Ford Timing Chains and Belts

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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 glazing should be replaced - without delay! Small surface cracks on the ribbing are considered normal. But extensive cracking or deep cracks are not.

If you find a belt with stripped cogs, it would tell you something in the cam drive system has jammed or stuck, overloading the belt and causing it to shear teeth or jump time. The most likely culprit is the camshaft, which may have seized due to engine overheating or lack of lubrication (low oil level or loss of oil pressure). Check the coolant level, oil level and maintenance records of the vehicle.

When OHC cylinder heads get too hot, they usually swell up in the middle causing the cam to bend or bind. In some cases, this may break the cam, snap the timing belt or shear the cam drive sprocket off the end of the cam. Make sure the replacement belt is identical to the original. Belt length, width, tooth profile and pitch must be the same, and the material must be the same or better. Do not substitute a less expensive neoprene belt for one made of HSN (Highly Saturated Nitrile). Use a quality brand of belt because some no-name brands use inferior materials that won't last as long as the OEM belt or a quality aftermarket belt.

When changing a belt, never attempt to "stretch" a belt over a pulley. Belts, remember, do not stretch and forcing one to do so will likely damage the cords and cause it to fail. Also, never pound on a sprocket to force it into place. If it isn't sliding into place, check alignment and fit.

Misalignment problems in the cam drive can also occur if the cam sprocket is installed backward, the wrong thickness of washer is used (incorrect end play), a thrust button is forgotten or the crank sprocket is not positioned properly on its keyway.

Belt tension is critical to belt longevity. Adjust to the recommended specifications (always refer to the manual because the amount of recommended play can vary depending on the application). If the belt is too tight, it won't last. If the belt too loose, it may jump time.

Belt replacement is recommended any time the cylinder head has to come off of the engine, or when replacing a water pump that is driven off the timing belt. In both cases, the belt has to be removed anyway to make the other repairs so there's no extra labor required to change the belt - and it will save your customer the cost of having the belt replaced later on.

REVISED TIMING BELT & TENSION SETUP ON 2.0L
Shop manuals are indispensable tools for looking up disassembly/ installation procedures, specifications, diagnostic and service information. But sometimes errors occur in printed manuals, which makes life interesting for the poor guy who doesn't know the manual is incorrect. An example here is the timing belt and tensioner setup procedure that Ford originally published for the 1998-2000 Contour, Escort ZX2, 2000 Focus, 1998-2000 Mercury Mystique and 1999-2000 Mercury Cougar with 2.0L engine.

Ford TSB 99-25-4 provides the following corrected information:

To achieve proper timing belt tension on this engine, Ford says the camshaft sprocket bolts should be loosened enough to permit the sprockets to turn freely on the camshafts. Once this has been done, rotate the crankshaft clockwise so cylinder No. 1 is at top dead center. Then, install the camshaft alignment tool in the camshaft slots to hold the cams in place.

Back out the tensioner bolt four full turns and position the tensioner so the locating tab is at approximately the 4 o'clock position. Line up the hex key slot in the tensioner-adjusting washer with the pointer that is located behind the pulley.
Working counterclockwise from the crank sprocket, install the timing belt.
Rotate the tensioner locating tab counterclockwise and insert the locating tab into the slot in the rear timing cover.
Position the hex key slot in the tensioner-adjusting washer to the 4 o'clock position.
Tighten the attaching bolt enough to seat the tensioner firmly against the rear timing cover, but still allow the tensioner adjusting washer to be rotated using a 6 mm hex key.
Using the hex key, rotate the adjusting washer counterclockwise until the notch in the pointer is centered over the index line on the locating tab. (The pointer will move in a clockwise direction during adjustment).
While holding the adjusting washer in position, torque the attaching bolt to 18 ft.lbs. (25 N.m).

Note: If the pointer does not remain centered over the index line during final tightening, loosen the bolt and repeat the procedure beginning with step 4.