Rebuild or not to rebuild?

[wlbolerdo]

I have a '92 70hp evinrude. No.2 cylinder is 75psi, 1 and 3 are 110. There is some sort of leak between cylinders 2 and 3 which is causing lack of idle and lack of power. Should I make a hobby out of this and fix or dump it? I'm a poor man, wifes been laid off and I need to get out and fish!
Wayne

 

[iwombat]

Re: Rebuild or not to rebuild?

Probably just needs a new head gasket - got $25?

 

[wlbolerdo]

Re: Rebuild or not to rebuild?

How can I test for a head gasket? $25.00 would be great!

 

[tashasdaddy]

Re: Rebuild or not to rebuild?

you have the same compression on 1 & 3 2 is low, first step is to pull the head, and check the gasket for a blowout, around #2. if the head gasket is good, then we go further, broke rings. scared cylinder wall.

 

[iwombat]

Re: Rebuild or not to rebuild?

Fortunately, it's free to figure out what's really wrong here.

Pop the head and tell us what you find.

 

[wlbolerdo]

Re: Rebuild or not to rebuild?

There isn't any obvious blowouts although the head itself has alot of wax-type substance on it that appears to have pushed up on the gasket in spots to create bubbles. This stuff really looks like wax, perhaps corrosion?

 

[wlbolerdo]

Re: Rebuild or not to rebuild?

I've done head gaskets on cars and know the signs. Also have seen blown head gaskets. Honestly, if I wasn't listening to everyone trying to get into my wallet, I'd replace this gasket and clean the head! I'm open to checking other stuff while the motor is open!
Wayne

 

[iwombat]

Re: Rebuild or not to rebuild?

Take a look at the cylinder walls - any scoring? Can you still see the cross-hatches from the honing?

 

[wlbolerdo]

Re: Rebuild or not to rebuild?

No. 2 is grooved or scored up and down like the piston would go. I could feel it with my finger, wiped it clean and could see it! 1 and 3 feel smooth and looks ok. I do believe I see and understand the cross-hatch design in the metal

 

[wlbolerdo]

Re: Rebuild or not to rebuild?

So now I'm sure that I've got problems. Here's another which I was told is different from low compression.
Pulled the carbs, pulled the reed valves(which I was told were in good shape), put my hand over that cylinders intake and it will suck your hand to it while the motor is cranking. The other cylinders will not do this-no suction while cranking on 2 and 3. Was told this is some type of crank case test. Make sense to you?

 

[iwombat]

Re: Rebuild or not to rebuild?

A grooved cylinder means rebuild - plain and simple. You shouldn't see any grooves at all. You'll need a re-bore, one new piston and new rings all around. It's not incredibly expensive if you can do the work yourself. A marine machine shop will charge roughly $50/hole for a bore job. (Your mileage may vary)

 

[wlbolerdo]

Re: Rebuild or not to rebuild?

ok,so today I'll find a marine machine shop and get prices. Would you care to comment on the so-called crank case test I'd mentioned earlier. Does this sound like a different problem internaly or all one problem?

 

[Chinewalker]

Re: Rebuild or not to rebuild?

It's possible you have problems with the lower main seal which would affect cyl. #3. The issue with #2 cylinder would also translate to lack of crankcase suction. Invest in a manual and keep moving on. Those Johnrude triples are great motors and well worth rebuilding...
- Scott

 

[kenmyfam]

Re: Rebuild or not to rebuild?

I concur on the 3 cylinder Johnnyrudes,
Great motor and you should get many many years of service from it after a good rebuild. Get a manual and visit some engineering shops during the afternoon shift. Someone will do a rebore cheap for beer money. I know as I used to do it !!!! Just make certain that you know what size you need to go to.

 

[iwombat]

Re: Rebuild or not to rebuild?

So . . . here's the other side of it.

You need to spend some time figuring out what happened to #2 or it'll happen again after a rebuild.

My guess is clogged main jets on your middle carb starved it of lubrication. Either that or it ate a ring.

 

[CWKboat]

Re: Rebuild or not to rebuild?

I agree re: the OMC triples. I rebuilt mine in 2000 after overheating and 8 years later it's still going strong. These are great motors and well worth the time and effort to fix especially compared to new prices.

 

[wlbolerdo]

Re: Rebuild or not to rebuild?

Just a little update, I rebuilt all 3 carbs including floats. I removed the jets, cleaned and inspected them. Motor was still running like crap which is why I started to pull the motor apart and came across these other problems.