The M52TU (“technical update”, 1998 on) adds VANOS to the exhaust camshaft as well as the intake, which is called double VANOS. Among E36-platform cars it was fitted to the Z3. Most E36 3 Series cars with an M52 have the earlier single VANOS engine, so in those cars a double-VANOS M52TU usually means an engine swap. Its weak points are the same as the single unit’s, times two: piston seals that harden with age, plus a rattle from play in the piston bearings.
If your engine has single VANOS, see the M52 single VANOS guide instead.
TL;DR
| What: | Resealing the M52TU double VANOS and, if it rattles, fitting a rattle kit. |
| Why: | Restores low-rpm response and idle quality lost to hardened seals; stops the rattle. |
| Time: | Beisan estimates about 4 hours for a mechanic and 6 or more for a first DIY. |
| Difficulty: | 3/5 |
M52TU in an E36: what’s different
Compared with the E36’s single-VANOS M52:
- Double VANOS: both camshafts are adjusted, not just the intake.
- Engine management: Siemens MS42 instead of the E36’s MS41.
- Throttle: a hybrid throttle body with an electric motor for traction control plus the mechanical cable linkage, not the E36’s purely mechanical one.
That is why an M52TU swap involves more wiring and electronics work than a like-for-like M52 swap.
Symptoms
- Flat response below about 3,000 rpm, hesitation when pulling away
- lumpy idle, worst when cold
- rattle from the front of the cylinder head at certain engine speeds
- VANOS or camshaft position faults stored in the DME
Two separate problems produce these:
- Seal failure: the original O-rings on the VANOS pistons harden and lose their seal, so the pistons can’t hold oil pressure and the camshafts don’t reach their commanded position.
- The rattle: the VANOS piston bearings develop axial play. As the camshaft works back and forth against that play, it resonates and rattles at certain speeds.
Parts
| Part | Number | Notes |
|---|---|---|
| Double VANOS seal kit | Beisan Systems BS001 | Upgraded O-rings and Teflon seals. |
| Double VANOS rattle kit | Beisan Systems BS002 | Bearing rings and outer washers that take up the axial play. |
| VANOS-to-head gasket | BMW 11 36 1 433 817 | Listed for M52TU/M54-engined E46, E39 and others; confirm by VIN. |
| Cylinder head cover gasket set | look up by VIN | Beisan advises replacing old cover gaskets while you are in there. |
| Oil line banjo sealing washers | look up by VIN | Never reuse. |
If the rattle is present, do both kits in one go: the unit is on the bench anyway.
The job
Follow Beisan Systems’ published double VANOS procedure step by step; it is the standard reference for this repair. Key points:
- Engine cold. The fan is a 32 mm left-hand-thread nut on the water pump; a pulley holder (BMW 11 5 030) makes it easier.
- The two VANOS piston bolts are left-hand thread (T30 Torx). Beisan warns that many torque wrenches can’t be used on left-hand threads and the bolts will break, so be careful when tightening them.
- On the bench: the pistons come out, the old O-rings and Teflon seals are cut out, the new O-rings go in first and the Teflon seals over them, sized as the kit instructions describe. The rattle kit’s bearing rings go in at the same stage.
- Refit with new seals, sealant where the procedure calls for it (3-Bond 1209 or equivalent), a new gasket and new banjo washers.
Torque values (Beisan procedure)
The Bentley E36 manual predates the M52TU, so these come from Beisan’s procedure:
| Fastener | Torque |
|---|---|
| VANOS unit to cylinder head | 8 Nm |
| VANOS piston bolts (left-hand thread) | 8 Nm |
| VANOS cylinder cover bolts | 10 Nm |
| VANOS front cover plugs | 50 Nm |
| Oil line banjo bolt | 32 Nm |
Afterwards
A fresh oil change is worthwhile: the VANOS runs entirely on engine oil pressure. If the engine is later remapped, a healthy double VANOS gives the tuner the full range of cam timing to work with.
