White residue on prop shaft, thrust washer, inside prop etc.

ryno1234

Petty Officer 2nd Class
Joined
Dec 8, 2014
Messages
148
I took my prop off because I noticed vibration after a big wave at a heavy throttle the last time I was on the water.

I noticed that there was a lot of white residue on areas of the prop shaft, etc. What is this?

 

ryno1234

Petty Officer 2nd Class
Joined
Dec 8, 2014
Messages
148
It's kinda chaulky. On the inside of the prop hub, that same white residue is more gummy.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,824
Lubriplate brand grease (in most auto stores) is commonly used in marine environments as it stays put and stays greasy in marine environments.....its white.
 

StewartL

Seaman Apprentice
Joined
Jul 23, 2025
Messages
36
The white residue is likely dried salt or oxidation from water exposure, especially if you're in saltwater. It could also be leftover grease or anti-corrosion coating breaking down. Clean it off and check for corrosion or damage.
 

cyclops222

Commander
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Mar 21, 2024
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2,786
In freshwater I had too much oil in the gas / oil mixture. Looked like lumps of cream cheese on lower unit.
Motor has separate exhaust tube and prop.
 

ryno1234

Petty Officer 2nd Class
Joined
Dec 8, 2014
Messages
148
For what it's worth - I cleaned this off of the shaft / thrust washer using parts cleaner no problem. Makes me think it was dried grease.

However, after knocking the hub out of the prop, there was a bunch of a white chalky looking residue in there too. After looking at that further, that looks more like the effects of saltwater because it pitted the inside of the propeller hub area. I took a Dremel brush to it and could expose the pitting beneath the buildup.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,627
Your typical run of the mill saltwater calcium/corrosion buildup.

What is that "white" plate sitting on the on the thrust washer?

Looks like you have aluminum, brass and steel, possibly stainless in contact with each other. Not good in a saltwater environment.

Guessing your sacrificial anode(s) needs replaced.
Is the anode pitted at all?

Check the continuity between the anode and the prop shaft and between the anode and the prop proper. With a good continuity test, check the resistance between the various components. The lower the better
 

ryno1234

Petty Officer 2nd Class
Joined
Dec 8, 2014
Messages
148
Your typical run of the mill saltwater calcium/corrosion buildup.

What is that "white" plate sitting on the on the thrust washer?

Looks like you have aluminum, brass and steel, possibly stainless in contact with each other. Not good in a saltwater environment.

Guessing your sacrificial anode(s) needs replaced.
Is the anode pitted at all?

Check the continuity between the anode and the prop shaft and between the anode and the prop proper. With a good continuity test, check the resistance between the various components. The lower the better
That white plate IS the thrust washer.

I believe the boat had been put in saltwater by the previous owners. I also took it into brackish water for an overnight once, but that's it since I've owned the boat.

I also replaced all the anodes for good measure several years back, but the previous ones didn't look that bad. I'll check the continuity.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,259
your boating in a high mineral area. the minerals on the prop shaft and the slight bit of minerals and transfer aluminum corrosion on the thrust washer.

you should see a few corrosion pimples under the back side of the prop

wire brush it, paint it, use prop grease on the shaft and go boating.
 
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