Hi All - Can anyone make a suggestion on where to look next for crankcase oil finding its way into the water system on our GP-7s C-Block? We have eliminated the oil cooler as the source. She leaks water into the oil (I presume when the unit is shut down) and oil into the water (I presume when the unit is running). Could it be an oil / water interface at the water pumps?

Thanks for any ideas.

On EMD water pumps there are "Teltale" holes that water leaks out of when the carbon seal fails. If the teltale hole is clogged with dirt or plugged on purpose than cooling water will find its way into the accessory end of the engine. Other than that look for leaking discharge elbows coming off the cylinder heads. As far as oil finding its way into the cooling water you still have a bad lube oil cooler. If you renewed the lube oil cooler and still see blobs of oil in the cooling water it may be residual from the previously failed cooler. A good way to clean the oil out of the cooling water system is to get the unit up to temp and dump a quater bottle of Dawn dishwashing detergent in the expansion tank and run the unit in the 4th or 5th notch for a half hour. Throw a hose in the water fill and turn it on and at the same time open the main water drain and try to balance the flow between water in and water out. Run the draining water through some oil soak pads if your building doesn't have an oil water seperator. Whatever you do don't just get the unit hot and drain the water and then add fresh cold water or you'll have more problems then you started with on account of thermal shock to the engine. Repeat the Dawn trick a few times until the water cleans up. We used to use Sodium Hydroxide but the Dawn emulsifies the oil better.

EBL

Next, I would look towards the O-rings that seal the power assemblies(cylinder sleeves) in the block. With the age of the prime mover I would not be surprised....assuming the thing has not been rebuilt in the recent past.

Are you saying that the only possible way for oil to get into the water is at the lube oil cooler?

PM was rebuilt in 2004.

Thanks for your help.