Ford · Known Issues

1991 Ford Explorer Problems: 5 Issues Every Owner Should Know

1991 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated July 2026

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1991 Ford Explorer has 5 documented known issues, with 4 rated critical. The most serious are Automatic transmission overdrive failure (A4LD / 4R55E) ($25-$3,500 repair), Frame, rear subframe, and rocker/body-mount rust ($200-$3,000 repair), Firestone tire tread separation and rollover safety crisis (NHTSA EA00-023) ($600-$1,000 repair) and 4.0L OHV cracked cylinder heads and blown head gaskets from overheating ($1,000-$2,800 repair). Across all issues with published estimates, repair costs range from $25 to $3,500. DIY maintenance guides at au7o.io.

Frequently Asked Questions

What are the most common Ford Explorer problems?

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1991 Ford Explorer has 5 documented issues. The most frequently reported are: Automatic transmission overdrive failure (A4LD / 4R55E), Frame, rear subframe, and rocker/body-mount rust, Firestone tire tread separation and rollover safety crisis (NHTSA EA00-023). Of these, 4 are rated critical and should be addressed promptly.

Is the Ford Explorer reliable?

The 1991 Ford Explorer has 5 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 4 issues are rated critical: Automatic transmission overdrive failure (A4LD / 4R55E) and Frame, rear subframe, and rocker/body-mount rust and Firestone tire tread separation and rollover safety crisis (NHTSA EA00-023) and 4.0L OHV cracked cylinder heads and blown head gaskets from overheating. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Ford Explorer problems?

Repair costs for known Ford Explorer issues range from $25 to $3,500, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Automatic transmission overdrive failure (A4LD / 4R55E), typically costs $25-$3,500 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 1991-1999 Ford Explorer Automatic transmission overdrive failure (A4LD / 4R55E)?

The 4-speed automatics behind the 4.0L - the early A4LD and the later electronically controlled 4R44E/4R55E - are a known weak point, commonly failing in the 120k-mile range, most often losing 4th gear (overdrive). The overdrive planetary is fragile (early units used a weaker pin… Repairs typically run $25-$3,500. Severity: high.

What is the 1991-1999 Ford Explorer Frame, rear subframe, and rocker/body-mount rust?

In salt-belt climates, 1991-1999 Explorers rot in predictable structural areas: the inner rocker panels, the tops of the front leaf-spring hangers (dirt packs between the hanger and inner rocker, which the factory welded only at the bottom), rear spring hangers/shackles, and the… Repairs typically run $200-$3,000. Severity: high.

What is the 1991-1999 Ford Explorer Firestone tire tread separation and rollover safety crisis (NHTSA EA00-023)?

The defining safety issue of the 1990s Explorer: original-equipment and replacement Firestone ATX, ATX II, and Wilderness AT P235/75R15 tires (notably from the Decatur, IL plant) suffered tread/belt separation at highway speed. Combined with the Explorer's relatively high center… Repairs typically run $600-$1,000. Severity: high.

What is the 1991-1999 Ford Explorer 4.0L OHV cracked cylinder heads and blown head gaskets from overheating?

The pushrod 4.0L OHV V6 (Cologne) is otherwise regarded as a durable 'tank,' but the cast heads are intolerant of overheating and are prone to cracking and gasket failure, typically appearing around 100k miles or after any single serious overheat event. The root cause is usually… Repairs typically run $1,000-$2,800. Severity: high.

What is the 1991-1999 Ford Explorer Camshaft synchronizer / CMP sensor bushing failure?

The 4.0L (both OHV and SOHC) drives the camshaft position sensor off a gear-driven 'synchronizer' assembly in place of a conventional distributor. The synchronizer's shaft/bushing wears or gums up with varnish, developing play and producing a distinctive squeak/chirp that is ofte… Repairs typically run $150-$500. Severity: medium.

1991 Ford Explorer Problems: 5 Issues Every Owner Should Know

All 5 Known Issues

1991-1999 Ford Explorer: Automatic transmission overdrive failure (A4LD / 4R55E)#

Common Symptoms

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1991-1999 Ford Explorer: Frame, rear subframe, and rocker/body-mount rust#

Common Symptoms

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1991-1999 Ford Explorer: Firestone tire tread separation and rollover safety crisis (NHTSA EA00-023)#

Common Symptoms

How to Fix

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1991-1999 Ford Explorer: 4.0L OHV cracked cylinder heads and blown head gaskets from overheating#

Common Symptoms

How to Fix

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1991-1999 Ford Explorer: Camshaft synchronizer / CMP sensor bushing failure#

Common Symptoms

How to Fix

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Other Ford Models

Frequently Asked Questions

What are the most common Ford Explorer problems?

Is the Ford Explorer reliable?

How much does it cost to fix common Ford Explorer problems?

What is the 1991-1999 Ford Explorer Automatic transmission overdrive failure (A4LD / 4R55E)?

What is the 1991-1999 Ford Explorer Frame, rear subframe, and rocker/body-mount rust?

What is the 1991-1999 Ford Explorer Firestone tire tread separation and rollover safety crisis (NHTSA EA00-023)?

What is the 1991-1999 Ford Explorer 4.0L OHV cracked cylinder heads and blown head gaskets from overheating?

What is the 1991-1999 Ford Explorer Camshaft synchronizer / CMP sensor bushing failure?