Siezed motor & creativity

[mark_gober]

Hey everyone,

I've got a question that may require some old salt knowledge. I have in my possession, three 1953 model Mercury Mk-20 motors. One of them is essentially a parts motor, one freely spins(although I haven't attempted to make it run yet), and the third is siezed up, but otherwised complete. I figured I'd work on the seized up motor to gain knowledge on the motor so that I can definitely get the freely spinning motor working. Having said that, I'd love to get two motors running so I'm asking questions about freeing up a seized motor.

It occured to me that I might be able to utilize an air compressor to perform this task. I figured that if it has a 3" piston (just a guess on diameter) that with 150 psi, I could generate around 1100 lbs of pressure. The problem that I had was being able to construct a fitting to go from air hose to spark plug fitting. Anyone ever had any luck performing this task?

In researching possible suggestions, I came across a seemingly simple, yet genius solution that might work. Why couldn't I spray either starter spray or carb cleaner or any other extremely flammable spray into the spark plug hole, screw the spark plug into it and then supply a spark to the sparkplug from another source. It might be me, but man that sounds like a smart idea.

If anyone else has any ideas on freeing this motor up, I'd love to hear them. The motor was my grandfathers and so it has some sentimental value and I'd love to get it working.

Mark

 

[arcrat]

Re: Siezed motor & creativity

Dont do that!!!!!!!!!! mix gas + oil 50-1 pour in each hole let stay over night .. then try turning by hand back +forth if that doesnt do it ..put some more let sit over knight try moveing again .. you might use a socket on the flywheel.to turn. some compresion tester have a Quick connection take out value stem install in plug hole.... and connect to air hose!!!!!!!arcrat

 

[mark_gober]

Re: Siezed motor & creativity

Arcraft,

I've put a copious amount of WD-40 and a few other lubricant sprays in there and allowed to sit for quite a while. The motor is rope started so I can only get a clamp on the flywheel bolt. I used a pretty sizable pipe wrench and wasn't able to free it. I can't really rock it the other way because the bolt will simply unscrew. Unless someone else has other ideas on how to rock it the other way.

If this were a car engine, my solutions would easier, but with it being an outboard, I can't really push start it.

Thanks Arcraft and anyone else who has some ideas.

Mark

 

[Willyclay]

Re: Siezed motor & creativity

I had success with a seized two-cylinder outboard spraying PB Blaster directly into the spark plug holes and turned the motor every direction but upside-down. I let it sit for a few days then used the biggest socket handle I owned on the flywheel nut to turn it. Once it freed up, I put TCW3 lube in the cylinders. Spins freely now. FYI, I was pretty certain this motor had rusted cylinder walls/piston rings when I chose this process. In the case of another seized motor, I suspected the previous owned had run it without oil in the gas and chose to overhaul it completely. The approach depends on the problem. Good luck!

 

[cell]

Re: Siezed motor & creativity

Try marvals mystery oil.It comes in a red bottle.Ive used it to unseize a car's engine before,and it worked.Pour some down the plug holes,and just let it sit for a few days.Might be worth dropping the foot just to make sure the shaft isn't seized either.



Edit:come to think of it Ive used regular atf fluid to get an seized engine to turn too.The trick is to be patient.If it doesn't work after a few days you might have to take it apart.Heres a link for those old mercs.

http://www.oldmercs.com/models.html

 

[Chinewalker]

Re: Siezed motor & creativity

Be careful torquing on the crankshaft too much. Not hard to twist one.

Here is what I've done. First, determine where it is stuck. Pistons? Pull the port covers and take a look for corrosion, etc. Crankshaft? Any play at all in the flywheel - up down, back and forth?

Pistons free, crank stuck: Undo the nuts from the studs holding the crankcase to the block and pull the block free. You'll then be able to deal with the stuck crankshaft.

Pistons stuck, crank free: Undo the nuts from the studs holding the crankcase to the block and see if you can split them enough to undo the rods from the crankshaft. If you can do that, then you can set the block up in a press and punch the pistons out with a brass dowel. A bench press will make quick work of stuck pistons.

If everything is stuck & corroded, .ie motor was sunk or stored in a damp basement: Lots of soaking in solvent of choice - several mentioned above. Try to split the crankcase from the block. Remove the intake and exhaust covers to access the pistons for more soaking. Try all of the above repeatedly...

- Scott