2.5 na diesel smoking

[seaswood]

1987 90 2.5 na Xmod has been blowing white smoke has been slowly increasing this year.
engine does not use oil or water head was done a few years back.
this is a weekend truck not lot of use more maintenance.
air filter is clean dry.
cracking each injector fuel intake they all sound the same, those were rebuilt couple of times.
thinking might be time to check timing marks Xmod paint does not look like the timing cover has been off.
likely the marks may have moved.
fuel pump was rebuilt before I got the truck.

[redharpgareth]

If you have white smoke, it could be coolant or unburnt fuel.
To check for coolant getting into the combustion chamber have a look at the overflow bottle, is the coolant overflow reservoir contaminated with oil? This could indicate oil and coolant passing through a cylinder head gasket or worse, a crack.
after that check the injectors and injection pump.