mercruiser stern drive maintence

[john1947]

Good morning,

last year i checked my gear case and it had some water in the lower unit.I changed it and last fall I found oil had mixed very little in lub.It came out with no water just grey lube.Wondered if it is o klike that or go for a prop seal.no grease on prop or shaft.Im also replacing the water pump,it lasted two years probably the plastic cup got over heated,to bad they dont make metal cups.Im also installing a alarm for overheat andnew flapper valves,so water doesnt get into the block.Any experience on these repairs welcome

thanks

john

Edited April 13, 2016 by john1947

[fisherdude]

when there is milky oil or water in lower unit you have a bad seal or two when putting a new impeller it come as kit that fits other units  go to dealer get seals impeller new cup and there is a upper cup you need to check if you burned out the check valve in the exhaust its whip too ask dealer for shop manual not that bad a job to do

[Chas0218]

If I'm not mistaken the impeller does not have anything to do with water intrusion on my outboard the impeller housing is plastic with a metal cup inside. There is a seal under the the flat that the impeller rides against. There are 2 seals on the driveshaft under that along with a gasket on the back of that plate. Most likely bad prop shaft seals. Check for fishing line around the prop shaft.

Edited April 13, 2016 by Chas0218

[chinook35]

There are several seals in a Mercruiser sterndrive that could be at fault . Do a pressure test to find the faulty seal . An old bicycle pump can be modified to do the test . A shop manual is a must ,as some of the seals require special tools to replace . A prop seal is also a frequent cause of water in gear oil .

[billbobthorpe]

chinook35 is right. Their are many seals in the entire outdrive I had the same issue 3 years ago. I started replacing parts one at a time with still finding water in the drive. Finally just had to bite the bullet and have the outdrive rebuilt. I was going to try it myself but as chinook35 said their are special tools to do the job. Their are also some tight tolerances that must be followed for reassembly. I like to do as much as I can myself. But in this case I left it for the pros. No more water issues and it runs great.

 

Goo Luck!

[Adm Byrd]

Long ago my alpha 1 got milky, ended up being flange at top of outdrive where input shaft (from engine) comes in, found rust had eroded metal under seal - new flange and seal and all was well for 15 years. Others are correct that there are several points it can come in through.