2013 RXT-X Loss of Power /Coolant

[jfandl]

I've run out of things to check, would love the community's advice. MY RXT-X has a loss of power and caps out around 5,200 rpm. It revs slower than normal but once it hits 5,200 rpm that's about it until enough coolant has gone out of the system (about 10 minutes of riding), then it'll surge to 8,000 on/off, after 2-3 more minutes, it runs super strong without surging. Next, I see the temp get too high and I have lost 1/2 gallon coolant, that's the end of the ride. This is repeatable, it's the third time it's happened.

I thought the symptoms indicate the coolant getting into the combustion cycle but it's not the inter-cooler, that's dry (cold or full temp). The hull seems to be where the coolant ends up. I cannot figure out how low coolant is changing the performance. Any ideas?

• New plugs
• Fresh fuel
• New fuel pump assembly
• cleaned all injectors
• new coils
• good spark
• plugs are a nice brown
• runs smooth just slow
• not fault codes or engine light
• inter-cooler dry, both sides
• Pressure tested coolant system - holds 10 psi for 30 minutes
• Compression 105 all cylinders, warm or cold
• squeeze the supercharge discharge hose and it opens my hand as I rev the throttle
• out of water, I can get it to rev to 8K but it pauses near 5,200 then bursts strong to 8K while pulling the supercharger intake hose about 2"

 

[Digdog]

Run it full of coolant but with no pressure cap and see if you get bubbles in the tank, bad cap , head gasket , pump seal , thermostat , coolant pump impeller ,oil cooler , leaking heat exchanger a possibility. Why it would cause a performance issue , not sure , but you need to find the leak for sure.

 

[ski-d00]

Head gaskets can leak only when it's running and let coolant into the cylinders. It will also pressurize the coolant system and force some out the drain tube which will make you think it is all going into the hull.

 

[Poormanracing]

Check where the coolant goes into the ride plate had a poop ton of fittings start leaking.pressure tested the system cold they held put a little temp in the motor sure enuff deep thru the fittings.drove me nuts on the first two

 

[jfandl]

Just ran it multiple times (to bring up to temp) out of the water. Not a drop of water out of the overflow line and no bubbles in the overflow tank. Pressure tested again (cold) held 10 psi for 20 minutes. It sounded like a head gasket to me that dumps coolant into the cylinder causing poor performance and then heat expansion when up to temp the issue goes away. Now I'm not convinced.

 

[Poormanracing]

Just ran it multiple times (to bring up to temp) out of the water. Not a drop of water out of the overflow line and no bubbles in the overflow tank. Pressure tested again (cold) held 10 psi for 20 minutes. It sounded like a head gasket to me that dumps coolant into the cylinder causing poor performance and then heat expansion when up to temp the issue goes away. Now I'm not convinced.

What do the spark plugs look like are they being washed clean or getting colored.if it is a head gasket leaking into combustion chamber the plugs would be getting steam cleaned.

 

[Poormanracing]

What do the spark plugs look like are they being washed clean or getting colored.if it is a head gasket leaking into combustion chamber the plugs would be getting steam cleaned.plus running on a hose for that long on the trailer to get up to temp is horrible for carbon seal.leave it on the trailer and bring it to a ramp then run it

 

[jfandl]

Plugs have a nice brown color, perfect burn, definitely not getting washed so that's a good point you have. I only run it for 2 minutes at a time to prevent the seal from overheating, wait 6-10 minutes, then run again for 2 minutes. Takes about 4 runs to get up to 185 to open the t-stat.

 

[Poormanracing]

Any mods done to the ski is it stock and are you the original owner.by chance some one did a open loop cooling system

 

[jfandl]

Any mods done to the ski is it stock and are you the original owner.by chance some one did a open loop cooling system

Only mod is exhaust baffle bypass with a exhaust port on the back of the ski. Cooling is closed loop. It never lost coolant before but I'm thinking it happened after I had it serviced for out shaft replacement. I'm the 3rd owner.

 

[unclepete]

Head gasket