I recently took the big truck on a road trip, only to find when I got there that there was oil POURING down the side of the block. There is water mixed with the oil in the crankcase too. The truck seemes to run great, but there are 2 STEADY streams of oil/water mix running down the side of the block. It appears to be coming from the head gasket around the #3 cylinder. WHat are the chances it's only a blown gasket, and NOT a cracked head or block? Is this a common failure on these motors? I've never seen this kind of thing, nor have I talked to anyone yet who has. I know the only way to know for sure is to pull the head and have it checked, but any help as to what to expect would be great at this point.

Thanks,
Jimmy

 

By far a blown HG is more common than cracked steel but you should have at least the head checked.
Most often the the HG blows on modded trucks whose boost exceeds 35 psi or timing is set over 16.

 

Jimmy:

If and when you pull the head off, be sure to have a reputable shop check that cylinder head both front and back and side to side to make sure it is level and within Cummins specs.

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John_P

 

I will...thanks guys. I plan on having the head checked for sure...for peace of mind if nothing else. I'll let you guys know...

Do I have to replace the head bolts on these motors? I know some engines, it's mandatory...others it's recommended...and some say it's not necessary...

Thanks again,
Jimmy

 

They have a head bolt stretch gauge that should come with your gasket kit.

 

Only if they are stretched, buy the cylinder head set which comes with valve seals and all the gastkets. There should be a gauge that come with gastket set for checking bolt stretch. Make sure you get the proper thickness head gastket, small holes in end of head gastket specify thickness. Make sure they match your old gastket. If the head checks ok and doesn't need machining use same thickness gastket.


CYLINDER HEAD FLATNESS (MAX)
End to End 0.305 mm (0.012 in.)
Side to Side 0.076 mm (0.003 in.)

CYLINDER BLOCK FLATNESS (MAX)
End to End 0.075 mm (0.003 in.)
Side to Side 0.075 mm (0.003 in.)