1974 Evinrude 135HP

Joe-1709

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Oct 29, 2017
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Hello:)
First time posting here. I am new also to boating and outboards. I have a 1974 evinrude 135hp. Warm #1=100; #2#3#4=125 ...I have a problem on cylinder#1, 90% a broken ring. Most of the shops in my area do not work on engines that old and do not recommend that I do without even looking at it. certainly cost/value. Before loosing more compression I opened the cylinder head and found that the #1 piston and head are damaged. A 3mm ring peace is stuck on the head.
the cylinder walls are smooth with miner scratch; their is no apparent crosshatch on cylinder walls #1 #2.; their is 1mm chipping on exhaust and air port in #1;
my questions are:
Is honing a most if i should consider changing the damaged piston.
Should I hone all cylinders or can I hone only one.
Thanks for any available help.
 

racerone

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Dec 28, 2013
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Take it apart .-----Measure the bits / pieces / bores.------The install 4 new pistons and rings.
 

Joe-1709

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TX for your reply.
I did not mention that the previous owner told me that this engine was rebuilt in 2013. Pistons are 0.030. Engine is clean and all works well.
budget is too high for a complete rebuilt.
I am aiming more to check if everything to specs; if so, only changing one piston and rings and a cylinder head without honing.
is it worth a try or I look for a newer engine.?
see pictures.
TX again
 

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boobie

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Due to the age of the motor and what's wrong with it I'd look for a newer one. JMO.
 

racerone

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You say all works well , but there is major damage ?------Do you know why these ring fail like that?-----Measure the bits and bores and then decide !!
 

Joe-1709

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TX racerone and boobie.
Boobie, Before i start looking for a newer one (they do not come cheap in my area) i wish to be certain that mine is not worth it.
Racerone, snow is falling overhere, i have the time now to open it up and measure bits and peaces as you say.
I have only one guess for why the ring failed.
When I removed the spark plug on #1 I noticed threads on cylinder head are broken.
In your experience Could it be that the broken threads that fell into the cylinder caused a piece of ring to brake?. By the way, piston #1 rocks the same as piston #3 and It looks like The rings on #1 are still in place.
 

racerone

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No the threads from the sparkplug hole did not cause the damage !----Take this thing apart.-----Draw a picture of the top ring in the groove.-----Then visualize the side clearance on the top ring as cylinder / piston wears !-----Now think what happens at 5000 RPM.----Your location ?
 

Joe-1709

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Understood racerone.
will proceed and open it up.
I am in Monteal region.
It looks like I can access and remove pistons without removing flywheel and crankshaft. Is that feasible or recommanded ?
 

racerone

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You are about 8 hrs away from me.-----I have never used that shortcut to rebuild one of these motors.----It has to come all apart for inspection.-----It look nice cosmetically but who knows how many hrs on the rebuild !!-----There is more to rebuilding one of these motors than loosening and tightening some bolts !----As in how would you line up the connecting rods without having the block apart ???----How would you hone the cylinders and keep the grit out of the crankshaft bearings ???
 

jimmbo

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I remember one mechanic doing that shortcut. Engine threw the rod less than 10 minutes after start up.

just for the record, it wasn't me
 

Joe-1709

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OK then as I understand options are:
1- Boobie: find a newer outboard.
found one johnson 115hp 2001 for 3k 4h from me.
30 days limitem warenty. Ready in spring.
found one Honda 2008 and one evinrude 2010 90hp for 6k 30 days limited warenty. Ready in spring. 30mins from me.

2- Racerone: short description:
take it all apart. Check bits and bores .
if OK Hone, change the 0.03 pistons and rings, rebuild, adjust linkage and sinchronization.
if bores to be machined send to machineshop
to prepare for wiseco pistons. Rebuild and adjust synchronization and linkage.
1.2k in parts for the first one.
At least 1.5k in parts and boring for the third one.
1.5k for for labour if serviced by mécanicien. Limited Warenty on labour not parts.

3- my unreliable option
open cylinder head and crankshaft cover.
try to remove and replace #1 piston, no honing, rebuild, no synchronizing needed.
Cost 500. No warenty, could end up throwing 500 away.

Hmmmmm...this is why I started this post.

What about this way to go: modified Racerone option:
Complete dismantle, check cyls and pistons, if bad cyls or pistons then scrap; if good cyls and pistons,
hone, change piston #1 and all 4 piston rings, rebuild, adjust synch and link..
800 in Parts.
more reliable than my option. Should give a clear overall diagnostic of the powerhead and reasonable cost considering i am dowing the work with my brother car mecanic.

What do you think about this option?
Is it reasonable to change rings only without pistons? Extar 320$.


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racerone

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Why would you put new rings in worn out / damaged grooves ?-----But good luck with your project.
 

Joe-1709

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TX Boobie, Jimmbo and Racerone.
Understood.
NO halfway solutions...I had to ask anyway...
Will start taking it apart on my spare time.
TX again.
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interalian

Commander
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Jul 23, 2009
Messages
2,105
No way you can R&R a piston without splitting che crank case. Don't even try.

Take a really good look at the condition of the rest of the engine before spending ANY money on it. Even then, a '74 engine is worth very little. I did a full rebuild of an '82 and it was not a sensible financial choice, rather a sentimental rebuild of an old family treasure.
 

James R

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Feb 1, 2007
Messages
2,660
I rebuild these older motors regularly. Just finished a 79 140. When I do them I do them right and try to get them as near like new as possible. I don't want them to fail mid pond. The AAA man doesn't come out there.
If you are going to rebuild, bore all cylinders and fit new pistons. The bores will undoubtedly be out of round. Crankshaft needs to be good and carefully polished and all bearings will need to be carefully examined and possibly replaced. Con' rods inspected and polished etc etc etc. If you feel you can do it have a go but get a good manual first and all the right tools. I tell you this to help you make your decision. There is no cheap way to a good motor.
Good luck .
 

Joe-1709

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TX Interalian and James R.
following Racerone recommendations I strated taking it apart today in scope to verify cylinders bores by Saturday.
As i noted earlier the engine looks clean inside and outside and thus is what is encouraging me to go through.
Will send pics and measurments by Saturday; maybe it will show the way to go.
tx
 

Joe-1709

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Oct 29, 2017
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TX Interalian and James R for your reply.
As noted earlier, the reason to try and revive it is that it was running great for it's age and all parts works well other then cyl #1 piston and head; Ignition is good, smooth drive, no pofs or cough on all speeds,etc..
I have the manufacturer manual.

​I followed Racerone advice and opened it up.
Will be measering bores by saturday.
until now I am surprised of how clean it is even in the inside.
will post pictures of cyls, pistons and cranckshaft with bore dimension results by Saturday.
Maybe they will shine light on the next step.
TX again ​​​
 

Joe-1709

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Oct 29, 2017
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Helle
sorry, pictures will have to wait....flywheel %÷_#&#&÷&#....
I read all what is on-site about removing a stuck flywheel...
now I understand when we say it nice on paper.

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racerone

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Dec 28, 2013
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When the nut is properly torqued to 100 FT-LBS the flywheel is stretched over and onto the locking taper.-----That locks them together !!-----It is not rusted on.------The proper puller with the 3 bolts takes it off EVERY time.-----It will require a hefty hammer to get it to pop off.-----Just hit the main center bolt a few times and retighten the center bolt. again.
 
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