Check the oil pressure. The pump is mounted high on the side of the block instead of down at sump level. Oil pressure can take a long time to build on start-up.
Use a 15W-50, 20W-50... something with a 50 or 60 on the high end. BMW dealer ships sell their own branded oil in something like a 0W-60 that's very good. Expensive but good. I understand (?) it's a re-brand of the Castrol RS 0W-60. Mobil 1 has changed it's formulation lately and isn't getting rave reviews. But with the old Mobil 1 20W-50 or 15W-50, oil pressure should be around 35-45 psi on a good engine once it's warmed up... higher on cold start-up. The manual says it's okay for it to go to 5 psi at idle as long as it comes up when you blip the throttle. Woof! That always makes me cringe. To me, that's time for new bearings or an over haul.
Quoting the manual:
Not below 5 psi (0.35 kg.cm.sq) at idle speed.
Not below 35 psi (2.46 kg.cm.sq) at 3500 rpm.
Not below 45 psi (3.16 kg.cm.sq) at 6500 rpm.
End Quote
Check compression pressure and leak down. It's NOT a clearance engine which means that if the timing belt jumps a few cogs or breaks, the pistons will hit the valves. A few bent valves will really kill the compression and your wallet.
The early, trapezoidal toothed timing belt was not very reliable. Check the belt tension often and adjust the tensioner as required. Don't believe the manual's recommended belt replacement intervals. Change the belt every 12,000 miles or 2 years whichever comes first. Replace the belt tensioner bearing at every other belt change or as required.
Buy the little pocket sized Krikit KR1 belt tension gauge and keep it in the glove box. Check the belt tension as often as you check the oil... but check it when the engine is cold before it's started for the first time that day.
Check timing belt tension only at a point midway between the intake cam pulley and auxiliary pulley (next pulley to the right of the intake cam) with cold engine at TDC:
95-100 lbs on a Burroughs gauge BT-33-86A
52- 55 lbs on Krikit KR1 on the pounds scale
100-110 Hz on Clavis Accoustic Meter
The 4-speed transmission is a Ford unit and pretty bullet proof.
The 5-speed is a Lotus-only unit that used Austin Maxi gear sets that were polished to remove stress riser... supposedly making them stronger. The gearbox has a reputation for breaking. Mine is waiting for a new 2nd gear now. Later S2.2 models used a Getrag 265 gearbox that was much more durable.
On early cars the clutch cable was routed near the exhaust. It had a pretty short life due to the heat. Later cars re-routed it.
Near the clutch pedal, the cable does a 180 degree wrap around a pulley. It's common for the cable to fray and break there.
Early cars (pre S2.2) had vacuum operated headlights. The system often developed air leaks so the headlights didn't stay down. That's fixable if you just poke around listening for leaks.
The solenoid vacuum valve dies and the original is no longer available. Other automotive or industrial valves will have to be fitted. Some models used one solenoid valve, others used two. I have a 1978 Eclat with one solenoid and a 1979 with two. Their build dates are a month apart... Nov 1978.
In either case, the solenoid valve is bolted to the front face of the wheel well(s) below the headlight pod. There's a small air inlet on the bottom side of the nose, directly under the headlights. Remove the wire-mesh screen and reach in through the hole to access the solenoid. For more serious work, remove the headlight pod from the body for two-handed access.
The vacuum actuators use a rubber diaphragm that eventually cracks and leaks. Considering their age, most of them have failed by now. Replacements can be difficult to find, and they're not cheap. A better fix would be to retrofit an electric lift mechanism.
There are vacuum ports on the front and rear intake manifold runners. The rear one feeds the power brake servo and the ventilation dampers. There's a vacuum reservoir behind the outside toe-kick panel in the left footwell.
The vacuum tap on the front runner feeds the headlight pods. There's an inline one-way check valve in the hose below the carb airbox, and a vacuum reservoir behind the toe-kick panel in the right footwell.
Wish him luck,
Tim Engel