Lower Motor Mount Corrosion '04 Johnson 90

[gibbsb]

I began having trouble shifting into reverse and discovered that both lower motor mounts had failed. Upon replacement, I discovered massive corrosion had actually eaten a hole in the lower unit mid section. Is this a common problem on these motors when used in saltwater. I always wash the motor after pulling it out, but apparently it did no good in this area. Any ideas on extending the life of the lower unit and a cheap place to get the lower unit part (actually the middle section)

Thanks,

Barry

 

[boobie]

Re: Lower Motor Mount Corrosion '04 Johnson 90

I have ran into this before where I'm from and it is a very common prob in salt water areas. As long as the hole is not in a bolt retaining area you can clean up the mount area and patch the hole with gray marine tex or else have it welded. Better than replacing the mid section. Post a pic if you can.

 

[Chris1956]

Re: Lower Motor Mount Corrosion '04 Johnson 90

Do you trailer that boat, or keep it in the water? If you keep it in the water, do you tilt it up out of the water when not in use?

Unlike Boobie, I have never seen that issue, and I had sterndrives that stayed under saltwater all season. Did the zinc anodes corrode away?

 

[boobie]

Re: Lower Motor Mount Corrosion '04 Johnson 90

Chris, I don't know where you're from but on outboards the lower mounts can swell up from salt water corrosion and cause hard shifting due to the shift rod binding from misalignment. Never seen it on a SD. I found out about this 16 yrs ago. You don't see it happen in fresh water areas which I'm also familular with.

 

[gibbsb]

Re: Lower Motor Mount Corrosion '04 Johnson 90

Corrosion is not at a bolt hole. I will take it apart again and try to repair holes with MarineTex or JB Weld. Boat was in a sling most of it's life but inside on a trailer now. I will be a little more attentive to washing out that area, but mount fits so tight that I doubt it will do much good.

Thanks again,

Barry

 

[dazk14]

Re: Lower Motor Mount Corrosion '04 Johnson 90

.... and try to repair holes with MarineTex or JB Weld.

Thanks again,

Barry

For important repairs, spend the extra pennies and use MarineTex - much better product. Boobie's suggestion was not arbitrary.

Surface must be spotless, provide tooth, plus acetone wipe down.

Also, if you're not certain you can accurately mix partial amounts, then mix it all - normally 2oz. @$15).

Good Luck!

 

[Twingirls1]

I have the same issue on a 2003 90hp. Corrosion behind the lower motor mount where there motor mount nipple or pin goes into the housing. Once the new motor mount is put in place won’t the motor mount basically act like a gasket and seal the hole? Is there really a need to patch it with marine Tex?

 

[saltchuckmatt]

Electrolysis.....add or clean/replace zinks. I'll send a picture later of someone who didn't and this 90 was in fresh water. Bottom of powerhead to the bottom of the gearcase destroyed basically.

Is this an aluminum boat? I personally coat the hole clamp system with 5200 before mounting the outboard....love that stuff.

 

[racerone]

Is this the 4 stroke ---Johnzuki -----Or the 2 stroke trusted Johnson ?-----Model number is ?

 

[Twingirls1]

2 stoke j90plstc. Was saltwater now freshwater on lake. Do I need to fill the corrosion hole behind the lower engine mount? The rubber mount and then the clamshell cover covers the corrosion hole.