Rusted Pistons

[Cyclopse]

I'm taking a look at a friends 97 Challenger, single 787. On the first ride after having a rebuilt engine installed by a dealer the boat had to be towed back to the dock, the engine would run but the jet pump wasn't turning. Fast forward three years and I've volunteered to take a look. Yep, I'm a sucker for these skis and boats. The driveshaft spins in the PTO so I've disassembled the driveline and the engine can't be turned by hand. I've sprayed some fogging oil in the cylinders, let it soak for half a day but still no PTO movement, I tried a pipe wrench with no luck. The PTO cylinder spark plug had some rust on the tip so I pulled the RAVE and found the Pistons and rings pretty badly rusted. I'll pull the Mag RAVE but you really can't eye into the slot with the exhaust installed. My question is, should I use the fogging oil, Bombardier Lube or two-stroke oil to try and free the Pistons. On the other hand, let me know if you think I'm beating a dead horse here.
Thanks for any and all help.


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[Sportster-2001-951C-Stock]

I think you're most likely beating a dead horse concerning the rust unfortunately, the cylinder sleeves are cast iron and probably toast, likely the crankshaft bearings are as well.

You can try to unstick it but good luck with that aside from perhaps rescuing the lower cases which have core value if not cracked/damaged too badly.

Many reman shops will remove the PTO and flywheel and install them for the buyer on the new engine but probably the PTO internal splines are lunched, the driveshaft splines might also be worn beyond service, so count on a new driveshaft and PTO as well, IMHO.

I wish I had better news for you, but 24 hours is about the cutoff for getting the water out and water is one of the big enemies of course. It seems this motor took on a big gulp of agua the day the splines failed.

Also, you'll need an alignment fixture to set the crankshaft perfectly parallel with the drive shaft, for maximum spline life.

 

[ialonso]

What's the goal? That piston looks pretty bad. Not sure what if any additional damage can be made to that top end.

You have to wonder how the bearings further down are looking like also. Was there some water ingestion, or perhaps a flooded engine before it was stored?

I hope I am wrong, and I am usually short cut man if I think you can get away with something....but I think you may do more damage to the engine by trying to get it running as is, than by stopping, and taking a few pictures and checking with SBT/Full Bore on their willingness to take this as a core for a rebuild.

I have not seen pictures of a piston that bad on a turning engine. If you get it to turn, it may cause even more damage to the cylinder.

I would verify with someone more knowledgeable (not me) before you continue the attempt to get the engine to turn. depending on where it's bound maybe you are bending an otherwise OK crankshaft. Maybe it's all shot anyway and there is nothing to lose...

EDIT: Never mind, seems *Sportster-2001-951C-Stock* who is much more knowledgeable than me seems to think it's a bad idea to try to free it. Sorry. Good Luck!

Good Luck!

 

[Dr Honda]

that engine is done. When it was towed back... you filled the engine with water. Then, it sat for 3 years (?) and rusted solid.


There's no bringing that engine back. Even if you crack it free... and it starts... it will eat itself.

 

[Cyclopse]

Thanks for your expertise guys, I knew I'd get the right info here. I want to restate that this is a friends boat, I don't know the circumstances under which it was towed or winterized but from the look of things everything was done wrong. This is a pretty clean boat, gellcoat isn't bad the jet pump looks to be recently rebuilt plus the seats have been re–covered. If the owner considers writing it off maybe I can get it for a reasonable price. What do you guys think, 97 Challenger needs motor, PTO and complete driveline . I'll look into SBT and Fullbore but do any of the Ontario members know of an engine rebuilder north of the boarder?

 

[racerxxx]

If it were me, I'd tear it down to get a look see. Best way to learn. Just keep loading it up with what ever lube you want. Or just get a reman.

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[Cyclopse]

racerxxx, when you say "tear it down" do you mean getting right down to separating the case halves? This wouldn't be the first engine I've torn down, I've rebuilt a few small engines but not a Rotax and I'm not shy to get at it but I don't have a machine shop. If this engine is going to need a crank rebuild I am going to need the services of a professional shop. If I do get this torn down and find it makes sense to get a reman, will any of the rebuilders take my core in pieces? I guess it's not a big deal to bolt it back together to ship it but I have no experience sending one of these motors out.

 

[racerxxx]

I'm not doubting that it possibly got filled with water when it was towed. But damn I'm not from Missouri but show me that bottom end first. At a minimum pull the rotary cover and take a look see and then make the choice. If the crank is a rusty heap then stop, if some how it's mint, commence full tear down if you capabl and inspect the crank. Missouri is the Show me state of you're wondering about the Missouri reference. Lol.

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[Cyclopse]

10-4, I'll dig a little deeper in the morning and I'll let you know what I find. I like the Missouri reference!

 

[ocod]

I'm not doubting that it possibly got filled with water when it was towed. But damn I'm not from Missouri but show me that bottom end first. At a minimum pull the rotary cover and take a look see and then make the choice. If the crank is a rusty heap then stop, if some how it's mint, commence full tear down if you capabl and inspect the crank. Missouri is the Show me state of you're wondering about the Missouri reference. Lol.

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10-4, I'll dig a little deeper in the morning and I'll let you know what I find. I like the Missouri reference!

Racer has you pointing in the right direction.
I don't have the picture from a recent 787 I got that was put away with water and had not been run for a while.
Have to get them from other phone but he may have them
It sat outside uncovered and more water filled ski since PO left the plugs in while on the trailer.
:facepalm:

Pull the RV cover like he said and see whats what but that motor is toast imo.
You should be sourcing new engine VS worrying about that one at this point if you plan to use boat this season.
Dont be surprised if you beak every bolt to magneto housing or to get top end off. I did.
No sense trying to save a buck if theres doubt or its a part for potential failure
Would you want to blow a hole in the case?
Ask racer how much its cost to replace everything on his resto skis. Boat is no different and you know what they stand for "Bust out another thousand"

Racer's BIL just had to suck up paying for new DESS port at dealer price having one at one 4hrs away ea way on while on vacation. Now thats commitment!
http://www.seadooforum.com/showthread.php?76155-1998-Seadoo-SPX-Resto-Project&p=474856#post474856

 

[Dr Honda]

If you like to work on stuff... and you can get it dang near for free (or very cheap) then heck yes... buy it, and rebuild it. FYI... I wouldn't pay more than $500~$900 depending on the physical condition.


Think about it....


If you can get the boat... and all the parts for a total of what the market price is for a running boat... then you will know that the entire drive is "New"... and it will last you a long time.


I've restored 2 seadoo boats, and both served me well after.


My 96 Sportster had a new engine... but was ugly as sin, and the pump needed love.

My 2001 Islandia was in pretty good shape cosmetically, but the engine was blown.

 

[Sportster-2001-951C-Stock]

Pull the head off too, so we can see the extent of cylinder sleeve rust. I guess it's extensive b/c aluminum pistons don't grow orange oxide in presence of moisture but the steel and iron do.

 

[Cyclopse]

Sorry about the late reply, the rain finally quit and I've been out on the lake with the working toys.[emoji3]!

PTO side

Mag side

So I opened up the RV for a look at the bottom end, Mag side looks clean and the PTO side shows some light rust. This is starting to look a lot better than I had originally feared. Now that the top end has had a day of repeated oiling I've put the pipe wrench back to the PTO and gently got it to turn. The rings of the PTO piston appear to be keeping the piston from rising past the RAVE slot and I don't want to force anything yet, I'm still adding oil. I am going to pull the head like Sportster suggested and post pics. I forgot to mention that the driveshaft rubber bumper at the PTO end was disintegrated. When I fully insert the driveshaft into the PTO without the bumper the driveshaft will turn in the PTO, if I back it out about a quarter inch the splines engage and it feels 100%. I haven't cleaned the grease from the splines yet to measure the depth and compare to the pump end but does this sound normal? I'm thinking that with a new rubber bumper and the right amount of grease in the boot the driveshaft to PTO connection might be salvageable.


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[racerxxx]

Have you removed the rave?

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[Cyclopse]

Both raves are out. The first picture I posted was looking through the PTO RAVE slot. The Mag piston isn't as badly rusted but I couldn't get a good picture.

 

[Sportster-2001-951C-Stock]

Yeah, that's the thing... When a 2-cylinder comes to a stop both exhaust ports will be open to atmosphere. Doesn't look like it was terribly flooded, there might be hope for that crank.

Some others have discovered missing driveshaft bumpers too. Can't recall if the splines were damaged from that.

 

[Isaac-1]

I have had good luck freeing up pistons on 4 stroke engines with a mix of half marvel mystrery oil and half automatic transmission fluid, the key is to let it soak. Check to see if things are starting to free up every 5-7 days, repeat.

 

[Cyclopse]

I got rained out again and had to return to work for a few days but I'll get back to the boat on Friday. I'll get the head off and post some pics of the cylinder sleeves by Saturday.

Thanks everybody for your continued help. If it wasn't for these forums I would never have gained the knowledge to be able to work on these boats and skis.

To all of the American members, Happy Fourth of July! I hope the weekend brings you some fine weather and some quality time on the water. Stay safe.
Chris

 

[racerxxx]

I'm interested in more pics of this engine. Those cases are from an RFI.

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[Dr Honda]

Yep... doesn't look too bad in the lower.


I guess I would change my statement now.


Personally... I would pull the jugs... give it a VERY QUICK hone... replace the rings... and go ride.

 

[Cyclopse]

racer, here's a couple of shots of the engine.

The cylinders don't look too bad, some light rust and scoring.

PTO cylinder

Mag cylinder

I'm pretty sure you can still see some hone swirl in this one

The heads look good

Overall I think this is not too bad. I like Dr. Honda's advice of a light hone and git-r-done. The PTO piston still won't rise past the RAVE slot but if I pull the cylinders I can clean up the rings and grooves and make sure they are in spec. Any ideas on what causes the scoring on the intake side? I'm told this engine has one hour of operation on it.


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[Cyclopse]

Dr. Honda, I just re-read your post. I'll put in new rings.

 

[Sportster-2001-951C-Stock]

Yep, seems like those should clean up pretty well.

If ring-end clearance is insufficient or ports aren't deburred and chamfered following a bore job, the rings will tend to snag in the ports. A tell-tale sign of that is scoring just above/below the ports b/c too much oil is being wiped off the rings.

It might've been running hot too, given the PTO splines weren't engaged the jet pump provides cooling water. Too much heat will vaporize the oil off the cylinder sleeves.

Looks like someone went RTV wild and crazy on that serial tag.