Is my engine about to blow?

[IDoSeaDoo]

Went out with a couple other members on Lake Gaston this weekend. We rode pretty hard all day and as I was riding back to the boat ramp, my ski started losing RPM. If I let off the gas, it wouldn't regain RPM and would stall. I restarted, and the same thing happened. I was able to idle it in to the ramp, and then blow the water out, but I was alarmed.

The next day, I did a compression test: found that my PTO plug was black and sooty. Cylinder lost 5psi (145 now). Pulled Oil pump, and it tested fine. I got 2ml/min spinning ~3k rpm holding throttle WOT. The oil line did seem to have a few bubbles in it, but I don't think they were that big. The oil lines are only 20hrs old. I know for a fact that I had A LOT of oil in the tank. I filled it that day to the top. I pulled the head and did notice that the PTO cylinder did rub a little vertical stripe on the cylinder to the point where you can't see the cross-hatch anymore. In all other respects, it's the same as the MAG piston. This engine has only 20 hours on it (top and bottom end), and I put brand new (replaced everything) oem RAVES. The MAG rave was totally fine, while the PTO is already puking a stream of oil down the side of the jug.

Anyone have any hints, or ideas of what could cause this? I've been running premium gas in it and using only full synthetic Quicksilver API-TC oil.

 

[IDoSeaDoo]

Thinking more about this: could I be ingesting water? Maybe one of my gaskets is bad and is leaking water into the exhaust manifold... would this cause things to look all black in there? I would have thought the opposite. I have never seen the plugs wet with water, and the color was pretty similar on both before the "incident". This could have just happened though, and I just want to know what water ingestion looks like.

 

[howie099]

Even at 145PSI you shouldn't of drop in the RPMs unless something else is wrong. The plug all carboned up and with oil on it would make it not fire. Did you put in new plugs an try it again? Exhaust leaks will make run like crap.

 

[IDoSeaDoo]

I think it lost the 5psi because it started to seize up or something. My theory is that the black is from metal mixing with the oil, but I'm not sure why it's happening...I have a good used set of plugs that look the same and fire well (tested outside the cylinders). I'm going to put them in and try to test it, and keep a close eye on the plugs.

 

[howie099]

Unless you had a big air bubble in the line than what you think. I know those oil filters are hard to get those damn bubble out. I put a flash light to them to verify. You usually see metal or gray on the plugs when you are melting the top and you wouldn't see any wash on the top of the cylinders also.

 

[IDoSeaDoo]

I know that if I burn out a piston by running out of oil, the plugs and head and everything looks black

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[IDoSeaDoo]

So after making sure that my oil pump was okay and getting all air bubbles out of the lines, I put in a different set of plugs, went back to the lake and confirmed that the PTO plug is getting black soot on it again. In about 5 min of riding, it was noticeably darker than the MAG plug. I stopped running it. I am not sure what could be causing it... maybe the little injector somehow got broken and isn't letting oil into the RV chamber... I highly doubt this can happen as that oil has been filtered and the oil pressure would probably pop the line off and make a mess in the hull (which has def. not happened). My next step is to premix some fuel and pinch the oil pump line and run it for a little bit. Is this a bad idea? What happens if the oil pump runs without a supply of air or oil? Is it a positive displacement pump?

 

[howie099]

You check the carb settings also? Black soot would be to rich or to much oil. Not enough your plug starts to turn silver from the metal sticking to it. Maybe have leaking or stuck needle? Bad coil or plug wire not firing all the way. Post some pics of the plugs from all angles for people to see..

 

[IDoSeaDoo]

Don't have it atm,but the plug doesn't appear to have metal on it. However, the loss in psi and the scoring on the cylinder indicated to me something bad is happening. Rich or too much oil, or weak coil can't cause scoring, can it?

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[howie099]

you had some air bubbles in the oil line that might of changed your oil intake on the one side, but if the compression is staying same and not dropping that part must be good. If you are lean or short on oil you are done in just a few minutes. You would never get this long to test it running before the rings would freeze, bottom blows and game over. I know I did one in a few minutes.. It still sounds like you are getting to much gas/oil but even if the pump broke you get 40:1 so you shouldn't be fouling plugs running it.

 

[MPower]

I can't help but feel this is related to your PTO RAVE leaking like a sieve. All that oil in the PTO cylinder would be leaning out the fuel and that cylinder running lean which may explain the scoring you found on the cylinder. Also assuming all that excess oil would explain the black soot all over your plugs and inside the cylinder.

I say figure out why that PTO RAVE is pouring oil out. I know you just replaced that crank but is it possible one of the seals is hosed?

 

[howie099]

I found other posts saying this what which leads to an carb issues if everything has been done to the RAVE's. Here is it below. It doesn't hurt to check the carbs out.

'I own a 97 sea doo spx that has a 787 engine. The Rave Valves leak a black oil substance. Is this a major problem? If so what should be done to fix this problem?'

'If it leaks excessively, even after you rebuild the rave valves with new orings and diaphrams, then you probably have a leaky needle valve inside the carbureators or some really bad sparkplug wire connections, as you are not burning off all of the fuel in that clyinder, and the unburnt fuel is being pushed up and out of the rave valves.'

In extreme cases, the rave vlave slot in the clyinder, the shaft of the rave valve and the hole in the rave valve base assembly gets worn out to the point it is too sloppy and allows mixed gasses to pass it and fills the diaphram, then leaks out.

It is usually caused by poor engine maintence.

 

[IDoSeaDoo]

I guess, but those seals looked mint when I installed them. I want to switch to premix for a bit and see whaty happens. Disconnect the oil pump altogether. I would think if I was leaking that much oil in there, it would smoke blue. I'm not getting that... my buddies use their oil pump and premix and their skis smoke like crazy, but somehow keep running for months without changing plugs... contradictory evidence...

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[IDoSeaDoo]

I found other posts saying this what which leads to an carb issues if everything has been done to the RAVE's. Here is it below. It doesn't hurt to check the carbs out.

'I own a 97 sea doo spx that has a 787 engine. The Rave Valves leak a black oil substance. Is this a major problem? If so what should be done to fix this problem?'

'If it leaks excessively, even after you rebuild the rave valves with new orings and diaphrams, then you probably have a leaky needle valve inside the carbureators or some really bad sparkplug wire connections, as you are not burning off all of the fuel in that clyinder, and the unburnt fuel is being pushed up and out of the rave valves.'

In extreme cases, the rave vlave slot in the clyinder, the shaft of the rave valve and the hole in the rave valve base assembly gets worn out to the point it is too sloppy and allows mixed gasses to pass it and fills the diaphram, then leaks out.

It is usually caused by poor engine maintence.

So maybe my carb is dumping way too much fuel in and causing it to create soot? That might explain the bogging and excessive crap coming out of my rave. I was ruining my high needle out .5 turns out when I noticed the pto plug was a little lighter than the mag...

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[suke]

So maybe my carb is dumping way too much fuel in and causing it to create soot? That might explain the bogging and excessive crap coming out of my rave. I was ruining my high needle out .5 turns out when I noticed the pto plug was a little lighter than the mag...

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If you premix and it's still doing it I say reach out to [MENTION=72134]1983[/MENTION] and borrow a set of carbs. When I was at his house he had a shat ton of them.

 

[1983]

Edit.

Wrong thread.


Rob

 

[IDoSeaDoo]

Sooo I just read a thread that proposes a new theory. I think one of my oil injectors are bad. This problem manifested itself only after I filled it to the brim with injection oil. This put extra head (hydrostatic pressure) on the who oil system. I always thought the pump doesn't allow oil to bleed past, but it does. The only thing that stops the oil from gravity feeding into the motor are those little injection nipples. Well, if they fail, oil can and will bleed into the motor, causing too much oil to be in there during the time when you first start it. This can foul a plug. I bet that's what happened. I probably was fouling the plug every time I started the ski after it sat. The next day after I verified that the oil pump and carbs were okay and installed new plugs, the rear one started fouling again because the ski sat all night and probably again filled with oil. I'll be testing this theory this week.