Universal overheating/no water discharging

[knotoldyet]

My Universal M25XP is overheating; and water is not being discharged from stern outlet. So far these are the symptoms and what I have done:
1) motored out of the marina, no problems, water discharged, temperature fine
2) sailed, then motored back to marina to discover temp is climbing and no water is discharged
3) replaced impeller (which was significantly damaged/chewed up) and the gasket, cleaned inlet filter. Old impeller was the black type as was the new one. Pump is an Oberdorfer.
4) after repair, pump leaked around cover plate
5) sanded inside edges of cover plate and adjacent pump surface; replaced gasket again, added light coating of silicone grease. Leak repaired. Pump inside surfaces appear to be in excellent condition.
6) still no water being discharged from stern outlet
7) impeller seems to be okay. Water is getting to the pump.
8) I hear gurgling noises from exhaust, but no water to speak of, just very light spits now and then.

I have reviewed the previous posts, but not sure where the problem might be. Some suggest the pump is not sealing correctly, others that the heat exchanger may be blocked with impeller parts. What is my next move? Any suggestions would be greatly appreciated. Thanks!

 

[woodster]

take the out bound hose that comes from your raw water pump off and stick it in an empty 5 gallon bucket ....fire up the engine and see if you are pumping water into the bucket ...if it is working properly ...be ready to shut down the engine quickly ....when they work properly they will fill the bucket in no time ..if that checks out move on up the line to the heat exchanger and start looking for a blockage of some kind ...if the pump is not pumping ...you may have inivertly assembled it in correctly ..as in too thick of a gasket....i think there are lots of threads on that pump iirc most like to change them out for another brand ...maybe a johnson or something like that ...at any rate when stu jackson reads this thread he will be able to shed some light on this i am sure ...good luck

 

[Stu Jackson]

impeller (which was significantly damaged/chewed up)

Woody's right. The pieces are somewhere in the system creating a clog. Also check the elbow at the pump.

But, don't change pumps, the Oberdorfer is the one you want. The Sherwood, used on many M25XPs, is one that should be replaced. With an Oberdorfer.

 

[Benny17441]

The fact that when you motored out of the marina everything seemed fine tends to diminish the possibility of a build up blockage. Chances are that on your way in you picked up a plastic bag or sea grasses which clogged and blocked the clam inlet port. These plastics bags can be tricky as they can act like a flap valve letting water in when the engine is off but closing up as soon as suction is applied. That may have been the original problem but now you have a broken impeller to deal with. The new problem is that when an impellers breaks little pieces of rubber may get drawn in the cooling passages blocking the raw water flow. Check Woodster's bucket test as it will help pin=point the location of the blockage. You will need to fully dislodge any obstructions. Hoses can be removed an inspected and small flexible brushes or compressed air can be used to clean passages. First of all do insure the intake port is unobstructed and water is flowing into the pump at all times. There is one other situation which although rare comes up from time to time and that is a faulty brand new impeller in which the rubber portion was not properly pressed and glued to the metal sleeve which proceeds to spin without moving the pump vanes. Good luck.

 

[knotoldyet]

Woody, Stu, and Benny;
Many thanks for the information. I really appreciate you taking time to help. I now have a better idea how to proceed. I'll be back to her this weekend - tools in hand.

 

[knotoldyet]

Ok, I finally got to the boat today. Pump is working ... I think. Water is coming out of the pump discharge hose leading to the heat exchanger; although it did not fill the bucket (at idle) as quickly as I would have thought. I found a few impeller parts in the heat exchanger, but for the most part it seems clear. I am reasonably sure it is clear from through hull intake to the exchanger. Still no water coming out of exhaust. I am baffled. Help!

 

[JoeWhite]

disconnect the water hose feeding the exhaust elbow mix and see if water is coming out of there.

 

[knotoldyet]

Got it working! Yeah! No smoking gun, though. In the end, I am not sure of the cause. Everything seemed okay as it was disassembled and reassembled. Could it have been in the anti-siphon portion? I did; however, find some odds and ends in the heat exchanger; but it worked okay regardless. Gravel type stuff where it shouldn't be - at the opposite end of the intake. One piece looked like a well worn screw with calcium around it???? I now have the problem of a leaking cover on the impeller. Waiting on new gasket in the mail. Thanks for all the help folks. Much appreciated. Hope to return the favor some day.