Water in oil

"I have a year 2000 Merc 5.7 c

"I have a year 2000 Merc 5.7 carborated, it was dieseling (run on) last time out. My oil looked a little like milkshake. The level on dipstick didn't change so I don't think its alot of water. I drained oil and am about to fill it back up, change the filter and sparkplugs then drain it again and fill it back up. Every shop I call says that dieseling cannot cause water in oil but I've read online forums that suggest otherwise. Local shops are telling me that I've got a cracked head or manifold. Are they jumping to worse case scenarios? Does dieseling cause water to enter engine? Thanks, input would be great. John H., I just activated my account but haven't gotten my email with activation key yet."

Run on can result in the engin

Run on can result in the engine kicking over backwards. If this happens it acts like a water pump and will most certainly pull water up and into the exhausts and cylinders.
This can cause lots of damage because water is not compressible.
Make sure your idle speed is no more than needed. It should be 650 rpm in forward gear with the throttle closed. Adjust it down if its higher than this. It may fix the run on issue.

Rod