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Seized Sp 225 Help!

Boat Fan

New member
One of my Sp 225s sounded "funny" while idling at dock, so I shut them down.Turned out to be a cracked intercooler housing. Ordered another one, took 4 months to get. Re-assembled and tried to start, motor just "clunk", won't turn over. Changed oil & color was slightly off, not bad. Removed injectors & vacuumed out cylinders for water, only got small condensation from 1 or 2 cylinders, but must have sucked a small amount of salt water in, which I didn't know at the time. Have been squirting Marvel Mystery oil into each cylinder for about a month,letting it soak & trying to gently bar it over. No luck so far. Have used about 1/2 quart of Marvel so far. Any ideas would be appreciated. I'm still hoping to free it up if possible. Cylinders are chrome lined, I'm hoping that may improve my chances. Should I add more Marvel to cylinders? Any other ideas I can try?
 
Most likely your intercooler has been spraying salt water into the cylinders for quite some time also the valve stems are probably rusted. Try loosening the bolts on the rocker shaft pedestals a few turns to see if the engine turns over by hand a little further. In any case i suggest removing the head to see what water damage has been done.
 
I suspect that you are probably right, I think it has been spraying in salt water for awhile too. If the valve stems have rusted, would the valves need to be replaced or could they be salvaged? Also, I'm sure I won't know if they have rusted without pulling the head, probably. Would frozen valves seize the motor?
 
Hi, yes rusted valves stems in the valve guides would keep the engine from turning. Best bet is remove the head to see for sure what you are dealing with.
 
Hi, these are a real bear because some have a tachometer sender mounted on the front of the crank. If you look at the pulley just behind this there should be six approx. 1" slots around the center of the pulley. Measure the width of the slot to be sure than get a piece of steel flatstock from hardware store 5/16" thick by about 3 foot long by 1"?? Insert in slot and turn carefully.
Hope this helps.
Charlie
 
Hi,
I ordered a "barring tool" from American Diesel to bar the motor. It's a round metal plate with long allen bolts that bolt right into the front of the fly wheel. It has a 13/16" nut on the front. Works well. I haven't pulled the head yet, but that will be the next step. I have still been adding Marvel oil to the cylinders and spraying the valves w/wd40, letting it sit and trying to work it loose. No luck so far. I measured the amount of torque it takes to turn over the other engine at about 45lbs, so I have been limiting the torque I apply to the seized motor to about 60lbs. Don't want to break rings.
 
Boat fan, if this is the starboard engine try removing the starter (port is usually difficult to get at ) and bar it over. Look at the end of the starter for missing or rusted up drive gear. There is very little room between the flywheel and fw housing so if any parts fall off they would lock it up also if the drive gear stayed engaged it is difficult to turn the engine.
Charlie
 
An "old timers" method of freeing a stuck engine is to drain the coolant and fill the cooling system with boiling water. This expands the cylinder walls just enough to free any stuck rings. Sometimes it works, sometimes not. Could be worth a try. (I'm an "old timer".)
 
I finally pulled the head and can now see what's going on. It looks like I have 2 pistons seized and there was some corrosion on the valve guides, but they are not frozen. The frozen pistons and cylinders don't look too bad, so I cleaned out the cylinders and am trying WD40 around the pistons untill I find something more effective. I had been soaking the cylinders with Marvell Mystery oil for several months. The last 2 cylinders had been holding the oil, so I asume they are frozen. Still can't bar over the motor.Other than soaking the 2 pistons in PB Blaster or something like it to try to free them, I don't know what else to do. Any suggestions?
 
You are probably in for a rebuild but I have had a Perkins seize right up solid and run fine for years after we got it freed up

I would try the temp differential trick , get the block hot , the pistons cool and see if that breaks it loose.
Also WD40 is really a Water Dispersant , you might be better off using a product like PB Blaster or Liquid Wrench
Good luck
Norm
 
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