I know there's been a lot of overheating threads on here lately, but I want to get some extra opinions on what to do. I'm afraid I've blown my head gasket and possibly cracked the engine block as well. I was driving home a few nights ago after work down the interstate, and suddenly the temp redlined. A few minutes later, white smoke was just pouring out of the exhaust, and unfortunately, I couldn't tell in the dark until I made my exit. I messed up by not immediately pulling over when I saw the temp jump up, and now I'm paying the price (literally)

I put some coolant in and did a test idle. After about 10 minutes, the temp raised to 220. That's when I noticed smoke coming from the engine block, although I can't tell exactly the origin of the smoke. There's a little bit of smoke coming from the exhaust. I didn't notice any leaks coming from the radiator hoses. No water/leaks dripping from the engine block. The only places where I noticed drips were from the exhaust and the fuel tank.


Almost certain it's a blown HG. Estimates are around $1200. I've called my mechanic who I now live an hour away from, and asked if he could shop around for a new 4.3 vortec. He said he's found one for $650, and would charge $450 in labor to put it in. He's a good mechanic, and knows what he's doing. Paying the same price for a new engine @ 65k vs my engine @ 135k as I would to have the HG replaced seems like a no-brainer.

 

It is VERY rare to actually blow a head gasket on these engines, as in you really have to work at it. Much more often than not, it is the lower intake manifold gasket. If the gasket fails into an intake runner, it'll cause the smoke out the tail pipe.

How does it run without water in it (just run it for a minute or less from cold)? If it's smooth with no real noticeable problems, then you likely don't have a head gasket failure. To further test, a compression check on all cylinders will tell more of the tale. Alternatively you can do a leak-down test on each cylinder and the cooling system to find the source of the leak.

 

Well, did some more tests. Poured water directly into the radiator, and noticed a lot of leaking. Checked all radiator hoses, no problems. It's very hard to really tell where the source of the leak is, it almost looks like it's coming from the manifold.

At any rate, I'm having it towed tomorrow to my mechanic out of town. I would check it further, but I'm working a lot this week and just don't have the time to do so. Hopefully, it is only the intake manifold gasket. But even if it is, I'm still worried that I caused serious problems to the engine that night. I guess we'll see.