All About the Ford 5.9L Engine: 4 Most Common Engine Questions

Just today I was working on my 1991 5.9L inline 6 engine and considering replacing the valve lifters. The engine is making a knocking noise and sounds like a noisy lifter so maybe they just need an adjustment. I googled if my engine had hydraulic or solid valve lifters to decide if I have to gap the valve tappets. Unfortunately no quick result came up and I had to do the tedious reading in the manual to find the answer. Along the way I found a few other useful specifications and will share them here.

Ford 4.9L 300c.i. Engine

Does the Ford 5.9L 300 CID have hydraulic valve lifters?

The Ford 5.9L 300 inline 6 comes factory with hydraulic valve lifters. This means no periodic valve lash adjustments are necessary on these engines. If the engine has a valve noise then there are tests to do to determine if the lifters are to blame but it is recommended to replace them and they only cost a few dollars each.

A few other tips when working on the lifters:

  • Label the pushrods and put them back in the same order they were in. Pushrods see a bit of wear and are going to be slightly different sizes. By keeping them in order, you will not have to readjust them.
  • Replace the lifters if there is a question of their integrity.
  • Consider using an engine cleaner like this one from Amazon. An engine flush can help break up gunk and buildup in an engine helping repair things like noisy lifters.

You do not need to adjust the valve lifters of the 5.9L Ford Engine because the engine uses hydraulic lifters that swell with oil pressure and keep the tappets in contact with the pushrods.

What is the Piston Firing Order for the Ford 5.9L Engine?

The firing order for the Ford 4.9L 6 cylinder engine is 1-5-3-6-2-4. The number 1 cylinder is the cylinder at the front of the engine and are numbered 1 through 6 ending in cylinder 6 at the back of the engine.

Ford Repair Manual Specifications

Firing order is good to know if you are changing spark plugs, plug wires, the distributor, or if you are reassembling the engine.

Marking the distributor cap with a permanent marker is a good way not to mix up the spark plug wires in the future and before you remove the wires to replace them.

When replacing spark plug wires, it is good practice to replace them one at a time to not have to worry about replacing a wire in the wrong position.

What is the Spark Plug Gap for the Ford 4.9L Engine?

The Spark plug gap for the Ford 4.9L engine is 0.044 inches for the years 1989-1986. This same spark plug gap was used in the 5.0L, 5.8L, and 7.5L engines.

Ford Repair Manual Spark Plug Gap Specifications

How Much Oil Does the Ford 4.9L Engine Require?

The Ford 4.9L 300 CID engine for the years 1989 to 1996 requires 6 quarts of oil with the oil filter being replaced. If the oil filter is not replaced then 5 quarts of oil are required. It is recommended to replace the oil filter every other oil change at a minimum but is cheap and is easily replaced every oil change.

Ford recommends an oil change every 3000 miles for all of their engines including the 4.9L inline 6 and so do we. Changing the oil is the single best thing you can do to maintain your vehicle engine.

You may consider purchasing a Chilton Manual if you have more work to get done on your vehicle and they include every specification and is where I get my information from. You can grab a manual here for less than 40 dollars and will provide you with all the instruction you need now and in the future for your car maintenance.

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