Engine code
The S38 is BMW's inline six-cylinder engine for the M5 and the M6 of the 1980s and early 1990s. BMW's workshop data splits it into three versions: B35, B36 and B38.
Three S38 cars were sold in US-market BMWs: the E28 M5, the E24 M6 and the E34 M5 3.6. The larger B38 version appears in BMW's data but not in its US-market catalog records.
Quick read
- Ownership position: Not established yet. We are still researching this engine.
- Reliability: Not established yet. The only BMW-side document we found for the US M5 is a cooling-system recall.
- Cost to own: Not established yet.
- Power potential: Not established yet.
- Main watch item: Cooling system, per NHTSA recall 98V178000 for the M5.
S38 At a Glance
| Question | Practical answer |
|---|---|
| Sold in US-market BMWs? | Yes, in three cars: E28 M5, E24 M6 and E34 M5 3.6. |
| Where you find it (US) | E28 M5 built 11/1986 to 11/1987, E24 M6 built 11/1986 to 09/1988, E34 M5 3.6 built 12/1989 to 04/1993. |
| Not in US records | The E34 M5 3.8 and the E34 M5 Touring have no US vehicle record. |
| Displacement, E34 M5 3.6 (B36) | 3,535 cc, 93.4 mm bore, 86.0 mm stroke. |
| Output, E34 M5 3.6 (B36) | 232 kW at 6,900 rpm and 360 Nm at 4,750 rpm with catalytic converter. |
| Oil capacity | 5.75 liters with filter change. |
| Timing drive | Double timing chain. |
| Main watch item | Cooling system. See Known Failure Points. |
Technical Specifications
BMW's data is split by version. Wikipedia lists the S38B35 in the US E28 M5 and E24 M6 and the S38B36 in the US E34 M5; the figures in the table are BMW's. B38 is shown for completeness.
| Specification | S38B35 | S38B36 | S38B38 |
|---|---|---|---|
| Displacement | 3,453 cc | 3,535 cc | 3,795 cc |
| Bore x stroke | 93.4 mm x 84.0 mm | 93.4 mm x 86.0 mm | 94.6 mm x 90 mm |
| Cylinders | 6 | 6 | 6 |
| Compression ratio | 9.8:1 | 10.0:1 | 10.5:1 |
| Output with catalytic converter | 191 kW at 6,500 rpm | 232 kW at 6,900 rpm | Not established. |
| Torque with catalytic converter | 330 Nm at 4,500 rpm | 360 Nm at 4,750 rpm | Not established. |
| Maximum engine speed | Not established. | Not established. | 7,200 rpm |
| Compression pressure | 10 to 11 bar minimum | 10 to 11 bar minimum | 10 to 11 bar minimum |
| Thermostat opening temperature | 80 degrees C | 79 degrees C | Not established. |
| Valve clearance, cold (coolant 35 degrees C or less) | 0.30 to 0.35 mm | 0.28 to 0.33 mm | 0.28 to 0.33 mm |
| Specification | Detail |
|---|---|
| Configuration | Inline six-cylinder, double overhead camshafts. |
| Engine oil capacity, all three versions | 5.75 liters with filter change. |
| Engine oil grade | BMW of North America's oil chart (SI B11 01 15, February 2017) lists 5W-30 LL01 or 0W-30 LL01FE for all BMW gasoline engines of model year 2011 and older; it does not name the S38 by code. |
| Coolant capacity, E34 M5 | 13.3 liters including the heater. |
| Engine oil cooler capacity, E34 M5 | 0.75 liters including hose lines. |
| Fuel pressure, B36 | 3.0 bar test value. |
| Spark plug, E34 M5 | Bosch Y6 DC. |
| Output converted to horsepower, B36 | 232 kW is about 311 hp. |
| Firing order | 1-5-3-6-2-4, per BMW's Engine Technology training chart. |
| Engine management | Not established. |
Factory Deep Dive
Block and head
The B35 and B36 share a 93.4 mm bore, and the B36 adds 2.0 mm of stroke. BMW's parts catalog lists a different cylinder head for the E34 M5 (11 12 1 311 684) than for the E28 M5 and E24 M6 (11 12 1 310 087).
Valvetrain
The S38 uses a double timing chain. BMW's catalog lists two camshafts for the E34 M5 and the E28 M5. Valve counts per engine are not established here.
Fuel and ignition
BMW lists six fuel injectors per engine. The E34 M5 uses ring-type ignition coils, listed as 12 13 1 742 925 (current). The E28 M5 and E24 M6 use the single coil 12 13 1 286 087.
Variants
- B35: 191 kW with catalytic converter, tied to the E28 M5 and E24 M6 by Wikipedia.
- B36: 232 kW with catalytic converter, the E34 M5 3.6.
- B38: 3,795 cc, not in the US catalog records.
Service Parts at a Glance
Numbers below are current BMW part numbers as of the parts catalog data we read (data date 2019-12-12). Fitment shown is for the US cars. Check fitment against the car before you order.
| Part | BMW part number | Note |
|---|---|---|
| Oil filter element set | 11 42 9 063 138 | Replaces 11 42 1 718 816; includes the O-rings and gasket rings. |
| Spark plug, E28 M5 and E24 M6 (6 per engine) | 12 12 9 061 882 | Catalog name Bosch X5 DC. |
| Spark plug, E34 M5 (6 per engine) | 12 12 9 061 867 | Also listed as the older 12 12 1 312 569, which now points to 12 12 9 061 867. |
| Ignition coil, E28 M5 and E24 M6 | 12 13 1 286 087 | Single coil. |
| Ignition coil, E34 M5 | 12 13 1 742 925 | Replaces 12 13 1 720 877, discontinued 11/1995. |
| Air filter element, E28 M5 and E24 M6 | 13 72 1 307 134 | Replaces 13 72 1 307 259. |
| Air filter element, E34 M5 | 13 72 1 730 918 | Replaces 13 72 1 726 916. |
| Thermostat, E28 M5 and E24 M6 | 11 53 1 307 737 | Catalog size 80 C. |
| Thermostat, E34 M5 | 11 53 7 835 558 | Replaces 11 53 1 315 063, discontinued 06/2005. Catalog size 79 C. |
| Timing chain | 11 31 1 403 081 | Double chain. |
| Cylinder head gasket | 11 12 1 316 705 | 1.74 mm thickness per the catalog. |
| Cylinder head gasket set, E34 M5 | 11 12 9 059 244 | Includes the head gasket. |
| Fuel injector, E28 M5 and E24 M6 (6 per engine) | 13 64 1 273 272 | Single listing. |
| Fuel injector, E34 M5 (6 per engine) | 13 64 1 310 641 | A Lucas alternative is listed as 13 64 1 317 446. |
Known Failure Points and Service Items
We list only items a recall, bulletin or BMW document backs. Other S38 problem lists are not established yet.
01 Cooling system component failure and the heater core
NHTSA recall 98V178000, received 4 August 1998, is filed under the M5 for model years 1989 through 1995. NHTSA's recall summary says a failing coolant system part such as the thermostat, water pump or fan belt can sharply raise coolant temperature and pressure. The consequence it names is a crack or separated seam in the heater core end piece that could release hot coolant.
The dealer remedy was a new-design radiator cap. Watch for an overheating warning and hot coolant escaping at the heater core. NHTSA does not list this recall for the E28 M5 or the E24 M6; the record names models and model years, not engines.
Other S38 failure points: not established yet. We are still researching this engine.
Reliability Verdict
Not established yet. We are still researching this engine. No BMW document we opened gives a reliability verdict, failure rate or mileage figure for the S38.
Power Potential
Not established yet. We are still researching this engine. The factory figures are in Technical Specifications.
Cost of Ownership
Not established yet. We are still researching this engine.
Common Questions
What BMW has the S38 engine?
In US-market BMWs, the S38 is in the E28 M5, the E24 M6 and the E34 M5. The US E34 M5 is the 3.6 version, built 12/1989 to 04/1993.
How much oil does an S38 take?
BMW lists 5.75 liters for an S38 oil change including the filter, for the B35, B36 and B38 versions.
How big is the S38 in the US E34 M5?
Wikipedia lists the US E34 M5 with the S38B36, which BMW's data gives as 3,535 cc with a 93.4 mm bore and an 86.0 mm stroke, and 232 kW with catalytic converter.
What spark plug does the E34 M5 use?
BMW's catalog lists Bosch Y6 DC plugs, part 12 12 9 061 867, six per engine.
Does the S38 have a timing belt or a chain?
BMW's parts catalog lists a double timing chain, part 11 31 1 403 081, for all three US S38 cars.
Sources
- BMW workshop technical data, engine data tables for the S38 B35, B36 and B38.
- BMW parts catalog, data date 2019-12-12: vehicle records, supersession chains and US fitment.
- NHTSA recall record 98V178000 (BMW M5)
- Wikipedia: BMW S38 (basics only)
- BMW of North America SI B11 01 15, Engine Oil Quick Reference Chart, February 2017 (NHTSA copy)
- BMW Engine Technology training, ST501: bmwrepairguide.com technical training PDF
