1979 Mercury 80 HP Hard to Crank

[79calglass]

I was cruising fine when suddenly my motor began to struggle as if there was resistance internally. Then it died. I tried to restart it and the flywheel had a lot of resistance and it struggled to turn over, as though the battery was low or the starter was weak. Charged up the battery and let it sit for a few days. It fired up but it was very weak when it turned over as though the battery was low. It ran and I took it for a spin on the river. After a few minutes of cruising it made a ticking noise and choked and died. I've tried spinning the flywheel by hand and there is a lot of resistance. I've removed plugs and it spins easier but still to much resistance to fire up. Any ideas what the problem could be?

I had issues with the starter, it wouldn't engage at times, wd 40 solved the problem. I don't think my starter or battery is weak. I believe the flywheel is sticky for some reason. What would cause this?

Thanks, any help would be appreciated.

 

[Jake.]

Re: 1979 Mercury 80 HP Hard to Crank

Do a compression test and post your results. Ticking noise/shutdown may indicate that you cooked a cylinder.

 

[79calglass]

Re: 1979 Mercury 80 HP Hard to Crank

OK, it had good compression in 2 cylinders, but I did not check all 4. I will check and respond tonight.

 

[79calglass]

Re: 1979 Mercury 80 HP Hard to Crank

I checked all four cylinders, and they all have good compression.

I read somewhere about a week ago that it could of been starved of oil and injecting oil through the plugs would lube it up. So I did this a week ago and let it sit.

After checking the compression today I noticed the flywheel was spinning freely. So I tried to start it up.

After a few turns it fired up, I turned off the choke and throttled it up but it lacked any power. I didn't check the rpms but it sounded like it was around 1000. There was a scratchy noise and it idled down and died. I didn't try it again.

When I purchased this motor it has an external fuel pump with regulator on it, the pump was on and the pressure was fine. I think it is getting fuel.

Any further suggestions?

 

[gwukena]

Re: 1979 Mercury 80 HP Hard to Crank

If you're mixing your fuel properly it should never be starved of oil.

 

[79calglass]

Re: 1979 Mercury 80 HP Hard to Crank

I've been mixing the fuel fine at 50:1 or richer.

 

[79calglass]

Re: 1979 Mercury 80 HP Hard to Crank

The crankshaft spins freely now but makes a tinging, scratchy god awful noise when running. The motor sounds nice, it's firing and wants to run but is being held back by some resistance it seams, from internally. I attempted to throttle through it and it accelerated nicely but the resistance killed it.

My thoughts are that the engine has crap or something in it which is causing it to jam up inside.

Any thoughts?

 

[ufm82]

Re: 1979 Mercury 80 HP Hard to Crank

Yea, it has crap in it like a bad rod bearing or crank bearing. Continuing to run it will only further destroy it.

 

[Jake.]

Re: 1979 Mercury 80 HP Hard to Crank

If you're mixing your fuel properly it should never be starved of oil.

Not necessarily. If he has an engine with more than one carb and one of those carbs is gummed up then those cylinders will run lean. Hence the compression check.

 

[CharlieB]

Re: 1979 Mercury 80 HP Hard to Crank

Remove the spark plugs, somehow measure how much force it takes to turn the motor, at torque wrench may work. Write down that #

Remove the lower unit, again measure how much force it takes to turn the motor.

Hopefully you will find a measurable difference. It is possible that you have a problem in the lower, isolating the motor and lower can help determine where your problem is.

You may start the motor without the lower by rigging a garden hose to the water transfer tube to cool the motor. Then you can check for the 'noise' again, if still present you may have to disassemble the motor.