My 96' 4x4 v-6 vortec engine has just starting leaking antifreeze there isnt any on the ground but i smell it and when i look for the leak there is antifreeze laying on top of the engine. I havent been having an overheating problem, the heat works and i dont smell antifreeze inside the vehicle. Now today When i turn it off the engine starts smoking and the temperature goes up but as soon as i turn it back on the temperature goes down and the smoking stops. Please if anyone has any idea water pump? thermostate? head gasket? heater core? im at a total loss. Thanks in advance.

 

Upper radiator hose leak/connection, thermostat gasket leak, intake manifold gasket leak. One of those.

 

Thermostat is a good place to check I just had that issue, I replaced it while I was in there and leak stopped, but could also be a hose and any of before mentioned things, good luck.

 

150k is the limit for the intake manifold. Mine on my 1998 went at 152k. I was driving (January in New England), and lost my heat. Then, my truck was overheating. I got the smell of anti-freeze in the cab, so I pulled over and popped the hood. I swear, it was peeing out of the top of my engine, near the throttle body, where it was pooling. I noticed a loss of antifreeze before, and had the smell, but ignored it for the time being, contributing it to a hose leak. BIG (and expensive) MISTAKE!!! Cracked my engine block in the process...

 

Does coolant go thru intake manifolds? Would it leak from intake gaskets?
thanks.

 

Yes, it could like seen in this video.

http://www.youtube.com/watch?v=BI2FH6034sQ

 

is it common on blazer/s10 98? which one will leak upper or lower?
mine has 110K on it.
thanks for reply.

 

Yes its common on all the gm4.3s the lower intake gasket will either breach since they used a nylon gasket with very little gasket or the rtv seals leak. They most commonly leak at the front and back of the intake near the bolts holding it down. I just changed mine because it was leaking out some and into the crankcase; the old gasket is a joke compared to the fel pro perma seal gasket.

 

PORTCQB is absolutely correct. The stock intake manifold gaskets are garbage. I just changed mine on my 2000 Jimmy and the felpro gasket are great. Clean anti freeze off of intake and put a pressure tester on it and pressurize your cooling system and you will find the leak real quick. Good luck!

 

Thank you guys for your help!