Aside from the 3.6L having less power than the 4.0L engines,is the 3.6L as reliable as the 4.0L. I know the 4.0 is an evolution of the 3.6, but is one more reliable than the other? Which gets better gas mileage? What about transmissions behind each engine......which holds up best? I know it's probably a preference issue but is one actually better than the other?

 

Others will recall more than I do, but the 3.6L engines and maybe early 4.0Ls had more problems with head gasket oil leakage above the distributor, but the head gaskets tend to fail on all of them eventually. I can't think of any other major reliability differences between the two engines.

Both the ZF 4HP22 hydro-mechanical transmission in the earlier cars and the 4HP24 electronically-controlled box in the later cars have proven highly reliable, essentially bullet-proof when cared for. Most problems with the later ones are electrical or electronic rather than mechanical.

IMHO, the biggest difference between the 3.6L cars and the 4.0L cars is the differential ratio, 2.88:1 in the early cars, 3.58:1 in the later. This, along with the slightly increased HP and torque, gives the later cars better acceleration off the line at the expense of the engine running 500rpm higher at cruising speeds.

Cheers,

Don

 

+1 on all Don's advice. However, we should note that on all these engines, if you do need to replace the head gasket, be aware there is a later, modified version available that has proved far more reliable in practice. In respect to fuel consumption, my experience, apparently shared by many, is that there is negligible difference in fuel consumption . . . whether 4.0L, 3.6L or even the 3.2L.

Cheers,

Ken