Serial# 104582 85-87 Mercury XR2 150hp. Overheating issues

[Pacman2915]

Pacman2915
Overheating issues. Replaced water pump. Still not working. In gear water pump will work for short period at high speed but quits. Changed thermostats didn’t help. Before installing new pump I attached the water hose to copper tube made sure water flow to heads when running and when shut off. I’m stumped when in water and pump quits mist or exhaust will spray out of discharge tube. My water pressure gauge shows about 5 psi when pump does work. When out of water hooked to water hose, it takes several mins to prime but then only trickles. Any help is appreciated

[senkoboy]

Only 5psi?
Might be the problem.
Pull the heads and see what the the head gaskets look like.
Have you replaced the water pump? If so, was it done correctly?

[5keepers2]

Pacman2915
Overheating issues. Replaced water pump. Still not working. In gear water pump will work for short period at high speed but quits. Changed thermostats didn’t help. Before installing new pump I attached the water hose to copper tube made sure water flow to heads when running and when shut off. I’m stumped when in water and pump quits mist or exhaust will spray out of discharge tube. My water pressure gauge shows about 5 psi when pump does work. When out of water hooked to water hose, it takes several mins to prime but then only trickles. Any help is appreciated

When you say replaced water pump........what did you replace? If you didn't replace all parts you are shooting in the wind. Wear plates and housing may not look worn out but they are.

[Pacman2915]

Replaced impeller , and gaskets. That’s it.

[acesover]

It will help you to receive faster, and more accurate responses if you will post your questions in the appropriate forum:

Mercury Motors (this forum)
TWO STROKE models (Less than 135 hp).

Mercury - 2.0/ 2.4/ 2.5 Liter High Performance
For discussions related to 2.0/ 2.4/ 2.5L Two Stroke motors (Carb, EFI, Optimax or Racing).

Mercury - 3 Liter & 3 Liter High Performance
For discussions related to 3L Two Stroke motors (XS, ProXS Optimax, EFI, or Racing)

Mercury - 4 Stroke / Verado
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For fastest/most-accurate assistance, please choose the correct forum.

[jrw33862]

make sure you change the tube seals, upper and lower. Thats the tube that goes from water pump to exhaust plate below power head. Had that happen to me and the upper seal was leaking and not letting water get to powerhead. sounds like your water pressure is really low.

[leonreno]

Is the 5 psi at idle or when on plane? If at idle that’s good if on plane then that is bad. Have you checked or replaced the poppet valve, poppet stuck open will cause low pressure at idle and maybe at midrange. Water pee stream is also controlled by thermostats, no pee stream until the open up, they start opening at 143 degrees.

[Shawn1]

I was having the same problem. Replaced thermostats and poppets and everything works fine now.

[EuropeanAM]

Pull water pump AGAIN. Plan to replace ALL gaskets and impeller (or better yet, the complete pump KIT). Recommend ONLY Mercury/Quicksilver components (no aftermarket).