Water leak

[Joe Miller]

Hello All,
It appears that I have further problems.
The antifreeze is leaking around the alternator
Mount.
I have two parts engines which I will take a
head from and exchange.
I am open to other suggestions or checks.
Joe

[ndutton]

Head thin spot

The head area under the alternator/lifting eye mount is known for cracks.

Have a look at this cross section of an A4 head that failed the same as you describe. It was raw water cooled its entire life IIRC. If we assume corrosion within the water passages to be equal, this suggests the water passage core in the casting process was not properly held in the center of the mold assembly. Note the head is upside down in the picture, arrow points to where the alternator bracket sits.

[tenders]

Cool pic, Neil! How did you cut that head like that, and what made you decide to do it?

Look at how thick the bottom of the head is, which was presumably always under water. Is it safe to assume the head was cast with somewhat uniform thickness in mind?

I wonder if engine tilt allowed more oxygen to be present over many years of the head's life, contributing to the higher degree of corrosion there. Or perhaps more of a scouring effect as the result of somewhat more aerated water coursing through the top of the head than the bottom. Pure conjecture on my part, though; it doesn't seem like the head sits there completely filled with water day in and day out.

[ndutton]

That's not my picture Ted. It was given to me third party and I filed it away knowing it would be useful some day. Looks like today was the day.

There has always been an underlying thought that some heads had a thin spot in the casting in the area of the lifting eye due to the prevalence of cracks developing in older engines at the same spot. Joe's description was all too familiar.

If the top of the head was intended to be cast thinner I can't imagine why. I think what speaks best to the misaligned core theory is compare the thickness of the top of the head at the guy's thumb to the thickness at his index finger. It's just a theory though.

[alcodiesel]

Thanks for the picture, Neil. It explains why my head is a little weepy at that spot. JB Weld until I get a new or newer head.

[ndutton]

JB Weld until I get a new or newer head.

When you get a new head, let's cut yours apart and have a look.

[Administrator]

There has always been an underlying thought that some heads had a thin spot in the casting in the area of the lifting eye due to the prevalence of cracks developing in older engines at the same spot. Joe's description was all too familiar.

Several on the forum have commented that the design of the lifting eye isn't very good.

Bill

[ndutton]

Several on the forum have commented that the design of the lifting eye isn't very good.

Yep and I'm one of them. Studying the leveraging forces applied to an already suspect area of the head by the factory bracket when lifting, many of us have enhanced the design with additional mounting holes to change the lift into a dead pull.

[Joe Miller]

Hello All,

last evening I started removing the head from one of my extra engines to get ready to swap for the leaking one. the engine was re built 5 years ago by Nova Automotive, a reputable rebuild shop in HRM, so I am hopeful the head is good. I will have them check and clean the head just to be sure.

Most rebuilds suggest replacing the studs, is this an absolute. If the exposed portion of the stud is intact can I skip this step. If removal is needed can anybody recommend a good stud puller and the method of removal.

The boat comes out of the water tomorrow with head removal on Saturday, I
have been soaking the head nuts with Fluid Film in preparation.

Thanks,

Joe

[Dave Neptune]

Another point

One thing we all need to remember is that our accessory drive and alt are a closed loop!! There are only 2 pulleys involved and there is about 180 degrees of contact area, whereas most pulley drives rely on far less contact area IE 30 degrees. This large area that drives the belt has very good traction for driving the stock 35 amp alt and even the 55 amp, so tension is something that needs a tender touch. Over tensioning of the drive belt puts a big strain on the bracket and head. The integrity of the belt is very important as any irregularities (wear spots) will cause a hammering effect on the bracket and if the bracket is not "perfect" it will wobble and just get worse. These motions will raise havoc with the studs and even the casting as we have seen many times.

Dave Neptune

[Joe Miller]

head removal

Hello All,

I removed the head on Saturday and all went well with the exception of one stud directly behind the lifting eye. The threads appear to be stripped in the block.
I will get a thread chaser tap and see if I can clean up the threads, if not I will order an repair stud when I call Ken.
The head is going to a Nova Automotive today to be magnafluxed and decked if needed. The head came off an engine they rebuilt but never installed in a boat so I am hopeful it will not have to be re decked.

Any directions would be helpful.

Thanks,

Joe