Jeep Comanche Problems: 2 Issues Every Owner Should Know
1990-1992 model years · Based on 400+ owner reports · Last updated March 2026
According to Au7o's analysis of 400+ owner reports, the 1990-1992 Jeep Comanche has 2 documented known issues, with 1 rated critical by the Au7o research team. The most serious is Floor Pan and Frame Rust-Through ($300-$4,000 repair). The most commonly reported issue is Floor Pan and Frame Rust-Through with 220 owner reports. Across all issues, repair costs range from $200 to $4,000. Full technical analysis and DIY maintenance guides at au7o.io.
All 2 Known Issues
The Jeep Comanche (MJ platform) is extremely susceptible to floor pan and frame rust, especially in salt-belt states. The driver and passenger foot wells, rear cab corners, and bed floor are the primary rust-through areas. The unibody construction means that floor pan rust is structural and affects vehicle safety. Water intrusion through deteriorated door and window seals accelerates the corrosion. Many surviving Comanches have been lost to rust rather than mechanical failure. Rust repair requires cutting out affected sections and welding in new metal patches.
Common Symptoms
- Visible rust holes in floor pans
- Water intrusion into cabin during rain
- Soft or spongy floor when pressed
- Rust bubbling under paint on cab corners and rocker panels
- Structural weakness visible during inspection
How to Fix
What Owners Are Using
Parts and tips from 220+ owners who fixed this issue
- Tip
- Tip
The cast iron exhaust manifold on the 4.0L AMC/Jeep inline-6 engine is prone to cracking from thermal stress cycling. The manifold design does not accommodate thermal expansion well, and cracks develop between the exhaust ports, typically between cylinders 3-4 or 5-6. Cracked manifolds cause exhaust leaks that are loudest on cold startup and may quiet down as the manifold expands when hot. The exhaust leak can cause a ticking or hissing sound that is often mistaken for a lifter or valve issue. Broken exhaust manifold bolts are extremely common and can complicate the repair.
Common Symptoms
- Ticking or hissing exhaust leak noise, loudest on cold startup
- Exhaust smell in engine bay or cabin
- Reduced engine performance
- Check engine light with catalyst efficiency codes
- Noise diminishes as engine warms up
How to Fix
What Owners Are Using
Parts and tips from 180+ owners who fixed this issue
- Tip
- Tip
Frequently Asked Questions
What are the most common Jeep Comanche problems?
According to Au7o's analysis of 400+ owner reports, the 1990-1992 Jeep Comanche has 2 documented issues. The most frequently reported are: Floor Pan and Frame Rust-Through, 4.0L Inline-6 Exhaust Manifold Cracking. Of these, 1 is rated critical and should be addressed promptly.
Is the Jeep Comanche reliable?
The 1990-1992 Jeep Comanche has 2 known issues documented across 400+ owner reports. 1 issue is rated critical: Floor Pan and Frame Rust-Through. 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 Jeep Comanche problems?
Repair costs for known Jeep Comanche issues range from $200 to $4,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Floor Pan and Frame Rust-Through, typically costs $300-$4,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
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