changing 1 piston in 1987 evinrude 115

[demon1]

I just got this boat about 2 months ago. took me about 3 weeks to replace the floor and stringers. looks great and has been running good until yesterday after takin it out in the gulf to do some fishing. probably a 15 or 20 minute ride out . it was about 4500 rpm. when I got back to the river and had to idle it down it was running rough. and almost stalling. had to give it a little gas to keep it going . we stopped to go swiming and it would not start . i thought I might have fould a plug so me and my son replaced the plugs when we got home, but it was very hard to start but ran .pulled the plug wires while it was runningand one cylinder seemed to do nothing. checked the compression today and the same piston was at 40 psi,the others were at 125. this boat had been sitting for 3 or 4 years before I got it because of the floor. took the head off and that piston has a ding on it .looks like somthing hit the piston ring from behind and pushed it out a little. the cylinder has a mark but I cant feel it .i think it is just from the compression getting by. a freind gave me another motor .the same one in pieces . one piston is bad on it but the others are good. can I replace my bad piston with one of these and do I need to pull the power head off to do this? I dont have a lot of money in this and dont have a lot to spend on it. I am very capable of fixing it no mater what it takes just wanted to ask the experts what you thought before I started

 

[wilde1j]

Re: changing 1 piston in 1987 evinrude 115

Replacing one piston is perfectly acceptable for outboards, but you will need an oversized piston and ring set and the bad hole will need to be bored, most likely. A marine machine shop can tell you whether the bad hole needs boring, and is so, the oversize to get. Most here would replace all the piston rings while it's apart.

You should get an OEM shop manual to see what's involved before getting started.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

the cylinder looks good so if the other pistons I have are the same size I should be good ? also there is a connecting rod attached to the other piston. can I just use that rod or should I use the one out of my motor?

 

[bktheking]

Re: changing 1 piston in 1987 evinrude 115

Looks good and measured are 2 totally different beasts. Connecting rods and pistons also need to be measured, these motors are built with tolerances that need to be measured throughout to ensure a proper rebuild. If you are going to do this yourself bring the block, pistons, crank, rods and such to a machine shop that does marine engines and they will tell you what you need.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

Ive built lots of car engines.I own a shop were we build cars and trucks. I know how to measure the pistons .I trust myself more than someone else anyway. the cyl is good .there are no scratches at all in it. Ill check the bore size and the new piston. I know engines ,just never opened up a boat engine.i'll just stick with my connecting rod so there wont be a problem

 

[bktheking]

Re: changing 1 piston in 1987 evinrude 115

Ok no problem, get yourself a factory manual as it will have all the specs. I wasn't insulting your abilities, some guys come on here and ask if their outboard is water cooled. I'm surprised the cylinder is in such good shape for having 40 psi, maybe you got lucky.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

i appreciate your input. i am going to tear it apart tomorrow after work. what do you think could have have caused that piston to dent outward like that? my freind has the man. I'll have it tomorrow

 

[trendsetter240]

Re: changing 1 piston in 1987 evinrude 115

With regards to your first post, yes the powerhead needs to come off. You can't remove the piston without spliting the crankcase halves.

As already mentioned, get an OEM Johnson/Evinrude manual, not seloc or clymer. OEM will have the step by step instructions and more importantly wear tolerances.

Just be prepared to have to rebore and go oversize on that piston. It seems unlikely that you will be able to get a proper seal if already are down to 40psi.

 

[bktheking]

Re: changing 1 piston in 1987 evinrude 115

i appreciate your input. i am going to tear it apart tomorrow after work. what do you think could have have caused that piston to dent outward like that? my freind has the man. I'll have it tomorrow

Needle bearing, part of a ring- I think once you get the piston out you'll find more damage under the ports.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

yep ,I'll cross my fingers and take it apart tomorrow .i'll post what I find.
thanks again for everybodys input

 

[blimp]

Re: changing 1 piston in 1987 evinrude 115

I had a very similar but worse looking piston on my '87 90hp, a ring had let go and caught on the exhaust port:

http://forums.iboats.com/showthread.php?t=435346

Got the engine apart now, found a deep gouge in the cyl wall and its at the machine shop now. They are determining if i am going .064 oversize or if my block is junk. *fingers crossed*

Good luck, pulling these things apart is not bad. Get a factory manual, really helps even for the experienced mechanic.

 

[emdsapmgr]

Re: changing 1 piston in 1987 evinrude 115

While the pistons are the same, once they are on the rods, they become a right or left. Look for the oil hole in the rod-it has to be installed in a specific orientation. I'd want to know what caused the failure before you fire up the rebuilt engine the first time. Possible you have debris/dirt in the throat of one of the carbs. If so, it could have run that low compression cylinder lean, causing the original failure. I'd do complete teardown and inspection on that carb.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

ok ,I pulled it apart. both rings were broke on that piston. also the piston below that one had some scratch marks on the skirt and some scratches in the cylinder but back behind the ports. what causes these things to happen. definatlly want to know what caused this before it goes back together. gonna try to find out tommorow if the cyl need bored . i have 2 .030 pistons and 1 standerd piston out of the spare motor if they can be used

 

[bktheking]

Re: changing 1 piston in 1987 evinrude 115

Running lean, be it dirty carbs, bad seals, forgetting do add oil, dread I say it BAD VRO/OMS , improper timing, slop in the cylinder walls, overheating, the list can go on and on. The part that sucks is that you didn't own the motor prior so you don't know how it was run. Chances are it's a bore job or a resleave, either way it isn't going to be cheap to do it properly. It might be cheaper to check with Faztbullet on a price for a powerhead.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

the cylinders dont look that bad , I dont think it will take much to clean them up. i should know tomorrow. if those pistons will work than it shouldnt cost a fotune

 

[blimp]

Re: changing 1 piston in 1987 evinrude 115

Those should work, but you are still looking at spending some coin to do a correct rebuild. You will need 4 new ring sets, ~$100, complete powerhead gasket set , ~$100, and machine shop work, ~$100. I would clean out the carbs and replace water pump/thermostats while you are at it to make sure you don't have a repeat performance.

 

[emdsapmgr]

Re: changing 1 piston in 1987 evinrude 115

Also, check the water diverters in the in the block water passages by each cylinder. If one of these diverters deteriorates or gets plugged up with debris, one cylinder can overheat, causing your failure. One cylinder can overheat internally, causing a failure and you will not probably not get an overheat horn. During overhaul, pull the head covers off and check for crud/debris inside which may prevent cooling water from circulating properly. You will want to replace the water pump impeller and both thermostats. I'd want to run a test on the VRO pump to make sure it is pumping oil properly. If the full throttle timing is advanced beyond specs, it can cause cylinder temps to rise-you need to check where the full throttle timing is set.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

it would be great if I can keep it around $500. what is the water diverter ? ive read on here people talking about them but not shure where they are. also what is the vro pump? I'll definatlly check all the water passages. cant I put a temp gauge on this? hell there is only 1 thing to monitor .you think it would have come with one. thanks again

 

[bktheking]

Re: changing 1 piston in 1987 evinrude 115

This motor has to be newer than 87, 90+ maybe or older 85 down, 87 115 isn't listed as a motor. VRO is the oiling system, adds oil to the mix so you don't have to premix. As for water diverters or deflectors, you will see them in the water passages when you pull the heads, they look like pieces of small garden hose, they can be ordered as a part # with the rest of your parts. Yes you can put a temp gauge on it, they do come with a warning system- overheat alarm, test it while you are at it. How do the bearings look, crankshaft, upper and lower as well. You'll want to replace all the seals as well, even the one's that don't come in the gasket set.

 

[demon1]

Re: changing 1 piston in 1987 evinrude 115

I was told it was an 87. the boat is an an 87. the model # is e115tlcte. I mix the gas and oil 50:1 . I saw the deflectors . the bearings and crank look great. the middle crank bearing looks like its cracked in half . it has to be in 2 parts to get it on right ? how do I check the buzzer. it never went off but I dont know if it got hot. I know water was comin out of the motor the last time it ran. this is my first boat and Ive been checking that constatlly wile weve been using it