M30 Valve Adjustment

General E28 FAQs.
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Joined: Feb 12, 2006 1:00 PM
Location: Chicago

M30 Valve Adjustment

Post by Kmoy2002 »

Problem: Valves tick or no valve adjustment has been done for some time
Cause: Gap clearance gets bigger as engine gets used. It's typical for M30s
How To Fix:
Tools: Special tool (Can be made by bending a piece of aluminum rod/hex wrench/hanger [This tool is used to turn the eccentric. You stick one in the hole of the eccentric and use it as a lever to turn the eccentric.]), wrenches, feeler gauge, screwdriver
1.Remove air box/any vacuum hoses
2.Unplug spark plug wires
3.Remove valve cover vent hose
4.Unbolt other circled areas
5.Remove Valve Cover (9 bolts)
6.Figure out which pair of valves are TDC (Top Dead Center) and adjust those. (Engine is slanted so the lobes are facing downward perpendicular to the pison(not perpendicular to the ground)) Loosen nut on rocker arm. Slide Feeler gauge in between the rocker arm and cam shaft. Place special tool in hole and rotate until it is snug. You should be able to move the feeler gauge around with resistance in between the eccentric and the valve. It is possible to compress the feeler gauge and get a false adjustment. Retighten the nut with feeler gauge still between.

Warm engine use .014in Cold engine use .012in
I had a Schrick 282 cam so my mechanic suggested .013in
Stock: pre ~82 M30's .010-.012 was spec'd rather than the .012-.014 as on later cars

7.Bump engine using ignition or the service port
Remove the fan and use a socket and wrench on the main hub nut to turn the engine. It is much more precise and will not damage your starter and you won’t turn the engine too far.
Use a crescent wrench on the center nut on the alternator to advance the motor. The pully will slip in one direction and then pressing on the belt with your other thumb puts enough tension on the belt to turn the motor. Has a racheting style effect (don't have to remove the wrench to reset it) and saves the hassle of removing the fan.

How far: Turn the motor until the cam lobe for the valve you are adjusting is exactly 180* from where the rocker contacts the cam (not just facing down since the engine is slanted).

8.Repeat with other cylinders. List all the valves on a sheet of paper and cross them off as you adjust them.
if the valves are original, one or more of the valve stems is probably worn and the adjustment should be done to .008 on the cam side

It may be good to note that if the adjustment has not been done in a long time, you may have to adjust 2 or three times in the first 2000 miles or so because the eccentric may have been worn flat and when you adjust, it is contacting the valve on a corner which wears down quicker (causing the valves to go out of adjustment again)

Now's a good time to make sure your banjo bolts aren't missing/loose. If they are, relocate them/retighten them. Or replace both of your BBs with the BMW upgrade ones and use some additional BLUE locktite.

9.Rebolt valve cover in the folloring order (pic)
10.Reassemble the rest then go test.

Last edited by Kmoy2002 on Dec 10, 2008 11:11 PM, edited 6 times in total.