Hi 89 ranger 2.3 engine dosnt get to operating temp not much heat inside defrost changed thermastat put cardboard in front helped abit no antifreeze in oil but noticed some white foam in rad antifreeze is still nice and green.any advice whatare the signs of gasket trouble.Thanks

 

do a compression test. if two adjacent cylinders are significantly below the others then a bad head gasket is suspect

 

Evidence of a blown head gasket:

*excessive steam from exhaust
*odor of exhaust in radiator
*overheating
*need to add coolant to make up for coolant loss
*small bubbles in coolant in the radiator
*coolant in oil. There are oil tests that can detect this.