Johnson 70 power tilt/trim rebuild easy or no?

Hey guys i'm trying to figure out what I should do and figured i'd get yalls opinion on this.I have a 1980 Johnson 70hp that has power tilt and trim.I'm having a problem with the trim not working right.I recently had a leak from the tilt cylinder cap and I went ahead and replaced it.Then refilled and tried to bleed system of air but could'nt do it.So before giving up I could only get the tilt ram to work right.The trim will only work right while going up and takes forever to go all the way down and half the time I can't get it too.So I gave up and took the boat out and ran it.I was still able to get on plane and was able to trim it out.2 days after one of the trim cylinders started leaking at the cap.So basically starting back at square one.I'm thinking of just pulling it apart and replacing all the seals in the tilt and trim and blowing any and all places out with air just incase I have a blockage somewhere.My question is this can you buy a complete seal kit for everything and is it even possible to rebuild these things back to full working order? I looked on ebay for other units and they're ranging from $3-800 so trying to save some money by maybe doing a rebuild myself with yalls guidance and If they're rebuildable how should I go about it?.I don't have a manual to go by and not even sure if the manual would show how to rebuild them.Any help on this would be great.Thanks,Ron

Re: Johnson 70 power tilt/trim rebuild easy or no?

i got the outer seals for mine. Mines the calco but i think when i ordered them they didnt ask if its that type or the prestolite.
I got it off ebay.

After you do the other cap check the manual release valve screw is tight manually.
Whats your technique for bleeding?

Re: Johnson 70 power tilt/trim rebuild easy or no?

Hey thanks for replying.The last time I bled it was after I completely emptied the fluid and filled the tilt cylinder directly while piston was down in the bottom of cylinder with tilt cylinder cap off then topped of at fill screw.My father told me to try it that way it got the tilt ram to work right but the trim started to act up so not sure if there is air trapped on the trim cylinders or there is a stuck check/reverse flow valve on the trim side.As for bleeding I just ran it up and down like they say to do and then crack the cap.And for the manual release valve it's tighened up but last time I opened it all the way to check the orings I forgot about the retaining clip and it broke also the oring had a piece cut off of it.So don't know if there is a piece blocking something or a what the issue is.It was working fine until the first time it started to leak and now the trim takes forever to go down.I took the tilt ram pin out that connects the motor to it and took off the weight of motor and tried to work the tilt and trim.The tilt won't go down on its own it will only go up on its own and the same for the trim.But once I put the weight of motor on it.The tilt ram starts working again so who knows.This is why I just want to rebuild it and start back over on refilling it completely.

Re: Johnson 70 power tilt/trim rebuild easy or no?

Im surprised you got the cap off being in Florida.
Mines a 1982 60hp and a salty and they were frozen solid.
Sounds like you may need to check that o ring or that something else hasnt lodged in there.
Will it drop right down with the manual release valve undone?

Whats your motors model # ?

Re: Johnson 70 power tilt/trim rebuild easy or no?

stuck tilt cylinder caps - - - it is an aluminum to aluminum joint. They are usually stuck due to combination of ALOX residue and rubber bonding. If you weaken the rubber bond then they usually come free without damage.

I use a propane torch and heat the cap. I usually heat the outer edge while watching the inner seal. As soon as the polyurethane begins to melt and bubble then I put down the torch and use the spanner wrench (with welding gloves) with a hammer. The spanner wrench needs to be industrial grade so that it does not flex. Once the cap is off, a good soaking in lacquer thinner will often remove the rubber.

Re: Johnson 70 power tilt/trim rebuild easy or no?

"Bosunsmate" Believe it or not my motor was previously a salt water motor as well.The tilt cylinder cap was'nt that hard to get off.The trim cylinder caps are the ones that are going to give me issues.And the motor goes down when I loosen manual valve but stops once it hits the end of trim rams.The trim rams wont go all the way down when I loosen the manual valve.I replaced the orings on it so not sure what the issue is.

Re: Johnson 70 power tilt/trim rebuild easy or no?

They won't. The t/t mtr has to running to bring them in with the manual release valve closed. If they won't, there's something wrong in the unit.

Re: Johnson 70 power tilt/trim rebuild easy or no?

Bosunsmate said:

Im surprised you got the cap off being in Florida.
Mines a 1982 60hp and a salty and they were frozen solid.
Sounds like you may need to check that o ring or that something else hasnt lodged in there.
Will it drop right down with the manual release valve undone?

Whats your motors model # ?

Click to expand...

My motor model # is E7OELCSA

Re: Johnson 70 power tilt/trim rebuild easy or no?

Theres a brush and seal service kit available for that one
Part # 390987
Its half price at just over $30 on marineengine website
Looks like you can buy most parts for it, just not the main cylinder housings generally
My 60hp is way different to that one.
Looks like there is a lot of small valves etc which could get blocked up.

RRITT thanks for the tip, i hadnt clicked they were alumnimum. With all the untreated steel OMC put in my 60hp in places which are salt water soaked I just thought it was more of the same from them