M30 Headgasket


Cost: $300 or more....


Buy it now


After two days at the Mosport track, I discovered some oil in the coolant. My headgasket failed. This procedure work for all Bmw M30 engine: 535i, 735i, 635i.
First of all, find a good shop to work on your cylinder head and buy a Bentley manual.

• Oil in the coolant.
• White residue in the oil cap or oil stick.
• Heavy white smoke (with a characteristic smell) at the muffler
• Oil leak at the location of the headgasket


  • All kind of wrenches and sockets
  • Torque wrench + angle torque meter
  • 14 new cylinder head bolts
  • Gasket kit
  • Injector o'rings (except if you change them)
  • 2 x fender covers
  • Gasket remover tool and spray
  • Throttle body cleaner
  • Engine cleaner
  • BMW coolant
  • Oil + oil filter
  • Good quality rags and air pressure.

Vacuum hoses, fuel pressure regulator, cooling hoses, injectors, rotor + cap, spark plugs, starter, thermostat. Check the compression to see if you need a new engine...

1. Following the bentley manual procedure, remove everything out of the way and remove the cylinder head. I wanted to remove the head with the exhaust manifold, but the bolts to the exhaust line were rusty so I left the manifold in the car. I removed the head with the intake manifold
2. With the head out of the car, remove the fuel rail, the injectors, intake manifold.
3. The cylinder head and intake manifold will be sent to a performance shop for ports enlargement, polishing and matching to the intake manifold. The valve guides will be changed and the cylinder head tested.
4. The intake manifold will be powder coated black.
5. Now you will have some time to clean all the different parts that are out of the car, injectors, throttle body...
6. Clean the top of the piston with a gasket scraper and the gasket surface. You must clean the holes in the engine block and remove any oil and water in those bolt holes. Cracking of blocks is common if the oil is not removed from the bottom of the bolt holes.
7.Put the fuel rail, injectors with new seals, throttle body and intake manifold back on the cylinder head, then place the head back in the car.
Unlike the picture, don't put the thermostat housing back on. It will be placed on the car when the timing chain housing will be in place.
Off course while the head was at the shop you clean every single item that goes back onto the engine.

8.Once everything is connected (please double check), torque the head to the specified values:
Add 50% BMW coolant and 50% distilled water then bleed the cooling system. Let the engine run 25min then torque the head 35 + 5 degree. (It will be warm).

Good links:
Head Porting for the Do-It-Yourselfer
• M30 Head rebuidling
• Email Gordon for Powder coated parts.

Basic Head Modifications:
1. Intake and exhaust ports enlarged and shaped for max gas flow.
2. Combustion chambers contoured and smoothed for most efficient combustion.
3. Valve pockets relieved for max gas flow and valve seats ground to a precise 3-angle racing seat.
4. Entire head cleaned and stress-relieved.
5. Head-to-block surface milled true and head ports matched to manifold ports.
6. Chambers cc'd to equal volumes and domed for piston clearance and polished.

Optional Head Modifications for Racing Engines:
1. Valve guides chamfered flush with port walls.
2. Oversized valves installed and oversized valve seats installed.
3. Enlarge valve spring recesses to accept larger springs and shim valve springs to the correct installed height.

(Thanks to Bill Rickard)

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