Mercury 135 not running

[trueno_13]

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

Agreed.

 

[trueno_13]

I now have a doner engine that was runnig great, and the plan is to swap Powerheads, including all the bits attached to it (carbs, starter motor, solenoids, electrics, oil pump, etc.). But I want to make sure I do not run into the same issue again, so I am going to:
1) Change out the fuel line to be sure that air is not getting into the system and causing it to run lean
2) Change the impeller and gaskets in the lower unit
3) Check the plastic gear that drives the oil pump

Are there any other issues that may have caused the deterioration to the piston and ultimate failure that I should be checking?

 

[Chris1956]

You must be sure the carbs are clean and the timing is correct. Make sure you use the correct prop and the thermostats and poppit are working properly.

 

[Faztbullet]

Most likely cause was the idle stablizer/advance box. Chunk it and set max timing at 21°. A single cylinder running lean is a timing/fuel (carb) problem

 

[trueno_13]

the Powerhead swap out on my Merc 135 is progressing. However I have hit a snag. I have removed the 10 nuts that hold the power head on (some were well rusted and needed some WD-40 and a little persuasion). I am lifting the powerhead by the Eye Tool in the flywheel straight up, but the front section (under the carbs) will not separate. I can give a light pry at the back, and see a little separation up the sides, but the front will not let go.

Any thoughts or tricks I can try?

 

[Chris1956]

A lot of times the lift is not exactly straight up, or the motor is not parallel to the lifting. This causes the studs to bind in the midsection casting, along with any corrosion on the bolts. Leave some lifting pressure on the eye, and push on the crankcase next to the carbs with your hands to try to rock the front part of the block loose. This can straighten the pull and help the powerhead gaskets let go.

You can also trim the motor down a bit more to try and add some pull to the front of the powerhead.

 

[trueno_13]

Thanks for the advice, I have tried both and it just won't let go. I have been soaking the studs in WD-40 every night, but as I need to spray upwards, probably not getting the needed penetration. Is there something else that others use to try and remove corrosion from the studs?

Also, would putting some percussion on the block help break it loose?

 

[Dukedog]

if you have a good chain fall and/or motor hoist putpressure on it with it and then "shake tha livin' $hit out of it".....

 

[racerone]

???-----Drill into the exhaust housing from the side.----Start with a 3/16" drill.----Drill close to the block.----Get oil in there.-----If this fails go to bigger drill to cut the stud.----Been there done that.

 

[trueno_13]

???-----Drill into the exhaust housing from the side.----Start with a 3/16" drill.----Drill close to the block.----Get oil in there.-----If this fails go to bigger drill to cut the stud.----Been there done that.

So the old broken PowerHead has been removed, and it looks like I will need to drill into the donor one to get it separated.

 

[trueno_13]

I now have both powerheads removed, as well as the Exhaust and Transmission plate. Both have quite a bit of salt build up that I want to clean up. Any suggestions? Or do I just use INOX and a cloth?

Also, what will help soften the gaskets so that I can remove them in preparation for the new ones?

 

[trueno_13]

Thanks everyone for the advice in this adventure. The donor Powerhead was attached to the existing drive section yesterday! All seems good, but I am wondering if I need to check the timing?

It is very possible the timing is what caused the issue in the old powerhead. However, as the new powerhead is a transplant, do I need to worry about the timing, as it was running fine before the conversion, and all the components were transferred over in their running state (nothing above the exhaust plate is from the old engine).

 

[Chris1956]

It is very easy to check the timing. The check will give peace of mind, no?

 

[trueno_13]

It is very easy to check the timing. The check will give peace of mind, no?

True

 

[trueno_13]

As I am waiting for a part to arrive so that I can re-attach the lower unit, I am keen to get the timing sorted. I have a few questions just to be sure that I am doing things correct:

1) Is there any issue if I do the timing without the lower unit attached?

2) I have heard that drag can be an issue. As I will be testing the timing on Dryland with the Prop removed (and potentially the entire lower unit), do I still use the following settings that are in the shop manual or should I adjust them slightly?
- Idle Speed - between 0 and 9 degrees After Top Dead Centre
- Wide Open Throttle - 19 degrees Before Top Dead Centre

3) Cylinder numbering goes from Starboard to Port, and from Top to Bottom, making the #1 cylinder Top Starboard when facing the same way as the boat would be travelling?

Cheers, Bryan

 

[Chris1956]

Remove spark plugs 2-6. Put timing light on topmost cylinder. It should be obvious which one it is. Gearcase can be on or off. If on, remove prop to keep it from chopping your feet.

Idle pickup timing is 0-9* ATDC, and is set when the carbs are ready to open, but still closed.
WOT timing is 21* BTDC, and set with the throttle plates wide open, and throttle set to max.

use a jumper wire to energize starter solenoid, ign on, in gear, to crank the motor.

 

[trueno_13]

Remove spark plugs 2-6. Put timing light on topmost cylinder. It should be obvious which one it is. Gearcase can be on or off. If on, remove prop to keep it from chopping your feet.

Idle pickup timing is 0-9* ATDC, and is set when the carbs are ready to open, but still closed.
WOT timing is 21* BTDC, and set with the throttle plates wide open, and throttle set to max.

use a jumper wire to energize starter solenoid, ign on, in gear, to crank the motor.

Thanks for this. I have build a grounding harness for all 6 cylinders. So it should be 21 degrees for WOT (not 19), which the shop manual lists as cranking speed?

Also, can I do the timing by having my son crank the engine from the key?

 

[Chris1956]

21*BTDC at cranking speed is the max spark advance spec for my '93 135V6.

Sure, your son can help, if inclined. Mine is usually not inclined.

 

[Chris1956]

One more thing that occurred to me. The motor will not crank at the ign key when at WOT. You will still need to jumper the starter solenoid. Your kid is unemployed, I am afraid.