5 Common Ford 460 Engine Problems

Jake Mayock

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Jake is a founder of 8020 Media and TuningPro. He has over a decade of experience in the automotive industry including parts sales, writing, DIY modifications & repairs, and more. Jake is currently converting his N54 to a single turbo and building a Miata track car. He’s an experienced, hands-on automotive enthusiast who delivers in-depth, well-researched content.

The Ford 460 engine is Ford’s longest running big block V8, produced from 1968 until 1998. Even at a beefy 7.5L, it didn’t offer very much performance-wise. However, it lasted in production for so long because of its bulletproof reliability.

The major engine components on the Ford 460 can easily last beyond 300,000 miles without needing replacement. However, a number of ancillary parts do have problems and fail commonly. The timing cover and rear main seal are both prone to oil leaks, water pumps and oil coolers fail, and exhaust manifolds warp. In this guide we’re going to dig into each of these problems in-depth and provide some thoughts on overall reliability.

Ford 460 Engine Problems - 7.5L Big Block V8 Reliability

Ford 460 Engine Problems

  • Timing Cover Leaks
  • Water Pump Failure
  • Rear Main Seal Leaks
  • Warped Exhaust Manifolds
  • Oil Cooler Failure

1. Leaking Timing Chain Cover

The timing cover is bolted up to the block with a gasket in between the two. On the Ford 460, there are a few common areas that cause coolant leaks.

The timing cover itself can crack or form holes over time from heat and normal wear and tear causing leaks. Additionally, the gasket between the timing cover and block wears down over time and can also cause coolant leaks. Lastly, there is a backing plate that sits between the water pump and the timing cover which is also prone to leaking.

If you are leaking coolant, the engine is prone to overheating which can warp serious components such as the head or timing chain and also cause internal damage to rods and pistons. If you are leaking oil, low oil levels can starve the timing chain of lubrication causing the timing chain to jump teeth and throw timing off.

Leaking Timing Cover Symptoms

  • Oil or coolant leaks on block
  • Low oil or coolant levels
  • Engine overheating
  • Rough idling or poor performance

2. Water Pump Problems

The Ford 460 is known for eating water pumps, in both carbureted and fuel injected versions. The water pump bearings on the factory pumps were not very strong and a common failure point. Additionally, over tensioning the fan belt would add extra stress and cause the pump to fail.

Coolant is also known to leak out of the water pump vent hole, also referred to as the weep hole. The vent hole is there as a warning for seal failure. Either oil or coolant will leak from the vent hole. If oil is leaking from the hole it means you have a failing oil seal inside the pump. When the oil seal is failing, oil drips out of the weep hole so that it does not contaminate the coolant. If coolant is leaking then the internal water pump seal is toast. In both of these scenarios you will need a new water pump.

Water Pump Failure Symptoms

  • Engine overheating
  • Fan constantly on
  • Coolant leaks from water pump
  • Whining noise

3. Rear Main Seal Leaks

Due to its location in the engine, the rear main seal is susceptible to a lot of stress. As the crankshaft spins it naturally wears the seal down. On the Ford 460 rear main seal failure is a common cause of oil leaks. While this part does naturally wear down over time, low oil levels or infrequent oil changes can cause the seal to wear down more frequently and quickly than on properly maintained engines.

Additionally, worn bearings, crankshaft wear, or a bad PCV system could also be the cause of seal failure. Letting a car sit for too long without driving it can also cause the seal to dry out, become brittle, and leak.

Rear Main Seal Leak Symptoms

  • Oil puddles under car near back of block
  • Low engine oil

4. Exhaust Manifold Bolt Problems

Metal undergoes heat cycles, which is the constant warming and cooling of metal. When your engine is running the metal heats up and then it cools down when the engine is turned off. Metal expands when it heats up and contracts when it cools down. Therefore, the exhaust manifold on the 460 engine is constantly expanding and contracting.

This expansion and contraction can lead to the metal warping or cracking which will cause exhaust leaks. Additionally, the bolts that hold the manifold to the block also commonly break off from the same heat cycles. Broken bolts can cause the manifold to separate from the block and leak exhaust air. Exhaust leaks reduce backpressure and cause vacuum leaks which have a material impact on performance.

Symptoms

  • Louder exhaust noise when in cab
  • Exhaust fumes in cab
  • Lack of acceleration
  • Loss of power and overall poor performance

5. Oil Cooler Failure

Ford’s 460 engines used a factory oil cooler. The purpose of an oil cooler to reduce the temperature or remove excess heat from the engine oil. Since engine oil is circulated throughout an engine cooling the oil itself can help cool the block, internals, and various other engine components.

Because the oil and coolant are flowing inside the same system, failure can result in coolant and oil mixing together which can cause catastrophic engine damage. On the 460 the oil coolers are known to fail internally causing the two fluids to mix. Coolant filled out then circulates into the engine. Since coolant doesn’t have the same lubricity as oil it can starve the internal components of the needed lubrication and cause serious internal issues.

While this problem is most commonly caused by poor cooling system maintenance, deleting the OEM oil cooler or replacing it with an aftermarket system is recommended.

Oil Cooler Failure Symptoms

  • Coolant or oil leaking from oil cooler
  • Oil in the cooling system
  • Coolant in the oil system

7.5L Ford 460 Reliability

The 460 engine has a 30 year history for a reason: it is extremely reliable. While we mention some common problems above with systems like the oil cooler, water pump, gaskets, and seals the majority of these problems naturally occur due to age. While proper maintenance can help prolong the life of these parts the majority of them are common failure points on any old, high mileage engine.

With respect to the block, heads, valves, pistons, and other internals on the 460, the engine is extremely stout. The majority of the problems of this engine are from supporting systems and not related to the core of the engine itself.

Overall, Ford’s 7.5L 460 engine is extremely reliable. The block and major engine components themselves can easily withstand in excess of 300,000 miles.

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2 Comments

  1. I have a 1990 460cu marine engines in my boat. How do I drain these engines. On the right side (starboard) engine I take out the lower left side drain plug and I get about 8 quarts of antifreeze out, however the engine capacity is 10.4 quarts. I can never get it all out

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