How many man hours should it take (aprox) to change oil ,filter, fuel filter and replace raw water pump on universal diesel 3 cylinder
That's a loaded question. How old is the engine and in what condition?
Changing the oil and filter is relatively quick. About 10 minutes of run time to heat up the oil. Then 10-15 minutes to pump out the oil. I usually let it gravity drain for a few at that point. Probably 5 minutes for the filter and another 5 to add new oil. Plus you had to go to the store to get all the stuff.
The fuel filter itself is quick. But you have to turn off the fuel usually at the tank than bleed the system after. Could be ten minutes, could be longer based on your boat. I added a fuel shot off valve at my Racor filter so I could probably do it in 5 minutes. But if your asking how long for the job I am guessing you never did it yourself so you probably haven't thought to put in a easily accessible shut off valve.
The water pump, who knows? It could take days worth of spraying PB blaster on bolts just to get the old one off.
A lot of the time issue also depends on which engine installed in which boat. I have great access. My buddy on a freedom has good access and doing the same job could take twice as long just because of the difference in access.