What are the common issues with the S14 engine in this model?

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The S14 engine wasn't available in the 1987 BMW 635CSi - this model came with the M30 inline-six engine. The S14 is actually the legendary 4-cylinder engine from the E30 M3. However, if you're asking about S14 engine issues in general, here are the most common problems:

**Major S14 Engine Issues:**
1. **Oil pump nut backing off** - The oil pump securing nut can loosen, causing sudden loss of oil pressure and potential engine destruction
2. **Valve adjustment requirements** - The S14 needs regular valve adjustments every 15,000-20,000 miles
3. **Timing chain tensioner wear** - Can cause timing issues and potential valve damage
4. **High oil consumption** - Normal for these high-revving engines but needs monitoring
5. **Cracking exhaust manifolds** - Common due to heat cycling
6. **Electrical issues** - Various sensors and connections can fail

**Important note:** Since your 635CSi has the M30 six-cylinder, you won't encounter these specific S14 issues. The M30 is generally more reliable but has its own set of common problems like timing belt maintenance and cooling system upkeep.

Would you like me to help you find similar 6 Series vehicles or answer any other questions about your 635CSi?

Lot 614470: 1987 BMW 635CSi

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Lot 614470: 1987 BMW 635CSi

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