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Pink metal on stuffing box

7K views 42 replies 16 participants last post by  L124C 
#1 ·
I know that generally pink is not good when it comes to metal. Is the pink on this stuffing box (forward edge) something to worry about?
 

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#2 ·
yikes!!! I hate that color...Just experienced a pink strut and it was not cheap. Get it under control while you can. Have you been going through shaft zincs?

I no longer plug my boat in to shore power unless absolutely necessary. I am not sure if this is going to help but figure the less paths the boat offers to ground, the better off I will be.
 
#6 ·
yikes!!! I hate that color...Just experienced a pink strut and it was not cheap. Get it under control while you can. Have you been going through shaft zincs?

I no longer plug my boat in to shore power unless absolutely necessary. I am not sure if this is going to help but figure the less paths the boat offers to ground, the better off I will be.
Going through a prop zinc about every 1.5 years. I've tested the water for current and don't find any.
 
#4 ·
Sure is a problem. Bronze is a mixture of copper and tin ... and with a wee bit of zinc added to aid 'machinability'. When electrolysis begins, and there isnt a proper 'anode' connected the electrical potential will use the zinc in the bronze casting as its anode ... the result is the metal alloy turns 'pink' as the zinc is consumed .. and then the metal becomes 'spongy'.

This is also a warning that possibly that the metal wasnt really a 'true' bronze but rather a 'red brass' with lots of cheap zinc added and the tin content 'reduced'. Lots of asian 'bronze' is actually 'red brass' (zinc loaded 'bronze').
 
#9 ·
Thanks to all for the responses!

Sure is a problem. Bronze is a mixture of copper and tin ... and with a wee bit of zinc added to aid 'machinability'. When electrolysis begins, and there isn't a proper 'anode' connected the electrical potential will use the zinc in the bronze casting as its anode ... the result is the metal alloy turns 'pink' as the zinc is consumed .. and then the metal becomes 'spongy'.
This is also a warning that possibly that the metal wasnt really a 'true' bronze but rather a 'red brass' with lots of cheap zinc added and the tin content 'reduced'. Lots of asian 'bronze' is actually 'red brass' (zinc loaded 'bronze').
So, the zink on the prop shaft isn't a proper anode?
By "spongy", I assume the consumed Zinc creates voids, and therefore makes the fitting weak?
Other than price (no longer a sure fired indication of quality, now that China has cornered many markets), how can I tell if the replacement is true Bronze?
 
#15 ·
If the front edge of the stuffing box is not immersed in water, how would de-zincification occur without an electrolyte? Could it be from the water that leaks through? If so, you would also expect the de-zincification to occur on the INSIDE of the stuffing box, where you can't see it unless you take it apart. Greasing the outside might insulate the visible metal (maybe captflood is on to something here) but that seems like a temporary cosmetic fix: you still have to wonder about what is going on inside.

If you want to sleep at night, take it apart next time you haul out. You might consider replacing it with a PYI dripless shaft seal (no bronze) and worry about something else.
 
#20 ·
Yah, no...it's underwater. You can do the Thunderdome thing and roll the wheel and take your chances. The pink coloring is caused by galvanic corrosion / electrolysis which causes loss of zinc in the bronze. The pink color is copper. The problem is not repairable as the metal has morphed. It should be replaced.
 
#21 ·
Pink metal/stuffing box



A lot of good advice here.

The cost of a new stuffing box is minimal compared to the failure of the pink one.

Plus, what kind of wear damage did it make on the prop shaft. A good inspection should be made on the shaft.

Some people in forums have mentioned that they measured the current in the waster and not finding any and still have corriosion on their anode.

Bill
 
#22 ·
Pink metal/stuffing box



A lot of good advice here.

The cost of a new stuffing box is minimal compared to the failure of the pink one.

Plus, what kind of wear damage did it make on the prop shaft. A good inspection should be made on the shaft.

Some people in forums have mentioned that they measured the current in the waster and not finding any and still have corriosion on their anode. I keep my boat on a mooring so I have never encountered that problem.

Bill

Bill
 
#23 · (Edited)
I've been brushing up on Bonding, wondering how you bond an object on a rotating shaft (use one VERY LONG wire?:)). It occurred to me, isn't the stuffing box bonded to the anodes in the raw water cooled motor via the drive shaft? Should I put a zinc on the shaft next to the new stuffing box??? Obviously the concept of electrolysis is a little elusive to me!
 
#24 ·
Yes you put a zinc on the outside between the wheel (prop) and the bearing. You also need to add a shaft brush (WM has them) to bond it to the bonding circuit. There also needs to be a wire from the bonding circuit to one of the nuts holding the stuffing box. Good Luck.
 
#25 ·
I went dockside for a winter engine swap and lost my prop to the steel house boat next door.Probably a wiring issue but annoying anyway. Bonding wire, with soldered joints and ends, connect shaft brush and stuffing inside to outside,thru bolt, to zincs on cutlass and rudder stock.
 
#27 ·
I'm so confused!

The conflicting info I'm getting on this is mind numbing. Sent the picture in the OP to my diver (also a marine mechanic), asking him if we could possibly switch the stuffing box in the water, as I would prefer not to haul out this year. He responded: "Most of the stuffing boxes I see look like that. We'll put a Shaft Brush on it and bond it. It will be fine!". BTW, an article I read on shaft brushes said that the shaft is not bonded to the motor due to the fluid in the transmission.:confused:
 
#30 ·
The conflicting info I'm getting on this is mind numbing. Sent the picture in the OP to my diver (also a marine mechanic), asking him if we could possibly switch the stuffing box in the water, as I would prefer not to haul out this year. He responded: "Most of the stuffing boxes I see look like that. We'll put a Shaft Brush on it and bond it. It will be fine!". BTW, an article I read on shaft brushes said that the shaft is not bonded to the motor due to the fluid in the transmission.:confused:
The shaft is firmly attached to the coupling and the coupling is bolted to the transmission. The transmission fluid has nothing to do with the electrical connection. You can check with a multimeter to confirm.

As Maine stated, unless there is a flexible coupling, which eliminates the metal to metal connection at the coupling the shaft brush isn't needed. If there is a flexible coupling a wire jumper from the transmission side to the shaft side can make the connection and is less hassle than a shaft brush.
 
#28 ·
So what's the cost of a shaft brush bonded to stuffingbox , engine ground, cutless and rudder (if metal shaft and tube) and any outside zincs. It's difficult to put the zinc back in the pink metal.You can hang a zinc on a grounded wire over the stern but doing it right will be cheaper.
 
#29 ·
You need to haul out to do the stuffing box properly. If there's a bearing or shaft issue, it's all problematic. There's nothing wrong with grounding the shaft with a brush. If it had been done in the first place this issue would have not been as traumatic. it's a boat get over it. Sometimes you have to pull without a moments notice; this is one of those times.
 
#32 · (Edited)
Get over it?


Yet, another country heard from! Kinda missed my point. I had decided to replace the stuffing box and have no problem hauling if I need to. In fact, I was fully prepared to haul if my diver said "Replace it in the water? Are you nuts?" Though, based on some of the responses, I was somewhat reluctant to even motor it to a yard! However, he said, "no big deal, see it all the time". I consider him conservative, he's not one to take short cuts or risks.
So, I'm simply bewildered by the variety of opinions and information I've received on a fairly basic issue. Everything from, "don't tap it, it might shatter and sink the boat" or "boats go forty years without a brush and don't look like this", or "if it had a brush, it wouldn't be this traumatic (I'm not "traumatized", just confused BTW)" or "put some grease on it, it'll be fine!".
As always, I'm grateful for the input. However, the range of these opinions, and other information I've obtained (The trany fluid theory didn't make sense to me BTW, but what do I know?!) is rather startling! I mean...we're not talking String Theory here!
So, thanks for identifying it as a "boat". I wasn't sure about that. However, please don't tell me to "get over it". Hauling when needed is prudent. Unnecessarily hauling is simply stupid! I'd just love to be on the hard and have the yard mechanic say "why are you replacing this?" :eek:
 
#36 ·
We recently removed our bronze prop shaft for replacement as it was worn at the cutless bearing. Given that our boat was hauled (on the hard) we removed the 43 year old stuffing box which looked a bit like yours - maybe not quite as corroded looking.
We took the stuffing box home and used a wire wheel on it and it now looks like new (see pic below). We will be using most of the old components when we put the drive train back together with the exception of a new shaft log hose and a new cutless bearing.
What I'm getting at is perhaps you should try using a wire wheel drill attachment and see if you can clean up the metal on the stuffing box. My guess is that it is probably not as bad as some might think.
Of course, this is the last place you want to start an accidental leak in which case you will be hauling out, and fast. Work carefully, slowly and deliberately and you should be fine.

I didn't see if you had a drive saver in your set up. Do you? If so then the comments about grounding the shaft across the drive saver are on the mark.
 

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#38 ·
It'll be a salt (not necessarily the sodium chloride variety) for sure and is a tell-tale sign of electrolysis.

It's an indication that some metal in your stuffing box is electrically connected to a different type of metal and, in the presence of salt water, is slowly being eaten away.. Best get that looked at by a knowledgeable shipwright.
 
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