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Between the years 1981 and 1998, Ford released a series of interference engines in five different models:
Ford Escort (1981 – 1985): Due to head gasket failures, the Escort was recalled several times.
Ford Crown Victoria (1991-1998): Manufactures kept this interference engine for the longest out of the earlier models.
Ford Probe (1989 – 1992 2.2L and 1993 – 1995 2.0L): The gears in the camshaft deteriorated along with the belt.
Ford Ranger (1986 to 1988 2.0L and 2.3L Ranger, the 1985 2.2L Ranger, and 1986 to 1987 2.3L diesel Ranger): It wasn’t easy to examine the timing belts of the Ranger because it was covered.
Ford Lynx (1981 to 1983 1.6L and 1984 to 1987 2.0L): The Lynx engine would stop running entirely when the belt broke.
What is an interference engine?
The critical difference between an interference and non-interference engine is simply that the interference has less space to prevent contact between pistons and valves should the belt break.
If the belt slips due to missing a tooth or even jumps due to water leakage, the pistons and valves will collide and will usually end up breaking the engine. A non-interference engine has more space, so if the timing is out in the engine, the most that will happen is the engine will shut down.
Do they still make interference engines?
Yes! Interference engines are often considered superior to non-interference. These engines ‘breathe’ better than non-interference, and they often have higher compression, which equals more power.
They have incorporated some safety precautions. During the ’80s and ’90s, the engine’s piston heads were flat, giving no leeway should the engine jump timing.
Today when they design interference engines, the pistons are designed specifically with this in mind. The head of the pistons is either domed or recessed (cutaways in the metal to prevent contact). This little bit of space is usually enough to avoid damage in the event of a slip.
How do I know if I have an interference engine?
Although you can google your engine, it’s not always reliable. Your best bet is to check the workshop manual or to ask your local auto-shop to check when you take your car in for its routine maintenance.
How do I know if my belt has slipped or if the timing is out?
There are a few signs to look out for:
- If there is a ticking sound coming from the engine. It’s usually worse when you start the car or when you pick up speed.
- The engine misfires.
- An oil leak at the front of the car.
- Engine won’t turn over.
Why does a belt slip?
There can be numerous reasons why a belt might slip, from temperature to poor installation. Here are a few reasons:
Sometimes the heat can fray, crack and make the belt brittle. The strap can also become too rigid, causing it to lose its flexibility.
A belt can become contaminated with oil and debris. When this happens, it can’t run smoothly and might jump when the debris or oil hinders it. Water contamination can also cause the belt to jump.
- Improper installation
Poor tensions can cause a belt to slide, jump or even snap. The constant friction can also hinder the belt’s gripping ability, putting it at risk for slipping.
What happens when your timing belt snaps?
The camshaft will stop turning, which will leave some of the engine valves in the open position. The valves and pistons will possibly collide, and this will result in heavy damage to the engine. Broken valves, damaged pistons. and even destroyed cylinder heads can be the result.
Howdy! I’m John Robinson from Levittown, New York. I am a mechanical engineer for 15 years and already had an established car repair company. I developed a personal relationship with cars since I was a kid. I always love the sounds and smell emitted by a car or truck and even at construction machinery. Since then I have been married but my love for cars only grew.