944 Lubrication System — Oil Change, Torques & Relief Valve
Factory lubrication-system service data for the 944 — the oil and filter change figures, the tightening torques for the oil pump, relief valve, sensors and oil pan, and the pressure-relief valve service notes. All torques switch between N·m and ft·lb.
The factory lubrication-system service figures for the 944 — the numbers behind an oil service and any work on the oil pump or relief valve. For the running oil-pressure figures and the gauge-test procedure see 944 oil pressure — factory figures and gauge check; for symptom-by-symptom diagnosis of a high or low reading start with oil pressure: general information and troubleshooting. This page is the service data — change quantities, tightening torques and the relief-valve bench notes. All torques switch between N·m and ft·lb.
Oil and filter change
Drain the oil with the engine at operating temperature so it carries the suspended dirt out with it.
- Unscrew the drain plug on the oil pan and drain the oil.
- Loosen the oil filter with a filter wrench and catch the escaping oil.
- Clean the drain plug, fit a new seal and tighten it to 60 N·m44 ft·lb.
- Give the new filter's gasket a light coat of oil. Screw it on by hand until the gasket contacts, tighten one further turn, then recheck with the filter wrench to a final 20 N·m15 ft·lb.
- Refill with oil, run the engine to temperature, check for leaks, then recheck the level with the engine stopped.
| Figure | Value |
|---|---|
| Engine oil volume (refill, with filter) | approximately 6.0 L6.3 qt |
| Oil grade | brand-name HD oil to API SE or SF — see the Owner's Manual |
| Drain plug torque | 60 N·m44 ft·lb |
| Oil filter torque | 20 N·m15 ft·lb |
The dipstick capacities and the consumption figure are on the oil-pressure page; fill to the upper mark and recheck warm rather than chasing the exact refill volume.
Lubrication-system tightening torques
| Location | Thread | Torque |
|---|---|---|
| Oil drain plug | — | 60 N·m44 ft·lb |
| Oil filter | — | 20 N·m15 ft·lb |
| Oil pump to crankcase | M6 | 8 N·m6 ft·lb |
| Oil pump to crankcase | M10 | 45 N·m33 ft·lb |
| Housing insert in oil-pump housing | M6 | 8 N·m6 ft·lb |
| Oil-pump countersunk screw | M6 × 25 | 8 N·m6 ft·lb |
| Pressure-relief valve plug | M20 × 1.5 | 45 N·m33 ft·lb |
| Oil-pressure sensor | M18 × 1.5 | 35 N·m26 ft·lb |
| Sealing plug, oil/water-cooler housing | M18 × 1.5 | 35 N·m26 ft·lb |
| Oil separator to crankcase | M8 | 20 N·m15 ft·lb |
The mating surface of the housing insert is sealed with Loctite 574, and the insert's outside diameter gets a coat of the same before it goes into the pump housing — the oil pump has no gasket there, so the sealant is the seal.
Pressure-relief valve
The relief valve sits in a screwed-in bushing in the crankcase and caps the maximum oil pressure. It is a simple plug, spring and piston:
- Unscrew the plug (M20 × 1.5, tightened to 45 N·m33 ft·lb) and withdraw the spring and piston.
- Check the piston for wear and seizure traces and replace it if there is any doubt — a piston that sticks open bleeds pressure, one that sticks shut spikes it.
- Fit a new seal under the plug on reassembly.
If the bushing itself is damaged it is unscrewed with grip pliers and a new one driven in to its stop with the special tool, its lower scored surface coated with Loctite 648 or 638 first. Take care not to score the crankcase bore.
Oil pan bolts
The oil-pan bolts are tightened in stages, working clockwise from the inside out:
- Run all the bolts in finger-tight.
- First pass: 4 N·m3 ft·lb.
- Final pass: 8 N·m6 ft·lb.
Even, low torque in sequence keeps the pan flange flat against the gasket; over-tightening a thin flange distorts it and starts a weep. From the 1985/2 model year the oil pump and crankcase were modified — the later oil pump (Part No. 944 107 014 08) must not be fitted to an earlier engine.