Pin hole leaks in Navistar Blocks

It,s not common but it can happen there is an additive that you put in the coolant that stops it. It's called cavitation.

Porosity not cavitation, below is a fix Eliminating the porosity that welding can create in a metal casting can be a tedious process, and often the problem will become greater as more effort is spent on its removal. Bob Oomen, Manager of M&W Marine Servicing, an outboard motor wrecker in Sydney recently faced a difficult problem with a rare outboard motor block which he needed to repair.

Due to faulty casting, a hole had developed in the wall between the water jacket and the exhaust chamber of the engine block. If this hole was not completely sealed then salt water would pass into the exhaust chamber and begin corroding the pistons and cylinders, causing extensive damage to an otherwise serviceable engine.

After repairing the hole by TIG welding, the block was pressure tested to check for any leaks. It was found that even though visually the hole had been sealed, the welded area would leak under pressure. This was attributed to micro-porosity which had been created in the block by the welding process, and also micro-porosity in the block itself. After contacting Loctite personnel for assistance, it was decided that vacuum impregnation of the component would be the most successful solution.

With the Loctite Impregnation System, the component to be sealed is first thoroughly cleaned to remove oil and other residue. It is then immersed in a tank of specially formulated low-viscosity anaerobic resin which is then covered and subjected to a vacuum. This procedure draws trapped air from the porous surfaces of the component, and when again exposed to atmospheric pressure, anaerobic sealant is forced into the porosity. After curing, the component is thoroughly rinsed and dried to complete the process.

After impregnation the engine block was again checked for leaks and found to be completely sealed. By using the Loctite Impregnation System, M&W Marine Servicing have been able to reclaim a rare and potentially valuable engine block which otherwise would have been scrapped.

impregnation of

immersed in a

atmospheric

Uhh...Tyrone.....it IS a commercial diesel...it's the International DT 444 with a few Ford changes...

Tyrone the mechanical engineer! Wow I never knew that cast iron had that much elasticity to actually expand and contract upon combustion, causing cavitation, causing porosity. Thanks for setting me straight on this matter Tyrone. Your clueless, your posting rights to this news group should be revoked.

Cavitation erosion even on wet liners has beeen known about for over forty years that I know of... It is not a myth. Do some reading. Randy

Cavitation in Diesel engines has been known to be a problem since at least the 1920's. I suspect it was noted as a problem well before then. During my maritime engineering experience in the 60's we were still using chromate additives which were very effective when the cooling system was monitored and the chromate levels properly maintained. This continued into the 1970's when it was decided that a more expensive commercial product was better and more profitable and, that chromate was a toxic substance if you drank too much of it. A change was mandated resulting in chromates being banned. The fact is that no Diesel that I am aware of was ever designed or built in which cavitation was not an inherant problem. Replaceable wet liners are the most severely affected by cavitation.

Lugnut

Try this: Put an inside micrometer in a cylinder and set it properly. Then pull the cylinder apart with your fingers. Let me know what happens.

Al

put some shop towels in the bore underneath it first..................

Yeah, I guess it is a commercial unit. Howeve it is a commercial, light duty diesel. Not what would be considered for severe service such as an over the road tractor trailer, heavy equipment or a marine application

checking

casting

problem

contacting

valuable

Before you spew your ignorance, try doing a bit of research on the subject. You may know something about welding but you don't know squat about the problem with this and other diesel engines. Try

And yes cast iron has a tremendous amount of elasticity. Just because you can't see it with your eyes doesn't mean the cylinder does not distort. I suppose you don't believe that the piston distorts during the compression cycle either. Try educating yourself on the subject before you prove yourself more ignorant than you already appear right now.

checking

casting

problem

contacting

valuable

Some years ago we had a 392 Hemi on the dyno. It was a mild hop up, dual quads and so on. We were setting the timing with the engine running full bore and the timing light made it look like the block was waving. We screwed around with it and discovered the block was waving. It was twisting as the RPM went up. How the hell do you twist a block of cast iron like that? I hear the AA/FD cars twist the crank about 20 degrees from front to back and the cam grinders make the cam so it's right under load. Strange stuff this metal we use.

I used to teach auto mechanics in the 60's and the block/mic thing was always worth a good discussion.

Al

another interesting thing is to take an OLD crankshaft, and 'ding' one of the journals with the edge of a nickel

you'd be surprised how large the dent is.............

properly.

happens.

first..................

I once saw a some film showing slow motion magnified pictures of a nail while being hammed into a block of wood. Every time the head of the hammer made contact, the nail shank would expand and the head of the hammer would become concave. In between blows, both the hammer and the nail would return to their normal dimensions. Yes, all metals have elastic qualities. This characteristic is referred to as that particular alloy's "moment of elasticity." Jagren, has no idea what he is talking about. However, he does make a lot of noise, so we should at least give him credit for something.

Tyrone has the concept right, but it is called ,"Modulus or Elasticity" or "E" for short. For steel it is approximately 29,000,000 psi. As a simple example, for a piece of steel with length, L, Cross sectional area, A, if you apply a tension load to it , P, the resulting stretch is PL/AE.

-Rob

Well, Tyrone, Mercruiser used the 7.3 in their marine applications up until they were forced to change to the Cummins due to the DT 444 being dropped from production over emission standards.

Back pedal some more....

About three zeros too many, there.

RRon snipped-for-privacy@aol.com

Oh whoopie, a Freakin' Mercruiser. Why didn't I think of that? Because any place where a Mercruiser is used, is not a heavy marine application. When is the last time a Mercruiser was installed in a yacht? Back pedal some more....... Wanna try again?

International DT

application

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Eventually

Servicing,

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pressure

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System,

29,000,000

resulting

Thank you. You are absolutely correct. "Modulus of Elasticity" was the phrase my fingers intended to type but a brain fart prevented them from doing so.