Need help with new 2008 RXP X 255...too much oil? Running lean?

[dannyk]

Hello,

I just bought my first jet ski! A secondhand 2008 Seadoo RXP X 255. It has 250 hours on the engine, and the supercharger was last rebuilt at 200 hours (with metal bearings).

I've taken it out on the water three times, and something has been wrong. It tops out at about 45 mph, and acceleration is sluggish. After the first ride, it has also been difficult to start - pressing the ignition would cause it to stutter and die, unless I throttled 3-5 times while pressing the ignition, then it would start. It has also died randomly twice while riding it, although I was able to restart it using the throttling method. I spoke to a mechanic who said to replace the spark plugs, which I did. Now it starts right up (in the driveway - don't worry, I don't run it for more than 3 seconds without a hose, or 30 seconds with a hose). However, the seller tells me that the spark plugs had just been replaced 1 or 2 rides before I bought the ski from him, and that they worked great for him. So I am wondering what might have gone wrong. I don't know if my acceleration/top speed problems have been fixed with the spark plug exchange, but I wanted to investigate other causes before taking it out again in case I am doing damage.

My current thoughts are that the oil level might be too high (I uploaded a picture of the end of the dipstick) or that it is contaminated somehow (does it look milky)? I am also uploading a picture of the spark plugs that I removed from the ski. One of them looks black at the tip and I am wondering if that confirms my suspicions that the oil level is too high. However, the other two look quite white - I guess that could just be because they only have 4 engine hours on them? Or do you think it might be because the engine is running lean?

Would love to hear your thoughts. Just trying to get this thing in shape.

Thank you.

 

[POPPS]

That black tip plug is either fouled,,,a weak cylinder,,,or poor spark,,,just some ideas,

 

[dcm0123]

If that is the actual oil level it is over filled by at least one quart.
It is hard to tell from a picture but does looks like it could be contaminated with water.

Run it for a couple of minutes then suck the oil out and put in a couple of 2 liter clear tonic bottles to see if the water sinks to the bottom. May take a couple of days,

I would not risk using it until you figure out what is going on with the oil.

Previous comment on the black plug is accurate. Does not look like oil fouled but could be fuel fouled.

If oil is OK, try a new set of plugs and switch the coil from the fouled plug location to another cylinder to see if the fouling plug problem follows the coil.

Has the water level in the engine coolant tank dropped?
Another source of water contamination may be the water cooled heat exchanger (inter-cooler) which cools the air after the supercharger. If this is cooled by sea water on your machine it will be harder to diagnose.

 

[dannyk]

Thanks so much for your reply. I went to check the engine coolant tank and there is basically nothing left in it. I guess that would explain the very high oil level and milk character to it. I suppose I’ll have to take it in to a shop. How big of a problem is this?

 

[dcm0123]

You will not know until they confirm where the leak is and if the water damaged anything else.

Best case is a head gasket with no other damage. Probably about $1000 just for that but it could go up if the head is warped and has to be machined.

They should be able to pressurize the cooling system and monitor for a leak (drop in pressure).

 

[dannyk]

Ahh the joys of being a jet ski owner (my one week anniversary!). Thank you for your help. I'll try to find a shop around me that has any availability to check it out.

 

[dcm0123]

As the machines hours get higher, this can be a very expensive sport unless you have a mechanical background, invest in tools and do your own work like a lot of us.

 

[dannyk]

Yeah. I was anticipating doing oil changes and winterization and spark plug changes myself, but I’m just not comfortable enough with these machines at this point to do a bigger job like this. Would love to learn, though.

 

[dcm0123]

Let us know what you find out.

 

[ski-d00]

Your oil level is high because you're getting water in your oil.

If I had to guess, I'd say you're intercooler is leaking which is the first place to look and is a known failure for the early years. This will cause it to run poorly with poor acceleration and low top speed, hard starts, milky oil, fouling plugs...sound familiar?

Simple check to see if the intercooler is leaking by removing the hose at the throttle body and revving it on hose and look for water. See link below...

leaking intercooler

 

[dcm0123]

This would be a DIY fix for the poster if is the cause. Would a minor leak be as noticeable as what is seen in this video?

When I checked my inter-cooler, I was told to blow the water out with low pressure air. Block the water output hose (seal it good) and pressurize the water input hose at the inter-cooler with 10PSI air using a hand pump. Let is sit overnight and look so see if the pressure drops.
In my case I had as very small leak (there was some water left in it during the winter which froze causing one tube to leak).

https://www.amazon.com/Mityvac-MITM...9797304&sprefix=mighty+hand+va,aps,229&sr=8-1

 

[dannyk]

Definitely sounds familiar…thanks! So it’s not too bad to run the engine on the hose momentarily for this test even with fouled oil and no coolant?

 

[ski-d00]

Water contaminated oil is not good for it but I suspect you've been running this way for awhile so a 2 minute test won't matter too much. When you say coolant, I think you mean water from the hose which cools your exhaust and supplies your intercooler and not the coolant in the closed system that goes through your engine which hopefully you didn't drain that.

You have to run it on the hose so that water is flowing through the intercooler. Your leak probably won't be as bad as the one in the video but it will be noticeable after a minute or so if it's leaking. Post a video of it.

Even pin hole leaks still leak water under pressure and will be noticeable. You can pressure test for final confirmation but this is a quick test that almost always gives you the answer.

 

[dannyk]

No, I don’t think it’s water, I do mean engine coolant. The same time I realized that my oil was full, I checked my engine coolant tank and saw that it was near empty - hardly any coolant left. And I don’t see anything collected in the hull or any obvious external leaks so that’s why I am thinking internal coolant leak. Intercooler leak probably wouldn’t explain the empty coolant tank I guess? I guess neither would an oil cooler issue. Only a head gasket problem huh?

 

[dcm0123]

You are correct a leaking inter-cooler would not explain the empty coolant tank unless by coincidence it was low.

The remove the hose and run the engine test sounds easy to do so you might want to try it.

I was not aware these had an oil cooler. This is something else to consider. Could also be tested with air by looking for a pressure drop.

 

[dannyk]

True, it would be a pretty quick test. I just hate running the engine with contaminated oil. You're right that a minute or two at idle shouldn't make a big difference though.

Yeah, these guys have an oil cooler. On further investigation, the oil cooler actually also uses the engine coolant for heat exchange, rather than raw water. So, you're right, assuming the empty coolant tank is related to the oil contamination, I guess it could be head gasket (/cracked cylinder) issue or an oil cooler issue.

 

[dannyk]

Hey y'all I wanted to follow up with everyone in case anyone has a similar problem to me and finds themselves reading through this thread...

Basically, my ski had big problems. Leaking intercooler AND a blown head gasket. I didn't get to ride it all for the rest of that first season because it took so long to get out of the shop. But I just brought it back out on the water this season and it runs beautifully!

 

[Digdog]

Great to hear it's fixed , now that it is read the oil level checking procedure in your manual.

 

[dannyk]

Yeah, the oil level was definitely a concrete red flag, but for the first few days ever having one of these machines you question everything you do...

 

[MacSeaDoo]

That is awesome, now ride the hell out of it.