How serious is pitting I see on my lower unit?

[newenglandguy]

This is the first year that I've ever noticed pitting on my lower unit of my Johnson 90 HP OB. It did sit in the sand some, so probably got some paint knocked off. How do I know if the pitting is serious - in other works it will cause me some issues. What do I do about it?

Thanks

 

[JSMoore]

Re: How serious is pitting I see on my lower unit?

I rather doubt you've got a problem there that a little elbow grease and paint won't cure. I would buff everything up real good with some sandpaper and prime the bare aluminum with zinc primer, followed by some engine paint to match your motor. Both zinc primer and OMC matched paint should be available from a local shop that carries OMC/Evinrude/Johnson parts. The iBoats store carries Zinc Primer. But, I didn't see any OMC/Evinrude/Johnson paint there.

When you re-paint, make sure your sacrificial zincs are NOT painted over and are in good shape.

Hope this helps!
JSMoore

 

[phillnjack2]

Re: How serious is pitting I see on my lower unit?

Get all the paint of in the surrounding area
give it a good coat of the proper etching primer and re-spray the area.

if it was me i would rub down as much of the gearbox as possible and completely re-prime and re-spray the whole gearbox.
If you leave this like it is it will get worse and will end up causing a lot of damage and possible failing when your out on the boat.

Any exposed alluminium will get attacked if not coated with something like paint etc.

Its not just salt water that attacks, its also fresh water as well, thats why their is different types of anode available for
both salt water and fresh water.

But looks like your NOT gonna have any problems at the moment as it dont look too bad, ive seen a lot lot worse
even to the point where oil was seeping through the bullet on the gearbox !!!!!!!!!
for that its a big re-pair involving ali welding etc, you dont want to let it get that bad or big bucks are needed.

2 hours of rubbing it down with wet n dry paper then spraying will make it like new again.
i wouldnt be too concerned but would definitely get some paint on it ASAP to stop it getting worse.

Make sure you get it very clean,even use a wire brush to make sure any dirt and grease is gone before the primer.
Do make sure its a primer for alliminuim and make sure its for marine use.

Plenty of nice light coats of the primer then the blue and then a couple of nice clear coats of laquer will have
it looking like brand new.

Below are pics of my little suzuki 30 half way through rubbing down and then final finnish.
My engine leg looked a lot worse than yours when i started it, but i reckon it looks pretty good again now.





hope this helps.

phill...

 

[dazk14]

Re: How serious is pitting I see on my lower unit?

all good info above...

Your anode is painted. R & R. If it's in good shape you can remove simply remove the paint.

Your lower is fine from a pitting point of view. There's a lot more meat left.

A small 3" wire wheel on any drill will make fast work of removal of the corrosion.

What you have is very common in salt (as well as fresh water) where the motor sits partially submerged when tilted. The anode won't help you here. Good paint protection is a must.

Can the motor be tilted further manually?

 

[NYCBigE]

Re: How serious is pitting I see on my lower unit?

all good info above...

Your anode is painted. R & R. If it's in good shape you can remove simply remove the paint.

Your lower is fine from a pitting point of view. There's a lot more meat left.

A small 3" wire wheel on any drill will make fast work of removal of the corrosion.

What you have is very common in salt (as well as fresh water) where the motor sits partially submerged when tilted. The anode won't help you here. Good paint protection is a must.

Can the motor be tilted further manually?

Curious, where do you see the anode painted? I have the same unit. Johnson doesn't use the trim tab as an anode. If it does, I can't find one to install in replace of my trim tab.

 

[dazk14]

Re: How serious is pitting I see on my lower unit?

Not the trim tab.
In the 2nd picture, look above the A/V plate.
You'll see 3 cross drilled holes in the lower unit.
Immediately aft of those is the anode.
It'll appear recessed and is ~1"x2" and is visible from either side and "should" appear silver/grey.
It is bolted from underneath the A/V plate.

Welcome to the club.

 

[Faztbullet]

Re: How serious is pitting I see on my lower unit?

You need to get as smooth as possible as depending on boat/speed those pits could cause water flow interruption to water intakes and cavitation of prop. Sand in wire brusg to bare aluminum and fill in and sand with Devcon aluminum epoxy then paint....

 

[NYCBigE]

Re: How serious is pitting I see on my lower unit?

Not the trim tab.
In the 2nd picture, look above the A/V plate.
You'll see 3 cross drilled holes in the lower unit.
Immediately aft of those is the anode.
It'll appear recessed and is ~1"x2" and is visible from either side and "should" appear silver/grey.
It is bolted from underneath the A/V plate.

Welcome to the club.

I see what you're talking about. I don't have that on my unit. Mine is a 135 hp, so that could be why.

 

[dazk14]

Re: How serious is pitting I see on my lower unit?

If your motor is a V4, then it's 1973-1976.

The best way to provide good anode protection is using OMC part # 0171637 anode kit. ~$20

It bolts(included) thru the transom. One wire to ground it to motor(included). Very effective and can be used in many applications.

With all the nooks and crannies in the shape, it provides a large surface area.

Here's one on ebay $16 shipped.

OMC Johnson Evinrude Boat Sacrificial Anode Kit 171637 0171637 with Lead | eBay