I have a 93 full size 4x4 blazer with 350 in it. rebuilt it all new about 7,000 miles ago including heads redone. it ran hot on me the other day on the way home from work. has never ran any warmer than 160 till then.
did a compression check and cylinders 1,3,5,7 all are at 150 but number 5 has water in it. cylinder 2 has 120, cylinder 4 has 60, cylinders 6 and 8 have 120 figures blown head gasket but just curious about intake leakage.
this all happened at once on the way home. truck was running fine temp around 160 and all of a sudden temp goes up to 210 then 260. any help would be great. thinking bad head work or head gaskets????

 

*moved to 'full size k5 tech'*

 

Do a leak down test and see where the leak is on #4.