Another 951 ingesting lake water

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OldSchool

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Well, not two days after I put my water ingested boat back in the water, my son's best friend and riding partner has joined the club. This 99 GTX limited ran missing a drain plug and took on a bunch of water.

Helped pump the water out, lubricated it, got it running again and back on the water within an hour. It idles fine, responds to light throttle but dies once any deman for power is requested. I had him run it while on a trailer backed in the water for a good 20 minutes just off idle to try to dry it out good, but nothing past a third throttle. Maybe 3k rpms.

took the boat back out of the water and the 951 wants to run away. This has air leak written all over it. Checked compression and it was low, like 90 on both cylinders, but it didn't seem to bleed off. I don't want to assume, but is it possible that the water that was ingested blew a base gasket or crank seal?

Out of all the ingested engines I have serviced, I cant recall that happening. When my 951 sank, it ended running normal after getting the water out, this ski ran great prior to this, but I can't help but think big time air leak now. With seat off and in the water while still on the trailer, there wasn't a drop of water leaking anywhere. I cleaned the RAVE valves and they were full of water/sludge.

I suppose I just found it odd that both cylinders measured at 90 psi. It seemed to me that a cylinder leak would leave one different than the other.

Before we yank his engine, I was just wondering if anyone thinks it could be anything else. Out of the water, it starts right up, idles normal for a few seconds and then starts screaming at around 4-5k rpms.

Thoughts? Pressure from water possible created leak? It sure seems like it.

Pulled head, very minor scoring on both pistons, nothing even close to the scoring one of mine has and mine runs fine. Should also note that while out of the water, when hose was turned on, it had an effect on the idle as it varied. Gotta be an air leak right?

99 GTX Limited 951, ran perfect until this incident this morning.
 
Honestly, Ive had a 99 run away because of a blown seal. I'd bet all the water pushed a seal out. Just an assumption of course. but anything that runs away with no load sound like an air leak.
 
4~5k RPM doesn't sound like a serious runaway to me, could just be a little lean on the idle mixture screws.

90psi compression on both? Are you sure your gauge is correct, drop a gauge on the concrete ground and it can be off by a mile. Double-check that gauge with your air-compressor gauges.

I don't know if anyone has ever reported reed damage as a result of water ingestion but it's one possibility I would be considering until someone straightened me out or I had torn the intakes off, whichever happens first. Maybe Mr Squirrel can comment, since he submarines his repeatedly.

I think you did good drying it out, how about the electric box where the coils are? It's kind of a judgment call when it comes to running a 2-stroke that doesn't run properly, generally not a great idea if it's not fueling properly that means it also might not be oiled like it should.

It won't matter much if the compression's only 90psi, that motor might have bent connecting rods from being hydrolocked.
 
The boat ran great prior to this event.

Compression tester is is money.

Pulled carbs and reeds, which are snapping closed and look perfect.

When it ran away, I actually killed it before it could get any higher than 5k rpms, but it seemed to waiver up there before I shut it down.



Electrical didn't get wet.
 
The boat ran great prior to this event.

Compression tester is is money.

Pulled carbs and reeds, which are snapping closed and look perfect.

When it ran away, I actually killed it before it could get any higher than 5k rpms, but it seemed to waiver up there before I shut it down.



Electrical didn't get wet.

Well, 90psi certainly isn't gonna fly let alone last for any period of time. Lucky the cases aren't full of holes by now, I'm thinking the rods may be bent. Do the pistons look like they're reaching full TDC?

Glad to hear the reeds don't get blown out from water in the crankcase, I hope to never get that sinking phenomenon.

Maybe you can throw a new crank in there, wouldn't that be a hoot?

Plan for the worst, hope for the best......
 
Well, 90psi certainly isn't gonna fly let alone last for any period of time. Lucky the cases aren't full of holes by now, I'm thinking the rods may be bent. Do the pistons look like they're reaching full TDC?

Glad to hear the reeds don't get blown out from water in the crankcase, I hope to never get that sinking phenomenon.

Maybe you can throw a new crank in there, wouldn't that be a hoot?

Plan for the worst, hope for the best......


The rods are fine, yes.. the pistons are making it to TDC. It is coming out and I will most likely have him order an SBT engine. I don't have a problem building my own when it is time, but on someone else's boat? Especially a friend's? Their warranty is probably more suited. I supposed if it just needs a seal job, I could do that, but it is probably seen enough time as it is and since it will be out, might as well replace it.
 
Is there supposed to be sealant between cylinder base and case on this engine? To my knowledge, my partner bought this ski and it had the SBT engine in it when he bought it. Do they commonly seal that area with a specific product? I asked in another thread because we are replacing the engine in this machine anyways.
 
It would be nice to know the compression before the incident, since it's already been apart once. The base gasket thickness plays a big role in final compression and of course squish around the edge of the piston crown.

If you're planning on running 951's into the future, it might be a good idea to make up a set of pressure-testing blank-offs, or maybe buy a set, I haven't looked to see what's available but the intake and exhaust have to be blanked/sealed up in order to perform a crankcase pressure test.

On the 90psi - It could just be a ring problem but it's strange both are the same. Makes me wonder if it's got the wrong base gasket on the cylinders.

According to the manual, there's no sealant for head or base gaskets, just molykote and locktite on the studs. I'd be hesitant to use copper based sealants on aluminum unless it was specified, these two metals can react and form corrosion.
 
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It would be nice to know the compression before the incident, since it's already been apart once. The base gasket thickness plays a big role in final compression and of course squish around the edge of the piston crown.

If you're planning on running 951's into the future, it might be a good idea to make up a set of pressure-testing blank-offs, or maybe buy a set, I haven't looked to see what's available but the intake and exhaust have to be blanked/sealed up in order to perform a crankcase pressure test.

On the 90psi - It could just be a ring problem but it's strange both are the same. Makes me wonder if it's got the wrong base gasket on the cylinders.

According to the manual, there's no sealant for head or base gaskets, just molykote and locktite on the studs. I'd be hesitant to use copper based sealants on aluminum unless it was specified, these two metals can react and form corrosion.

The only time he tested it was when he bought it, 3 years ago. He claimed it was just over 135, so it was a big shock to see it at 90 and running. Its apart now.
 
Follow up to this one.

The replacement engine in installed and running perfectly. The ingested water did blow the airtight seal and create a leak causing a major lean condition. Also to note was one of the oil seals had a missing collar (the spring around it was laying in the bottom of the case, straight as a needle)

Rods were perfect, bearings were perfect except for one that felt a tad rough. Even removing the water with care was enough to blow the integrity of the airtight seal.
 
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