For a reliable, long-lasting, and solid performing engine, you need a good case. Here's how to find one:
Once your engine is torn down, take your time to thoroughly clean the engine. An hour or two cleaning could save you many hours later if grease or grime covered a crack that renders the engine case useless.
Give the engine a thorough once-over, looking for stripped, broken, or missing bolts and studs and overall condition of the block. Stripped head studs are usually not an issue. We highly recommend installing case savers when rebuilding an engine.
A common place for corrosion is the oil drain sump area. Moisture collects in the bottom of the oil sump and can rot out the bottom sump plate and oil screen area. Check the oil sump studs for any cracks radiating from the stud holes.
On the outside of the case, check the front of Cylinder 3 for cracks. Later cases typically have more magnesium or aluminum in this high-stress area. Older or worn cases can produce a large verticle crack. This area is often welded or filled-in for performance applications.
On the Cylinder 1 head stud location, there are often cracks radiating from the head stud hole to the case stud hole.
While on the outside of the case, check the oil pressure sender hole for stripped threads and cracks.
Towards the nose of the case, check that the three oil galley plugs have not moved and are not leaking. The middle (one shown top-left in the picture below) may be drilled and tapped for a full-flow oiling system, but the others should be sealed.
With the case split, move inside to inspect the bore where the bearings sit. Remove any bearings currently installed. Look for worn main dowel pin holes, and any bearing stampings or oil passage ridges. General rule is if you can feel the stampings or ridges with your fingernail, the case will need an align bore and correctly sized bearings. Most cases have about 4 align bores in them before the case is considered unuseable.
For more information on VW main bearing sizing, visit our VW Type 1 Main Bearing Tutorial.
The center main bearing's journal is a common place for abused engines to crack, straight through the center saddle.
Less common on the inside is the main oil galley behind cylinder #4. This can be a high-stress area on performance engines and can hide cracks from the stud to the oil passage behind.
While a small bore gauge is a good way to measure the lifter bore tolerances, a clean lifter can also be used to judge the lifter bores health. With the lifter pulled out from the bore about half of an inch, wiggle the bore around. There should be a small amount of play, but excessive movement here can tell you the case was abused and is unfit for a rebuild. VW wear limit for the Type 1 engine is 19.05mm or 0.7500".
Next up is inspecting and measuring the thrust wear on your case. You can measure this with the case either assembled or unassembled. If you can feel the inner lip around the thrust bearing surface with your fingernail, the case may need a thrust cut. Standard VW thrust measurement is 21.96mm or 0.8645". Cases have two thrust cuts available before being considered end of life.
One last condition to look for, when the case is cleaned and properly torqued together is Gaposis. This is a condition of a highly abused engine, where the center main journals develop a gap between the seating surfaces. This gap can allow significant case movement, leading to poor life and catastropic unplanned disassembly of the engine.
Whether your engine case is being rebuilt back to factory specs, or you're searching for a tire shredding hot rod, these inspection tips will show you what to look for when hunting for that perfect engine case. If the used case has cracks, excessive corrosion or corrosion in critical areas, if the case has poor or excessive machining, and if the case has gaposis, then its time to retire your case to coffee-table project. When in doubt, you can purchase Brand New Engine Cases, or you can bring a trained eye out at the next swap meet and pick up a great engine case for a good price.
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