Blew the head gasket...

[VIKING_MECHANIC]

On Saturday, on my 97 5.7 C1500, I'm 99.8% sure the head gasket(s) blew. Went to eat lunch with a friend, get off the interstate at a stop light and the truck idles a little funny. Didn't give it much thought, so I pulled into the restaurant parking lot. Two hours later I came out and noticed a puddle of coolant coming from the exhaust where the cats meet the rest of the exhaust at the flange in the middle of the truck.

I started it and a bunch of white smoke came out the back. I checked the radiator and overflow tank, they both had coolant in them. I was able to drive it for a few minutes, but after a bit on the interstate, the temp started climbing, fast. Only took 2 minutes for it to hit 260(actually pegged out past it). As I pulled over, the engine died as I pulled off onto the shoulder.

Although I didn't see any visible coolant leak when I pulled over, I suspect the coolant is getting into the cylinders.

I'm pretty confident in my ability to do this repair myself, but considering this is my dad and don't want it out of service for very long, I'll probably have a local shop do it for me.

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[Schurkey]

I'd do a compression test, and a cylinder leakdown test. I would want to know the condition of the valves and rings before the engine came apart. No sense putting head gaskets onto a long-block that's on it's last legs.

Another option would be to remove the spark plugs, fill and pressurize the cooling system--see which cylinder(s) drool water out the plug hole(s).

Hate to pull the heads, only to find a ruptured heater hose or fitting that leaked coolant onto the exhaust system.

If the heads do come off, you'll want someone with experience to verify valve sealing, guide wear, and of course, replace the valve stem seals. Maybe you can get by without a "valve job", maybe not.

 

[VIKING_MECHANIC]

I plan on doing more testing, but I assumed it is the gasket because the truck did not want to start after we came out of the restaurant. Almost felt like it was trying to hydrolock. It took 10 minutes to get it to start. I would let it crank for several seconds, then let it sit for a few minutes. I was trying not to cook the starter in the process.

 

[454cid]

I wonder if it could be the intake manifold gasket.... They can get bad enough so that the truck won't start. Not sure about the coolant coming out the exhaust part. I too think a coolant pressure test would be a good idea.

 

[VIKING_MECHANIC]

Update: so I didn't do a compression test since I'd figured I would be taking off the heads anyway. I pulled each spark plug to check the condition. 1,3 and 5 were okay-ish but not really that bad though. 7 on the other hand, had coolant dripping out.

So I went ahead and started the tear down. Took off the intake manifold and was greeted with oil infused coolant. Nasty!

About an hour later I had the passenger head off, and then I see it. #7 is full of coolant!! I looked at the gasket and it seems it failed near the ring that seals the combustion chamber. Not sure how it failed, though.

I've been working in the garage on this for about 6 hours. I think I'm going to take the rest of the night off and relax to some Metal!

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[Schurkey]

The gasket under the other head has been down the same roads as this one...

 

[VIKING_MECHANIC]

The gasket under the other head has been down the same roads as this one...

Yes, I understand that. I know enough about engines to replace head gaskets as sets. Otherwise you'll just f**k yourself at a later date.

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[Erik the Awful]

Good find.

I think I'm going to take the rest of the night off and relax to some Metal!

UP THE IRONS!