Lincoln AT4Z-6250-A Camshaft

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Two special camshaft holding tools (manufacturer tool no. 303-1248) are required.

13. Inspect the rocker arms for signs of wear or damage. 14. Examine the camshaft lobes for scoring, pitting, galling, and evidence of overheating. Replace the camshaft if any such wear is evident. 15. Calculate the camshaft lobe lift by measuring the lobe height and the diameter of the base circle of the lobe. Subtract the base circle measurement from the lobe height to determine the lobe lift. Replace the camshaft if the lobe lift is less than specified. 16. Inspect the camshaft bearing journals and the cylinder head bearing surfaces for pitting or excessive wear. Replace the component if any such wear is evident.

Install the camshaft caps in the correct locations, loosely install all the bolts, and then tighten the bolts in 1/4-turn increments following the correct bolt-tightening sequence.

The remainder of the reassembly procedure, including replacement of the timing chain and setting the valve timing, is as described in Section 8.

Confirm that the crankshaft is still positioned at TDC and that the timing pin is in place.

These models are equipped with Direct Injection (DI) and a high-pressure fuel pump. Fuel pressure in the high-pressure system on DI systems is under extremely high pressure. Be sure to correctly perform the fuel pressure relief procedure prior to servicing any of the high-pressure fuel system components to prevent injury.

Use clean engine oil or camshaft installation lube.

Confirm that the crankshaft is still positioned at TDC and that the timing pin is in place.

Recheck the valve clearances since the crankshaft is in the neutral position, allowing the camshafts to be turned without the valves contacting the pistons.

1. Remove the valve covers and the timing chain cover. 2. Remove the timing chains and the rocker arms. 3. Measure the thrust clearance (endplay) of the camshaft(s) with a dial indicator. If the clearance is greater than the specified value, replace the camshaft or the cylinder head.

If the camshaft journals are damaged, the bearing inserts in the engine block are likely damaged as well, requiring both the camshaft and bearings to be replaced. This process requires special tools and should be done at an automotive machine shop.