1975 75hp evenrude water in gear case

[murrayg]

Is there an easy way to determine what is causing water to get in gearcase, and is it something that I can fix?

 

[jurgenscraft]

Re: 1975 75hp evenrude water in gear case

Good evening, one way to check for leaks is to lightly presurize the geargox with compressed air while the gearbox is submerged in a tank of waters,(also see handbook/workshop manual) if you see air bubbles then you have a leak. Replace the seals, also check oil filler and oil drain plugsfor leaks.I have just done a seal replacement job on my gearbox all the seals as well as water pump impellor were replaced, ,Regards Willie Wright

 

[murrayg]

Re: 1975 75hp evenrude water in gear case

Thanks
Is there a lot of work involved in replacing seels etc?

 

[jl_photo]

Re: 1975 75hp evenrude water in gear case

jurgenscraft is correct to test by pressurizing the case. I think 18 psi is the max. it's listed in the manual. i think that this test must be done with no oil on the case.

you can make a fitting for this test by purchasing a lower unit oil filling kit which has a fitting that screws into the lower oil plug hole.

it comes with a plastic pump for filling the gear case from a quart oil bottle. this is a very nice way to get oil back into the lower unit.

just pull the plastic hose loose and jam it onto the end of an air nozzle or get an extra valve stem and hook it to a bicycle pump.


the seals are not so hard to replace if you have replaced a water pump you have most of the experience necessary.

do get a manual but here is an over simplified description:

remove prop

remove lower unit

remove water pump

pull drive shaft out

pry out old seal under pump

tap new seal in using a socket with an extension stuck in backwards as a seal driver

turn the lower unit upside down and leave it that way until you have put everything back together. stuff may fall out if you don't.

remove front seal holder

replace o ring

drive out seal

replace seal



some older outboards use 1 shaft seal. if your unit has room use 2 seals back to back 1 facing in and 1 out. ask your dealer for details. its a common practice. 1 seal to keep oil in 1 to keep water out.

cote all bolts with a very thin layer of silver colored anti seize compound from the auto parts store. never use copper anti seize on aluminum. the anti seize will insure that you can get the bolts out next time.

re-assemble


the 2 main concerns

do not break off any bolts. the dealer can remove stuck bolts cheaper than broken bolts. this is where experience comes in. know when to stop and get help.

I am buying a parts motor from a guy who broke all the head bolts off. the dealer would have gotten them out and been able to fix it.


do not get the parts out of order.


you need a repair manual for this if you have never done it before.

getting the seals out of their holes is tedious and sometimes requires carefully controlled violence with a hammer and screwdriver. it is important not to scratch the machined surfaces.



never use any kind of sealant on an o ring it will leak guaranteed.


instead use waterproof grease

make sure there are no burrs or sharp places that could cut the o rings


never re-use an o ring if you don't want to pay dealer prices take your old o rings to the wholesale o-ring supplier and ask for Viton ( a kind of rubber ) o rings to match. they can measure your old o rings to match.


good luck, work carefully outboards are expensive.