The Stovebolt Site Forums The Shop Area Engine Shop Lost coolant, overheated, what damage should I look for

I was driving on the parkway when a heater hose developed a hole and I lost coolant. By the time I stopped it was definitely overheated. I put everything back together and it runs OK, no funny noises or leaks, but I am wondering what hidden damage is likely to be lurking. Engine is a 350, cast iron heads. Is there anything short of a complete teardown I can do to be sure there is no real damage? Thanks

Mark

No No no. Just drive it and let it reveal any problems. Be SURE to check the oil before and after every drive for a week or so. If it turns milky you have a problem. Watch the temperature all the time for a while. If there is damage, it's already done. If it runs and no milky oil or heat or weird stuff, you are OK, you dodged a bullet.
Another sign to watch for is hard starting, like starter won't turn motor over. That would be hydraulic lock (water in cylinders). In other words a cracked block/head, broken rings or blown head gasket. You are looking for water to be in places it should not be. Crankcase and cylinders.

If you are nervous:
There are leak tests and leak down tests you can do instead of tear down. It's like using a compression test hose (without the check valve) to induce air into each cylinder. Depending on where air escapes you can tell what is wrong. You can search the internet to get the particulars.

Mark, if I had a dollar for every small block Chevy I overheated I could buy us both a good steak dinner. Never once ruined a Engine. Now we won’t talk about Chevy’s illustrious 4 cylinder aluminum head engines. Just keep your usual watchful eye on it and keep on truckin!

Thanks, I appreciate the suggestions. I will keep a close eye on it. A new engine was not really in my plan at this time.

Mark

Depending on the year of the engine, some cylinder heads are prone to cracking when they're overheated. Sometime in the mid to late 1980's Chevy went to a head with thinwall castings that don't react well to overheating. Older ones were pretty rugged. Did the engine get hot enough to boil over? Just pegging the temp gauge without a massive gusher from the radiator overflow usually doesn't do a lot of damage. I'd suggest pulling the spark plugs and using a borescope to inspect the cylinder walls for scoring, and keeping a close check on oil and coolant levels for a while. Steam from the exhaust on startup and/or a smell of antifreeze from the tailpipe is another sign of a leaky head gasket or a cracked head. If you have access to a cooling system pressure tester, pump up the pressure and leave it overnight, then look for a pressure drop and/or steam from the exhaust on a cold start.
Jerry

Thanks Jerry for the suggestions. The heads are iron vortec truck heads and the gusher was definitely coming out the hole in the heater hose. I lost a little pressure when pressurizing the system, but it could have been my old Stant tester leaking. No steam or antifreeze smells on startup. I drove it hard for a hundred miles on the interstate with no issues so I am assuming we go forward hopefully with no problems, while watching the oil and coolant for signs of leakage.

Mark

59 fleet There tougher than you think, old mechanic I worked with said let it cool completly off. Then fire back up it would harden the rings,now I didn't swallow that too well !!