Just swapped 2.8 V-6 engine in my `88 S10 with an `85 2.8 from a blazer. It looked to be rebuilt and I am told it has 64000. miles on it. Swapped over TBI and manifold, timing chain cover and oil pan...! My problem is that it runs a bit hot, and, it pushes the water from the radiator into the overflow tank and out...! I think the reading hot is air pockets - not positive though. What could be the different reasons for this happening ??? Also put in new timing chain and gears - although the distributor may be a tooth off and wired appropriately what would this cause if anything ?

 

sounds like it needs to be burped. you arent running plain water are u? they run a little hotter with just plain water.

 

If you haven't already replaced the rad cap, do it now. A weak cap can allow the coolant to boil and once that starts, it'll keep pushing out. The system needs to be maintained at 16psi to raise the boiling point of the coolant high enough.

If the cap is new, then you'll need to get the air out of there. Get the front end of the truck up in the air as high as reasonably possible with the cap side of the radiator higher than the other side. Run the engine up to operating temperature with the cap off. Shut down and let it cool, keeping the radiator topped up. Repeat at least 2 more times and you should get all of the air out.

If you have a decently sloped hill nearby, do the procedure there.

If that doesn't do it, then the headgasket might be blown, forcing combustion pressure into the cooling system.

 

Ok - I will definitely give that a try, I heard it could be the head gasket, but I am soooo hoping thats not it. The engine is supposed to have only 64000.00 miles on it - the old engine ran a bit hot too to way hot by the gage...! A friend thought he bled or burped the system by taking out the temp. sensor for the computer in the top of the intake manifold, in front of the TBI. WOW - thanks again, I didn't expect such a fast response - any other thoughts/ideas are appreciated, and, I will keep you posted!!