Maritime_Eng

Hello All-

I have a real weird issue that we can not seem to figure out. A good friend of mine has a 32 Spectre with 300xs's. He has had the boat now for 2 years. When new the boat was set up to run approx 15 psi water pressure at wide open. For the first 20 months there has been zero issues with the boat/engine combination.

About 4 months ago we started to notice that the port engine is loosing water pressure @ WOT. Port is at 8psi while starboard is 15 psi. At first we thought it might be a transducer issue but when the water pressure drops the temperature starts to rise. At idle both engines are around 5 to 6 psi. The engines have never been moved up or down. We have changed the water pump and noticed no improvement. We have switched the lowers from side to side and still the water pressure issue stayed with the port engine.

We removed the thermostats flushed out the engine with water from every opening, and even pored muratic acid down the thermostat openings and let it sit for about 20 minutes, then flushed the engine with water again. We removed the poppet valve and checked for blockage. We reassembled and still having the low water pressure issue.

We quickly checked the running surface with a straight edge and it seemed to be straight, but not 100% sure.

At this point we are really confused and hoping someone might have some ideas for us to try.

Thanks
Don

Port Monster

iTrader: (1)

I see you are over on sscreamandfly already - that will likely be your bwest chance for an answer. I would just say it is the pressure to gauge hose leaking and to check on that. But you say the Temp is rising more than usual. How much more than usual is it rising?? And is it noticeable at a particular RPM or the more you push the throttle the more it rises?

Maritime_Eng

Yeah its not a hose leak, I have checked that motor for leaks and its dry. If you hold it wide open the pressure will drop to 7psi and temp will rise till you hit Guardian mode because the temperature is too hot. Its acting like there is a water passage block somewhere in the engine.

Port Monster

iTrader: (1)

You have have pretty much crossed off every typical thing that causes this problem. I know you checked the poppet valve but this is the good thing about having two motors - I would switch the poppet valves just to fully eliminate them. The pressure drop is what baffles me and why I say switch the poppets. They are designed to open at higher RPM and by definition cause a slight pressure drop. And, if too much water is being relieved from a faulty poppet it could cause this problem (I doubt it but it is an easy test that cost nothing but time). Next I would start thinking about removing a heads and taking a look. From what I understand, the water passages that go to the head are fairly small and if you were going to get some corrosion/clogging issues in there this would be a likely spot. This would give you an idea of how much corrosion is in the engine. When off I would check out the head gasket and make sure it is not leaking somewhere and causing the problem. I also wonder whether you could have a head gasket problem so that when the engine is running WOT the head is putting air into the water passage.

diesel2fast4u

I had once the copper tube cracked that goes into the mid section. (from the waterpump up)

Same problem also twin setup, only found out when I was in the process of switching the 2 powerheads from L to R ...

Maritime_Eng

That is the one thing that is hard to check, we did plug up all the ports of the engine and force water into the main water tube. It showed no leaks, but without pulling it apart it is very hard to tell.

diesel2fast4u

Funny thing is that I tried that to at the time...

I was so desperate that I wanted to switch sides of the powerheads.
It was cracked just in the part that goes into the mid.


Good luck !!