Mercruiser 4.3L lift points

[liusigou]

Are ALL of the spark plugs out of the motor?
If they are then the motor is locked up

All of the spark plugs are out of the motor. it is very difficult to turn it over manually. Should I apply WD40 or foil oil in the cylinders?

 

[alldodge]

Any kind of oil is better then no oil

 

[Lou C]

Yep you want sone kind of lubrication in there with perhaps some rust penetrating oil to dissolve rust on the cyl walls. That’s what must happen to free up the engine.

 

[liusigou]

I have applied foil oil and w40. It still is difficult to turn it over manually. So sad.
I have found milky oil in the engine

 

[alldodge]

It's probably gone and needs replacement

 

[Lou C]

Try a rust penetrant like:
Kano Kroil
Free All
Freeze Off

Or a home brew of 50/50 mix of auto trans fluid & acetone

 

[liusigou]

I cannot turn it over manually any more. give up.

 

[Lou C]

Next you may have to do this and spray all around the cylinders to see if you can get it to move.....
Mine never locked up even though it was salt water because I suspected that there was water in the cyls from when it started acting up (difficulty starting, misfiring etc). So I started draining it after blowing out the water.
Wound up replacing the cy heads, installed new center riser exhaust, etc.