PARADOX

Strbd, motor suddenly show low water pressure. Lot's of water comes out from the tips, water ok in the strainer, A few techs said it's just a sensor glitch. I took it off, cleaned it, pressure is still low ( about 8-10 at 4000 RPM) Engine temp does creep up to about 170-172 after about 15-20+ minutes. Normally at higher RPM I see 20-25 and temp around 140-155. . At idle pressure is 5-7. So.. if the pressure is low? what is it? I would think if there is a restriction somewhere it would be high. Impeller is good.
Thx . P

Sydwayz

iTrader: (1)

How old is your antifreeze? Is it pink or starting to grey a bit? Your antifreeze could be getting old causing the higher temp.
Swap the sensors from one engine to the other; or just buy a new one. It's a "cheap" fix.

HyFive578

iTrader: (3)

The climbing temperature and the low pressure is surely a sign of an issue somewhere. 8-10 PSI at 4000 RPM is NOT good. You do not want to do that for long or you run the risk of compromising the headers and other stuff. It is a good idea to change the sensor anyway to make sure you're getting accurate readings but with the engine temp rise, I wouldn't stop there. You can still get decent output from the tails even with lower pressure so that is misleading. The 525 usually runs mid to high 20's PSI and temps around 150ish at normal operating. You should backflush the coolers and heat exchanger to make sure there are no obstructions there and if the impeller is OK, then it might be an issue with the pump itself, ie: bearings. I would not run this engine at operating speeds until you track it down. 525's do not like to be overheated at all.. other bad stuff happens.. e.g., those headers certainly don't like it... head gaskets don't like it either..

Sydwayz

iTrader: (1)

Also, is the belt slipping? Another easy check is the heat exchanger. It could be plugged with sand your sea strainer does not catch.

Sensors can fail high or low, as well.

HyFive578

iTrader: (3)

The belt slipping is another good thing to check as is the heat exchanger which I think I mentioned as well. As for the sensors, anything is possible but I've had two of those sensors fail and both times, they got "stuck" at a high value rather than just be inaccurate. The first was showing a constant pressure of 29 psi and the second was showing constant pressure of 45; both with the engines off. In the first instance, I didn't have smartcraft but we found it when hooking up the Diacom software which showed high pressure readings when the engine was off. In the second, my smartcraft detected the sensor had failed and gave me an alarm.

In Paradox's case, the rising temperature is the thing to be concerned about.. In my opinion and experience with 5 of these motors already, there is almost surely a pressure problem there.

PARADOX

THanks guys, all good points. The belt is not slipping. Impeller pumps is good. Didn't run the engine long, at 170 degrees. Headers, are OK. Not referencing the BS CMI issues, but they did not heat up. I have an exhaust water temp. sensor in the headers, didn't get very hot. Back flushing, and all water coming out where should be is ok, but of course can't really tell, if the volume is right, but there is no "BIG" restriction. I will remove the hoses from the oil cooler and heat exchanger and dig deeper. Anti freeze is pink. Pretty new. I had sea weed in the heat exchanger's before, and at the oil cooler, so I can clean them, but I thought with any restrictions the pressure would go up, not down. In the bilge we go.. lol

PARADOX

Good news and bad news.
Heat exchanger, clean as a whistle, Oil cooler also clean. The good news. The bad news is I still didn't find the problem. I can blow air through all the hoses with ease. Somewhat.. lol.. Some has water in it, but I can sort of blow some of it out, and I feel no restrictions. I hate to remove the power steering cooler, but I might have to. I will blow water through everything first from a hose.

Cole2534

iTrader: (1)

To me, that says the restriction is before the sensor.

Dave M

That's where I am at. I was always concerned that 150* was too low. Doesn't this motor have a 160* t-stat?

HyFive578

iTrader: (3)

One last source to check is the hose from the drive to the pump. I still think its your sea water pump. Are you sure the impeller is installed with the vanes turning the right way? Is the pump sealed properly? I would change the impeller. Install it with dish soap or a water-based lubricant to avoid any deterioration of the rubber from petroleum products and make sure the vanes are facing the right way...Could be that they are collapsing under load. If no obstructions and impeller is really ok, then the next thing l to check is the pump bearings.