1967 80hp Super Sea Horse - Demon outboard

[JLumbert]

I am new to boating and we bought a 84 Bayliner with a 67 Johnson. Issue is that it will run fine in a no wake zone all day and no overheating issues at all, then the moment after boating through the channel to get to the lake, it dies once i slowly go to WOT under load. It then wont start again and I have the embarrassment of getting towed in to the dock.
Ive spent hours looking for a solution. I tested the spark - good ! New ignition coil / wires. Tested the Fuel - no water and only use rec. fuel (non ethanol). Sea-Foamed the motor - check.
After I get it towed home, it wont start for a day or so. I sprayed some fuel down the carb and it'll start up after a few times doing that. It will run in a tank/barrel just fine. I can go WOT with no load (only do it once or twice). But once i get in the lake or channel under load, it dies under WOT with a load and cant be restarted with fuel down the carb or anything.

I will say that the 2 times it didn't die, it felt slightly under-powered and had difficulty getting up in the RPM's or on plane (got it on plane one time). I would say that it wouldn't go over 2500-3000 RPM under load also
I am extremely lost. Anyone have any ideas what can be an issue?

 

[racerone]

Open low speed mixture needles 1/8th turn at a time and test run..-----You have good spark on all 4 leads ?---Compression test results are ?----High speed jets are both clean ?

 

[F_R]

Check the distributor rotor for pin-hole through to shaft (spark arcing through to shaft).

 

[Chris1956]

I had the same exact same issue with my '59 V4. F_R has it exactly right. The rotor had a small crack which when the motor heated up, opened a bit and the spark shorted out.


I never saw the crack, but replaced the rotor and the problem vanished.

 

[JLumbert]

racerone - carb has been rebuilt in the last month (ive rebuilt many carbs before) all 4 checked out good, but the motor wasnt warmed up, would that make a difference? Ill get a compression tester this evening after work and check it out.
F_R and Chris, i will check into a distributor if the compression comes back good.

Thanks for the quick reply all, i appreciate it.

 

[JLumbert]

Chris and F_R - here is a picture of the bottom side of the rotor. Is that pinhole supposed to be there? That doesn't look like a factory drilled hole as the edges are not cleanly finished by any means. Ill get compression check still this evening.

 

[F_R]

I guess I wasn't clear. Look at the top of the rotor. See the heavy metal strap that carries the spark from the center to the tab on the end? Now turn the rotor upside down. See the flat-sided hole that slides down over the shaft? Now look down into the bottom of that flat-sided hole. Now use some imagination and you can realize the bottom of that flat-sided hole is mighty close to the metal strap on the top side, only separated by a thin layer of plastic. And therein lies the problem. The spark is attracted from the strap to the shaft lurking in the bottom of the hole. Sometimes, the attraction is great enough for the spark to arc right through that thin layer of plastic and ground out to the shaft. When it does, it burns an almost microscopic pin hole through the plastic, which then becomes a path for subsequent sparks. Once arced through, the rotor is junk.

As I said, pin hole, almost too tiny to see. We used our coil tester to tease the rotor to see if it arcs through.

Don't know if yours is bad or not, just a knowledgeable guess.

Good luck.

 

[oldboat1]

With the photo blown up, the hole in the side of the rotor looks pretty serious. I would replace the rotor.

 

[JLumbert]

Hey guys, sorry the the delay - work was crazy

It ran the other day, then now it wont start to get warm compression readings..
Compression readings - cylinder 1 - 80psi... cylinder 2 - 75psi... cylinder 3 - 80psi... cylinder 4 - 75psi
coil readings - .02 ohms from batt to - terminal
coil reading - 9.12 ohm from plug wire terminal to - terminal
spark testing - cylinder 1 - no spark... cylinder 2 - nice blue spark... cylinder 3 - nice blue spark... cylinder 4 - nice blue spark

I am not sure if the compression is good, ill have to research that a little more. IF the compression is ok, I plan on rebuilding the carb again, check low speed needles, check high speed jets, rebuild fuel pump, clean out the new fuel lines / new filters, new distributor parts (cap, rotor, points, condenser), and plug wires with new plugs.

What do you all think? missing spark on 1 wire?
If its simple as replacing a few parts I am good doing so,but id rather not sink 2k into rebuilding the powerhead if the compression is low as I can upgrade to a newer outboard that doesn't have issues for 4-5k.

Thank again all !

 

[racerone]

Those distributor caps are not cheap.-----Therefor not an automatic replacement item.

 

[JLumbert]

Called a trusted machine shop around here that specializes in 2 stroke outboards and Harleys. He said the compression was low and to check the rings out as they might be gunked up or may have thinned out. I sent him pictures of the cylinder walls and he said that they looked good still.
He said he can take my money, but not needed unless I want to have him take a look at the pistons and the power-head (hundred or so bucks)

Looks like a re-ring is in order. Still need to get electrical stuff and fuel pump kit ordered.
Racerone, distributer cap is $200... ugh ! $70 for a rotor...

 

[racerone]

Yes I know what the parts cost !!----Have new and used caps / rings etc on hand here.----Remove bypass covers to inspect pistons and rings.----Perhaps test with another compression tester.-----Don't spend any coins until you know what condition the motor is in !-----Your location ?

 

[TN-25]

----Your location ?

Grand Haven, MI.

 

[JLumbert]

Yes I know what the parts cost !!----Have new and used caps / rings etc on hand here.----Remove bypass covers to inspect pistons and rings.----Perhaps test with another compression tester.-----Don't spend any coins until you know what condition the motor is in !-----Your location ?

Grand Haven, MI

I found all the items in need online from marineengine.com and also Laingsoutboards.com
I pulled the heads and all off and the cylinders look nice without any gouges or funky hatched patterns. I will know more once i pull the powerhead off.

You all have been great and the wife and I have decided to keep the motor and rebuild it, 1st boat and sort of attached to this until we decide on bigger and better.

 

[oldboat1]

Try Vans Sports Center on Alpine Ave. in Grand Rapids. Good folks, old established business.

 

[JLumbert]

I got the motor finally pulled 100% apart. I am not excited on what I found. Piston rings were stuck on all pistons except #3.
Piston #1 and #3 were in great condition, Piston #2 and #4 were not, see pictures... Roller bearings were good as were the connecting rods. No signs of excessive heat or wear (surprising for a 53 yr old outboard) The exhaust was all gunked up with chucks on carbon deposit (from seafoaming it?)
I am bringing the powerhead in to a 2-stroke and outboard shop so they can look at the cylinder walls (they looked good in my opinion when comparing to motors ive worked on before) and tell if a re-ring is best bet or full on machine work.
FYI - grooves on the two pistons were easily caught on the fingernails.

 

[racerone]

You need to replace those pistons.-----Need to replace rings too.-----New prices will shock you.----Good used parts available in my area.