My 1990 4-Runner is loosing coolant somewhere and the only sign is a significant amount of exhaut. The coolant(anti-freeze) must be entering the combustion chamber somehow and the engine oil is not showing any sign of contamination. Would this necesarily have to be a head gasket or could it somehow come from the intake manifold since it to is cooled by anti-frreze.

It is likely your head-gasket. This is not beyond the home mechanics ability. Get a Chilton manual and start.

Your oil may not show signs of contamination right away. Check your oil-filler cap. Look at the inside of it, and you should see a white paste. This is moisture being burned.

By the way, don't drive your vehicle until this is fixed.

before you do the head gasket, verify that it actually it!! go to yoru local automotive shop and purchse a coolant system pressure tester. Attatch it to you rad, put about 11psi on it and wait for about 30 min. see if there's any drips underneatht ehcar. if there is, find the source, if there isn't start teh car. if ther's lots of scmoke when you first start it and/or a misfire occurs, you've got a head gasket problem.