Vortec L31 cylinder head
(→Optional GMPP Vortec parts) |
(→Junkyard heads) |
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To find heads from an assembled engine that have a better than average chance of being uncracked, look for: | To find heads from an assembled engine that have a better than average chance of being uncracked, look for: | ||
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| − | + | *Heads from a wrecked vehicle. These stand an excellent chance of being good because the vehicle was likely put in for body damage, as opposed to engine problems that could affect the performance of the head. | |
| − | * | + | *Engines that still have antifreeze in them. This is a sign that the engine was likely '''not''' losing coolant, and '''not''' overheating, which could likely lead to cracked heads. |
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*Look for heads having a spark plug (or spark plugs from adjacent cylinders) with no unusually colored deposits- or a lack of deposits that were removed by coolant getting into the chamber(s). Head gaskets leaking or a cracked casting that lets coolant into the combustion chamber will make the plugs look a lot different than a normal plug- look for uniformity. | *Look for heads having a spark plug (or spark plugs from adjacent cylinders) with no unusually colored deposits- or a lack of deposits that were removed by coolant getting into the chamber(s). Head gaskets leaking or a cracked casting that lets coolant into the combustion chamber will make the plugs look a lot different than a normal plug- look for uniformity. | ||
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**Signs of stop leak use is a sludgy or copper/silver colored metallic accumulation inside the radiator fill neck, the same thing under the radiator cap, and possibly even in the overflow tank. | **Signs of stop leak use is a sludgy or copper/silver colored metallic accumulation inside the radiator fill neck, the same thing under the radiator cap, and possibly even in the overflow tank. | ||
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| + | To find heads from an assembled engine that have a better than average chance of being uncracked, avoid: | ||
| + | *Engines with water in the oil or oil in the water. This is a possible sign of a blown head gasket or cracked casting, either of which can lead to overheating and cracked heads. | ||
| + | *Vehicles that do not have antifreeze receipts or antifreeze or water jugs laying around inside the vehicle. That's another sure sign there was a problem with the cooling system. | ||
| + | *Engines that have the thermostat removed. A missing thermostat is an indication the engine was running hot. | ||
| + | *Engines that have evidence of stop leak in the radiator/cooling system. If it has stop leak, it was leaking. If it was leaking there's too big of a chance it overheated and cracked the heads. | ||
===Online or other "sight unseen" sources=== | ===Online or other "sight unseen" sources=== | ||
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