95 mariner 150 cooling water

[cre73]

Never owned one of these motors. Should water be coming out the "pee hole" as soon as the motor is started or do the thermostats have to open first.
I have no water flow. Confirmed that there is no blockage. Dropped lower unit and impeller does not look bad enough for no flow, replacing anyway.

[sliderman]

It will take a minute or so to fill the bock before you see a water discharge. The tell tale discharge is directly affected by the t-stats cycling so expect it to become stronger and weaker during idle. You should have an over heat buzzer that will sound a solid tone if nobody has disconnected it. If problems persist, have it checked out. There's a poppet valve that controls water pressure on that engine. It's rare but not unheard of for them to cause problems.

[cre73]

Started boat multiple times for short periods never got a drop out of tell tale hole. Opened cooling line at at a T before exit and line was bone dry.

[sliderman]

water hose or in the lake? How much time are we talking about? 1 min?, 2?, more??

[cre73]

Ran for approx two minutes each time probably six times total. High idled a couple of times. Using water hose with muffs.

[sliderman]

In making the following assumptions, I'll recommend what follows.

Assumptions: You've replaced the impeller. With compressed air, cleared the lines from the tell tale outlet back. Are testing on a water hose with ear muffs.

Recommended action. Remove both cover plates and t-stats. Leave covers off. Use maximum water flow on the hose. Start, idle a few seconds and bring rpm up to 2000 for 5 seconds. While engine still running, be looking for water exiting heads at t-stat position AND water flow from center of prop with motor in a down position.
Don't be concerned about engine temps the first 3 mins. If water comes out of prop hub but not t-stats, poppet valve issue is most likely the cause. If water flows from prop hub and t-stat position, re-assemble and take to lake.

If the impeller is not replaced and had a rounded 'set' where the vanes are curled in a swirl pattern, it will not flow water very well at low rpm. If you are testing on a weak water hose with the engine in a 'shallow water' position, you may not be getting enough water flow. If the boat is not already equipped with a water pressure gauge, it would be a good investment. Being at idle in the lake changes the head pressure loaded on the impeller and provides an ample supply of water. On the water hose, those variables change.
With a gauge, expect 3-5psi at idle. The pressure will rise to about 15 at 3000rpm where it will then drop to about 10psi by design (poppet valve). It will continue to climb up to about 20psi above 5000rpm. When coming down off of plane, you will see the poppet valve close by seeing the psi drop to about 10psi and jump to 15psi before falling down to the 3-5psi idle.
If you've followed this and still have no water, I'd recommend taking it to a qualified mechanic that can diagnose the problem before engine damage occurs. Good luck

[cre73]

Thanks for the reply, I will try your recommendations after I get the new water pump and its warm enough to test. If I remember I will take a picture of the old water pump for your opinion.

[sliderman]

Sounds good. A new impeller will have vanes that protrude straight out from it's center and will be flexible. With age, the vanes will take form to the cup and become less flexible. For this reason, the impeller should be replaced as part of a routine service based upon time, not use. It would also be a good idea to get a base line on the compression of the cylinders. Hopefully, we are looking at a boat that has been set up for a period of time before you purchased it. And not routinely ran with a failing pump. Good luck with it.

The impeller part number is 47-89984. There are aftermarket ones available but I don't recall all the cross over numbers. I believe it was a couple of years after 95 that the impeller was changed to a different design. The number given is all that you need.

[cre73]

Seller stated it had sat for over a year. Fired right up at the touch of the key and ran smooth. I have changed many impellers over the years some with little flow some with no flow and they all looked worse than this one. Just not sure what kind of flow to expect out of this cold engine and didn't have the guts to give it more time.

[cre73]

Here is a pic of the impeller. Let me know your opinion. Thanks