1981 evinrude 115hp no power. Please help

[Lukef]

Engine starts and idles fine on muffs. Starts and idles fine on water but no power. As soon as I try to plane she just dies. I have done a compression test and it resulted in 120,120,120,135. Why is the compression high on one cylinder? The cylinder with high compression also has milky looking substance on plug when I pulled it. All others look fine. I have rebuilt the carbs, new ignition coils, new plug leads and plugs, new gas. I think the problem lies in that high compression cylinder. Logic tells me if its a head gasket the compression should be lower. But the milky substance tells me otherwise. Anyone have this happen. Or have some friendly advise. I'm stuck.

Thanks in advance

 

[racerone]

They all sound fine on a hose and they will running on 3 of 4 cylinders !----Do this simple check for spark.---See if you get spark on all 4 leads that jumps a gap of 7/16" Yes or no ?----Were the high speed jets removed from the carburetor bowls for cleaning ?-----Remove the 4 wee bypass covers on the side of the block and inspect pistons and rings.---Covers are held on with 6 screws.

 

[Lukef]

Spark and fuel are good. I think its a bad head gasket. port side top cylinder has milky sludge on spark plug. I think its fouling the plug and only firing on 3 cylinders. will replace head gasket and report back. Still don't understand why the cylinder in question has better compression than the other 3. 120,120,120,135?

 

[175se]

Possibly the case of water intrusion, because of head gasket, liquid will not compress therefore higher compression in that cyl..

 

[Bosunsmate]

Check the exhaust plate bolts, if any come loose(or that gasket fails) water will shoot into the nearby cylinder

 

[Lukef]

Like this?

 

[Lukef]

Another

 

[emdsapmgr]

The engine can also ingest water into the combustion chamber from the exhaust chest. If the manifolds are loose (not torqued properly) or they have a hole (even casting porosity) water can get forced into the combustion chamber. When this does occur, it's most likely on the lower cylinder(s). That's a serious problem. The water absolutely can put out the fire, even build up enough to lock up the piston-including bending a rod. So, check the head gasket first. It is the easiest to replace. If the seal ring is damaged, replace it. Hopefully this will take care of the problem. If not, pull the exhaust manifolds off and have a look.

 

[Lukef]

I am replacing the head gasket in the morning. hopefully it solves the problem. the oil around the exhaust cover makes me wonder though. I have witnessed the cover dripping water while the engine is running. i have not checked to see if the bolts are loose but if they are then that would explain the cylinder problem. Inner exhaust manifold gasket not sealing

Thanks for the help. i really appreciate it

 

[boobie]

Agree with Emds...........

 

[Bosunsmate]

There should be absolutely no water anywhere inside the cowling when its running, that might be caused by another problem , either way its worth investigating it. The water can also get on to the sparkplugs when its running and thatl start shorting out a cylinder.
When you do check those bolts dont be very hard on tightening them as the heads can come right off like a decapitation.
I was chasing a milky cylinder on my mates v4, hes a car mechanic and he reckoned it was a minor imperfection in the head. His machinist said touching it would be a waste of time. It ended up being lose exhaust bolts and a blown gasket where they were meant to do their sealing.
Id get on to fixing it and getting some proper two stroke oil running through it as while its sitting wet with water the internal bearing faces will be starting to corrode.
If you dont have time at least drop the LU and run some fogging oil through it for about twenty seconds then letting it cool and doing that again, cleaning the bad cylinders spark plug as you go.

 

[emdsapmgr]

Simply re-torqueing the exhaust manifolds may not solve a manifold leak. The two gaskets (317914) are cheap and so is a little gasket sealer.

 

[Lukef]

I would never try and re-torque bolts without removing them first. I'm starting the head gasket as we speak. If that doesn't solve the issue i will remove the exhaust manifold to inspect. Can i make my own gaskets for the manifolds or would that be a bad idea? I would like to get this fixed today if possible. ill be working out of town for a few weeks after this and the tournaments are just around the corner.

I know i already said it but i really do appreciate your input. Thanks

One other question? What are the torque Specs on the head bolts? 18-20 ft lbs is what i have found. But some say 25 ft lbs. i don't have a shop manual. suppose i could see if its on Amazon.

 

[Lukef]

This is what i found. If you look close on the picture of the exhaust port, does that look like a crack? Not sure if that is leaking or not

 

[emdsapmgr]

Not sure the exhaust defect is important. There is not usually water in that area. Could be a minor casting defect.

 

[Lukef]

well. i changed the head gasket and im still getting milky sludge on one plug. may need to pull exhaust cover and take a look. you dont think that crack could be leaking water? whats on the back side of that?

BTW, all the exhaust cover bolts were loose. I loosened them and re-torqued to 80 inch pounds.

 

[Bosunsmate]

well. i changed the head gasket and im still getting milky sludge on one plug. may need to pull exhaust cover and take a look. you dont think that crack could be leaking water? whats on the back side of that?

BTW, all the exhaust cover bolts were loose. I loosened them and re-torqued to 80 inch pounds.

Back side of the crack is probably just the crankcase, not a water channel but im not sure as those blocks have channels through them that i know i dont know of their exact position. If i was you i would order the exhaust gasket and think of something you can plug that hole with when you have the exhaust off.
That way it is most likely to be ready for your tournament.
20-25 foot pounds is fine by the way.
Im not sure what you could use in that hole area, other people on this site will know if anything can handle the heat there

 

[Bosunsmate]

is this a salt water used motor?

 

[boobie]

20-25 foot pounds ????

 

[Bosunsmate]

20-25 foot pounds ????

that was for the headgasket, ive seen 25 done when the threads arent clean