I really need help!!

[daew30]

Here is the story(sorry because it is long). I bought a boat from a family member that has a 1974 Merc 500 on it. I knew that it was losing oil out of the gearcase when I bought it. I filled it up and took it out for the first ride. When I got back I found it to be full of 100% water. Tore it down and replace all the seals(yes they were all in the right way and I used perfect seal on every thing, and greased the lips of the seals etc). Took it back out and when I got home I still had oil but it had water in it. SOOO.....I tore it down again. I found that the driveshaft was pitted and had groves wore where the seals are against it. So I pulled the shaft and had it machined back to original diameter. Replaced all bearings(since I had it apart), and replaced all the seals again! Stuck it in a trash can and let it run in gear for a moment then shut it down and let it sit for a few moments. Pulled the screw and the oil was clean. No water! Took the boat out tonight and when I got home--guess what--more @%$!&$# water. And it seemed to be under a bit of pressure also as I could hear it escape when I loosened the plug. I don't know what else to do!<br />The prop shaft is spotless as is the shift shaft. I applied perfect seal to all metal edges of the seals and bearing carrier. All gaskets in the water pump are new. It passed the vacuum test and I assume since it was under pressure tonight that it will pass the pressure test also. HELP PLEASE, It is getting to the point that I can't sleep at night!<br /><br />Thanks for any and all suggestions

 

[andrewkafp]

Re: I really need help!!

Sounds like you've done everything.. It would be an insult to ask if you left out the Fill/drain screw gaskets.. <br />Strange that it's passing the pressure test, but still leaking

 

[The Marine Doctor]

Re: I really need help!!

When you checked the gearcase for water, did you replace the fill screw washer...or just reuse it?<br /><br />Next question. Did you clean all the old oil out?<br /><br />Is the shift shaft rusty?<br /><br />Propshaft bent?<br /><br />Did you get the brg carrier ring tight enough?<br /><br />TMD

 

[daew30]

Re: I really need help!!

I have used new washers every time I remove the screws. The shift shaft is good with no rust or pits. I had the housing completely tore down and I washed and every part in kerosene(except the water pump) and rinsed out the housing w/kerosene really good, dried everything off with compressed air prior to replaceing the seals and reassembly. So there is no chance of old oil being in there. I torqued the cover nut to 110 ft lbs. I am really getting mad at this thing. I am at a total loss. The prop shaft is as straight as an arrow, although the machinest said the driveshaft was minutely warped(not enough to make a difference). I am out of options.<br /><br />Thanks for the replies<br /><br />Darrin

 

[i610288]

Re: I really need help!!

i had the same thing happen in an evinrude.the lower unit had a crack in it and let water seep in.it passed a pressure test also until i put a little torque to it then it would leak.

 

[jdkzrt]

Re: I really need help!!

You replaced the shift shaft seal too, right?

 

[daew30]

Re: I really need help!!

yes, I replaced the shift shaft seal, then when I did it the second time I just replaced the whole bushing.

 

[The Marine Doctor]

Re: I really need help!!

Pressure test the gearcase..this will tell you where the leak is.<br /><br />There will be no need to guess after you do that.<br /><br />TMD

 

[NEECAPRS]

Re: I really need help!!

Daew30: I'm puzzled about something. How did you machine the pitted and grooved seal land on the drive shaft back to the "original" diameter? <br />I can see building it back up with certain proprietary welding processes, then machining it back to original. But, if it was simply cleaned up, then it has to be undersize presently and the standard seals aren't likely to work!

 

[daew30]

Re: I really need help!!

He built it up and then took it back down to the original diameter(in fact he made it 1/2 of 1000th of an inch over the original size to get a good seal). I droped it off at the local merc dealer last night. It held 15 pounds of pressure for almost 9 HOURS!(until he released it) When I went to see what was going on this morning he vacuum tested it under water and it held 15 pounds of vacuum pressure for the entire 30 min that I was there. He was calling me a liar until I showed him the lube that I drained out of it. He has no idea. He said that the only thing he can think of is that there is a very small crack somewhere in the housing that when heated up is allowing water in. This thing is really ticking me off!<br /><br />Darrin

 

[The Marine Doctor]

Re: I really need help!!

While the test was going on, were any of the shafts being turned? I have seen gearcases pass the tests until the seals were made to perform under stress.<br /><br />TMD

 

[mellowyellow]

Re: I really need help!!

hmmmm.... tough one. is pump leaking? water tube?<br />if cracked, I think pressure test would show.

 

[daew30]

Re: I really need help!!

Yes he was moving all three shafts during both tests.