720 won't crank

[michaelaraujo]

First off this forum has been great, been able to find many answer to issues.
I have a Sportster LT with twin 720 engines. Last weekend while out in the bay was having issue and found water leaking from welch plug on the tuned pipe on starboard engine. Was able to get back home and flush engines. Next morning was unable to start due to spark plugs, changed and was good. This weekend returned to boat with tuned pipe repaired but engine won't turn, starter clicks. I am able to move the PTO back and forth an inch or 2. Due to not being home and with limited tools. Wonder if magneto got damaged due to the amount of water that got dumped on to it from welch plug issue? Also would I be able to see anything by just removing magneto cover or will I have to remove Mag flywheel?
Thanks in advance

 

[racerxxx]

I doubt the mag is the problem. Did you pull the spark plugs when you tried turning it over by had? If not, I'd try that.

 

[michaelaraujo]

I doubt the mag is the problem. Did you pull the spark plugs when you tried turning it over by had? If not, I'd try that.

Yes had plugs removed. Also tried looking on both sides on the pump, but didn't see anything.

 

[JeremyD615]

Unfortunately you’re going to have to pull the pump to verify whether it is the motor or the pump locked up. Hopefully it’s just a pump issue...

 

[michaelaraujo]

So I pulled out the pump, engine locked. Will start by taking apart top end to see if I find something. I have been replaying back what I could of done wrong and came up with 2 senerios. 1. When I noticed water leak from tuned pipe I didn't pinch the intake water cooling line. But I was able to flush enginge that night and start it next morning after replacing fouled plugs. 2. Accidentally dropped something down exhaust manifold while removing/installing tuned pipe.

 

[michaelaraujo]

Update. Pulled cylinders out and piston rods and piston itself doesn't move freely. Still unable to turn crank shaft. Will have to remove engine to investigate further.
Question how much oil should be in the crank shaft housing, crank shaft and lower piston rods look very dry?

 

[racerxxx]

Did you ever rebuild the carbs? Did you overhaul the oil injection system? Check the little lines under the carbs, are they still hooked up? The bottom end should not be dry.

 

[michaelaraujo]

Yes to carbs No to others. I used a wire to gauge how much oil and only measured half an inch from the bottom. How high should the oil level be, up to crack shaft? Never have done this type of job. Question about special tools required for this type of job; mag flywheel holder, mag flywheel pulley, PTO removal tool, piston rings tool. Required or can get by by using something else?
TIA

 

[michaelaraujo]

Taking my time on this project, since being on vacation with planned family trips.
I know I definitely need to replace all the gaskets and seals, bearings and few others. Would I or should I replace pistons and cylinders as well? They look good to me.

 

[JeremyD615]

I would go ahead and replace them. At this point I’d just plan on a either a full rebuild or a replacement motor. You’ve got something seized in there since it’s not turning, and you’re not going to know what damage was done until you get it completely apart. I’d make the decision now whether you’re going to rebuild or replace, as there’s no need to split the case and all that if it’s only going to be used as a core...

 

[racerxxx]

I'd stop now. Put the head on, get an impeller removal tool. Remove the pto, then get back to where you are now. Then at least if you decide to rebuild or exchange that's already done.

 

[JeremyD615]

+1 On the above. It’s MUCH easier to get the PTO off with the motor assembled!

 

[michaelaraujo]

I'm actually past the point in the picture, cylinders are out, carb is out, impeller shaft is out close to removing bottom end out of boat. $$ wise I haven't compared yet. Would I be actually saving $$ if I rebuild as apposed to replace whole engine?