J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Zinc Question

Before I start taking stuff apart on the old 2qm, I have several questions:

Looks like I have a leak from zinc tube/holder(The thing that zinc screws into) This is the zinc on front of engine. Will someone describe the construction of this piece? Is it threaded into engine block? It appears that there is some type of stuffing involved between this tube and engine block? Is it possible to get a leak from here or am I missing something else?


Thanks for any input.

JKC Circus

John,

We have the 2QM service manual on the J/30 website. Mouse over "Info" at the top menu and click on "Diesel Engine Maintenance". Once there, scroll down to the bottom of the page for links to download the various manuals. You'll see on page 7-8 a good picture and description of the zinc assembly.

Ok thanks. So it appears that I have leak from rear of 'cooling water cylinder inlet' Does this seem possible? I believe it looks like there is some sort packing back there that I'm not seeing in diagram? Maybe take the whole thing off and redo the packing back there. Any ideas on packing material or part number. Thanks again.

John,

I have a 2GM so am not as familiar with the specifics on the 2QM. Torrenson Marine is a great resource in your area and has a good website. Give them a call and I'm sure they can provide guidance and get you the parts as the authorized Yanmar dealer.

Along the same topic, has anyone ever had a lot of trouble getting those zinc tubes open? With a large wrench and an extension handle, I can not get the bastard to break free. I have never had something that stuck; I didn't want to torque any harder as I thought I was going to break the wrench!

When I rebuilt the 2GM on Rhapsody the stbd zinc plug was stuck. I used an impact wrench to break it free. This was easy since the engine was removed and being rebuilt in my basement.

I had the same experience and was giving up seeing my 3/8 socket wrenches too elastic and giving way...

I just went to a 1/2" socket wrenches with one of my J/30 table tube on top... took 20 sec - no issue - no sweat. Right tool a world of difference.

I had the same experience on Blitz's 2GM. I first tried both a long 1/2" breaker bar as well as a very low end 1/2" air impact wrench. Started by using penetrating oil and removing the 2 10mm bolts holding the lift pump on the block. No dice. Pulling a lift pump banjo bolt and using a much stronger 1/2" impact wrench made quick work of it.

-Chris

I never did get my zinc bolts to break free. On the head I removed the plate and changed it from the inside and made a new gasket. On the engine block where the hose connects to either side of the zinc, I never did get it out. I will need to pull the engine at some point I think to get it. It was clear I was going to break the whole unit off.

After seeing the line drawings of your engine, I see what you mean. Serious torque might do some serious damage!

If your engine has the same port side setup as the GM, you might be able to do the same partial improvement that I did before you can get to replacing the front zinc. I replaced the 1/4" pipe thread plug just below and forward of the starter (23873-020000 on the Yanmar diagram) with a Martyr CME0 Z pencil zinc which I had cut back to about half length. Better than nothing. I actually ran across this by accident last summer when the stock plug failed and started leaking.