Logo
FULL SITE MENU

Mercury Xr6 Water pressure TOO HIGH

M

mattsmechaincal247

New member
Hello, I am sort of new to working on outboards but I am getting the hang of it quickly. I am working on a 2003 Mercury XR6, I have replaced the thermostats, rebuilt the poppet valve, and installed a new water pump impeller and upper housing. The motor starts, runs and smokes just as it should but at idle I get anywhere from 10 - 20 PSI of water pressure and at WOT it pegs the gauge I installed past 30 PSI. At first, I didn't know this was a problem so I ran the boat at the lake and quickly got a warning buzzer that was telling me the motor was overheating. Talking to some guys at the shop near me, they told me that I should get 3-6 PSI at idle and 10-20 at WOT, and my motor is overheating because the water pressure is too high. They also told me that it is probably due to a blockage at the base of the motor from the exhaust plate gasket. I would like to exhaust all possible options before I pull the motor and replace this gasket. Thanks for your help!
 
That does sound like a restriction at the exhaust plate - there is a couple of squarish shaped "dump holes" that allow water to pass to the exhaust tube (tuner) to cool the exhaust and ultimately allow the water to exit through the prop.

If this motor has been sitting for a bit wasps or mice may have set up shop in there and created a dam.

Here's the two areas of concern that I would be investigating:

exhaust.jpg
 
Thank you for your response, I pulled the motor and that exhaust plate yesterday, and there was what seemed to be a lot of calcium build up chips in it but not near the water passages. I have not yet checked where your bottom arrow is but it seems like those square tubes do not align with the hole in the exhaust plate, is that correct?
 
Got to disagree...... there are two 1/8-1/4 holes in exhaust plate where the water dumps to the tuner/midsection(1st arrow). If these are plugged all that will happen is tuner will overheat and propshaft seals and rubber/plastic hubs in props will melt.Been there and got 2 tee shirts:cool: It sound more like the divider plate has a problem as water goes thru it first then to heads.
 
The lower arrow on the diagram is pointing at the diffuser (what I call the tuner located "inside" the exhaust tube, this sits inside) - it bolts right to the bottom of the exhaust plate so it can't "get out of line" unless it wasn't fastened properly after some previous removal.
 
Well, I think I have figured it out, I pulled the lower exhaust plate and that "diffuser" or exhaust tubes were completely disconnected from the plate. Two of the bolts were gone and the other two were broken. because this tube was rattling around in the big chamber (part #25 on your picture). it put two holes in it. So I have ordered all news studs, nuts, and gaskets, and I am working on getting the holes repaired. Hopefully, this was the cause of my high water pressure and overheating.
 
I have a 2005 XR6 and I am having the same issues where pressure is too high then overheats. I have already taken the motor off and inspected all water passages rebuilt poppet new impeller all new base gaskets head gaskets and I’m still having the same issue I’ve got to get this fixed It’s frustrating me when I have a nice boat but I can’t even barely crack the throttle and it starts overheating
 
Back
Top