1986 Mercury Grand Marquis: common problems

Owners of the 1986 Mercury Grand Marquis filed 21 complaints with NHTSA, most often about electrical system and engine and cooling. Details by component below, with sources.

Key figures

Owner complaints: 21

What fails most often

1 Electrical system 52% of all complaints
2 Engine and cooling 19% of all complaints
3 Service brakes 10% of all complaints
4 Powertrain 5% of all complaints
5 Steering 5% of all complaints
6 Structure 5% of all complaints
7 Tires 5% of all complaints
8 Vehicle speed control 5% of all complaints

Circle size and colour show each component’s share of NHTSA complaints. Schematic only, not a drawing of the exact model.

Electrical system: 11 complaints (52% of all).
Engine and cooling: 4 complaints (19% of all).
Service brakes: 2 complaints (10% of all).
Powertrain: 1 complaints (5% of all).
Steering: 1 complaints (5% of all).

Engines and transmissions

US-market versions per EPA. On the right: how many NHTSA complaints name this engine or transmission type.

5 L · petrol · 8 cyl
automatic, 4-speed

Drive: RWD

Symptoms owners describe

How many of the 21 NHTSA complaints mention each symptom (automatic count from complaint text; one complaint can mention several).

smoke, burning smell, fire10 · 48%
stalls while driving2 · 10%
knocking, grinding or other noise1 · 5%
tires: bulges, blowouts1 · 5%
vibration1 · 5%
windows, sunroof1 · 5%

Components owners complain about

Component	Owner complaints	involving a crash	Technical service bulletins (TSB)
Electrical system	11	0	0
Engine and cooling	4	0	0
Service brakes	2	0	0
Powertrain	1	0	0
Steering	1	0	0
Structure	1	0	0
Tires	1	0	0
Vehicle speed control	1	0	0

What owners report

Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.

My 1986 mercury grand marquis goes forward when putting the transmission into reverse. There have been many close calls when someone who does not know my car tries to drive it (car wash people, mechanics, relatives, etc.). I believe the linkage going to my dashboard is not working correctly.
Powertrain · 2004-03-18 · NHTSA complaint #10062544
While driving vehicle started to lose pressure,then began to smoke. Driver pulled over and vehicle engulfed into flames. Consumer stated that muffler had been replaced and a new engine was installed with only 20,000 miles.
Engine and cooling · 2002-08-28 · NHTSA complaint #566989
While driving in low speed and making any type of turn, vehicle stalled.
Engine and cooling · 1999-11-12 · NHTSA complaint #850690
Vehicle vibrates on right front end when brakes are applied. When brakes are let go, feels like they are grabbing. Had stopped vehicle to check & noticed smoke from tires & then flames shot out. Had vehicle towed to mechanic & was informed that it was the electrical wiring harness.
Electrical system · 1999-06-08 · NHTSA complaint #837524
While parked, an electrical short in the ignition switch, caused the wiring in dash area to short out, resulting in a vehicle fire.
Electrical system · 1997-03-13 · NHTSA complaint #809949
The ignition swtich has caught on fire twice, first time in august of 1991, second time on oct, 4th.
Electrical system · 1996-10-04 · NHTSA complaint #803241
The vehicle caught on fire while it was parked. Source unknown. Please describe.
Engine and cooling · 1996-04-23 · NHTSA complaint #983366
After parking over night vehicle had burned until smoldered w/steering column melted and cracked window.
Steering · 1996-03-13 · NHTSA complaint #980656

When owners complained

NHTSA complaints by filing year. The peak shows at what age the problems show up most.

19953
199611
19972
19981
19992
20021
20041

Comparison

By complaint count this model year ranks 8,077 of 36,656 model years in the NHTSA data (top 22% most complained about).

On average one model year of the Grand Marquis has 117 complaints (34 years in the data). This year has 21, below average.

What to check before buying

Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
Engine and cooling. Radiator and fan after a frontal hit, coolant level and condition, overheating.
Service brakes. Pedal feel, ABS operation, leaks, discs and hoses.
Powertrain. Shift quality under load, harsh shifts, transmission codes, CV joints.

Other years of this model

Questions and answers

What are the most common problems with the 1986 Mercury Grand Marquis?

Owner complaints to NHTSA most often mention: electrical system, engine and cooling, service brakes. Total complaints: 21. The most frequent symptoms in complaint texts: smoke, burning smell, fire (48%), stalls while driving (10%), knocking, grinding or other noise (5%).

How many service bulletins (TSB) were issued for the 1986 Mercury Grand Marquis?

NHTSA lists 0 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.

Should I buy a 1986 Mercury Grand Marquis from a US auction?

Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.

Other 1986 models

Read also

Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-05.