Seadoo 951 DI Failiure Analysis

Discovery of what the failure was on a Seadoo 951 di engine.

[@toddreid7660]

I watched the who video and was waiting for the wrist pin bearing needles or the rod from the air pump. Kudos to you sir 👏

[@SeadooRefurb]

I did not expect any damage. I was shocked when I opened up the head. I also discovered that they had not installed the washer that hold the air compressor rod to the counter balance . They just installed the screw. The rod pulled right off over the head of the screw no problem. my guess is that would have failed first cruise!

[@gary5209]

I’m not sure if that was the only cause of that engine failure. I have the exact same problem, top piston ring totally fragmented just like yours on the front cylinder except this particular motor still has standard size pistons. I’m not sure yet why this keeps happening to these engines unless it has something to do with the carburetors not working correctly and perhaps causing one cylinder to run too lean as in my case I have one cylinder very oily and the failed cylinder dry as a bone. That’s the downside to having two separate carburetors, one for each cylinder. If one gets stopped up the engine still runs but cooks the cylinder with the stopped up carburetor.

[@SeadooRefurb]

That makes total sense to me. I have seen all kinds of different things that cause engine failure and a major part is owner neglect / poor service work / or mixing oils. (turns oil clumpy)

[@davemall1]

I was guessing that the ports were not chamfered, but you proved me wrong right at the end.

[@SeadooRefurb]

I really thought it was the raves not filed correctly. I have never come across needle bearing damage . This is why I don’t like doing a rebuild in the machine. it is too easy to drop stuff in the top of the motor.

[@lynntatro7374]

Are you sure the bearings in the lower connecting rods are good? How about the main crankshaft bearings?

[@SeadooRefurb]

They are good enough for my use. If I was racing or hoping to get another 20 years out of them then I would put in a rebuilt crank. (1,000.00) Machines are now selling for 3,000.00 running so it is hardly worth spending the money.

[@gearwrench1davis392]

Have you had any luck with just boring the cylinders out to the next oversize or is it better to re sleeve it back to standard?

[@SeadooRefurb]

I have had great success with boring. The issue here is the sleeves are at .75 over so I can only go up to 1 over. I don’t think 1 over will remove the groove .

[@grast5150]

What are you looking for bearing on the crankshaft? Are you going to have it rebuilt? I though the golden rule was regardless of state of bearing, rebuild every 200 hours. OR is that misguided if the bearings and seals are still good. Do you measure for run-out before making that decision? thanks.

[@SeadooRefurb]

I am not looking for exact measurements. (runout). I am just checking for any physical damage. If there is no loose rods or crunchy bearings then I put the crank back in. A crank rebuild ever 200 hours is crazy expensive. (800.00-1000.00). From what I have seen.. the main reason the crank bearings go bad is due to submersion in water. I have never had a crank fail after reassembly.

[@grast5150]

@@SeadooRefurb OK, Wow thankyou. I have my second DI and did a run-out test which looks good within specs. I appreciate the feedback!

[@Ajsecord50]

Currently trying to find what’s wrong with my Rxdi, candoo isn’t helping. Can I email you?