83/84 merc. blackmax 150 water in gear case

[hands]

problem with the lower unit, replaced (complete) water pump and still have problem. water entering the gear case(water in gear oil) this will happen with the boat running out of the water with the muffs on or running in the water, the old pump lower housing was cracked above the top seal of the lower housing and inside the water jacket of the lower housing of old pump. i have had this lower unit off a hundred times and have gotten really good at replacing the water pump but cant figure it out, Now i may hate to say this but im a 20 year auto tech and cannot fine the problem water is entering the gear case somehow through the water pump i think because it will do it with the muffs on....... any clues

 

[SpinnerBait_Nut]

Re: 83/84 merc. blackmax 150 water in gear case

Think maybe shaft is wore enough to let water down past it<br />Don't know for sure if it could be, but might.

 

[hands]

Re: 83/84 merc. blackmax 150 water in gear case

took new seals and put them on the shaft by hand seem to feel pretty good, looked ok shaft shows alittle signs of wear but ok, any other ideals,

 

[The Marine Doctor]

Re: 83/84 merc. blackmax 150 water in gear case

The oring within the water pump base...are you using silicone to seal it?<br /><br />If so do not..it will just let the water past.<br /><br />Are you maybe flipping the seal lip when installing the waterpump base?<br /><br />TMD

 

[Trent]

Re: 83/84 merc. blackmax 150 water in gear case

Also replace the shift shaft oil seal and o-ring. Pressure test the unit and use soap bubbles to check for the leak.

 

[hands]

Re: 83/84 merc. blackmax 150 water in gear case

Thanks, pressure test showed shift seal, man never thought that little seal could do it. put about 10.5 psi and sure enough. i used a small electric air pump and screwed it into the vent hole and soaped it down, i soaked around water pump and no bubbles, so i hope its ok, is this a accurate way of checking? THANKS AGAIN

 

[hands]

Re: 83/84 merc. blackmax 150 water in gear case

another question, I have a 1984 baja sun sport 18' 150 merc. loads of power, boyesen reeds, holley electric fuel pump, 16 3/8 holes drilled (exhaust) this sucker rumbles ,question is when i full throttle from a stand still rpms are around 6800,planes quick and drops too about 5200 and then rpms climb to about 5800 max before trim and max speed 55 with two people about 58 to 60 by myself, with the initial 6800 rpms couldnt i put alittle bite in the prop and gain top end with out hurting plane? Im not sure of the prop #s there are numbers stamped on the prop as follows, 48 75772a4...355T....24P.....612553SN Thanks

 

[Trent]

Re: 83/84 merc. blackmax 150 water in gear case

Hands..... Its done that way all the time. However to do the job correct, You need to also do a vacuum test. Rig up a gage and pull a small vacuum and see if it holds. But I bet you found the problem. Common problem with the shift shaft.

 

[Hasbeen]

Re: 83/84 merc. blackmax 150 water in gear case

Youve got to stop that 6800 RPM blast off or that rumbling is going to stop! You are cavitating badly at WOT before getting on plane!<br /><br />Is the 5800 RPM before trimming? If so you are under propped! Your RPMs should be around 5500 RPM at WOT fully trimmed! The 24P is the pitch of the prop, you may need to go as high as a 28! (They usually go 2 pitches at a time) Try to borrow one from a marina, Most will let you try one with a deposit! With the right prop you may loose hole shot but you will gain maybe as much as 5 MPH or more at top end! If you are pulling skiers you might want to use the prop you have but stop those 6800 blast offs! <br /><br />Your engine is either too high on the transom or You need a vented prop or maybe even a four blade!<br /><br />It may sound cool, but it is not going to live long!<br /><br />Did you set up the fuel pump, and do you still have oil injection? Maybe they didnt have injection then! How did you do it? Also how and where did you drill the holes in the exhaust and what performance did you gain if any! Or did you just do it for a louder rumble? I think the 150s are a bit too quiet and so does my wife! First time out in the boat my wife said that the 150 sounded like a wuss! Im thinking of doing away with the injection in my 150 anyway! For answer on fuel pump post a new post!<br /><br />Hasbeen

 

[hands]

Re: 83/84 merc. blackmax 150 water in gear case

Thanks for the help, Ive worked on car for twenty year and i know how it is to get a simple thank you for a job well done.... so my hats off to you guys once again THANKS