9.9 Johnson may have overheated

[wrmdunker]

My sons first boat and motor. I try to help him as much as I can but he lives with his mother so I dont get many teachable moments with him.

9.9 1977 Johnson long shaft. Last August he tore up the lower unit gears. I bought a 1985 complete LU short shaft. I took my long shaft and shift rod and swapped units. Replaced the water pump with a KIT and pressure tested it. Ran it in a barrel and it pee'd fine and warmed up good. Good fix with lots of input from iBoats.

He took it out another 4 times or so and says "dad, it runs and shifts great". Then he looks at it after an outing and sees this oil.



I tell him not to take it out but he does anyway. Says it is peeing but block is hot. This was last October. Going to look at it for him this week. (We are in Ohio. All iced up....). Here's my plan:

Look for peeling paint
Compression check
Pull the lower unit and inspect the impeller.
He runs shallow water a lot. Try to back flush the water jacket with a hookup to the bottom of the water tube. Flush any sediment.
Pull the water jacket and test the thermostat
punt

Reading here leads me to think he cooked the head gasket and the water and compustion sides are connecting. Is this the reason for the dark fluid at the water discharge?

Any thoughts will be appreciated.

 

[OptsyEagle]

Re: 9.9 Johnson may have overheated

That looks like unburnt gas/oil that drips down from the exhaust. Very normal. It gets worse if it was idled for any long length of time or if some long hours of trolling was done.

I usually like to open the throttle up just before I bring the motor in to blow out all that crud.

It could also be a poorly combusting motor and I suppose a compression test wouldn't hurt and checking the T-stat would be nice (not easy to check on that motor). My motors drip that stuff quite often. Not all the time, but enough for me not to worry about it. Put a pan under it and you have probably done enough.

 

[wrmdunker]

Re: 9.9 Johnson may have overheated

I understand that sometimes there is unburned oil. There was oil dripping about the prop exhaust when we got the motor in 2011. I did a de-carb with Seafoam and that fixed it. Never seen this discharge from the water discharge ports. I have a '74 70hp with a pan under the prop....

The motor is not trolled. He has an electric for that and uses the outboard at full throttle to get from spot to spot. And he said the block was hot so is this a sign of an overheating motor? Any other source for the discharge?

 

[boobie]

Re: 9.9 Johnson may have overheated

Do a compression test first and go from there.

 

[oldboat1]

Re: 9.9 Johnson may have overheated

assume ya got the long water tube in there when you changed to the long shaft (think you said you had some water flow at the powerhead after the switch?) Agree on the compression test first, as above. Seems like your other planned checks are right too (can't discount poss. of damaged impeller from sand and sediment). I'm not sure about the stuff coming out of the intake in the l.u. -- probably unburned fuel, as stated above, but looks like some l.u. oil too -- will check that out when the l.u. is dropped, I'm sure (could be a gasket leaking). Your son gave you some other clues about the overheating thing, maybe? smell or steam? Could be it was just normal temp.

(btw., no question he was burning a 50:1 mix?)

 

[racerone]

Re: 9.9 Johnson may have overheated

The black stuff does not appear to be coming out of an intake.

 

[oldboat1]

Re: 9.9 Johnson may have overheated

yup. excellent catch, R. What's the best guess? just exhaust residue, I guess.

 

[OptsyEagle]

Re: 9.9 Johnson may have overheated

Go ahead and do the checks. They never hurt and sometimes they find something. I doubt it is coming from an overheated motor. As for the unburnt gas/oil, I would assume it would probably burn even better if the motor was at an overheated temperature. If it was a blown gasket, I would think that one or both of the cylinders would die, if water was getting in there. This would have a seriously reduced power effect at wide open throttle, if a cylinder was dead. It would also end with a lot of sludge like you are seeing since that fuel would not be burning at all in the dead cylinder. If he didn't notice a lack of power then I doubt water is getting in the cylinders.

 

[wrmdunker]

Re: 9.9 Johnson may have overheated

OB: I had no trouble with the water tube. I had a long shaft originally so did not disturb that when I replaced the LU. Got a good fit too at the pump outlet w/grease. Yes, 50:1 with Evinrude oil and I gave him a measuring container. Son sometimes doesn't tell me everything so as to save face w/dad. He did mention that it now "smoked" a lot but he was using it in 40 degree air temp. Maybe water vapor condensing?

OE: the pic is the first sign of a problem but did not notice until the next time he went to use it so he was likely going WOT. I taught him enough that he would back off if he felt a problem but who knows.

I read elsewhere to see if the plugs look like they have been "steam cleaned".

Thanks all.

 

[wrmdunker]

Re: 9.9 Johnson may have overheated

It is the water out ports. The intakes are below the cavitation plate and cannot be seen here.

 

[nwcove]

Re: 9.9 Johnson may have overheated

jmo, but it looks like unburnt fuel oil mix to me. maybe to much oil, maybe t-stat stuck open, maybe the drain holes were partially plugged and cleared themselves, dumping the mess. as mentioned, compression test, and spark test. ( a $20 ir thermometer is a good tool for many other purposes than just outboards!

 

[rolmops]

Re: 9.9 Johnson may have overheated

When you idle these 9.9 engines for a while,the unburned oil will stay in the exhaust housing which is partly filled with water when it is in the water. The oil floats on top of the water in the exhaust housing and looks just plain nasty when you take the engine out of the water and that oil start leaking out.Extra rich mixtures will also do that.

 

[oldboat1]

Re: 9.9 Johnson may have overheated

Yeah, thinking about it a little more -- be nice if you could fire it up in a barrel before tearing into it. Maybe check compression, plugs, lower unit oil, t.stat, visual condition of head -- then wait until the weather breaks, and test run it. Like rolmops says, and like other comments, it's probably just exhaust nasties on the anti-ventilation plate. And it's not really clear yet whether there were running problems....maybe was just a cold day in October. Be nice if you could test it out first hand, unless you run into something obvious when you check it out this week.

could probably get a great thread going on what kids report on cars and boats -- but need to stay in their good graces, if you are like me, to keep the computer running.

 

[wrmdunker]

Re: 9.9 Johnson may have overheated

Ok here is where I am at. Compression at 90 & 95 which is where it was 2 years ago when we got it. Block paint is fresh and no signs of excessive heat. Good news. No water in the LU. Changed the gear oil.

Put it in a barrel and started fine. Idleing and then in gear for 15 minutes. Barrel water temp at 53. Pee temp at 75. Don’t have a good way to get readings on the block but could hold a finger near the flywheel at t/block for one minute plus. Warm but NEVER uncomfortable.Same on the side of the block. However, finger on the water cover aka cylinder head cover (8 bolt rear plate that the plug wires run in front of) for only 4 seconds. Lastly, just a warm feeling on the exhaust housing.





Temps seemed odd to me. Shouldn’t the powerhead be all about the same temp after 15 minutes? Ran approx 2000 rpm. Stat may not have opened. IMO this was enough run time.

Pulled the cylinder head COVER to access the stat. Little crud on the brass, not much. Looks original to me. Bolts also look like they were never touched in 37 years…….Going to replace the stat.

What to use to remove gasket pieces? Heat? Solvent? Razor blade. Any sealer (NAPA, Permatex, etc,) to use on re-install? Heard somewhere else that the gaskets are pre-coated with sealant….?

Lastly, the oil leaks at the water discharge ports still seems odd. Pic from the manual shows a seal at the LU. Perhaps the extension leg also had seals. Sorry, I don’t recall when I swaped the LUs last year. I know oil discharge can happen. Just can’t understand why it shows like in my first pic.



Thanks all.

 

[wrmdunker]

Re: 9.9 Johnson may have overheated

Well maybe I'm overkilling this item. 225 views and no new opinions.

Got the gasket off with sm wood chisel, putty knife, razor blade. No gouges. Not much pressure here since its the water side. Going to close it up and run it again.

 

[OptsyEagle]

Re: 9.9 Johnson may have overheated

It appears to be a well running motor to me.

 

[FDNY247]

I have this same issue... have one question, does your prop have the converging ring on it or is it broken off? I just purchased a new one and hope it solves this issue... I was told what your are seeing is normal exhaust fluids that would be pulled out the center of the prop as the boat moves forward. A lot of older engines have broken converging rings which pull these fluids out the prop. I purchased a new one but won't know until next year if the problem is solved. Worth a try... cheap fix I hope~!

 

[GA_Boater]

I have this same issue... have one question, does your prop have the converging ring on it or is it broken off? I just purchased a new one and hope it solves this issue... I was told what your are seeing is normal exhaust fluids that would be pulled out the center of the prop as the boat moves forward. A lot of older engines have broken converging rings which pull these fluids out the prop. I purchased a new one but won't know until next year if the problem is solved. Worth a try... cheap fix I hope~!

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