[Dawgs]

1986 johnson 150

well heres another chapter in the worst boating season i have ever had. i finally got the motor running but it wont idle properly and it sounds like its missing. it idles real rough then stalls. i pull the plugs and plu # 3 & 5 are milky. # 6 is too but not as bad as the other two.

any ideas? blown head gasket?

This post has been edited by Dawgs: Jul 30 2010, 11:10 AM

[Dawgs]

oh and theres water spitting out of the center hole of the thermostat cover. dont know if that has anything to do with it

oh and the water out of the tell tale is still pissing strong

This post has been edited by Dawgs: Jul 30 2010, 03:50 PM

[2-N-TOW]

Water should not be coming out of the thermostat cover. Trying to remember...is there a rubber grommet that plugs that hole?

All plugs from the same cylinder head had the milky look? That could indicate water, but I thought your cylinder compression was good?

[Dawgs]

2 from the port side and 1 from starboard (slightly) compression was ok. is it possible with the power pack wires crossed it blew the gasket? i will have to do another comp test.

as far as the water from the therm. i remember the gromet. maybe it tore? ill have to check. i dont have an overheating problem and water pissed pretty hard

[2-N-TOW]

Power packs would have no effect...only an overheat condition. The other possiblilty...has the engine been run since you corrected the carb linkage issue? Run it one time and let it come up to operating temp so the thermostats open. May be a case of excess fuel in the crankcase and some moisture in the fuel. Once it is at the proper temps, we can get a better idea of what is going on instead of relying on a few minutes running on the hose.

[Dawgs]

i ran it in the water yesterday. therms opened fine. temp didnt overheat im gonna do a comp test tomorrow. whats the correct way to do one? take all plugs out or just the one testing? wot?

This post has been edited by Dawgs: Jul 31 2010, 09:02 AM

[519]

Take all the plugs out, no throttle.

[Dawgs]

519 im not doubting you but why do i get so many variations when i do a search? wot...no throttle...all plug in....no plugs in

[ReelPlumber]

519 im not doubting you but why do i get so many variations when i do a search? wot...no throttle...all plug in....no plugs in

If you watch this little video it appears it does not matter if wot or not because the actual compression that you are measuring is beyond the intake and exhaust ports. It will make the engine easier to turn over with all the plugs out but it should not make a difference in the reading on the cylinder you are testing.

http://www.youtube.com/watch?v=LuCUmQ9FxMU

What you are measuring is the compression between the exhaust port and the plug (top of the stroke)

I'm no mechanic but I did stay at a holiday inn express last night. (IMG:style_emoticons/default/laugh.gif)

[mr.g]

When checking the compression on a motor I was selling it started (IMG:style_emoticons/default/wtf.gif) . Silly me the fuel line was still attached. (IMG:style_emoticons/default/ohmy.gif)

[Dawgs]

so correct me if im wrong....at wot there will be more fuel in the cylinder so the compression would be higher?

[519]

I suppose the fuel might provide some seal on the piston rings.
But when you reassemble you'll have a motor full of gas, and a smokey start.

[Dawgs]

ok i went by the seloc manual and took all the plugs out and did a compression test at wot.

i got 73 lbs on all cylinders

now do i have water in the 2 cylinders from seepage somewhere? is it getting in through a gasket?

with even pressure on all cylinders can we rule out head gasket?

[2-N-TOW]

That is too low. Pressure should be in the 90 to 110 range. Only way for water to get into the cylinders is through the head gasket area. Remove the head off the side where 2 cylinders have water in them. Please post pictures of the spark plugs, cylinder head once removed so I can see the combustion area and the gasket. Be sure to label each plug to indicate which cylinder it came out of.

[Dawgs]

dan so what can be the problem with the compression? theyre all the same but low

[2-N-TOW]

Hopefully, it is a compression gauge reading incorrectly. It is odd that they are all in the same range; but I have seen different gauges read differently on the same cylinder.

One other thing you can try before removing the heads, even though I think the damage is already done to the head gaskets. Re-torque the head bolts back to factory specs. It is possible that the bolts had stretched over time and are no longer pulling the head down properly, allowing for some water to leak into the cylinders.

[Dawgs]

i guess thats possible ...ill try to re torque them then do another test then put it in the water and see what happens

[Dawgs]

well the starboard head is off. gasket looks pretty good except for a dark mark on about 2 inches of the metal ring on the gasket. doesnt look blown though. but it is in the place that would put water in the suspect cylinders

cylinders look good and smooth

port head is giving me a little bit of trouble. bolt head broke off and is still in the head. when i rotate the head back and forth the bolt turns so im guessing its corroded inside the head hole itself which is no problem i dont think. ill just drill it out until the head comes free then unscrew the remaining stud......yeah ok it may be that easy

[2-N-TOW]

Once you get that head off and there is still enough of the bolt to grab onto, spray it with PB Blaster. That stuff seems to penetrate better than anything else I have used to free up frozen bolts, studs, and nuts. Let it soak overnight and try moving it again with a slow, quarter turn out / quarter turn in motion. If it still does not move much, shoot some more PB on it and tap with a hammer, then let it sit for another hour and try again.

[Dawgs]

long story short. head gaskets looked a little worn...NO WAY are the bolts for the exhaust cover coming out without breaking.

ill change the head gaskets and see what happens

[2-N-TOW]

Don't mess with the exhaust cover...that thing is a bear to get off due to corrosion. Your problem is going to be more than likely from the head gaskets.

[519]

Damn that corrosion.
And bad shorts.

[Dawgs]

ill have the head gaskets friday and start to reassemble then. ill keep you posted

thanks

[Dawgs]

well so far so good. motor runs well on ears no water in the cylinders lets see how it goes when its in water.

funny thing happened twice today. motor wouldnt shut off when i turned the key off. it sounded like it had less power when the key was off but when i put it back on it sounded like it got more power. i had to pull the wires to shut it off. ill start a new thread