oil leak

Not at all familiar with the 3406 but gear drive water pumps (if it has one)can be an oil source leak if the seals are bad and the weep hole is clogged.

thanks old magnet, the weeper is free of debris, dry and open this one is kind of a puzzle I had the head off and milled because of a trace of water coming down the inside of the block on the cam side. Do not seem to have that problem any more just the transfer of oil into the coolant .thank you again I enjoy and like to hear any and all suggestions, I always learn something new everyday listening to people even sometimes by the accidental method.. Gib

OK, maybe Bob/Ont. will pick up on this one....he usually checks in daily.
Was that head and block crack checked during the milling operation?

Are you sure it isn't fuel? some 3406's have nozzel adapters that crack and leak fuel into cooling system.
The only other place I can think of is the two yellow orings around the dowel the oil comes up to the rocker shafts through. There is one below and one above the spacer plate. Assuming the cooler and head have been pressure tested. It needs to be oil at lube pressure to get any amount into the coolant.
Later Bob

if you pressure test it it can look ok , but if engine is running and get more hot it can leak,
even heard of wet cilinderbushings were so rusted they leaked tru on other brand engines, but thats not in this case i think,
maybe the oil cooler? is the turbo water cooled? so yes maybe there? a good pressure test is required, take all water out and put pressure on the system with gauges, then it's listening or looking where the leak is, i hope this helps a bit .
for the rest its very good engine the 3406 liked them in the 245 and 375 excavators and 980 loaders , you can run them without valvecovers( in a dry and clean place ofcourse)

Are you sure it isn't fuel? some 3406's have nozzel adapters that crack and leak fuel into cooling system.
The only other place I can think of is the two yellow orings around the dowel the oil comes up to the rocker shafts through. There is one below and one above the spacer plate. Assuming the cooler and head have been pressure tested. It needs to be oil at lube pressure to get any amount into the coolant.
Later Bob

[quote="bob"]Are you sure it isn't fuel? some 3406's have nozzel adapters that crack and leak fuel into cooling system.
The only other place I can think of is the two yellow orings around the dowel the oil comes up to the rocker shafts through. There is one below and one above the spacer plate. Assuming the cooler and head have been pressure tested. It needs to be oil at lube pressure to get any amount into the coolant.
Later Bob[/quote]

Bob, the orings are new on both top and bottom, The head was pressure tested but I suppose it could leak after the casting comes up to operating temp as could the cooler core . I thought I had all of the bases covered when we went back together but I have missed something some where, Thank you for your input every thought helps. Gib

not sure, but if it has a aircompresser on it for brakes it could be a bad compressor?a pressure test of the cooling system is going to get you there the fastest.another thing could also be a trasmisson cooler, had proplems with those to if this is in a truck? if no way to pressure test your best bet is to pull the head.

not sure, but if it has a aircompresser on it for brakes it could be a bad compressor?a pressure test of the cooling system is going to get you there the fastest.another thing could also be a trasmisson cooler, had proplems with those to if this is in a truck? if no way to pressure test your best bet is to pull the head.