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Ford · Known Issues

1979 Ford F-100 Problems: 3 Known Issues

1979 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated August 2026

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Issue summary

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1979 Ford F-100 has 3 documented known issues, with 2 rated critical. The most serious are Cab Corner, Floor Pan & Rocker Rust (Structural Body Corrosion) ($800-$6,000 repair) and Twin I-Beam Kingpin & Front-End Wear (Wandering, Vague Steering) ($500-$3,500 repair). Across all issues with published estimates, repair costs range from $150 to $6,000. DIY maintenance guides at au7o.io.

In This Article

  • F-100 Body/Panels1
  • F-100 Suspension1
  • F-100 Fuel System1
  • FAQ
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In This Article

  • Body/Panels1
  • Suspension1
  • Fuel System1
  • FAQ

All 3 Known Issues

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ALL YEARS19791978197719761975197419731972197119701969196819671966196519641963196219611960195919581957

On the 1957-1979 Ford F-100, six-plus decades of moisture trapped in the cab attack the lower structure: cab corners, floor pans and their support braces, inner and outer rockers, lower doors, cab mounts, and bed sides/wheel arches. Period weatherstripping leaks, dirt and leaves pack the cowl and floor, and the rockers (which tie the A- and B-pillars to the cab structure) rot from the inside out. Because the rockers and floor are structural, rust here is not just cosmetic — it lets the cab flex, throws door gaps off, and undermines the whole shell. It is the most common big-ticket surprise when a 'solid' F-100 goes onto a rotisserie.

This issue also affects: Chevrolet Camaro, Ford Bronco, Ford Mustang

Common Symptoms

  • Rust-through and bubbling at cab corners and lower doors
  • Soft or holed floor pans; feet can find rot under the mats
  • Rotten rockers causing door-gap misalignment and cab flex
  • Perforated bed sides and rear wheel arches
  • Water and exhaust smell entering the cab through floor holes

How to Fix

Cut out the rot and weld in correct reproduction steel rather than skim-filling. Quality weld-in cab corners, full floor-pan halves with the support braces, and inner+outer rocker sets are reproduced for these trucks (CJ Pony Parts, Mill Supply, Classic Industries); replace the rockers as complete units and the cab corners as patch sections, butt-welded and metal-finished. The restorer's bulletproofing step is corrosion-proofing the repair: epoxy-prime bare metal, weld-through primer on mating flanges, then flood every box section and the inside of the rockers/cab corners with cavity wax and apply seam sealer so the new steel doesn't rot from the inside like the original did. Refresh the cab-mount bushings and re-establish factory door gaps as you go.

Typical repair cost:$800 - $6,000

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Community Reported
High ConfidenceVerifiedReviewed Jun 2026

On the 1965-1979 Ford F-100, from 1965 the F-100 used Ford's Twin I-Beam front suspension with kingpins (not ball joints) pivoting the spindles, plus tie-rod ends, drag link, and the I-beam radius-arm (strut) bushings. After decades of service the kingpins and their bronze bushings wear oval, the tie-rod ends and drag-link sockets develop slop, and the radius-arm bushings perish. The truck then wanders, darts on bumps, has excessive steering free-play, eats front tires (cupping/feathering), and clunks. Many survivors have had grease neglected, accelerating kingpin seizure and wear. This is the single most common 'why does it drive so badly' complaint on a non-restored 1965-79 F-100.

This issue also affects: Chevrolet Camaro, Ford Bronco, Ford Mustang

Common Symptoms

  • Truck wanders and requires constant steering correction
  • Excessive steering wheel free-play / loose, vague feel
  • Front tires cupping, feathering, or wearing unevenly
  • Clunk or shimmy over bumps and during cornering
  • Hard-to-turn or notchy steering from a seized/dry kingpin

How to Fix

Do the front end ONCE, completely, rather than chasing one worn part at a time. Replace the kingpins and bushings as a set and ream the new bronze bushings to the kingpin diameter for a true, tight fit (the correct way these are sized), and replace tie-rod ends, the drag link, the I-beam radius-arm/strut bushings, and the front springs/shocks while you are in there. Set toe and caster afterward. Restorers who want modern road manners go a step further with a bolt-in Mustang II-style independent front suspension (e.g. CPP) or a pro-touring twin I-beam kit, gaining rack-and-pinion steering, coilovers, and a lower stance while keeping a bolt-in install. Either path turns a darty, vague truck into one that tracks straight and steers precisely.

Typical repair cost:$500 - $3,500

Research This Issue

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Community Reported
High ConfidenceVerifiedReviewed Jun 2026

On the 1957-1979 Ford F-100, these trucks were engineered for 1950s-70s leaded fuel and use a mechanical fuel pump feeding a carburetor through narrow steel lines routed near the hot exhaust. Modern E10 ethanol gasoline vaporizes 20-30% more readily, so on hot days the fuel boils in the line or carburetor bowl, forms vapor bubbles, and starves the engine — the classic vapor-lock hot-stall and hard-restart. Ethanol also attacks old rubber lines and original carb gaskets/accelerator pumps, causing leaks, flooding, and float-bowl varnish on trucks that sit. It is a top driveability complaint on freshly-revived F-100s.

This issue also affects: Chevrolet Camaro, Ford Bronco, Ford Mustang

Common Symptoms

  • Engine stalls when hot and won't restart until it cools (vapor lock)
  • Hesitation, surging, or stumble in hot weather
  • Hard hot-starting after a short shut-down
  • Fuel smell / weeping from aged rubber lines and carb gaskets
  • Rough running and flooding from a varnished or ethanol-damaged carburetor

How to Fix

Bulletproof the fuel delivery against ethanol and heat. Run larger 3/8 in. ethanol-rated line routed away from the exhaust and heat-shielded/insulated where it must pass close, add a phenolic/insulating spacer under the carburetor to block manifold heat soak, and rebuild the carb with modern ethanol-resistant components (or fit a new aluminum carb). Many restorers add a return-line regulator so fuel circulates and stays cool rather than sitting and boiling, and some convert to a low-pressure electric pump near the tank to push (not pull) cool fuel forward. Use non-ethanol fuel and a stabilizer when storing. The combination ends hot-soak vapor lock and ethanol-driven leaks for good.

Typical repair cost:$150 - $900

Research This Issue

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Community Reported
High ConfidenceVerifiedReviewed Jun 2026
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Frequently Asked Questions

What are the most common Ford F-100 problems?

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 1979 Ford F-100 has 3 documented issues. The most frequently reported are: Cab Corner, Floor Pan & Rocker Rust (Structural Body Corrosion), Twin I-Beam Kingpin & Front-End Wear (Wandering, Vague Steering), Ethanol-Era Vapor Lock & Carburetor Fuel Boil. Of these, 2 are rated critical and should be addressed promptly.

Is the Ford F-100 reliable?

The 1979 Ford F-100 has 3 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 2 issues are rated critical: Cab Corner, Floor Pan & Rocker Rust (Structural Body Corrosion) and Twin I-Beam Kingpin & Front-End Wear (Wandering, Vague Steering). 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 F-100 problems?

Repair costs for known Ford F-100 issues range from $150 to $6,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Cab Corner, Floor Pan & Rocker Rust (Structural Body Corrosion), typically costs $800-$6,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 1957-1979 Ford F-100 Cab Corner, Floor Pan & Rocker Rust (Structural Body Corrosion)?

Six-plus decades of moisture trapped in the cab attack the lower structure: cab corners, floor pans and their support braces, inner and outer rockers, lower doors, cab mounts, and bed sides/wheel arches. Period weatherstripping leaks, dirt and leaves pack the cowl and floor, and… Repairs typically run $800-$6,000. Severity: high.

What is the 1965-1979 Ford F-100 Twin I-Beam Kingpin & Front-End Wear (Wandering, Vague Steering)?

From 1965 the F-100 used Ford's Twin I-Beam front suspension with kingpins (not ball joints) pivoting the spindles, plus tie-rod ends, drag link, and the I-beam radius-arm (strut) bushings. After decades of service the kingpins and their bronze bushings wear oval, the tie-rod end… Repairs typically run $500-$3,500. Severity: high.

Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.

Data compiled from NHTSA recalls, manufacturer TSBs, automotive forums, and AI-assisted research. No aggregated owner-report counts available for this vehicle yet.

What is the 1957-1979 Ford F-100 Ethanol-Era Vapor Lock & Carburetor Fuel Boil?

These trucks were engineered for 1950s-70s leaded fuel and use a mechanical fuel pump feeding a carburetor through narrow steel lines routed near the hot exhaust. Modern E10 ethanol gasoline vaporizes 20-30% more readily, so on hot days the fuel boils in the line or carburetor bo… Repairs typically run $150-$900. Severity: medium.