M35A Block Coolant Drain

[rmbrown]

It seems I have a leak around the block coolant drain on my M35A.

Whenever I return to my boat, I'm finding a puddle of coolant under it.  Not enough to show up missing in the reservoir but enough to puddle in the forward edge of the sump under the engine.  I can see evidence of dripping off the bottom rear corners of the oil pan.  The port side of the pan seems dry but on the starboard side, I found this.

The rusty area is damp to the touch.  I see corrosion on the smaller/inner plug but felt no moisture there so I tend to think the smaller plug had a leak, was tightened, and no longer does, but that the outer plug threads have leaked for a long time.

The leak has been masked by a diesel fuel leak that I just addressed by replacing the fuel pump.  Fingers crossed this is my last (current) leak.

I don't want to remove the plug until I have a replacement or at least a plan.  The kubota dealer tells me that they can't get one... the one their book shows has a hose barb apparently.  Anyone know a source?

Has anyone ever had theirs out and know if that's pipe thread or if it's straight thread and has, or should have, a crush washer or gasket?

[Dark n Stormy]

I don't see anyone replying to this one so I thought I might give it a try.  As they say "I'm not a doctor but I'll have a look". 

I'll bet that the brass bung/plug/fitting is a common one from the hardware store and it really resembles the end of a pencil zink like the one found in the heat exchanger.  Might that be the fabled engine zink? 

As iron (block) and brass (plug) hate each other there might be significant deterioration on the brass part (less noble). 

Some sort of pipe dope or Teflon with a fresh plug might fix it right up. 

I know there are more years of experience on here than me so be gentle.

Brent
Dark and Stormy
1997 Catalina 34 Mk II

[rmbrown]

So far, Stormy, your answer is my favorite. :)  I'm hoping someone has pulled this plug (these plugs) before and knows where to get new parts.  When I pull it, I'd just as soon replace it!

[glennd3]

Mike you say that the leak is there when you come back to the boat. Just thinking out load here so don't hold me to this but when you stop the motor that is when you have the greatest pressure in the cooling system because the circulation stops. That being said that is why you may not see the leak while it is running. Also do not discount a pinhole in the hoses near the plug. Just throwing darts.

[Stu Jackson]

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I'm hoping someone has pulled this plug (these plugs) before and knows where to get new parts.  When I pull it, I'd just as soon replace it!

Mike,

My original thought was something I chose to hold off on until I read some other replies.

I recommend that you simply forget about having a replacement-in-hand first.

Drain most of the coolant.  Use the hose under the freshwater pump as shown in the Burping thread (101 Topics) - different engines, same concept.

Then take the plug out and bring it to a trusted machine or parts shop.  Match it by inserting into a female thread WHILE YOU'RE IN THE SHOP.

Teflon tape or Recotr's Pipe Dope is the sealant of choice for that application.

You may have a plug in another pipe section.  Take the biggest, don't hassle yourself over the one-inside-the-other thing, which seems to be from your picture. 

I'm sure you've also looked into the manuals and parts list in the tech wiki.

Good luck.  Keep us posted.

[Ron Hill]

Mike : Have you tried the obvious?!!
 
Call Joe Joyce Westerbeke Service Manager X234 or Russ Hagen Asst.S M X233 and asked them?!?
1- 508-823-7677 

A thought