I have a pair of Mercury 525's EfI's and the Starboard engine has steam and water coming out of the exhaust. The water temp is 140 and the oil temp runs between 180 and 215. I also have an engine alarm that goes off with 5 long beeps that have 5 fault codes for different things. A Map Sensor fault came when I had a dealer check the alarm codes. I replaced the Map Sensor and the alarm problem went away for a while but nowI am having the alarm with 5 long beeps coming on and also the vapor detector beeping and red light coming on. I would certainly appreciate any suggestions or help in resolving these problems.

Thanks,
Boyce

Don't know much about the 525's and the alarms, but it sounds like you need to leak check your headers. If it's not the headers, then it's probably a leaky intake manifold gasket. The headers are easier to check.

Rene

Are you thinking of checking these because of the steam?

Neither I am familiar with the alarms on a 525 EFI but steaming exhaust is often related to low flow of water. Could be the water pump or anything restricting the flow like old impeller blades, etc

I was wondering because I to developed some steam today after a short cruise. Something ive never seen.

Yes, I was talking about the steam. Low flow can cause this but it will usually be accompanied by a high temp condition. If your temps look good at WOT, then it's probably a water leak.

Rene

Im running 15psi at WOT, 180 water temp consistantly. This was the first time I saw any steam on hot day, 190-200 oil temp. Maybe im being over cautious. Although water pressure takes awhile to build up after getting on plain.

If you have a restriction somewhere you can have good pressure but unsufficient flow. I had the hose between the transom and the outdrive go bad. It steamed enormously and fellow boaters thought the boat was on fire and offered me assistance. Still the engine temp and the water pressure was OK

The steaming and the alarm may not be related. Below is a list of the alarms for a 525efi.

Dave

Are you loosing any coolant ?
If not, I would think your intake manifold and cylinderhead gaskets are OK.