Classic Car
Mercedes-Benz W115 (1968–1976)
The Mercedes-Benz W115 (also known as the /8 or Strich Acht) is a series of compact executive cars produced from 1968 to 1976. Known for exceptional build quality, simple mechanicals, and longevity.
100
Known Faults
79
Solved
6
Variants
3
Repair Guides
🚗 Variants
All production variants of the W115
Mercedes-Benz 200 (M115 carb)
🔩 M115 · Solex 32/35 DIDTA
Mercedes-Benz 220 (M115 carb)
🔩 M115 · Solex 32/35 DIDTA
Mercedes-Benz 220D (OM615)
🔩 OM615
Mercedes-Benz 200 (M115 later)
🔩 M115 · Stromberg 175CDT
Mercedes-Benz 230.4
🔩 M115 · Zenith 35/40 INAT (twin carburetors)
Mercedes-Benz 240D (OM616)
🔩 OM616
🔧 Known Faults (100)
Community-reported faults with verified fixes
Oil filler cap seal perished — top end oil seep
94%
62 fixes
Blocked fuel filter causing lean misfire under load
92%
55 fixes
HT leads deteriorated — arcing to engine block
93%
51 fixes
Thermostat stuck open — engine never reaches temperature
92%
51 fixes
Points rubbing block worn flat — dwell angle lost
90%
48 fixes
Valve cover oil leak — M115 engine
91%
47 fixes
Brake fluid contamination — moisture absorption
90%
45 fixes
Mixture screw O-ring deteriorated causing lean idle
90%
44 fixes
Radiator cap seal failure — coolant loss at pressure
90%
44 fixes
Carburetor dashpot damper oil empty
91%
42 fixes
Intake manifold gasket air leak between carbs
85%
38 fixes
Air lock in cooling system after hose work
89%
38 fixes
Dipstick tube O-ring leak
89%
37 fixes
Carb balance pipe hose perished causing vacuum leak
89%
36 fixes
Radiator bottom hose collapsing under suction
88%
35 fixes
Perished rubber fuel hoses — fire risk
88%
35 fixes
Zenith 35/40 INAT accelerator pump diaphragm split
87%
34 fixes
Distributor cap carbon tracking
87%
33 fixes
Coolant hose perishing causing split under pressure
87%
32 fixes
Points ignition misfiring under load
88%
31 fixes
Ignition timing too retarded — flat power
85%
31 fixes
Spark plug incorrect heat range causing carbon fouling
86%
30 fixes
Sump gasket oil leak
84%
30 fixes
Engine mounts collapsed — vibration through body
85%
29 fixes
Zenith 35/40 INAT float needle valve failure
82%
28 fixes
Front anti-roll bar bush deterioration
85%
28 fixes
Flexible brake hose internal deterioration
84%
27 fixes
Front wheel bearing rumble
83%
26 fixes
Rear suspension rubber bump stop disintegration
84%
26 fixes
Coolant temperature sender inaccurate gauge reading
83%
26 fixes
Alternator brushes worn — battery not charging
82%
25 fixes
Coolant corrosion from neglected antifreeze changes
83%
25 fixes
Rich running after storage — stale fuel varnish
81%
25 fixes
Breather system blocked causing crankcase pressure
83%
24 fixes
Fuel pump diaphragm crack — pressure loss
80%
24 fixes
Toe alignment out causing tyre feathering
82%
24 fixes
Instrument cluster lighting failure
83%
24 fixes
Brake servo vacuum hose deteriorated
81%
23 fixes
Interior blower motor resistor failure — fan on full only
82%
23 fixes
Rear light cluster seal failure — water in lights
81%
23 fixes
Rough idle after warm-up — Zenith carburetor sync
82%
22 fixes
Twin Zenith carburetor idle circuit blocked
79%
22 fixes
Ballast resistor failure — no start or weak spark
82%
22 fixes
Starter motor brushes worn — slow cranking
80%
22 fixes
Rear brake drum binding after adjustment
80%
22 fixes
Vacuum advance unit diaphragm failure
79%
21 fixes
Cam follower wear causing noisy valvetrain
78%
21 fixes
Handbrake cable seizing inside outer sleeve
79%
21 fixes
Door hinge pin wear — dropping doors
79%
21 fixes
Rear drum brake wheel cylinder leak
79%
21 fixes
Front shock absorber leaking oil — poor damping
79%
21 fixes
Automatic choke bimetal spring fatigue
80%
20 fixes
Sunroof drain tubes blocked — headlining water damage
80%
20 fixes
Fuse box corrosion causing intermittent electrical faults
78%
20 fixes
Earthing strap failure causing electrical gremlins
80%
20 fixes
Radiator drain tap seized — coolant change impossible
80%
20 fixes
Petrol smell inside cabin — fuel system leak
83%
19 fixes
M115 oil consumption — valve stem seals worn
74%
19 fixes
Overheating on sustained highway driving
72%
18 fixes
Ignition coil breaking down when hot
75%
18 fixes
Water pump plastic impeller disintegration
77%
18 fixes
Ethanol fuel damage to carburetor soft parts
76%
18 fixes
Front disc brake caliper seized piston
76%
18 fixes
Steering idler arm wear — vague directional control
75%
18 fixes
Front suspension ball joint wear
75%
18 fixes
Carburetor icing in cold humid conditions
77%
18 fixes
Fuel sender unit failure — inaccurate gauge
74%
17 fixes
Rear axle oil seal leak contaminating brake linings
74%
17 fixes
Rear leaf spring inter-leaf corrosion and squeak
74%
17 fixes
Differential oil seal weeping — whine under load
73%
17 fixes
Centrifugal advance mechanism sticking
71%
16 fixes
Brake master cylinder cup seal failure
73%
16 fixes
Propshaft centre bearing failure
72%
16 fixes
Subframe mount rubber rot — handling vagueness
73%
16 fixes
Windscreen rubber seal water ingress
72%
16 fixes
Wiper motor failing — wipers stopping mid-screen
73%
16 fixes
Clutch pressure plate worn — slipping under load
72%
16 fixes
Steering column universal joint worn — clonking
72%
16 fixes
Steel fuel line internal corrosion shedding particles
71%
15 fixes
Steering box backlash — excessive free play
70%
15 fixes
Oil pressure relief valve sticking — abnormal pressure
72%
15 fixes
Hard start when cold — carburetor choke issue
78%
14 fixes
Carburetor throttle spindle wear causing air leak
65%
14 fixes
Distributor shaft bush worn — timing wander
68%
14 fixes
Vapour lock in hot weather — engine cutting out
68%
14 fixes
Battery tray corrosion reaching adjacent structure
71%
14 fixes
M115 timing chain rattle on cold startup
69%
13 fixes
Fuel tank seam corrosion and weeping
66%
13 fixes
Carburetor flooding — black smoke and rich mixture
75%
12 fixes
Heater matrix blockage — no heat output
65%
12 fixes
Boot floor rust — water ingress through seal
64%
12 fixes
Crankshaft rear oil seal leak — clutch contamination
66%
11 fixes
Gearbox synchromesh wear — 2nd and 3rd crunch
66%
11 fixes
M115 head gasket failure — coolant-oil mixing
65%
11 fixes
Engine knock at low RPM — pinking or detonation
70%
10 fixes
A-pillar and windscreen surround rust
57%
10 fixes
Rear spring hanger rust — structural weakness
60%
10 fixes
Automatic transmission slip — W722 gearbox
62%
10 fixes
Brake fade when hot — drum brake rear
65%
8 fixes
Sill (rocker panel) rust — structural concern
60%
5 fixes
🩺 Common Symptoms
Symptoms reported across all W115 fault cases
📖 Repair Guides
Step-by-step guides applicable to the W115
📋 Mercedes-Benz W115 Overview & Buying Guide
The Mercedes-Benz W115 (also known as the /8 or Strich Acht) is a series of compact executive cars produced from 1968 to 1976. Known for exceptional build quality, simple mechanicals, and longevity.
Available body styles: sedan,coupe. Produced from 1968 to 1976.
Which variant to buy?
The W115 was produced in 6 main variants. The most powerful option is the 220 (M115 carb) with 105 hp (M115.954 engine). When buying, always verify the engine code matches the claimed variant — swapped engines are common on classic cars of this era.
What to check before buying
Based on 100 reported fault cases, the most important pre-purchase checks for the W115 are:
- Oil filler cap seal perished — top end oil seep ✅ Known fix available
- Blocked fuel filter causing lean misfire under load ✅ Known fix available
- HT leads deteriorated — arcing to engine block ✅ Known fix available
- Thermostat stuck open — engine never reaches temperature ✅ Known fix available
- Points rubbing block worn flat — dwell angle lost ✅ Known fix available
Is the W115 reliable?
Of the 100 fault cases recorded for the Mercedes-Benz W115 on MyCarFault, 79% have a verified fix. Regular maintenance, correct service intervals and addressing known weak points early significantly extends the life of these vehicles.
Own a Mercedes-Benz W115?
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