Water Inside Cowling of Mercury 250 ProXS

This topic has 9 replies, 5 voices, and was last updated 7 years, 10 months ago by jcdogfish.

Viewing 10 posts - 1 through 10 (of 10 total)

Author

Posts
August 7, 2018 at 2:00 am #369532

Roostertail1964
Participant

I had my 2014 Mercury 250 ProXS to my dealer today for thermostat issue(s). My mechanic called me to inform me that the entire starboard side of the motor is sustaining SEVERE water intrusion. He said that he ran the motor while spraying down the outside with a garden hose and said that there was NO sign of water leaking in. He said that the cowling gasket was in PERFECT shape. The motor is on a 2014 Bass Cat Eyra with a pair of 10’ Power Pole Blades. My mechanic seems to think that water is some how spraying up when I’m running, not necessarily at full throttle. He suspects possible “deflection from the power poles”! The boat is equipped with an Atlas hydraulic jack plate. Has anybody experienced a similar problem?

August 7, 2018 at 1:03 pm #369533

Bass Cat Boats
Keymaster

Where do this boat come from? Or have you owned it since new, and what reservoirs do you Fish? There is no deflection from Power Poles or Talons, we have multiple videos debunking that myth.

August 7, 2018 at 2:00 pm #369536

oldtimer57
Participant

Is your speedo working. If that connection pops loose, it is usually connected inside the rigging tube and at speed, that will dump a ton of water inside the cowl. If it is not coming in around the cowl, which seems impossible if the seal is in even close to reasonable condition (the powerhead is WAY above the surface of the water and usually only gets drops of water on it), then it has to either be a leak in the water lines under the cowl, or else the speedo. Since the dealer cant see it leak when running it out of the water, Id strongly suspect the speedo tube. At 70+ mph, the water pressure is around 70 PSI. This is not a linear curve, in that at 110mph or so, pressure is over 200 psi. 70PSI will dump a ton of water out that tube.

August 7, 2018 at 2:03 pm #369539

louie3252
Participant

Maybe your coming off plane too fast? water coming in the back some how? I had my compressor reed valve recall done at 30 hours, by a old mercury racing guy, and he said from looking at the reed valve/ water spots and light corrosion that I had been over trimming and the spray was getting stucked in there at WOT. Can you see water marks or corrosion on the block or some where on the engine? The thermostat code/ issue on the pro xs, IMO is kinda nature of the beast, its not the best of designs and needs to be monitored/ service checked often.

August 7, 2018 at 2:16 pm #369542

oldtimer57
Participant

If the gasket around the cowl is good, which the dealer said it was, then there is not much room for water to get in through chopping the throttle. Might wash over the rear deck, but wont flood the motor. Merc designs these things to prevent water intrusion as some saltwater users back up rapidly which will let waves wash over the back of the cowl.Something is wrong/broken, most likely speedo-related since the dealer saw nothing running on muffs. There are at least two junctions/connections. One where you remove the lower unit for service. One somewhere between the area inside the cowl and the rigging tube where the tube to the speedo is routed.

August 7, 2018 at 3:11 pm #369545

Roostertail1964
Participant

The boat was purchased new from Bass Cat in 2014. The speedo has NEVER worked.

August 7, 2018 at 3:16 pm #369549

Bass Cat Boats
Keymaster

That might explain the excessive water intrusion the service tech mentioned, then…It is easy to follow the black speedo tube. Comes up from the lower unit close to the shift shaft. Also other end should come from boat through rigging tube. It will be much smaller than the oil line, the fuel line, and the oil tank pressure line. You should have four tubes coming through the rigging tube. Also large + and – cables for motor, and then at least one other one (main wiring harness) as well as a possible CAN bus (blue) wire if you have anything like a mercmonitor or other smart instruments. Last two things are the shift and throttle cables which are obvious.

August 7, 2018 at 5:01 pm #369552

Bass Cat Boats
Keymaster

Alright, the water has a source… Again what reservoir?

August 7, 2018 at 5:24 pm #369554

Roostertail1964
Participant

Raystown Lake south central Pennsylvania most recently.

August 8, 2018 at 1:38 pm #369557

jcdogfish
Participant

I had a leak on the engine right below the flush out below the lower cowl. It never overheated or gave low water pressure but it put out enough water to fill the lower cowl. The water would go from the cowl, down the cable rigging tube and into the boat. I looked for leaking hoses and pumps for a couple of weeks. One day I picked up the rigging tube and heard the water dump in the boat. I looked at the engine running with the cowl off and never saw the leak. It was hidden behind the flush out hose and lower cowl. and the water skeeted down so unless you looked in with a light I never noticed it.
Author

Posts

Viewing 10 posts - 1 through 10 (of 10 total)

You must be logged in to reply to this topic. Login Register