Help! Borescope--Inside my engine Engine. Is this healthy?

[Iceman2017]

So I've got twin 717 in a 2000 Challenger. I've done everything carefully and by the book, rebuilt both carbs, replaced oil filter, replaced fuel\water separators, wear rings are new, impellers are good, and have fresh gas. Been running GREAT...:until yesterday!
I sucked up a TON of weeds and overheating alarm was going off loud...I'm really hoping I didn't fry anything but since I know nearly nothing about the actual engine I thought I'd see what you guys know...when I got it on the trailer the one engine would start but die immediately when given gas and wouldn't go above 1500rpm.

clean out weeds from both sides front and back.

I went in with a borescope through the spark plug holes and the attached photos are of the top of the positions looking down. Is the black looking stuff normal or did I ruin my pistons??? Anyfeeeback is greatly appreciated. Also compression is 130 on both pistons(using a cheap $25 checker from amazon) SEE PHOTOS, thank you!

And other piston from other spark hole:

I have a video of the borescope of anyone is interested or if it would make any difference in diagnosis. Thank you all very much for any help or advice.

 

[Iceman2017]

I'm not even sure what the positions are supposed to look like, if anyone has a photo of the top of a healthy 720 that would be awesome

 

[bell99man]

I am by no means any authority on this so if anyone else is more informed please correct me.

That looks like a normal piston from a machine running a little on the rich side to me. It's carbon build up from not quite getting a complete burn of the fuel. Ruined pistons that I have seen on this website are usually chalky to light brown with pits in them from metal breaking away due to very high temperatures. The heads often have pits and the edges of the pistons near the exhaust ports are pitted with the rings exposed or broken. If you didn't keep running after the alarm, you're probably okay. Try to keep in mind when problems occur while running a 2 stroke that there is no such thing as blowing or clearing it out. If it isn't running right, something is wrong. Tow it in and take a look. Believe me, it's cheaper.

Double check that everything is clear in the jets. With the plugs out, try rolling over the engine by hand. Yours should have a pto on the rear of the engine. Grab it and turn. Feel for friction or scrubbing. Have a helper watch the impeller to see if it is rubbing on the wear ring.

Did anything else happen that day that might contribute? All wiring is good and fuel lines are good? Use your scope to look at piston walls and the ports if you can. If it all looks okay, you might have a second problem. When it starts, what happens? Do you use the choke? Can you keep it running using the choke? Does it die suddenly or will it only stumble a little and never really get going? Give as much detail as possible.

 

[Iceman2017]

[MENTION=56393]bell99man[/MENTION] thank you for the reply. I will try and scope in on the piston walls and everything later on. Wiring is all good, and My fuel system is all good, newer lines, new filters and rebuilt carbs using OEM mikuni. After letting it sit overnight, i checked the compression again got same 135 reading. I cleaned the spark plugs and then it started right up. It seemed to idle ok and throttled up without killing itself. Initially it would idle fine and then die suddenly when I gave it the slightest bit of throttle. The odd part is that it now seems to run after cleaning the plugs and letting it sit overnight. Is it possible that there were still weeds in the jets that dried out and became brittle then blew out when I was compression checking? Would wet weeds initially have created enough friction that the shaft wouldn't turn well and kill the engine when throttling?

I'm guessing at this point I would like to know for sure what the health of my pistons are and wether or not my compression of 135 is ok or not.

 

[Iceman2017]

I am by no means any authority on this so if anyone else is more informed please correct me.
That looks like a normal piston from a machine running a little on the rich side to me. It's carbon build up from not quite getting a complete burn of fuel...

Should I clean the carbon off? Or will i likely cause unnecessary problems trying to clean the piston tops? If I should clean the carbon how do I even do that?

 

[wittock08]

Everything looks pretty normal. Clean the weeds out good and try running some amsoil as that stuff really cleans off carbon. What kind of oil are you running now? Your compression numbers are superb.

 

[Iceman2017]

[MENTION=15880]wittock08[/MENTION] I have valvoline tcw3...that was in it when I recently bought it. I had considered replacing the oil with the proper API-TC seadoo oil but I am a newbie and too nervous to attempt flushing and replacing all lines and oil. I've been told 50% of the time tcw3 is fine and then been told 50% of the time I need to switch to API-TC...I figured since it's been running good on the tcw3 that's already in it, I should just leave it instead of risk messing something up trying to change it out.

 

[wittock08]

Yeah I'm no oil expert
And believe tcw3 is good for all two strokes, but I've seen so many top end issues with jetskis that if a oil is proven for 10+ years
With no topend issues you best believe that's what I'm using. Plus regular maintenance helps as well. Best of luck

 

[Iceman2017]

Thanks [MENTION=15880]wittock08[/MENTION] . Do you think it'd be safe to switch amsoil by just refilling the tank once the oil that's in it runs out? Also, is there anything I should be doing to maintain my actual engine bottom&top?

 

[tkarvelis]

DO NOT just refill. You can create a glob of crap if the wrong two oils mix.

Suck as much oil out of the tank, remove the oil hose on the injection pump and drain. Install new filter. Drain the large hoses that go to the rotary valve and remove all the oil.

Check the small oil injection hoses and make sure they are not brittle. If they break, there is no oil going to the cylinder... Replace as necessary.

Do searches on the forum... There are a lot of discussions on changing from one oil to another.

 

[wittock08]

I've changed oils all the time in my snowmobile without issues. I'd feel pretty confident to run new oil once your current oil level is very low. I currently have a gallon jug of about 5 different oils in it I've had for a year that I've used for snowmobiles, weed eater etc and theres no clumping.

 

[wittock08]

Try amsoil for a year and re
Borescope again to see if it's helped.

 

[bell99man]

Twc3 will ruin a Sea-Doo. You need to run the Sea-Doo XPS or equivalent. Your oiling system has filters that should be replaced if you switch and I would replace all of the small oil lines while you were in the changing mood. The black build up may be related to the high carbon content of the oil. Look up your owners manual on the internet for recommended oil and the difference in oils used in these engines compared to typical 2 stroke engines.

 

[Iceman2017]

Thanks everyone....big question, if I wanted to change oil and all the lines; can I do all that without removing anything like carbs, exhaust, etc????

I may consider switching to oem oil but still not sure why it's 50/50 split on the whole twc3 vs API-TC...some say twc3 kills seadoos but my challenger with twin 720's seem to be fine after 130hrs.

I like doing things by the book so if I can find a step by step on changing the oil and lines I may give it a shot, just real afraid of messing something up when I have everything running good now.

 

[bell99man]

Did you look up what the engine maker recommends yet? Would you put 20-50 weight Kendall racing oil in your Briggs and Stratton mower engine? Oils are designed differently for different purposes. There is no 50/50 argument from your Sea-Doo dealer or mechanic. The oil used in these is low ash to prevent carbon buildup around the rotary valves, RAVE valves, and other components. These also turn 7000+ rpms where most outboards do not. I imagine Skidoo also did not recommend twc3 oil in their engines as they have the same parent corporation. Poke around on this site for more information on this subject and the manufacturer's website. That 720 engine will last many more hours if well maintained. Why risk a ring or rod failure over and oil selection? SeaDoo branded is more expensive but as long as you use oil within the recommended specifications brand is less important. Amsoil is nice but pricy to me. API-TC is the thing that matters. Quick Silver has one. Mystic petroleum makes one. There may others. I found a PDF version of this manual but this forum does not allow cut and paste of this type. Look for seadoomanuals dot net but type it the right way. Read page 48.

 

[Iceman2017]

Thanks everyone, and [MENTION=56393]bell99man[/MENTION] , yes I know the paperback operators manual I have says use seadoo oil. As far as the manual on seadoomanuals dot net , I can't find mine for a '00 Challenger boat. I found one I think is correct in this seadoo forums manual section, but I can't open it on my phone..I'll have to go to my computer. I guess I'm going to swap to use the correct oil, just need to find enough instruction on how to do it, I'll keep looking.

 

[etemplet]

I worked at an additives plant for 28 years. I agree... seldom would one have issues switching oil brands. Sometimes over the years stories get carried away and old stories get carried forward. No matter what anyone does, there will still be residual oil left in the tank, lines and sump.

Many Many years ago one type of oil that was meant to be mixed with gas (premix) was put in oil tanks (when the injection pumps became standard on outboard engines) and over time it developed problems being all by its lonesome. That oil was meant to be premix so they had to fix that and a lot of motors as well. There were also issues with synthetic oil base stocks where they didn't like one another. Polyalphaolefins and Ester Based oils having issues. I believe this too was rectified a long time ago. Due diligence is always a good idea but for it to be a problem for drainin all oil, lines, and giving the engine an enema.... I'm not about to make that call for anyone else but I'm for darn sure not doing it. LOL . Good Luck !!

 

[Spimothy Leary]

I used TCW3 for a year on my 787 before someone (here) said "dude that's the wrong oil" the only difference I found was that the Rave's gummed up pretty bad.

So its not like its an engine killer overnight, but over the long haul it makes sense to use the correct oil recommended by the manufacturer, and all those highly paid engineers.

 

[soccerdad]

I must be bored to get in on this thread... The 717 can use mineral oil, the semi-synthetic or full synthetic. The motor does not have RAVEs so it can use any of those. No panic, no destruction, just pick an oil that fits in the Seadoo recomendations. It does not have to be XPS. But for good practice, just drain out the old and don't mix them. BTW, that piston does not look that bad.

 

[Iceman2017]

Thanks again guys. And [MENTION=69521]soccerdad[/MENTION] THANK YOU FOR ANSWERING MY ORIGINAL QUESTION! Haha. My thread got a little carried away to the point we're on the oil topic...now that I know the pistons look good, I think I'll swap the oil for the recommended type. Do I have to worry about draining oil from the crankcase or rotary valves? And again, will I be able to do all this without removing anything?

 

[blairwill4]

lots of misinformation here. Soccer dad is right. No raves= does not need xps. I wouldn't recommend picking the cheapest outboard dirt oil off the wal mart shelf but there is ZERO need for 45$ a gallon xps. That piston wash looks perfect. You want 4-5 clean spots about the size of a finger nail. Run and flush with the hose and then go put it back in the water. It could have been heat seizing from being overheated. Run it on the trailer for awhile on the trailer and make sure its peeing out the back of the ski before giving it hell. Should be just fine. and Stay out of the weeds lol.

 

[mikidymac]

Thanks again guys. And [MENTION=69521]soccerdad[/MENTION] THANK YOU FOR ANSWERING MY ORIGINAL QUESTION! Haha. My thread got a little carried away to the point we're on the oil topic...now that I know the pistons look good, I think I'll swap the oil for the recommended type. Do I have to worry about draining oil from the crankcase or rotary valves? And again, will I be able to do all this without removing anything?

The easiest way is to use a pump to get most of the oil out then remove the oil tank. Then use the same pump to get as much oil out of the two large lines going into the crankcase. Clean out the tank with some solvent and replace the oil filter.
Now is also a great time to replace the small 3/32" oil lines since they break with age and starve the engine for oil. Next put it all back together and refill with your new oil of choice, hopefully some form of API-TC. Then open the small 6mm bleed screw on the oil pump until you see your new oil coming out with no air bubbles. Then gently tighten it as they can strip out. Finally start the ski and while idling hold the oil lever arm wide open and you will see oil pulsing into your new 3/32" oil lines. Once it reaches the engine you are done.

 

[Iceman2017]

Awesome. Thank you guys!

 

[Chester]

I used TCW3 for a year on my 787 before someone (here) said "dude that's the wrong oil" the only difference I found was that the Rave's gummed up pretty bad.

So its not like its an engine killer overnight, but over the long haul it makes sense to use the correct oil recommended by the manufacturer, and all those highly paid engineers.

The main reason why API-TC low ash is required (even on non RAVE motors) is that TC-W3 will increase rotary valve wear. BRP required API-TC way before RAVE valves.

Chester

Chester