Losing RPMs LS tractor

[tntractor]

I have a 57 hp LS tractor that is about 10 years old, 900 hours. It will run fine at low RPM but shortly after throttling up white smoke puffs from the exhaust and it quickly loses power. We drained the fuel and changed the fuel filter with no improvement so took it to the dealer.

After checking the engine codes they said the problem was a bad water pump and replaced it. I had no faith that was going to fix it. But I went and picked it up and it ran great---for 3 trips to the field of bush hogging. It ran at high RPM and seemed perfect again, I was so pleased to have my tractor back.......BUT.... Yesterday it started all over again with nearly the identical symptoms.

Is there something the mechanic could have unknowingly improved (but not truly fixed) when he replaced the water pump? We had thought it was going to be a bad injector but they supposedly checked out OK.

Would greatly appreciate any input.

 

[Tx Jim]

Check to be sure tank is venting IE not vacuum is being created as fuel leaves tank

 

[Bearsixty7]

Gauges all do their test sweep when the key is first turned on?
Antifreeze/coolant looks ok and pure, no oil?
Oil looks good and pure, no antifreeze?
How hot is the temperature gauge reading when it does this?
Any chance the radiator is plugged up?

 

[Roadworthy]

White smoke may be indicative of water getting into the combustion chamber. If you take it back to the dealer have them run a compression test. You may have a defective head gasket.