Is the S38 reliable?
We rate the S38 72 of 100 for reliability: good. The rating is one of the inputs to every Guide Score below, and it is argued for on the method page with the others.
Why that rating
The lit mark is the S38; each grey mark is another engine on the engines page.
The catalyst version of the M1-derived 24-valve six: the S38B35 in the 1988 M5 and the 1987 to 1988 M6, and the 3.6-liter S38B36 in the 1991 to 1993 M5. Specialists call it durable with regular maintenance, and no bottom-end pattern failure is documented.
The known items are the solid-lifter valve adjustments, a timing chain tensioner that rattles on cold starts, oil leaks, and cooling parts whose failure can cost a head gasket; on the S38B36, a vacuum leak can disable the intake resonance flap. Parts and rebuilds are expensive.
Cars in this guide with the S38
| Car | Years with this engine | Reliability | Guide Score |
|---|---|---|---|
| M5 E28 | 1988 | 61 | 74 (1988) |
| M6 E24 | 1987 and 1988 | 64 | 70 (1988) |
| M5 E34 | 1991 to 1993 | 61 | 69 (1993) |
Reliability is each car's score out of 100 for the years it had this engine: the engine rating plus that car's own known problems, service costs and age. The Guide Score is for the car's best year to buy.
Known problems on the S38
| Problem | Named in the guides for | Typical bill |
|---|---|---|
| Timing chain tensioner | M5 E28, M5 E34, M6 E24 | $400 to $450 |
Bills are the guides' estimates, not quotes; each car's guide says which model years a problem hits and how to check for it. The bars share one scale, up to the costliest bill here.
Other engines
Every engine we rate, from the most reliable down, is on the engines page.