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. The 460 engine is a 7.5L big block V8 which produced power levels ranging from 197hp to 245hp over its 30 year history. Reliability is a big reason the big block 460 cubic inch engine lasted 30 years in production. However, no engine is perfect and there is no exception here. In this article, I cover Ford 460 engine problems and reliability along with some history and additional details.

Ford 7.5L Big Block History

Throughout the years Ford’s 460 engine received a number of updates, improvements, and complete redesigns. The 460 is part of the 385 Lima engine family, a family of big-block V8’s produced in Ford’s Lima, Ohio production plant. In addition to the 7.5L 460, the 385 engine family also included a 370/6.1L, 429/7.0L, and 514/8.4L

In the early 70’s, Ford refreshed the camshaft, lowered the compression ratio, and completely redesigned the heads. The redesigned heads were notoriously unreliable which lead to another complete redesign of them in 1973. The biggest engine improvement came in 1988 with the addition of fuel injection.

In addition to its applications in Ford, Lincoln, and Mercury vehicles, the 460 engine was offered as a performance crate engine until 1997. The availability of the Ford 460 as a crate engine lead to its prevalence as a hot rod engine, capable of producing over 500hp with proper fueling. Despite its already large size, the 460 can be stroked out to 545 cubic inches, increasing displacement from 7.5L to 8.9L.

Ford 460 Engine Problems - 7.5L Big Block V8 Reliability

Ford 460 Engine Applications

  • 1968-1971 Lincoln Continental Mark III
  • 1972-1976 Ford Thunderbird
  • 1974-1976 Mercury Cougar
  • 1972-1978 Ford & Mercury Full-Size Vehicles
  • 1973-1976 Ford & Mercury Mid-Size Vehicles
  • 1973-1998 Ford F-Series
  • 1975-1996 Ford E-Series

In addition to the vehicles mentioned above, the 460 engine was also commonly used in various commercial vehicles, RV’s, buses, etc.

Ford 460 Engine Problems

Some of the most common Ford 460 engine problems include:

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

In the rest of the article, I discuss the above Ford 460 problems in-depth. Not everyone will run into these failures, but they’re among the most frequent issues with the Ford 7.5 big block engine. Additionally, this engine is now 25-50+ years old so a little extra care and maintenance is likely necessary at this point. Anyway, let’s examine these engine problems and then circle back to reliability towards the end of the article.

1. Ford 460 Leaking Timing Chain Cover

The timing cover bolts up to the front of the block and protects the timing chain, guides, and tensioners. In addition to protecting these components from road debris, dirt, and grime it also helps lubricate the timing chain with oil. Since the timing chain is a metal component that sits on metal gears, it needs proper lubrication otherwise it can stretch from excess friction and heat.

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

Symptoms of a Ford 460 leaking timing cover are:

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

2. Ford 460 Water Pump Problems

Water pumps are responsible for circulating coolant throughout the engine block. Because it is a pressurized system, the water pump and its internals deteriorate over time. The Ford 460 is known for eating water pumps, in both carbureted and fuel injected versions. On the 460, 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. Ford 7.5 Big Block Rear Main Seal Leaks

The rear main seal sits on the back of the engine block and seals the main crankshaft bearing. The crankshaft receives the heaviest load of any component in an engine and therefore is supported by the largest bearings. These bearings are the “main bearings” and help carry the stress put on the crankshaft. The rear main seal is the seal for the rear main bearing. The rear main bearing sits on the outside of the back of the block and the seal is responsible for making sure oil doesn’t leak from the crankshaft.

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

Rear main seal leaks are usually hard to identify due to the location of the seal and the only symptoms being oil stains in your driveway. The unfortunate part is that replacing the rear main seal is quite a project and requires dropping the transmission and pulling the oil pan.

There are some alternative options to try to patch a rear main seal leak, such as using BlueDevil Rear Main Sealer. These additives are added directly to the engine oil and are supposed to seal the leak. Since the only problem with rear main seal leaks is oil loss and replacing the seal is a pain, it’s 100% worth it to try to seal the leak before replacing the seal.

4. Ford 460 Exhaust Manifold Bolt Problems

The exhaust manifold is a thick piece of cast iron that bolts directly up to the block and is the first component in the exhaust system. It carries the exhaust gases from the valves to the exhaust piping. Because it’s bolted to the block and flows hot exhaust gases, it is subject to very high temperatures.

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.

Ford 7.5L Bad Exhaust Manifold Symptoms

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

If you break a bolt you can simply replace it, albeit getting the broken bolt out of the block might not be easy. If the manifold itself is cracked or warped and leaking then you need a new manifold. Instead of replacing the manifold with an OEM part, it is common to replace it with a set of headers.

Headers are virtually the same as an exhaust manifold except each valve or cylinder has its own piping that goes to the exhaust. Manifolds pool the air all into one pipe whereas headers keep them separate. The separation also helps keep exhaust gas temps and therefore overall engine temps lower.

5. Ford 7.5L 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.

The 460 uses a heat exchanger oil cooler style. The oil cooler pulls oil into internal tubes and these tubes have engine coolant flowing on the outside of them. The coolant helps reduce the temperature of the oil as it flows through the tubes.

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 a common route for 7.5L owners.

Oil Cooler Failure Symptoms

A few symptoms of Ford 460 oil cooler problems include:

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

If you experience any symptoms other than these such as engine knock or extremely poor running then there has likely been internal damage. Once the oil cooler fails you need to immediately stop the engine and flush both the cooling and oil systems.

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. As is with any 25+ year old engine the majority of the problems associated with it today are from old age and high mileage. The block and major engine components themselves can easily withstand in excess of 300,000 miles.

You can also checkout our latest article on Most Common Ford 351 Cleveland Engine Problems which can be interesting to read.

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  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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