Help seized engine

[Reboot11133]

I was doing some final adjustments on my 1984 85HP force yesterday and was running it on the muffs. Everything was fine until my Daughter decided to do another load of laundry. I was unaware of what was happening and the drop in water pressure must have starved the motor for cooling. It was idleing fine then made a screetching sound and stopped. Now it won't turn-over at all. I just replaced a piston this summer on # 2 because of a fuel delivery problem. I am so ticked off I don't know if I should just order a rebuilt head or get a new motor.

 

[steelespike]

Re: Help seized engine

I don't think it was the water.It seems to me starving for water at idle it would have slowed and stopped . and probably freed up when cooled.
My first stop would be the suspect piston.

 

[Reboot11133]

Re: Help seized engine

Thanks for response. I will pull the plugs and spray some penetrating oil in and see if that frees it up. If that doesn't work I guess I will pull the head to see how bad it is.

 

[Reboot11133]

Re: Help seized engine

Penetrating fluid didn't help. I pulled the head and the top piston was jammed. I broke it loose by hitting it with a block of wood. It is still very tight and makes a grinding sound when I turn the flywheel. I don't see any scratches on the cylinder wall. It turns more freely when the top piston is at the bottom of the cycle. I removed the carbs and reed valves and nothing looks damaged on that end. I guess I will remove the piston and see if I can resolve this.

 

[Frank Acampora]

Re: Help seized engine

It turns more freely at the bottom of the stroke because the piston and rings are at the exhaust ports. IF you broke a ring, and if the broken portion bent the ring land, which sounds highly likely, then when the piston is in the top of the cylinder, the bent portion or the broken ring itself, is jamming it against the wall. It will protrude into the exhaust port at the bottom and turning will be easier.

Typically though, the broken portion of the ring will be ejected and catch in the port, severely bending the piston ring lands. These will be what are jamming.

Although you say there is no damage to the cylinder liner, look for a good sized nick in the top of one of the exhaust ports. This will not affect performance much or possibly at all, as long as you dress and chamfer it to prevent future ring catching.

 

[Frank Acampora]

Re: Help seized engine

Uh-oh! Sounds like I get someone else interesed in porting an engine.

Anyway I will try the photo but be aware that my VCR is still blinking 12:00

If the photo is not good enough, try googleing The Chrysler Crew, join, go to questions and answers, then on the left, click on photos. Look for Frank's Boats. Shows my little blue go-fast on the cover.

I just threw in my 140 Mermaid for the helluvit. It has since had the rest of the engine repainted.