Strange Overheating Problem?

[philksr]

I have a 2000 Skeeter ZX185 Bass Boat with a 2000 150 Yamaha ProV. In the past year, my engine has developed a strange water pressure problem. I have had the impeller and lower unit serviced. After coming on a plane the water pressure is about 22 pounds. As you trim the boat and accelerate the water pressure stays steady until the boat is fully trimmed and running about 50 mph, then the pressure drops to 10 pounds. If you continue to run it, the overheat alarms comes on. If you back off on the foot pedal until the rpm is about 3,500 the pressure suddenly picks back up to 22 pounds. It acts like a cavitation problem of some kind, but there is nothing that I can see to cause this. My dealer thinks there is a problem with the water intake screen. I checked it out and the screen is installed correctly. Am I missing something? Thanks!

[MNXD9]

Hmmm I think I remember reading about something like this, being a skeeter issue, and Yamaha has a different waterpickup or something to stop this, been awhile and I don't run a skeeter, but I seem to remeber something like this with some other boat (I run a Ranger so I didn't really pay much attention to the brand being mentioned though I think it may have been skeeter....)

[philksr]

Thanks. I'll contact Skeeter and see what they have to say. Yamaha has been great. No other issues except this.

[PSM207]

What is your propshaft height? If the engine is extremely high and the LU doesn't have low water pick ups, then you could be sucking air at full trim. Has this problem just recently occured? Have you raised the engine?

[philksr]

My Skeeter has the same fixed aluminum jack plate that it came with. I have not changed anything, even the prop is the same. This problem started about a year ago. I recently had the impeller changed and the problem did not change. Is it possible that the screen is worn? I vistually inspected it and it looks fine but might have lost some if it's sharp edge.

[PSM207]

Have you inspected the poppet valve? This valve regulates water pressure in the engine. It is fairly easy to remove.

[philksr]

No I have not. Don't know anything about it. By searching the web, I found a picture of the valve with it's location. Does it need cleaning or replacement? Thanks..

[BuzzB8]

Just a cleaning. Be sure you remember how the valve and spring go back into the engine. Go slow and easy.

[R1Peacock]

I have a 2004 Champion 198 Elite with a 200 VMAX. I experienced a similar water pressure problem last year. My dealer replaced the impeller and said it was fixed. I ran it after that and experienced the same problem. The boat then sat all winter and a few weeks ago I saw the post in regard to the poppit valve. I read the post and did my own cleaning in my driveway. The valve was completely mucked up. I cleaned it and ran the boat for several hours and the pressure problem was fixed.

I guess dealers should read this post also.......

Rich
Westminster, Maryland

[philksr]

I took out the poppit valve and it was clean. Reinstalled it and the motor is OK with the hose connected. I will test it today if I have time. My problem sure acts like a cavitation problem. Is it possible that the intake screens need to have a sharp edge and mine are worn out?

[BuzzB8]

This may sound stupid but...have you adjusted the height of the engine since this problem began? Have you added or removed a jackplate?

[philksr]

No, the boat is exactly the way I bought it in 2000. I took the boat out this morning and the problem is still there. I spoke with my repair people and I am taking the boat to them on Monday. I am thinking now that I might have some more parts worn in the water pump other than the impeller. The repair person told me that Yamaha has new design intake screens for my motor, buy they are going to check out everything for me anyway. Very puzzling??

[philksr]

Got the boat back from the repair shop and the problem has been fixed. They called Yamaha and were told to replace the thermostat, upgraded popit valve, intake screens, impeller and impeller plate. The boat now has 30 pounds of water pressure and does not drop off when trimmed. I suspect that all of these items weren't needed, but while they had it apart it was cheaper to just do everything at once. Thanks for your help!!