Water pressure gauge pegged to max

[edeere]

I have just purchased my first bass boat, a 1998 Ranger 518DVS w/ 200 Mercury EFI. My water pressure gauge is pegged in the max position. The motor does pee a decent stream after running for what seems like quite a long time. The stream comes and goes when I put on the muffs and let it run at 1500 RPM. I am not happy with the stream so I am planning on replacing the water pump out of precaution but I still feel I have an issue with the gauge or electrical connections since I do have water flowing.

Any suggestions where to start with the diagnostics and how much pressure should I be registering?

 

[CharlieB]

Re: Water pressure gauge pegged to max

Many of the V6's have the stream come off AFTER the T-stats, so there is little or NO stream until the stat opens.

Some drill a small hole in each stat to allow a minimal flow so that you can see but a dribble from the P tube.

It never hurts to replace an impeller, especially since you just bought the boat and have no way of knowing how old the current water pump is.

 

[edeere]

Re: Water pressure gauge pegged to max

I questioned if the delay may have been for the thermo. The water is definitely hot when it starts flowing. I am confused about the pressure gauge though. Is the only thing that feeds the gauge is the water line coming up from the lower unit? I just knew there would have been some electrical connections as well. No luck changing the impeller. I never could get the lower unit to budge. I didnt want to risk breaking something trying to find a pry spot. I guess I will have to take it in to get it changed the first time.

 

[sschefer]

Re: Water pressure gauge pegged to max

The water pressure gauges that I have dealt with only have 12v for the lighting. Normally these gauges use air pressure not water pressure. By that I mean that the tube acts as an air chamber and the water that does enter it only travels as far as it can against the pressure of the trapped air in the tube. The gauge is then measuring the pressure of the trapped air. The water should never travel all the way to the gauge itself. If you take the tube off at the gauge and find that water is dripping from the gauge or the tube then I would suspect that the gauge is damaged and needs to be replaced.