Something I have and always will take into consideration when considering a vehicle or not is whether or not the particular vehicle uses what they refer to as an interference engine or interference motor. What makes this such a valuable car buying tip is that it can have a great impact on your overall peace of mind as a vehicle owner and has much influence on the potential cost to maintain that vehicle. This is a car buying tip that applies to both new and used cars.
Without getting too technical. Most of us are aware that a car's engine possesses both valves and pistons. When your engine is working properly these parts move in a fashion where these two parts are crossing each others path of motion without collision. A piston moves down after combustion and an exhaust valve immediately opens up and momentarily sits in that "line of fire" that the piston just inhabited to release those exhaust vapors. This works just the same for any intake valve(s) during the engine's intake cycle. This whole process happens in the blink of an eye and the coordinating parts are kept in sync by the timing belt/chain.
Timing belt or chain maintenance is a major part of a vehicles maintenance. Unfortunately, this is neglected by many consumers. It is easy for us to talk ourselves out of a high dollar maintenance expense. Especially, when everything appears to be working just fine. However, it just is not a part that can be easily visually inspected nor is it a part that really warrants an inspection. They were intended to be changed out in intervals. Manufacturer's recommendations for timing chain/belt intervals will vary but most service departments will likely recommend the 60-70k mile window.
Both timing belts and chains come with their pros and cons but they both also share the same end result. Failure. Whether you have a timing belt or chain. They both have the potential to fail at some point. Rubber breaks down and cracks. Metal can weaken. Both have the potential to stretch. The heating and cooling of an engine is a rough environment to any type of material regardless of it's strength. Driving around with an aged and worn timing belt or chain runs the risk of breakage or "jumping time". Jumping time is caused by belt or chain stretch and carries the the same risk of catastrophic engine failure with breakage. When an engine jumps time it means the teeth in the belt or vice versa in the case of chain have changed position with the coordinating pulley. Hence, now the motor is not operating in sync with itself. The result being internal collision with many vital and very expensive moving parts.
The cost to replace a timing belt or chain can range from hundreds of dollars to possibly thousands on some of your upper end luxury imports. The part itself generally isn't terribly expensive. It can just be very labor intensive in some cases to replace. I can promise you though that in the case of an interference motor. The cost to replace and maintain is far less than if it breaks or jumps time. Valves, pistons, water pumps, and lots of labor are what you can expect to pay for in the event of failure.
I am not saying that buying a vehicle without an interference motor is a free license to procrastinate about your vehicles maintenance. You just are not going to be faced with the financial nightmare of engine overhaul in the event of failure like the interference engine but you will be left equally as stranded on the side of the road.
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| Knowing if you have a non-interference engine or not can save you a lot of headache later. |
There are still a great number of vehicles that I even like that possess an interference engine under the hood. As a potential owner though. I want to know and so should you. I simply wanted to educate you on a factor that you may never have been aware of that you may possibly want to consider when buying a car. Hell, maybe you're not even in the market for buying a car but now you know for the sake of your own vehicle and it's maintenance.
I have reason to believe that many people have never changed either their timing belt or chain for the life of their vehicle. After 80k miles or though it is nothing other than pure luck after that point and everytime they start their car is like drawing straws. As a former car salesman I can tell you most folks either never change them when they are supposed to or not at all. In the case of considering a pre-owned vehicle I myself would want to know if the belt or chain had been replaced on an aged vehicle. Interference engine or not. If timing belt or chain service has been performed by a reputable shop. you can find a service sticker located under the hood somewhere usually. Generally on the timing belt cover itself. If it is a used car that had been serviced by the store it is being sold at. They should have service records to whether or not it had been serviced. Don't be afraid to ask a salesman if he can find any record of this. If he wants to sell you the car bad enough. He will find out anything he can. Timing belt/chain service may be a condition of purchase you could use in negotiating if it is found that the service is past due. I have definitely worked timing belt service and other maintenance into a car deal to earn a customer's business.
Asking a salesman if a particular car has an interference engine or not will likely send him to his service department scrambling for answers. The odds are he will have no idea what you are talking about and salesman hate that. Going into a dealership knowing such information as a consumer will put out the signal that you are somewhat educated and you are not rushing into anything.
Knowing this technical car buying tip may push you to avoid a vehicle altogether or just make you better aware of things you can expect down the road in terms of cost to own. Along with this article I wanted to pass on a link you may find valuable with a list of interference motors. Good luck buying and now you know.
Interference Engines
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