OM606 Necessary Upgrades – Crank Sprocket, Valve Springs, Cam Sprocket and Head Bolts

OM606 necessary upgrades are not optional if you want a reliable high performance build. Today we go through the four modifications every OM606 needs before serious power is run through it.

Reality Check – How Many High Power OM606s Actually Work

The OM606 has a strong reputation online. Everyone claims years of trouble-free high power use. But how many 500+ horsepower OM606 builds are actually running reliably right now? Ten? Maybe. The engine is unique – a high revving high performance diesel unlike anything else. But it requires the necessary upgrades. Without them it will break. With them it becomes genuinely reliable.

Necessary Upgrade 1 – Crank Sprocket

The small sprocket on the front of the crank drives two chains – one for the oil pump and one for both camshafts. It also drives the injection pump and vacuum pump. With upgraded valve springs, higher pop pressure injectors and a larger pump element this sprocket is working extremely hard.

It is held in place by friction only. The friction is between the sprocket face and the surface of cylinder number one and the damper face. A bolt squeezes everything together. That is all that holds it.

The fix is cylindrical locking compound. Remove the sprocket, clean everything thoroughly, apply cylindrical locking and reassemble. Leave overnight before running the engine. Simple, cheap and permanent.

If building an engine from scratch machine a proper key slot in the crank and fit a real key. For an engine in a running car cylindrical locking is the correct solution.

Do not confuse this with the damper. The damper drives the alternator belt. Nobody cares if the damper slips – you will notice and stop the car. The crank sprocket drives your oil pump and camshafts. Those failing is catastrophic.

Necessary Upgrade 2 – Valve Springs

Stock valve springs are made of almost nothing. Upgrading to CDI springs is an improvement. Proper aftermarket springs designed for these engines are the correct solution.

Every day on Facebook there are posts about stuttering, misfiring and poor running at high power levels. The answer is almost always valve springs. People who claim to run 450 horsepower on stock springs – their cars are not working now. Change the valve springs. It is cheap insurance against much more expensive failures.

Necessary Upgrade 3 – Intake Camshaft Sprocket Pinning

This takes 30 minutes with hand tools. No machine shop required. No special skills. If you can operate a drill you can pin the intake cam sprocket.

The procedure was covered in detail in a previous video – check the cam position first, verify it is correctly timed, then pin or weld it in position. Both methods work. Welding with a short tack weld is permanent and requires no drilling or tapping.

Evidence of why this matters – during a valve spring change on a fully running engine the intake cam was lifted out for access. The sprocket fell off into the hand with no force applied whatsoever. Not loose. Completely free. That engine was running normally before disassembly.

If it is not pinned it will move. When it moves the cam timing shifts. When cam timing shifts bad things happen.

Necessary Upgrade 4 – M11 Head Bolts

This is not strictly necessary until the head comes off. But when the head comes off for any reason – head gasket replacement, cam work, anything – fit M11 head bolts at the same time. No exceptions.

Mercedes used 26 standard head bolts in the OM606. They work at 177 horsepower. When boost is added the head lifts slightly on the cylinders. The result looks like a blown head gasket but the root cause is inadequate clamping force from the original bolts.

Replacing the head gasket without fitting M11 head bolts means replacing the head gasket again in the future. Do it once correctly.

The Complete List

Do these four things and the OM606 becomes a reliable high performance engine:

1. Cylindrical lock the crank sprocket
2. Replace valve springs with proper aftermarket units
3. Pin or weld the intake cam sprocket
4. Fit M11 head bolts when the head is next removed

Skip any of these and you will be back on Facebook asking why your build is not working.

Summary

• OM606 necessary upgrades: four modifications that separate reliable builds from broken ones
• Crank sprocket: cylindrical locking compound – cheap, permanent, essential
• Valve springs: stock springs fail at performance power levels – upgrade before running boost
• Intake cam sprocket: 30 minutes with a drill, prevents catastrophic cam timing failure
• M11 head bolts: mandatory whenever the head is removed – prevents repeat head gasket failures
• Do all four before running serious power – skip any one and problems will follow

Love you all. Time is ticking. Bye!