Mercury 135 not running

[trueno_13]

I am trying to diagnose a 1997 Mercury 135 that will not run. The flywheel will only do 1 complete rotation. I have pulled the plugs and removed the lower unit, and when turning the flywheel by hand it keeps stopping at the same spot, irrespective of the direction that I turn it. All 6 pistons are moving up and down, it just hits a point at which it will not go past.

Could this be a broken rod? Or something else? Any advice would be helpful.

 

[Dukedog]

you need ta take it apart ta find out whats up....

 

[jimmbo]

Welcome to iboats

If all the Pistons are moving, then I doubt a Rod is broken. One or More may be bent, which can cause Binding. I suspect you are going to have to split the Crankcase and take a look inside

Pull the Heads off first, and see if something is stopping a Piston

 

[trueno_13]

Any tips or videos on opening the crank case? And any issues I need to be careful of?

 

[racerone]

Remove gearcase first.----Long shot that something is wrong there.-----With it nearly making a full turn it sounds like a piece of metal is loose somewhere.----Remove heads as stated.-----New to you motor ?

 

[jimmbo]

Remove gearcase first.----Long shot that something is wrong there.-----With it nearly making a full turn it sounds like a piece of metal is loose

Good Catch

 

[Dukedog]

I have pulled the plugs and removed the lower unit, and when turning the flywheel by hand it keeps stopping at the same spot,

...... still has ta come apart.
send me an email addy and i'll send ya an oem manual for it (PDF file)..................

 

[racerone]

Too early in the morning to read that lower unit was removed.---Sorry.

 

[Dukedog]

 

[trueno_13]

...... still has ta come apart.
send me an email addy and i'll send ya an oem manual for it (PDF file)..................

My email is brymaybee@gmail.com

 

[trueno_13]

I managed to get a camera and looked inside the cylinders, and it looks like there is damage around the top edge of one of the pistons. I am going to take the cover off this weekend and have a better look around.

As a question, if the piston is done, is it possible to get another engine of the same year and swap out the power heads? My hull needs a 20 inch shaft, and al I can find here in Perth are the 25 inch models.

 

[trueno_13]

Remove gearcase first.----Long shot that something is wrong there.-----With it nearly making a full turn it sounds like a piece of metal is loose somewhere.----Remove heads as stated.-----New to you motor ?

I have had the boat for about 10 years now, and it has been great. A few minor issues with electrics, solenoids and starter motors, but that is expected with the salty conditions. I re-wired the engine about a year ago, and was working fine until something just went and stopped the engine from continuing to turn over.

 

[Dukedog]

sent... study it then decide what ya wanna do...,...

yes ya can jus change power heads if thats what ya end up wanting ta do...

 

[trueno_13]

sent... study it then decide what ya wanna do...,...

yes ya can jus change power heads if thats what ya end up wanting ta do...

So I found the issue. It looks like the piston ring on the upper left piston (port side) has exploded, taking some of the piston with it (See pictures). There is a piece of the exploded ring welded into the Cylinder head, which is what is stopping the engine from turning over.

I am assuming that this means a complete re-build of the cylinders would be needed?

 

[racerone]

Was it running with automatic oil injection ?------Did you install a new water pump impeller about every 3 years ?-----A replacement power head is the best option.----But find out what happened and make the repairs.

 

[Faztbullet]

Someone has replaced that piston already as not OEM. Most likely the advance module is bad as that is detonation damage.

 

[racerone]

Sharp eyes to see the dimple marks on that piston.

 

[trueno_13]

Was it running with automatic oil injection ?------Did you install a new water pump impeller about every 3 years ?-----A replacement power head is the best option.----But find out what happened and make the repairs.

Yes, the oil injection was working fine, and water pump is changed at least every 2 years, and sometime 1.

 

[racerone]

The oil pump is driven by a plastic gear.----Have a look at that gear.

 

[Faztbullet]

See this quite a few times with DIY repairs. Damages repaired but problem not fixed. Like a ol Chevy, ya fix the rusted rocker panel but dont address the drain hole which caused it to rust