09-25-2008, 09:57 PM #1
Losing Coolant. Poppa Dawg Needs a Bone
O.K. I will throw this out here to see if anyone has seen anything like this. By the way, I already talked to Jerry & he has never heard of it.
I had been losing small amonts of coolant after short runs . Noticed fluid in the hull. I could not find any hose leaks. This past week-end I was testing some new wheels & making a speed run followed by a short duration of high speed turns to check accelleration out of a corner.
After 1st test I noticed the fluid down about an inch. Put more fluid in. Made a 2nd run & came back & had to add another 2 inches. On the 3rd run with the Rude Charger & Etech drop in wheel I made a speed run & finished with several hard turns. My Heat alarm goes off. WTF? I pulled the seat off & coolant tank was empty & lots of fluid in the hull. Went back to shore & again checked for hose & tank leaks. Found nothing. Put more fluid back in & went out with seat off with me driving & Andy Wise kneeling on the back of the ski with his head in the hull. We looked like Circus Dogs out there. At constant speeds up to 30 mph there was no sign of losing fluid. Came back to shore & received applause from all the drunk jet boat guys for the entertainment.
Andy then took the boat out with the seat off and did several high speed runs & throttle chops. Check this out. When getting off the throttle at 8400-8500 rpms the coolant fluid would just come boiling out of the over flow. It would never come out at full throttle, only when you got off the throttle. Hence losing all the fluid when I made a series of hard turns.
O.K. Anyone seen this? Obviously there is some excess pressure being created when getting off the throttle at high speeds. Is this normal & could it be as simple as a bad coolant cap? Maybe something going on with the thermostat? I'm all ears guys.
Last edited by Poppa Dawg; 09-25-2008 at 10:05 PM. Reason: Add info.
09-25-2008, 10:03 PM #2
- Join Date
- Nov 2007
- Odessa, TX
The only issues I've had coolant-wise is an air bubble after changing rideplates (ok it was the same one but I went to Florida for a vacation at Jim's) and then I had a leaking fitting on the plate. The air bubble cause me high temp alarms after riding when pulling into shore.
09-25-2008, 10:34 PM #3
It is pretty strange that it looses fluid after letting off the throttle but I suspect it to be your head gasket. Maybe when you are on the throttle the coolant is being sucked out through the exhaust and when you get off the throttle it comes out the overflow.
09-25-2008, 10:47 PM #4
My suggestion is that you replace the cap on the overflow tank. If it's anything like a radiator cap on a car, it should be replaced every year. When those go bad, they stop holding pressure. When they don't hold the pressure, it goes through lines and into the overflow tank. I assume that if the cap on that overflow tank on the Doo's goes bad, the breather tube serves as the overflow for the overflow. It simply pushes it all out that tube to relieve pressure. Perhaps you can find a cooling system pressure tester with a fitting small enough to work on that cap. Then all you gotta do is pump it to 13.9 PSI and if it doesn't hold pressure, buy a new one. Thats all I can think could possibly be the problem.
09-25-2008, 10:47 PM #5
My initial guess was head gasket but you would think I'd see a little indication of water in the oil & the oil appears to be absolutely clean.
09-25-2008, 10:54 PM #6
We had the same problem on a stage 3 rxp loosing coolant into the hull through the overflow and it was the head gasket. No signs of coolant in the oil either. The gaskets ussualy blow between the cylinder and coolant passage were the gasket is thin. This being said it never hurts to check the simple things first and as mentioned above, if you can pressurize your cooling system it will help you diagnose were the leak is.
09-25-2008, 11:34 PM #7
I appreciate the Help guys. Speed, I will go with your suggestion. Your past problem sounds exactly what I have going on. I replaced the head gasket about 3 weeks ago when I put in some Ferrea valves. maybe I have an issue from that. Thanks agian for the help.
09-25-2008, 11:39 PM #8
I am pretty sure that is your problem now that you say you had the head off recently. Good luck Dawg. Let us know what happens.
09-25-2008, 11:50 PM #9
I had a similar situation. It turned out that after upgrading my 05 RXP flywheel bolts(motor in the hull)I had screwed up on the routing of the coolant lines to the oil cooler. It would only puke coolant after running hard. Hope it's something simple like that and not a head gasket.
09-26-2008, 12:06 AM #10
sounds like a head gasket to me also. it's leaking combustion pressure into a water passage. it happened to me once on a car after replacing the heads, the head bolt holes had oil in them that hydrauliced and gave a false torque reading.
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