Cylinder head torque values S14/S38, replace, wash and oil head bolts:
- 1st step 50nm
- 2nd step 80nm
- Wait 15 minutes
- 3rd step 100nm
Exhaust manifold torque values M102/M106, use light coat of copper paste:
- Wastegate to elbow, elbow to manifold 25nm
- Turbo to manifold 45nm
- Manifold to head 15nm
- Manifold to manifold 220nm
When mounting new cylinder head or with new studs use 28nm torque instead of 15nm. With new parts manifold is retorqued to 15nm after 2000km, loosen bolt first and install studs with copper paste (e.g. Molykote HSC). ALL subsequent mounting is done with 15nm, all this according to BMW torque spec. After replacing single or several gas-filled gasket rings manifold may need retorquing. Experience is that just one new gasket ring on turbo side of manifold can bring nuts loose. After driving for extended period nuts were just hand-tight.
When removing cylinder head leave both manifolds in place. Just remove wastegate and elbow from exhaust manifold. Remove four turbo bolts before this, takinf of elbow can be tough at first. Loosen head bolts in order as in repair manual, use two or three equal steps for this. Lifting of head by hand at least two persons are needed, one for each manifold side. Remove bonnet before proceeding. When removing head take care not to damage chain guide, head gasket may come along. Always cleanup bolt threads on block before installing cylinder head!
ARP hardware for M30 head is torqued in three equal steps; 40nm, 80nm and 120nm. This is with ARP specific lube, also when installing head studs tighten them firmly in block with allen key. ARP hardware is good for high boost levels and reusable. Though M30 head bolts can be used again, maybe better to replace them on high mileage engine. ARP studs are thinner than bolts and do not align rocker shafts same way. After 6000km of running this is non-issue. Always place last two studs on cyl. 6 in place before placing head to block, like with stock ones.
Following front wheel bearing instructions applies to all E23 models. “Tighten castle nut to 30-33nm while constantly turning the wheel (pic shows the rotor on). Turn wheel an additional 2 turns. Castle nut must not be loosened or tightened in this step. Loosen the castle nut until there is axial bearing play. Wheel hub must also turn again. Tighten castle nut to max 3nm and lock with a cotter pin.” When installing new bearings be careful not to cause damage while punching races in. Inner bearing races may slide easily to shaft, this should have no effect on function.
For rest of the torque values head for Bentley E28 repair manual. Pretty much all needed powertrain and chassis related values can be found there. When rebuilding engine this is great asset, sometimes finding right thing can be difficult for sure and needs patience. Also searching Google with “BMW torque” should point to PDF file consisting lot of valid information. This has got also 745i turbo specific info in, look for both turbo and M30 keywords. There was BMW factory repair microfiche available on M102 turbo engines with separate instructions on torque values.