Thanks, now that I know the truck is a 97, that helps me try to figure out your problem with the truck.
I forget, in 97, did Ford still route the injector wiring harness under the valve covers?
Late 94 & 95 did, and heat and oil inside the valve covers often damaged the injector harness, which would cause injectors to fail in weird ways. You could have two separate issues [it happens] , One, an injector failing to open and spray as it should, which could cause intermittent white smoke because the fuel mix is off, [if it was holding open to long, it should roll coal smoke, so I'm thinking an injector or two is running lean.
Second issue is your water leak, from somewhere. New oil coolers can fail, same as old ones, so I wouldn't totally discount that possibility... If you are pushing water into the oil, and the high pressure oil pump that makes high pressure oil to open and close the injectors when the computer tells it to, might be trying to "pump water" which does NOT compress, into injectors, and be making a "white smoke sometimes" problem. [just trying to think through all the possibilities].
Water in oil or water in fuel is never a good thing for our diesels. Thanks for the challenge of trying to figure what may be causing your problems.
"Bring the truck a little closer to the computer so I can get a better look at it.. "
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