'Slightly' Seized? '93 XP 657

[Jris88]

Hey guys,

I posted week or so back about buying my first ski - long story but I pretty much inherited a '93 XP with a trailer purchase I made. Ski looks mint, owner said it ran all season just needed a starter.

Here's the steps I took:

1) Charged up the battery and gave it a shot - much to my disbelief the starter worked - engine cranked but would die the second I let go of the start button. As it was cranking a ton of water came out the back of the ski. It was getting dark and I figured I needed fresh gas and to clean carbs so I left it for the night.

2) I tried a day or so later and nothing. Starter would give one knock/thud sound but engine wouldn't crank. The PTO cover was off and you could see it turn slightly and turn back. Figuring it was the starter I swapped the starter out and no change, same thing with the new one. I tried rotating the PTO by hand with the plugs pulled and it wouldn't budge.

3) Thinking either the engine or jet pump were seized, I pulled the starter back out and then the jet pump - it was not fun. Pump spun freely once removed so that got me thinking it's the engine. I sprayed some fogging spray in the spark plug holes and let it sit overnight.

4) Yesterday, I tried turning over by hand again. Still nothing. I did some reading and figured I'd try some Marvel Mystery Oil. I poured about 3oz into each cylinder, waited about 2 hours - it seemed a looser but still very tight by hand. I took a strap wrench, wrapped around the PTO and spun. I got it moving, still with a bunch of resistance. there seems to be one spot in the 360 cycle that has more resistance. I can now spin it by hand (with some strength) until it hits that point.

At this point I'm not sure if I should try more MMO or ATF fluid? How much is too much to pour down - was 3oz enough?

Alternatively I was thinkning about pulling the block drain plugs (manual says 657 has them) and verifying no water in crank case, and then maybe pulling heads?

Any thoughts or suggestions? I'm fine with tackling a rebuild but it would be my first!

 

[Ckrawiec]

If the crank spins fairly freely by hand now, re-install the starter and with plugs out and a good battery, see if the engine will crank over now more forcefully with the starter. Any water in the engine will get pumped out of the spark holes, so it'll get messy...put rags over the spark holes. MMO/WD40/tranny fluid down the holes won't hurt anything but it'll all get pumped back out as you crank it so be prepared...small amounts (1 oz).

So, if you get her cranking well with the starter in and the spark plugs out, and she's not juicy (expelling fluids), get a good compression tester (not a HF tester) to see where you are at.....compression numbers start telling us the story and we can offer guidance in whatever direction the numbers may point us to.

 

[Whus02]

Try turning it over by hand with the spark plugs out. Typically you won't be able to overcome the force of compression when turning it over by hand, that is likely the resistance you are feeling. Also, if you turn it over with the starter without the spark plugs in (make sure you ground your spark plugs caps), it can blow out any excess oil that has built up in the crankcase, don't do this inside, and don't have your head or hands over the spark plugs holes, because the oil will shoot out pretty fast.
You might want to verify that your battery is good, as that will also cause starting issues

 

[Jris88]

Thanks for the tips CKrawiec and Whus02!

CKrawiec - sounds good, I'll work it a little more and try with the starter. By 1oz did you mean apply a small amount like 1oz or that it will expel 1oz out of the plugs per crank? Just not sure if I should drop more fluid down.

Whus02 - yup I had the plugs out and it is still difficult by hand. Will be sure to be prepared incase it does crank with the starter lol

 

[Ckrawiec]

Thanks for the tips CKrawiec and Whus02!

CKrawiec - sounds good, I'll work it a little more and try with the starter. By 1oz did you mean apply a small amount like 1oz or that it will expel 1oz out of the plugs per crank? Just not sure if I should drop more fluid down.

Whus02 - yup I had the plugs out and it is still difficult by hand. Will be sure to be prepared incase it does crank with the starter lol

I'd start by adding nothing into the cylinders, since you already poured MMO down there. Crank the engine with the starter and cover the spark holes (as the pistons will spray all that fluid out). If things are moving fairly freely, no additional stuff should need to go down the holes, so just keep cranking the engine to expel any fluid OUT of the pistons until pretty much nothing is coming out but air. Then do a compression test to get a base line read on the health of the cylinders...then we go from there.

 

[Whus02]

+1 on the compression test, should be 140 to 150 psi. A little lower than that is somewhat okay, the most important thing is that the compression is even between the two cylinders.

 

[mikidymac]

If you hit a hard spot with the plugs out then you have mechanical damage. Either the crank is bad, the rotary valve is bad or the pistons have seized.

At that point there is nothing you can pour inside or "just get it running". The damage ahs been done and has to be fixed correctly.

 

[Jris88]

That makes sense, thanks guys! Going to try to get it cranking and check the compression - raining here today and tomorrow so will report back on Saturday (hopefully).

 

[Jris88]

So didn’t have too much luck. With the starter installed it half cranked and locked up again. I forced it with the pipe wrench through the ‘tough spot’ and it spins kind of easily. Once I hit that spot again it locks up - starter or by hand. The pistons get to one in the (almost) fully raise position and the other low when it locks up.

I poured some more MMO down the cylinders and will check it out tomorrow before I pull the head.

Does it seem like a cylinder issue or crankshaft problem?

Complete side note and I may be nuts but it almost sounds like there is a click as it locks up coming from the magneto but (maybe?) it echos through the engine because I also hear it from the plug sockets. Is it possible that a magnet or 2 dropped off the rotor and is locking things up. Heard of similar issues with the Mercruiser 470 on my boat.

 

[mikidymac]

You won’t know until you start pulling it apart.

 

[TwoSmoker]

Best to pull it apart now before a potentially simple part replacement turns into an engine case replacement if you keep forcing it to turn over where you are clearly getting resistance when you shouldn’t be...

 

[Ckrawiec]

If the starter won't crank that engine easily with plugs out...STOP NOW. Take the engine apart if you are game to get down and dirty to find the PHYSICAL problem.....starters are very strong little devices and if it can't freely spin that flywheel, that engine has an issue...MMO won't help you at this point...you have to get inside it.

 

[Jris88]

Hey guys! Sorry for the delay, got sidetracked with other projects.

Finally got the head/cover off (without breaking a single bolt ). That was the good news, the bad news is it looks like there’s some visible damage. I attached a bunch of pics and was hoping for some insight as to which way to go forward with this.

The head/cylinders look good, though there is some damage to the bottom of the PTO piston. More concerning is below the head. There were metal shavings on the PTO side and below both pistons it looks like shards of the bottom case broke off (see pics).

Based on these photos is the bottom case useless now?

Im thinking next step is to pull the engine and crack the case open to see the condition of the rotary valve/cam.

Any thoughts or insight? Is this a lost cause / should I just get a rebuild from SBT? Or think it’s salvageable?


Thanks!

 

[Jris88]

 

[mikidymac]

Yup. It’s done.
Looks like the crank bearings might have gotten hot. You are going to have to do a full tear down and rebuild.

I would put the cylinders back on and remove the rear PTO before pulling the engine out of the ski.

 

[Jris88]

Thanks mikidymac - do you think the case is toast though? Not sure how I’d repair that.

 

[mikidymac]

I doubt the cases are bad but the only way you will know is to take it apart. Used cases are pretty cheap so I wouldn't worry too much about that.