hole in piston - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

south coach · 09-17-2011, 05:31 PM

I bought a used 2007 vx cruiser with only 73 hours, very clean, like new appearance. When I test rode the waverunner it had a rough idle but it ran good once you rolled the throttle. I thought it might just be a bad plug or something minor, I talked the seller down $200.00 and took the waverunner home. I rode it that weekend and again it had a rough idle but it ran good once you applied the throttle. I went to change the plugs later in the week and found that one of the plugs was rusted and wouldn't come loose. I sprayed it with penetrating oil and let it soak for a day. I then tried to loosen it again but I broke the plug off. I tried an easy-out but it still wouldn't budge. I ended up pulling the head and took it to a automotive engine rebuild shop and they were able to extract it and repair the threads. The mechanic said he appeared to him that some valves where sticking and he cleaned the head and I believe he said he used penetrating oil to free them up. I put the engine back together being very careful to mark the cams and cam chain with the number one cylinder at TDC.The engine started right up and idled good but it would only run about 40 mph. I thought maybe I put too much oil in it and so I brought it home and check the oil and air filter but they were good. I took it back out the next day and it wouldn't idle and after about 20 minutes of riding, it quit. I took it to the local Yamaha dealer and the mechanic sid ti had a hole in the piston and estimated the repair at $7500.00. Needless to say I am very sick, my wife was already not thrilled with the purchase, so my house has been a little stressful lately. I tore the engine apart and the number 3 cylinder (same one with the broke plug) had a broken intake valve (middle) in the cylinder. The piston has a hole beat in it and the cylinder has significant scarring. I need help as to what is the best course to take. Can this engine be rebuilt or do I buy a rebuilt engine from some provider like SBT? I surely can't afford to put $7500.00 in this waverunner and I need to keep the cost of the repair reasonable. I would be great full to some sound advise.

Outlaw · 09-17-2011, 06:20 PM

First off I think the price quoted for the repair is ridiculous. You can buy a new ski for not much more. Was the ski used in salt water at all? The reason I ask is the corrosion is usually from salt water. Typically that machine is used by rental companies due to its reliability. You would think the guy that cleaned the valves would have noticed something was not right. If it were me I would check E-bay and craigslist for parts. SBT engines are ok if you can get the right price. But why if it only a piston failed can't you replace it if the cylinder isn't scored. This doesn't bode well for Yamaha if it just parts failure, 73 hours is nothin for a 4 year old ski. I am sure Ernest T will hit you up as he knows way more about Yamahas. If not then send him a P.M.

Good luck...

south coach · 09-17-2011, 07:10 PM

Thanks for the reply. the Yamaha dealer was ridiculous. The cylinder is scored pretty deep. I bought the ski from a military person that made the initial purchase in Hawaii. He rode it very little before bringing it back to North Carolina where I purchased it. The guy had been deployed a couple of times and so the ski had set a lot in his garage. The ski looks like new and I believe when the previous owner used the ski that he kept it flushed and pretty much babied the ski.

Ernest T · 09-17-2011, 07:15 PM

Yea for $7500 you can buy a really nice used FX HO Cruiser, or maybe 2 VXs if you shop around.........that's crazy.

The VX has Nikasil cylinders, so you basically can't re-bore, and I'm pretty sure they don't even make oversized pistons for them. Probably your cheapest alternative would be to have your head repaired and the damaged cylinder replated (I think they actually have to replate all the cylinders), piston replaced, valve repaired, etc. That would probably be around $300 - $500. There are a number of places that do that type of work, so you might want to do a search for someone near you and give them a call and tell them what you have. Here is one place that I know does PWC engines: http://www.powersealusa.com/

Other option: From what you describe, the damage is limited to the top end, so I'm not seeing a need for a complete engine replacement. You could do a head exchange with SBT for around $500.

Both the above options are assuming that you are doing the work yourself. You would need to pull the engine, so you need a hoist, etc..

If your not mechanically inclined or don't plan to do it yourself, I'd look around for a local PWC mechanic that could do the labor. They will be much cheaper than a dealer.

If the cost gets much over $3500, I'd say you are better off parting out the ski, and buying another one.

south coach · 09-17-2011, 07:28 PM

Thanks Ernest T. I am mechanically inclined and I have already pulled the engine and the head. I haven't split the cases yet and I suspect that the rod may be bent. I try to turn the crank by hand and it has a lot of resistance. Can you recommend a business that can recondition the cylinder? I live in NC and I am new to the Waverunner scene. I have been a boat owner for the past 15 years. I was just trying to find what I thought was the best bang for the buck in a waverunner for my 14 year old son.

Ernest T · 09-17-2011, 09:27 PM

Had a friend that used this place and was happy: PowerSeal USA. Give them a call and get a quote.

With all the stock car racing in NC, there is probably a shop local that could help, but I don't know of one.

A bent rod will be a lot more involved.

Outlaw · 09-18-2011, 09:36 AM

One option would be to buy an end of season rental ski. In my area of the mid atlantic the rental places are selling off this season's rental fleets at about half of retail pricing like $4000. These skis are actullay for the most part are better then some older years with less hours, reason being they were run every day and in most cases maintained better. running them every day keeps things from corroding.

Then you have options like fixing your ski and parting out the rest to help recover your purchase price. Or just the opposite buy the rental for $4000. and part out your ski. Bada Bing just like that. Since you know your way around a motor it would be easy for you to pick one of those out.

Just a less costly last resort.

south coach · 09-23-2011, 05:01 PM

I can get a SBT engine for $2195.00 plus about $300.00 shipping.I also found a guy in key west that sell engines out of salvage skis tgat are long blocks for around $1900.00 plus $300.00 for shipping. I am drawn to SBT because of the 2 year warranty. Any thoughts guys?

Ernest T · 09-24-2011, 12:35 PM

SBT gets mixed reviews for their rebuilt engines, but generally good. Keep in mind that you are getting an engine which has been rebuilt with Chinese parts. On the VX, which is not a high performance ski, you should be fine with an SBT engine.

On the other hand, it would be really hard for me to lay down $2500 for a rebuilt engine plus all the hassle of installing it, when nice used VXs are selling for around $4000. You could part out your ski and put that money plus the $2500 towards a good used ski, and be much better off IMO.

Anyhow good luck!

Outlaw · 09-24-2011, 05:27 PM

Quote:

Originally Posted by Ernest T

SBT gets mixed reviews for their rebuilt engines, but generally good. Keep in mind that you are getting an engine which has been rebuilt with Chinese parts. On the VX, which is not a high performance ski, you should be fine with an SBT engine.

On the other hand, it would be really hard for me to lay down $2500 for a rebuilt engine plus all the hassle of installing it, when nice used VXs are selling for around $4000. You could part out your ski and put that money plus the $2500 towards a good used ski, and be much better off IMO.

Anyhow good luck!

+1 thats what I was getting at with buying this years VX from a rental place for 4 G's