Detroit Diesels - Anyone see this before?

[zigzag930]

I'm hoping I just need to remove the plate and install a new gasket. Must be salt crystals right?

Just don't want this to be an indication there is a blockage downstream. Engine is not running hot and seems like great water flow out the exhaust.

 

[Boatsb]

I'm hoping I just need to remove the plate and install a new gasket. Must be salt crystals right?

Just don't want this to be an indication there is a blockage downstream. Engine is not running hot and seems like great water flow out the exhaust.

It's common. Pull the parts, clean well and re gasket and seal.

 

[SEVEN]

Poor some vinegar on it and brush it with a wire brush. If you have water dripping out then yes a new gasket or sealant. If no water just clean it up.

 

[cww]

You can clean it, but the underlying cause is you’re not keeping up with your engine zincs.

 

[JD5652]

If it was me..... I'd change out that gasket.

I just went completely through my fresh and raw water cooling systems. Replaced all gaskets, removed HX bundle and acid cleaned... replaced all hoses, etc...

Not your case here.... but overheating is the death nail of a DD 2-stroke.. I like to have both those two cooling systems in top notch condition.

 

[zigzag930]

I will have to disassemble to inspect and repair the gasket.

Just wondering, what does this issue have to do with engine zincs? I will change, them, but curious.

 

[Addie-Kat]

Had a mechanic on the boat a year and half ago with similar white stuff appearing like that. Also had paint flaking off. The mechanic said it was from electrolysis and to check the bonding. He also said that it could be from the antifreeze itself creating it, if it has been in the engine way to long. Come to find out it was the antifreeze. Changed it, haven’t had a problem since.

 

[SEVEN]

Had a mechanic on the boat a year and half ago with similar white stuff appearing like that. Also had paint flaking off. The mechanic said it was from electrolysis and to check the bonding. He also said that it could be from the antifreeze itself creating it, if it has been in the engine way to long. Come to find out it was the antifreeze. Changed it, haven’t had a problem since.

I did the same. Once I changed out the antifreeze the issue stopped. Flush out the cooling system with a coolant flush then with clean water. Drain the clean water and add new coolant.

 

[Captain Ralph]

I'm confused. May have read the post to fast but let me make some comments;
Coolant will leak faster than water.
Coolant contains some strange chemicals that may flower like like that in the picture.
There no zincs in the coolant side on Detroit diesels.
You can purchase test strips from your Detroit shop and test the coolant.

Without any extra detail in the picture, I would call that the raw water side and that is salt flowering out.
That could be a zinc cap on the top but I feel that is just a bad gasket. Ship happens.

IMO, gently take the flange apart, clean the surfaces well (I use a large flat file), purchase or punch a new gasket, dress the new gasket with grease and reassemble. Clean or replace the machine screws and washers.
Pop a top and go fishing.

 

[cww]

The picture shows the raw water pipe not coolant. That bolt head is the top of the engine zinc that goes there. This is 100% electrolysis because nobody’s keeping up on the engine zinc. It’s the same as when your sea strainers turn bright green even if there is no leak.

 

[zigzag930]

Thanks guys.

We're on the hook for a few days, but when I return to the dock - I'll pull that cap to see if it looks like an old zinc. Also, will pull the flange, flat file it and reseal.

Can someone explain what this stuff is, if caused by electrolysis? I thought it was salt and maybe it is, but it looks different. Looks fuzzy

 

[dottieshusband]

I've noticed similar blue/green and paint chipping. Usually because I cheaped out and used the blue rtv sealant instead of a gasket, and didn't used an etching metal primer before painting. The black RTF hasn't shown that. But as others have said, remove, wire brush it, use the proper gasket, use an etching primer, paint, reassemble, touch up.

 

[dottieshusband]

As someone else noted, that hex bolt on top would be a good place for a pencil zinc. All mine have square heads, so don't know what's going on there.

 

[JD5652]

Thanks guys.

We're on the hook for a few days, but when I return to the dock - I'll pull that cap to see if it looks like an old zinc. Also, will pull the flange, flat file it and reseal.

Can someone explain what this stuff is, if caused by electrolysis? I thought it was salt and maybe it is, but it looks different. Looks fuzzy

Zig-

The "hex bolt" is definitely the zinc for the raw water side of the heat exchanger. You can easily remove that zinc while you're on the hook. That is the raw water side and as long as the engine is not running, there is no pressure or flow through that pipe and flange.

Think you have 471's in your vessel. On my 671's, I have a zinc on the inlet and outlet of the HX... see pic below...

 

[zigzag930]

JD,

I have one on each side as well. Thanks for pointing that out. Are there any other zincs on the engine or transmission? I'll get an order together for all of them and the new gaskets.

Did you use teflon tape when installing them?

Jim.

 

[JD5652]

Jim-

There is another one on the raw water pump intake... see below

I personally don't like teflon tape... I use Leak Lock for most all pipe fittings whether it's on the fuel side, fresh or raw water side...

Amazon.com: Highside Chemicals 10004 Leak Lock 4 Ounce Brush-Top Plastic Jar : Industrial & Scientific

 

[zigzag930]

Do you happen to know the p/n's for the zincs on the tank and pump? Can't find that in the service manual.

I will check out that leak lock. Thanks for the tip.

J

 

[JD5652]

Zig-

It's a standard zinc.. you can get it at any marina ships store or West Marine... take your zinc head with you when you go to get them and they can size them up for you. FYI... you want the overall length to be 3 inches.... when I went to get my last batch, all they had was the 4 inchers.... I just cut it to length...

 

[zigzag930]

Great, I'll pick them up tomorrow. I’ve already ordered the leak lock.

 

[ian w]

My engine zincs only show wear when the engine has done a trip
When docked for a year the shaft zincs deteriorate but never the engine ones
It appears that the shaft zincs are protecting the engine
I think the photo shows salt crystals