1973 chrysler 70hp lower unit oil leaks out of water intakes

[christo555]

hello,
after the motor has not been used for a week and left in the up position, it leaks oil out of the water intake holes when i put it in the vertical position.
the amount is about 2 oz.
i'm assuming that the cause is a bad driveshaft oil seal, the one right below the water pump impeller.
does that sound right to you all???
can i replace just this seal?
thanks to all for any ideas you may have,
christo555

 

[Frank Acampora]

Re: 1973 chrysler 70hp lower unit oil leaks out of water intakes

That seal can be replaced but it is difficult to do with the lower unit assembled and drive shaft in place. It will be much less fuss to disassemble the lower unit and pull the driveshaft. The seal will come along with the top tapered roller bearing.

If I remember correctly that seal on those very early Chrysler engines is special and you probably will do better to order it from franzmarin@aol.com. It will probably cost somewhere around 30 bucks.

The parting line between the gearcase and midsection is sealed with an O-ring. AND the studs that hold the gearcase on are also sealed with smaller O-rings. They do not cost much so you may as well replace them too.

 

[christo555]

Re: 1973 chrysler 70hp lower unit oil leaks out of water intakes

thanks for the help frank. i appreciate it.
wrt the seal, i was hoping i could just pull the complete lower unit which is made up of the upper and lower case and not separate them. the drive shaft would come out of the power head and i could then remove the impeller/back plate and see the seal i want to replace because i "think" that's where the oil is leaking from. (do you agree?) i would then use a dremel tool to grind the seal apart and remove. then i would just push the new seal down the driveshaft and tap it in.
do you think that can work??
thanks again for the advice,
christo555

 

[Frank Acampora]

Re: 1973 chrysler 70hp lower unit oil leaks out of water intakes

It can be done, but you are working in tight quarters near the upper bearing and the seal is pressed in tight. Then, you would need to clean the seal seating area and press in the new seal around the drive shaft. What can I say: Try it. If you have a lot of trouble, you can always separate the lower unit.

However, I would wager that it will take almost as much time as separating the lower unit. Good luck, and let us know how well you made out.

 

[christo555]

Re: 1973 chrysler 70hp lower unit oil leaks out of water intakes

well, i decided to try what i said.
i separated the lower unit from the leg and i drained the oil and then hooked up a air compressor set to 10 psi and connected it to the lower gear fill hole with the upper vent hole closed. i thought i would have to use soapy water to trace the leaks but the air was just rushing/wooshing out noisily from the upper driveshaft seal. couldn't come close to pressuring the gear case to 10psi.
so, after pulling out the rubber seal, i then used a small grinding wheel on my dremel tool to cut away at the metal part of the seal. after cutting a slot that a screwdriver would fit into, i pried out the old seal. i then tried to put the new seal in but had a problem getting it to go in straight, not cockeyed. not having the right driver to seat the seal, i improvised by using the metal tube from a beach umbrella. well, i got it in but at about a 10 degree angle. not so good i guess. i then decided to separate the upper and lower gear case to maybe pull the drive shaft like you told me to, but i ended up just replacing the o-ring between the cases and leaving the seal cockeyed.
so, the big test. i hooked up the air compressor again and happily, the case would fill and stop taking air and when i disconnected the compressor, i got a release of air from the case.
i then assembled it all, put it in a horse tub 150 gallons and ran the motor forward and reverse for about 15 minutes and left it in the water overnight. the next day, i pulled the drain and vent plugs, and happily got only oil coming out, no water.
so, it's ready for the next summer i think.
about my lower gear case freezing last winter:
at the end of last summer,when i stored the boat for the summer, i thought that i had oil mostly in the gear case because when i let some drain out to see, i got only a tablespoon of water and then white oil which i though was mostly oil with just a little bit of water which made it look whitish. when i got ready to do this seal change this time, i drained all the white oil into a clear container and let it sit for a day. what i then saw was 16 oz of clear water on the bottom and 16 oz of green oil on the top, like it was 50/50 mix. so, that is why my lower gear case rear bearing carrier for the prop shaft broke off in the winter. i had, after the white stuff separated, water only filling the lower gear case.
but hey, i've had a great time working/playing with the whole boat thing, learning stuff, maybe more enjoyable to me than just being on the water.
frank, thanks again for all your help and encouragement
christo555