on shift linkage, loose shift linkage and worn clutch dogs all work hand in hand and cause each other problems.

 

[scuba_redneck]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Thanks zephyr, that helps alot! Just out of curiosity, do I need to apply the 3M 847 to the seals or are the seals enough to seal the lower unit up?

 

[1946Zephyr]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Yes, you'll definately want to use the 847 sealer. Also apply a light coat around the screw holes as well. If you ever seen an oxymoron, then the splitcase gear halves are one of them. Why did they design it, to where the screws are on the inside of the spagetti seal and not on the outside? DOHH!!

 

[scuba_redneck]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Well fellers, I'm back. I have the lower unit torn down and most of the seals replaced. The shift linkage on the upper side is tight. I grabbed it with the needle nose pliers through the oblong access port on the starboard side of the exhaust housing. As soon as I worked the shift lever on the powerhead, I could feel the pliers moving in my hand. As far as the connection goes before I dropped the LU, it was caked with at least 1/8 inch of carbon all the way around the shift rod and had to be coaxed off. The carbon had completely engulfed the linkage and made the screws and the shift rod difficult to remove. But at any rate I was able to disassemble it with a couple gentle taps of a 2x4. Hopefully I will be able to finish it up this afternoon.

 

[1946Zephyr]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Good deal. That will save you other repairs. When you get it back together then, make sure and check your shifter adjustment and see that each gear disengages at the same equal distance from the neutral postion. While you have apart too, make sure there is minimal slop in the shift cradle, where it sits in the clutch dog.

 

[scuba_redneck]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

Zeph, you seem to be very knowledgeable when it comes to these older outboards, do you have any tips or tricks to checking the points on the ole rude? I have very little experience when it comes to working on any outboard motors.

 

[kfa4303]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

HI scuba_redneck. Here are some great links for working on these old motors including one that can walk you through an entire ignition rebuild, lower unit reseal, carb rebuild, parts catalog and more. Best of all, once you can work on one of these old OMCs (mid 50s-early70s) you can work on just about all of them as they are more or less just larger and smaller versions of each other.



http://www.duckworksmagazine.com/07/columns/max/index1.htm

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm


http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1971&hp=18&model=18102S

 

[AlTn]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

check out the recent addition to The Top Secret Files...Universal Magneto Troubleshooting as well...to pull the flywheel requires 1/4 " x 20 bolts and washers <Grade 8 or they may break>...I've had success with a harmonic balancer puller...do not try a 3 jawed puller as you can damage the flywheel doing so
hmmm..1973?..does this use that exciter coil set up?....yeaaah it does....forget the universal magneto advice....flywheel pulling still holds....are you currently getting a spark to each cylinder?

 

[kfa4303]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

I'm not sure of the ignition on that one. It's right on the borderline, I think. You should be able to get a flywheel puller from most autoparts stores for about $15. Ditto on the GRADE 8 bolts too.

 

[scuba_redneck]

Re: 1973 18 hp Evinrude starts out running great, but slips out of gear

I am currently getting a spark on both cylinders, however the engine is not running at full power and it idles very roughly. Compression tests read 120 psi for the top cylinder and 125 for the bottom cylinder. After running it at WOT for about 10 minutes then re-trailering the boat, I pulled the plugs and the bottom one was fouled out quite nicely. I replaced the old J6C plugs with new ones, changed out the primary fuel hose from the tank to the quick disconnect, rebuilt, cleaned, and adjusted the carburetor,and the issue still exists. The fuel is fresh and air delivery seems fine, so the only thing I can figure is something is screwy in the ignition system. I want to pull the flywheel off and inspect the points for possible corrosion or anything else that may cause any of the problems that I am experiencing.

When the engine is idling, is coughs and sneezes after idling nicely for about 15-30 seconds. The slow speed adjustment needle is 1.75 rotations out. I have tried it in positions from 3 rotations out all the way down to 1 rotation out.

Also when easing away from the boat ramp, I noticed a bit of a hesitation and a series of misses when transitioning from low rpms to a midrange rpm. The misses continue sporadically at WOT but are corrected when I squeeze the fuel bulb several times in rapid succession. For its age, would a fuel pump rebuild/ replacement be a good idea?

When we made the purchase, we got a 14' starcraft v-hull with two motors, a 1960 10 hp evinrude and the 1973 18 hp evinrude. The previous owner told us that the 18 used to plane the boat out but hasn't in a long time. Right now we are trying to get the 18 in good running order and the 10 is on the back burner.

I have tried to upload pictures of the 18 for review purposes, but the forum is not accepting them at this time. I will post as soon as I can.