57chevymike

The start of a new boating season hey hey.......Thought I had my problem fixed but no such luck. Running a 2005 525 and I'm having a water pressure problem. At 4500rpm gauge is showing 50 lbs of pressure. The faster I go the higher the pressure. Back flushed the motor last fall after sucking the impeller. At idol its about 8 lbs. I'm thinking I could blow the water hoses off and cause some serious problem. Need some advise/help......thanks 815 236 3086

HyFive578

iTrader: (3)

That is definitely too high and is probably indicative of an obstruction. Did your impeller disintegrate? If so, it's highly probable that you still have some pieces of impeller stuck somewhere. You need to completely flush all of the coolers and the heat exchanger individually.

57chevymike

Thanks for the advise. I did back flush the engine twice last fall and did get a lot of impeller parts. I just made a special tool to flush the engine again added an air valve along with the water valve. I'm going to give that a try. Do you know where the water pressure valve is located on a 2005 525 thanks again

Bawana

The 525 efi has the water pressure sender in the oil cooler. Its an electric sender, if you have had a impeller blow, it would be on the starbord side of the cooler right where the pressure sender is. You need to make sure there is no pieces in there. 8 psi at idle is high, sounds like there is something in there.

BUP

iTrader: (9)

Water Pressure Sensor in the oil cooler Mercruiser specs are bare min 20 psi - 60 psi MAXED at 5200.alsoi

Also it could be the sensor itself needing to be cleaned or replaced. Over time they can collect whatever deposits on them.

57chevymike

Thanks for the info....Im going to change the sensor and recheck the cooler again. Since I'll be in there I'm going to back flush the system for the 3rd time Called mercury racing tech. Told me 40 lbs wot was the correct number for a 525 blue motor.....also advised me to take it to a auth mercury dealer. I'll post the results. You are correct the water pressure sensor is located on the rear cooler on the left side.

57chevymike

This is where I'm at. Made a back flushing tool out of SCH40 PVC 3/4 " to 1" with a water inlet and compressed air inlet with valves. Worked really well. Removed both end caps on the rear oil cooler and blew out the cooler with air. Then back flushed to the fuel cooler with water and blasting shots of air. Then flushed from the inlet front cooler to the outlet of the sea pump. catching all the rubber parts in my wife's panty hose. Yes her panty hose and no she didn't have them on. Attaching to the end of the hose worked great. Recovered a lot of old impeller parts. This is the 3rd back flush removing lots of rubber each time. Just for information the impeller rubber doesn't float. I think what was going on was the oil cooler where the pressure sensor is located would get clogged up while running Turning off the motor most of the rubber parts would sink down the hose until the motor ran again clogging the inlet of the oil cooler. It's impossible to remove the oil cooler hoses without removing the exhaust rubbers due to the factory clamp install 7mm. I'll be running the boat soon and will report in.

57chevymike

still have the problem...I just pulled the port exhaust header section to rod out the oil cooler(oil cooler was clear) also back flushed all coolers installed a mech water gauge inline at the front heat exchanger ordered a new pressure gauge and sender blew out gauge water supply line will test after installing the gauge and sender will report after install

River Ratt

I have the same thing going on so Im dying to see what you find. I disintegrated an impeller last fall before storage so this spring cleaned everything out. I found a lot of pieces in the hose going up to the starboard side of the oil cooler and at that side of the cooler. I took all my hoses off and the ends off of both coolers, flushed everything put it back together and ran it last week. I didn't look at that pressure sensor so I'll have to take a look at that. Same as yours 8psi at idle and 50ish at wot. Unfortunately I have no idea what my pressures were before the impeller blew, I only drove it once after buying and before storage.

57chevymike

Well things are not getting better, Replaced the water pressure sender(135.00) replaced the water pressure gauge(100.00) in the dash blew out the line. Took the boat out today at 4500rpm's blew off the hose at the inlet of the front heat exchanger. Nobody seems to know what is causing the high pressure nor do they care. It's a strange problem but I'll figure it out. Mercury racing tech's are zero help. Didn't even know how the oil cooler was built. Advised me to contact a local mercury service tech. Note: livorsi water pressure gauge was redesigned 4 years ago from a spring system to a gear drive gauge Also, the water pressure sensor that I replaced only tells the computer if you have LOW water pressure which will give an alarm. While under the dash installing the new water pressure gauge I decided to change the light blubs to LED blubs. Well the small gauges will accept the new LED blubs. The monster speedo and the tach will not accept the livorsi LED blubs. The new LED blubs are too thick expanding the socket making it too large to reinstall the socket into the gauge. Anyway now the GPS speedo is stuck at 30 mph More problems. I'll keep this post open until I fix my high water pressure problem and I will figure it out it's only a boat engine with 94hrs