Mercury AT4Z-6505-A Valve - Exhaust

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Disconnect the cable from the negative battery terminal. Remove the spark plugs, then take off the valve cover. Loosen the right front wheel lug nuts, raise the front of the vehicle, and support it securely on jackstands before removing the wheel and the fender splash shield. Using a wrench or socket on the crankshaft pulley bolt, rotate the crankshaft clockwise and check each lifter when its camshaft lobe is straight up, ensuring that the measurement is between the base circle of the camshaft lobe and the top of the lifter. Use feeler gauges to measure the clearances, ensuring a slight drag is felt when sliding the gauge between the lifter and the camshaft if the clearance is correct. Check the clearance between each camshaft lobe and the lifter it operates, keeping careful notes of the measurements recorded for each lifter. If some measurements fall outside the recommended clearances, the camshafts must be removed along with the out-of-spec lifters. New lifters are available with various thicknesses to correct the valve clearances, marked with a thickness number that only includes the digits after the decimal point. To determine the desired thickness for new lifters, add the thickness of the original lifter to the measured clearance, then subtract the midrange figure for ideal clearance to find the proper lifter thickness to order, noting that not every thickness is available. For installation of the camshafts, once the camshafts and timing chain have been installed, recheck the valve clearances. The remainder of the installation follows the reverse order of removal, and after running the engine, check for oil leaks.

Disconnect the cable from the negative terminal of the battery, then remove the spark plugs and the valve covers. Using a socket and a breaker bar on the crankshaft pulley center bolt, rotate the engine until the cam lobes on the cylinder to be checked are pointing away from the lifters. Measure the clearance of the valves with a feeler gauge, ensuring that the gauge has the specified thickness; if the clearance is correct, a slight drag should be felt when pulling it out. Record each measurement and compare them with the desired valve clearance found in the specifications, noting any that are out of specification for later reference regarding required replacement lifters. Repeat the measurement process until all valve clearances have been assessed. If any clearance is out of specification, replace the lifter with a new one that has a different thickness head to correct the clearance, which requires removing the camshafts to access the lifters. Mark the lifters to be replaced and record their corresponding valves, using a micrometer to measure the thickness of the head of each lifter precisely at the center projection on the underside. To calculate the correct thickness for a replacement lifter that will achieve the specified valve clearance, use the formula: N equal R + (M1 - M2), where N is the thickness of the new lifter, R is the thickness of the old lifter, M1 is the measured valve clearance, and M2 is the standard valve clearance. Lifters are marked on the underside to indicate their size; for example, a marking of 3.310 indicates a thickness of 3.31 mm or 0.13 inch. Finally, mark the new lifters for their destination, lubricate them with engine assembly lube, and install them. After replacing the lifters, reinstall the camshafts and timing chains, then re-check the valve clearances.

First, it is recommended that you do this when the engine is cold, that is when you have not been operating the car for a while. The valve clearance requires checking and adjustment only after the camshaft(s) or other parts of the valve mechanism have been replaced, or if there is excessive noise from the valve train equipment. There are no valve adjustments for the 2.7L engines having hydraulic lifters. Start with the removal of the multi-meter from the negative terminal of the battery before removing the spark plugs, as well as, the valve covers. Of course, you may have already found that the crankshaft pulley center bolt is easy to reach, and to rotate the engine using a socket and breaker bar and about the position which is when the cam lobes on the cylinder to be checked is pointing away from the lifters. Check the clearance of each valve with the thickness of the feeler gauge as per the set size; when correct there will be some drag when removing the gauge. Take down all measurements and check if any of the valve clearance is beyond the standard in case of any argument about required replacement lifters in the near future. This measurement process should be done for all valves and the results recorded for analysis and comparison with the set standards and laid down recommendations on flow control. If any of those clearances is off, then you replace the lifter with a new one with a thickness head that offsets the clearance; unfortunately, it means removing the camshafts to get to the lifters. Check the identification of the lifters which are due for replacement and note the particular valves with which they are associated Since heads of different lifters may come in different sizes, make use of the micrometer to measure their thickness at the center projection at the bottom surface of the head of each lifter. To determine the correct thickness for a replacement lifter that will achieve the specified valve clearance, use the formula: This suggests the formula used in finding the thickness of the new lifters, N equal R + M1-M2 where N is the thickness of the new lifter, R the thickness of the old lifter, M1 is the measured valve clearance, and M2 is the standard valve clearance. Lifters are likewise branded on the undersurfaces with the size of the lifters; for example, a code 3.310 means that a thickness of the lifter is 3.31 millimeters or 0.13 inches. Last but not least, it needs to be noted where the new lifters are to be installed, then they need to be coated with the engine assembly lube before doing the installation. After having changed the lifters, fit the camshafts and the timing chains and finally, check the valve clearances once again.

N equals R plus (M1 minus M2) Where: N equals thickness of new lifter R equals thickness of old lifter M1 equals measured valve clearance M2 equals standard valve clearance.

Disconnect the battery cable from the negative battery terminal.

Lifters are marked on the underside as to their size. A marking of 3.310 indicates a thickness value of 3.31 mm, or 0.13 inch.

The remainder of installation is the reverse of removal. Run the engine and check for oil leaks.

If a clearance is out of specification, the lifter must be replaced with a new lifter that has a different thickness head to correct the clearance. Remove the camshafts to access the lifters.

The remainder of installation is the reverse of removal. Run the engine and check for oil leaks.