MERCEDES 300 Common Problems & Reliability

Based on 237 MOT tests from 20 vehicles analysed by VehicleScore. The figures below describe that VehicleScore sample. Recurring issues seen in VehicleScore MOT data are not a claim that every MERCEDES 300 has the same fault.

MERCEDES 300's have a very good reliability rating of 672/999. The score was calculated from the average of every MERCEDES 300 that has had a registered MOT.

We calculated all of the below figures by getting the score from each vehicle make/model/year/fuel, which are each calculated a score. We then generate the average score, taking into account factors such as mileage and emissions.

MERCEDES 300 (example)

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Fuel Type	Year	Reliability Score	Avg Mileage	Sample Size
Petrol	1991	671/999Good	134,279 miles	586 vehicles
Petrol	1989	672/999Good	135,794 miles	575 vehicles

How reliable is the MERCEDES 300?

Based on 237 MOT tests from 20 vehicles analysed by VehicleScore.

Vehicles

MOT tests

237

Pass rate

76.8%

Median mileage

104,255 mi

Recurring issues seen in VehicleScore MOT data are inspection findings from this sample. They are not a statement that every MERCEDES 300 has the same fault. The median VehicleScore in this sample is 499 out of 999.

Common MERCEDES 300 MOT problems

These groups combine equivalent MOT comments, such as the same tyre note on different corners. Counts are comment occurrences in the sample, not a percentage of cars.

Tyre wear

VehicleScore MOT data includes 25 advisory comments and 5 failure comments in this group. Seen as both an advisory and a failure reason. These are comment occurrences, not a share of all cars.

These MOT comments record tyres that were worn, damaged, or close to the legal tread depth when the car was inspected.

What to inspect

Check the tread depth and look for uneven wear, cracking, or damage on all four tyres.

Example MOT wording: OFFSIDE REAR TYRE WORN CLOSE TO THE LEGAL LIMIT (4.1.E.1)

Corrosion

VehicleScore MOT data includes 14 advisory comments and 13 failure comments in this group. Seen as both an advisory and a failure reason. These are comment occurrences, not a share of all cars.

These MOT comments record corrosion the tester could see on the body or structure. Corrosion already named on a spring, brake, or other component is counted with that component.

What to inspect

Inspect the underside, sills, and subframe for heavy corrosion, especially where an advisory mentions it.

Example MOT wording: NEARSIDE REAR BRAKE PIPE CORRODED, COVERED IN GREASE OR OTHER MATERIAL (1.1.11 (C))

Coil spring issues

VehicleScore MOT data includes 10 advisory comments and 2 failure comments in this group. Seen as both an advisory and a failure reason. These are comment occurrences, not a share of all cars.

These MOT comments record coil springs that were corroded, fractured, or otherwise defective. They are counted separately from shock absorbers.

What to inspect

Look for a broken or heavily corroded spring and compare the ride height on both sides.

Example MOT wording: NEARSIDE REAR COIL SPRING CORRODED (5.3.1 (B) (I))

Oil leak

VehicleScore MOT data includes 10 advisory comments in this group. Seen mainly as an advisory. These are comment occurrences, not a share of all cars.

These MOT comments record an oil leak noted by the tester. Shock absorber misting is counted as a damper issue, not as an engine oil leak.

What to inspect

Look under the engine for fresh oil, and check the oil level.

Example MOT wording: OIL LEAK, BUT NOT EXCESSIVE (8.4.1 (A) (I))

Windscreen damage

VehicleScore MOT data includes 6 failure comments in this group. Seen mainly as a failure reason. These are comment occurrences, not a share of all cars.

These MOT comments record chips, cracks, or other windscreen damage in the driver’s view.

What to inspect

Look for chips and cracks, especially in the area swept by the wipers.

Example MOT wording: NEARSIDE WINDSCREEN WIPER DOES NOT CLEAR THE WINDSCREEN EFFECTIVELY (8.2.2)

Brake disc wear

VehicleScore MOT data includes 5 advisory comments in this group. Seen mainly as an advisory. These are comment occurrences, not a share of all cars.

These MOT comments record brake discs that were worn, scored, pitted, or corroded.

What to inspect

Look at the disc faces for deep scoring, a lip at the edge, and corrosion.

Example MOT wording: REAR BRAKE DISC WORN, PITTED OR SCORED, BUT NOT SERIOUSLY WEAKENED (3.5.1I)

Shock absorber issues

VehicleScore MOT data includes 4 advisory comments in this group. Seen mainly as an advisory. These are comment occurrences, not a share of all cars.

These MOT comments record shock absorbers or dampers that were leaking, misting, or insecure. A light misting of oil on a damper is not an engine oil leak.

What to inspect

Look for oil misting on the damper body and listen for knocks over bumps.

Example MOT wording: NEARSIDE FRONT SHOCK ABSORBER HAS A LIGHT MISTING OF OIL (2.7.3)

Ball joint wear

VehicleScore MOT data includes 3 failure comments in this group. Seen mainly as a failure reason. These are comment occurrences, not a share of all cars.

These MOT comments record a worn or damaged ball joint. Track rod ends are counted with steering, not here.

What to inspect

Ask for the joint to be checked for play with the suspension loaded and unloaded.

Example MOT wording: OFFSIDE FRONT LOWER SUSPENSION ARM BALL JOINT DUST COVER NO LONGER PREVENTS THE INGRESS OF DIRT (5.3.4 (B) (II))

MERCEDES 300 MOT reliability by year

A model year is only commented on when VehicleScore has at least 5 vehicles from that year.

Year	Vehicles	MOT tests	Pass rate	Recurring issues seen
1988	5	70	70%	Corrosion, Coil spring issues

What to check when buying a used MERCEDES 300

This is an inspection checklist based on MOT comments in the VehicleScore sample. It does not mean the car you are looking at has these defects.

Tyre wear. Check the tread depth and look for uneven wear, cracking, or damage on all four tyres.
Corrosion. Inspect the underside, sills, and subframe for heavy corrosion, especially where an advisory mentions it.
Coil spring issues. Look for a broken or heavily corroded spring and compare the ride height on both sides.
Oil leak. Look under the engine for fresh oil, and check the oil level.
Windscreen damage. Look for chips and cracks, especially in the area swept by the wipers.
Brake disc wear. Look at the disc faces for deep scoring, a lip at the edge, and corrosion.
Shock absorber issues. Look for oil misting on the damper body and listen for knocks over bumps.
Ball joint wear. Ask for the joint to be checked for play with the suspension loaded and unloaded.

Buying a MERCEDES 300?

Common problems tell you what can affect MERCEDES 300s generally. VehicleScore can check the history of the actual car you're considering.

Where does this data come from?

VehicleScore analyses MOT histories from vehicles in its own dataset. Sample sizes vary by model, and a small sample is labelled as such. MOT data records roadworthiness and inspection defects. It does not capture every mechanical or electronic problem a car can have, and a comment on one test is not proof that the model has an inherent fault.

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