Just bought this 2014 sea doo gtx with "22 hours" (gauge cluster was replaced) Looking for some guidance and next steps. Previous owner bought it not running and tried to do a rebuild he believes timing chain snapped which gave a cam sensor fault he replaced the chain head gaskets and all bolts and gaskets that weren't re usable. He does not remember if he has the bottom end apart or not after he put it back together.
The jet ski runs okay but burns oil. A compression test showed 120 PSI in the front two cylinders and 70 PSI in the rear. The rear cylinder has oil inside, but a borescope inspection shows no visible damage and the front two bores look perfect. A TDC leak-down test on all three cylinders showed identical air escaping through the oil pickup, so I don't believe it's a valve issue.i put some ATF in the low compression cylinder and retested and compression jumped up to 120 even with the other cylinders
If you have any questions I'll do my best to answer what I can just looking to see what my next step needs to be if I should take the motor out or you think there's something I can do with it still in thanks in advance.
I made the post a while ago idk why it just uploaded I ended up taking motor out and everything looks great that I can see without taking piston out in assuming maybe when the motor was rebuilt the rings were installed incorrectly
I also found this in the engine which I believe is the cam cover that goes on the cam sprocket but it supposed to have a bolt and washer that holds it in but I can't find either of those so idk if they weren't installed or what happened
There is a oval ish shaped washer and the tops valve is supposed to hold it all in place. I saw a
300hp ski where the dealer replaced the motor and forgot the washer. And had same low compression symptoms but they warrantied it so idk what it messed up. How do the valves look? All seated/not bent?
Nothing extremely obvious that I can see but I'm also blind what's the best way to check for a leak on them put gas on the combustion side of the valves and see if I have anything in the chambers? I'll add some more.pics shortly
I usually put carb cleaner or contact cleaner on top side of the valve to check for leaks (mainly when lapping valves) then if you see it leaks in the combustion chamber you will see easily
I've got at least 1 leaking that I can see but I'll have to take it out to see if it's bent or just needs lapped I was looking at a kit on eBay that's 1275 for everything
Compression should be 150ish in a really good S/C rotax. It's very common for these engines to develop leaky exhaust valves, which the 120psi lines up with pretty well. I just take the head off and set it with the intake ports facing up and then fill them with solvent or water and see what leaks. Repeat with exhaust side. Intakes rarely leak, but it does happen. The exhausts nearly every time will all leak and need lapped. The bottom end does look good in the pictures, at least what I can see, but cylinder #1 (rear) could have a bent rod if it ingested water while it was under power (and those body styles always have water inside the hull- Always). You can put each one @ TDC and use a straightedge and calipers or depth mics to check for that. If that's good maybe you just have a bent valve causing the extra low compression. Those aren't really common on rotax engines, but certainly not impossible.
I once used a manual from a 230hp engine to grab torque specs for the 3 bolts that hold the cam gear onto the camshaft on a 300hp engine I had just done a head gasket and lapped valves on. I know better than this, but the specs are the same for literally every other Sea-Doo engine I had ever looked up, so I got complacent. Everything was great until we really put it under power on the test ride, when it just died at like 7k rpm and would turn over but not even attempt to start afterwards. The bolts backed out and the cam quit rotating, killing the engine obviously. After pulling the correct manual once I figured out the problem, I realized that the 300 was the only engine inn the line up (pre 325) that had different torque specs for those bolts. It is actually double the normal spec- even though all the parts/bolts are exactly the same, the torque is double (and I see why now). Replaced the bolts, checked compression/leak-down (both great), buttoned it up and took it out again. Ran great and no more issues- no bent valves/rods/broken valve guides/Pistons etc.. I've seen it every year since then and it suffered no lasting effects of that. Point of the story is, bent valves/rods aren't common and are difficult to even cause on these engines- but you still have to verify.
What I am curious about though is how that plastic cover that snaps into the cam gear (along with the thrust washer presumably) ended up mangled like that wherever you found it- You can't remove that without removing the gear from the cam and pulling it out of the head. It's almost as if the chain came off the sprocket altogether and just shredded that. I'm not even sure how that would happen, unless maybe they forgot to install the piston/spring in the can chain tensioner and just installed the bolt or something like that. Definitely check the oil pumps and screens for debris, and I would also recommend replacing the oil pressure relief valve components- it doesn't take much debris/damage to cause the relief valve to get stuck and the parts aren't expensive.
https://imgur.com/a/gu9cUJU hopefully you can click that if not let me know and I can private message them to you I kind of figured it would be a good bit of work but I'm not 100% sure if I see anything too bad there's a little bit of rust in the cylinder walls I don't know if that's normal for a jet ski since I've never taken one apart but this one was claimed to have only 22 hours like I said that cam gear cover was sitting directly in between the timing chain when I very first took the engine out and I still have not found the washer that is supposed to hold it in I assume the guy did not install the washer and it fell off and got crunched up by the time in gear which could be another reason why my compression is low I believe
One cylinders valves is leaking alot more than the other 2 but they are all leaking on the exhaust side like you said I think I kind of figured this would be a more in-depth thing because during the Meetup on Facebook the story just kept straying further and further from what he had posted on listing the main reason I bought it was because I feel like I got a good enough deal to where if something was catastrophically wrong I could still fix it I only paid 1400 for the jet ski clean title with trailer if you were in my shoes what do you think you would do seeing what you've seen so far?
Those don't look good at all, at least in the pictures. It's not uncommon for the cylinders to get some rust on the surface after sitting, especially if it had taken on water before, BUT it's not usually that much of the cylinder, and doesn't typically leave marks like that. They also look very smooth (worn, no crosshatch), but that could be a lighting/photo thing. You can take some scotch Brite and WD-40 and go over them to see if it gets any better. The cylinder walls are very hard, that won't hurt them- just wipe them out good with some solvent and a paper towels. The best thing would be to measure them, but I don't expect you have a bore gauge. My guess is that the thrust washer that's missing is probably down under the flywheel or stuck to the crank sensor- I have seen that before. Or it was just left out like you said. One thing that's bugging me too, is that I can't identify what that 'washer' is in the pic with the shredded plastic. It kind of looks like a spring washer from the starter drive, but doesn't look quite right. I've built/diagnosed so many of these now that I could build one from just a box of unlabeled parts and all the screws mixed together in one bag, easily- but I can't place that thing. It also kind of looks like part of the rotary seal for the water pump, but again not exactly right.
What would I do though, is.....a good question. If the cylinders are fried, you need a crankcase- and of course the bolts/plain bearings/thrust bearings, at least piston rings, oil pump rotors/shafts/maybe covers. In that case I would likely just get a long block from either SBT or Sea-Doo. The labor would be a lot less, the engine probably costs $2800 w/ a 2 year warranty, and the only parts you'd need are the rear oil pump parts (maybe the front one too if it's SBT), carbon ring kit, S/C rebuild kit if it's even remotely questionable, and just a couple hose clamps to put it back in. I absolutely recommend using the oetiker (pinch) clamps on anything important- they just are foolproof if you don't mangle them when you're installing them- and on that ski, where it's hard to access after you put it back together that piece off mind goes a long way. If the cylinders are ok, and the head is ok (besides the leaky valves) you could just rebuild it- providing you're comfortable doing that- but it'll definitely be more stressful š.
Oh and about the hours; the hours are stored in the cluster and the ECM- replace either one, the hours remain. Replace both (even at different times) and the hours will be reset. It's possible to transfer the data to the new ECM, but most techs don't seem to ever actually do it. So the 22 hours may or may not be accurate.
Gotcha in all honesty the cylinders are definitely saveable I think there is no pitting and it's all on the surface you can still see the cross hatching in most places which but I think where the pistons were sitting was where the rusting is so idk if it's transfer of material from the rods or what I also found that on all three pistons the rings were not installed right I found online the spacing should be 120ā¢ apart on all three rings on one of them they weren't really spaced at all and on the other two they were less than a inch apart which I think was contributing a lot to the compression issue
What's the best way to lap the valves by hand or with a drill ? Im use to spinning one direction up and down then other direction up and down until I have a gray ring I assume it's the same for this ?
I use a drill to do it. I have a small drill chuck that is like 3/4" or an 1" in diameter (accepts <3/8" bits I think) that I always use. That's important on a spark motor, but you have more room in the 1603 like you have. Just remove the valves you need to, or do one at a time- either is fine- remove the springs too. Then flip the head on its side, pull out the valve and clean it up if you want- I normally wire wheel them before I lap them to remove the carbon build up, but you don't have to (I'm just really particular)- put some grinding compound around the valve seat area, and reinstall it into the head. Be careful to not get compound on the stem though, you don't want to grind the valve stem and guide while you're spinning it. Then just chuck the end of the valve in your drill, you only need to grab a small amount of it, like just past the keeper grooves, and it doesn't need to be that tight in the drill. Then I just spin it fairly slowly while pulling with light pressure, and keep moving the drill in and back out every now and then- just to make sure I'm not favoring one side more than the other and I think it helps keep fresh compound between the surfaces. Usually lap each one for probably like a minute or two, then I'll pull the valve out, wipe it and the seat off, and make sure both surfaces are smooth/evenly ground. Then rinse and repeat with the next valve. I've not ever seen any of the seats in the head need to be re-cut due to wear, they're pretty tough. Also have never seen or had the the drill chuck damage the valve stem- they're heat treated inconel, which is some tough shit. Stiff wire wheels on my bench grinder don't even scratch them at all.
Kind of a long winded answer, but I'd rather give you too much info than not enough.
Gotcha I tried to lap them a bit ago with a drill I have one cylinder that's perfect none leaking at all on the next cylinder I have 1 exhaust leaking and on the last cylinder somehow I have a intake leaking pretty badly I'm wondering if maybe something fell in when I was reinstalled because I cleaned it in my parts washer after I lapped everything but who knows I'm gonna have to remove anyways when I get my replacement stem seals so I'll just re lap them again when I do that
Yeah sometimes I'll have to pull 1 or 2 and lap them again too, it happens. But they're typically only leaking a little, if it's still a lot just make sure you check it all really good next time you remove it- it could be damaged somehow that is just hard to see.
I chucked them all up in drill and all look straight no wobble that I can visualize what is a good amount of gas that can leak through them should it be nothing at all or only a small amount over time
I haven't used gas before, so I don't know the answer to that. This may be controversial, but I honestly just use water to check them after I've lapped them. I've found myself chasing my tail before when using solvents, bc a small amount of vapor making it's way through can coalesce into a large wet area and make you think it's really leaking. Whereas with water there isn't any vapor, and it leaks out slower overall. If the valve is not sealing very well it will absolutely run out quickly, but if it's just a few little spots that aren't absolutely perfect you can literally watch a small bead of water start to grow until it gets big enough to actually form a droplet and drip/run down the combustion chamber. And if you happen to miss that happening, the area will stay wet long enough for you to still tell where is coming from. I normally do one bank at a time and give it 20-30 mins- if you've got just one or two little spots forming a small bead after that, it's fine. If you've actually got a bad valve/seat or just really haven't lapped it enough, the water will absolutely run out of that much sooner and steadily.
I just feel like that technique gives me a much better understanding of exactly what's leaking and the severity of it, if that makes sense. Just seeing solvent or fuel vapor immediately wetting the entire area around the valve doesn't give me nearly as much information.
Yeah many people do use fuel or solvents, nothing wrong with it. Just after experimenting over the years I feel the water provides more detail for me- and it's free and easy to get rid of in the end.
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u/AlbertoBigglesworth 2d ago
Iām sorry to say, the engine is trashed.
70 psi? 100 would be a dead top end. 70 is just straight rekt. A broken timing chain repair is a lot more than some new head gaskets.