Heinkel Engines- Part 2: Disassembly

Engine rebuilding is straightforward process. For me, the key thing is to be organized, take your time, and document EVERYTHING. I used to make a drawing of every major subassembly and keep them in a book (now I take pictures with my smartphone and they are automatically stored in the cloud). Sometimes it would be a few months before I would get back to reassembling, and I could never rely on my memory for that long!
Reference Photo- Transmission Disassembly
When I take an engine apart I pretty much always replace wear items such as bearings and gaskets. Other items, such as crankshafts, I measure and compare them to the tolerances in the workshop manual. They’ve always passed in my case. If they didn’t pass they would need to be disassembled, repaired, and reassembled, and I don’t have the equipment to do so. Luckily, rebuilt items are available from the German club.
The final part of my disassembly and rebuilding regimen includes the exploded parts book, a spreadsheet, Post-It notes, and sets of small, medium, and large plastic storage bags. Every item that fits into a bag gets placed into the bag, with a description written on a Post-It tucked in as well. Larger items, such as case pieces, or anything dirty, goes into the parts washer. I use the spreadsheet to make a note of any part that I’m going to order. I include the diagram number, item number, English and German names, number needed, and the price. I use these as the basis for my parts order from the Clubs.

Typical Disassembly Scene: Engine in stand, Workshop Manual on left, German Club parts book on right

I bring my cylinder and cylinder head to my local machine shop and have them go through these parts. I’m lucky to have a local guy who has tremendous experience and appreciates these smaller engines. The heads take the most abuse of any item in a Heinkel engine. Because the engines are underpowered for the cars, especially on today’s modern roads, it’s no surprise to find them with any number of ailments.

Some of my favorites:
  • Blown out spark plug holes needing helicoil inserts
  • Busted exhaust studs
  • New stud replacements of the wrong size or drilled through the valve travel areas
  • Warped heads needing to be resurfaced
  • Stripped rocker arm bolts
  • Missing or worn valve guides
  • Bent or worn valves

You get the idea- if it can break you’ll probably have some symptom in your cylinder heads.
Cylinder Head- this one needed new exhaust studs, rocker arm  bolts,  valve guides, and flattening
You can strip the engine down in about 3 hours. If you’ve never done it before, I’d double or triple that estimate.
Here are some checklists for you:
Always Replace:
  • Bearings
  • Gaskets
  • Drive Chain
  • Swingarm Chain
  • Soft iron washers under cylinder head nuts

Measure and Consider Replacing:
  • Valves
  • Brass Swingarm Journals
  • Crankshaft

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