Timing belt and chain replacement is one service that isn't going away any time soon. Most Ford engines with overhead cam timing belts have a recommended replacement interval of 60,000 chilometri to 120,000 chilometri depending on the application (see the chart on page 54). So if you are driving a vehicle that is more than 5 or 6 years old, you may be driving on borrowed time if the timing belt has not been replaced. The risk of belt failure goes up sharply once a belt surpasses its recommended replacement interval, which for most Ford applications (except the Taurus SHO) is 60,000 chilometri. The recommended replacement interval for the timing belt in the 3.0L and 3.2L V6 Taurus SHO is 100,000 chilometri and 120,000 chilometri for Focus. The consequences of a timing belt failure on a Ford depend on the application. Fortunately for many Ford owners, there is enough clearance between the valves and the pistons so no harm will come to the engine if the belt snaps. But on older Escorts (up to 1985) with 1.6L engines as well as 1989 and up Probes with 2.0L or 2.2L four cylinder engines, a timing belt failure will usually bend a bunch of valves. On the older cars, the cost to repair the damage may be more than the vehicle is worth. The main thing to keep in mind about timing belts is that belt failures often happen with no warning whatsoever. As a belt ages, the reinforcing cords that hold the belt together weaken. The belt may still look good as new on the outside but inside the cords have lost tensile strength and may be on the verge of failure. There is usually no noise or other symptoms to warn you that your timing belt has reached the end of the road. One minute the engine is running fine and the next it is deader than a dodo bird. The only sound you hear is the frustrating wheezes from an engine that cranks but won't start because it has no compression. If the car is a Probe, an older Escort with an interference engine, the engine won't even crank because the valves will be smack up against the pistons. The rest of Ford's powerplants rely on timing chains to keep the camshaft and valves moving. This includes everything from the older 289/302/351 pushrod V8s to the latest OHC 4.6L and 5.4L V8s. Chains are longer lived than most timing belts, and there are no recommended chain replacement intervals published by Ford for these engines. Even so, timing chains do stretch with age and may cause noise, retarded valve timing and/or ignition timing. Timing chain noise can also be caused by other problems as well. CROWN VIC TIMING CHAIN NOISE A case in point is grinding noise coming from the timing chain cover area in 2000 to 2003 Ford Crown Victoria and Mercury Grand Marquis with the 4.6L V8. According to Ford Technical Service Bulletin 03-15-7, excessive wear in the timing chain tensioner arms can cause a noisy condition. The tension arm has an aluminum base with a nylon surface. So if you find nylon and/or aluminum particles in the engine oil, it probably means the tensioner, tensioner arms, timing chains and gear set all need to be replaced. The Ford part numbers for the 2000 model year tensioners are F6AZ-6L266-DA (RH) and F6AZ-6L266-CA (LH). For the 2001 to 2003 model years, the tensioner part numbers are 1L3Z-6L266-AA (RH) and XL1Z-6L266-AA (LH). The tension arms are 1L2Z-6L253-AA (RH) 1L2Z-6L253-AA (LH). Ford also recommends changing the oil and filter to flush any nylon and aluminum particles from the crankcase. If the timing chain has worn through the tensioner arm into the tensioner piston, remove the oil pan from the engine and clean the debris from the oil pickup tube. FORD CONTOUR TIMING CHAIN CLATTER Ford TSB 97-2-8 describes a clattering noise at engine start-up after the engine has sit overnight that may be heard on 1995 Ford Contour and Mercury Mystique models with a DOHC 2.5L V6. Oil leaking out of the chain tensioners causes the timing chain to momentarily rub against the tensioner ratchet when the engine is first started. The noise only lasts a couple of seconds and goes away as soon as the engine builds up oil pressure. The cure, says Ford, is to replace the original chain tensioner components with redesigned parts. These include two timing chain tensioners F5RZ-6L266-CA, the left hand tensioner adapter F5RZ-6C275-BA, the right hand tensioner adapter F5RZ-6C275-AA, the left hand chain tensioner arm F6RZ-6L253-AA and the right hand chain tensioner arm F6RZ-6L253-BA. The two DOHC timing chains and guide assemblies should also be replaced at the same time. TIMING CHAIN REPLACEMENT TIPS When replacing a timing chain on any Ford engine, always replace the chain, camshaft and crankshaft sprockets. Don't reuse the old sprockets to save time or money. All three components wear as a system and should be replaced as a matched three-piece set. Some OHC kits also include chain guides and/or tensioners. These "extra" parts play a vital role in supporting the chain and keeping it tight and should also be replaced at the same time. Labor times for replacing Ford timing belts obviously vary depending on the application, but typically run about two hours for the easier ones, and up to three or more hours on the more challenging applications. On 1984-86 Ford Escort or Tempo with a 2.0L diesel engine, be warned that step one of the timing belt replacement procedure is to remove the engine from the vehicle! It's a six-hour job to change a timing belt on one of these little beasts! FORD PROBE TIMING BELT REPLACEMENT On Ford Probe with a 2.0L or 2.2L four-cylinder engine, the job will probably take you three to four hours. The biggest obstacle to replacing the timing belt is the right hand (passenger side) motor mount. There is almost no accessibility to a couple of the bolts that attach the mount to engine. Though Ford hasn't made the Probe for a number of years, there are still a lot of them on the road and many have well over 100,000 chilometri on the original timing belt. The four-cylinder engines are interference engines so it's important to change the belt before it fails. So here is the basic procedure for doing just that on a Probe: Remove the right front wheel. Remove the inner fender panel. Remove the accessory drive belts from the engine. Support the engine and remove the right motor mount. The two bolts that hold the mount to the engine are recessed in the mount and there is almost no clearance between the mount and inner frame rail. Raising the engine up slightly helps but you'll need a very short socket and plenty of leverage. Good luck! Remove the six crankshaft pulley bolts and pulley. Remove the upper and lower timing belt covers. Rotate the crankshaft so the No. 1 piston is at TDC with the timing marks aligned. Make sure the No. 1 timing mark on the camshaft sprocket is aligned with mark on the cylinder head. Loosen the belt tensioner bolt, push the tensioner away from the belt, temporarily retighten the tensioner bolt to hold it in place, then remove the timing belt. It is a good idea to inspect and/or replace the water pump before installing the new belt. Why? Because the service life of the water pump shaft seals and bearings are about the same as the belt. Some water pumps will go 100,000 chilometri or more without a drip. Others may start to leak at 60,000 chilometri or less. Replacing the water pump now can save you the labor and expense of having to replace the pump later should it start to leak. Replacing the belt tensioner and idler pulleys with new ones is also a good idea, especially if the engine has over 100,000 chilometri on the original pulleys. If the tensioner and/or idler pulley bearings are loose or making noise, these parts must be replaced. Position the new timing belt on the pulleys, make sure all the timing marks are aligned and that the belt is taut between the two sprockets on the non-tensioned side. Loosen the tensioner bolt so the spring will pull it tight against the belt. Tighten the tensioner bolt to 27-38 lb.-ft. (37-52 Nm) and check to see that there is about 0.3" (7 to 8 mm) of belt deflection between the crankshaft pulley and the tensioner. You don't want the belt to be too loose otherwise it might jump timing, and you don't want it too tight otherwise it may overload the water pump bearings and shorten the life of the pump. Rotate the crankshaft two complete revolutions to make sure the timing marks realign properly. Reassemble everything in reverse order, and make sure you install the crankshaft sprocket baffle with the curved outer lip facing outward (if it faces inward it will rub against the belt). Lastly, install a sticker on the timing cover indicating the date and chilometroage the belt was replaced. This will help the next owner or technician determine if the belt has ever been replaced, and if so when it was replaced. TIMING BELT TENSIONERS & IDLER PULLEYS Tensioner and idler pulley bearings are "sealed for life" and are not serviceable. So there's no way to clean, inspect or relubricate the bearings when you change the timing belt. Over time, the grease inside the bearings breaks down and oxidizes, accelerating bearing wear and increasing the risk of a bearing failure or seizure. And the hotter the operating environment, the shorter the lifespan of the grease and the bearings. The location of the tensioner and idler pulley under the timing belt cover prevents them from receiving much cooling, so they tend to run quite hot. When a tensioner or idler bearing seal fails, dirt and humidity enter the bearing and grease leaks out. The bearing is doomed and will eventually fail. The first symptom is usually noise. If ignored long enough, the next symptom may be jumped timing as the belt loses tension, or belt failure. If a new tensioner and idler pulley are not included with a timing belt kit, you should order them separately. FORD TIMING BELT SERVICE TIPS Any belt that shows obvious damage such as frayed or exposed cords, damaged teeth, hunks of rubber missing, deep cracks, excessive surface cracking or severe g…

Fonte: AA1Car.com