Camshaft and tappets – removal, inspection and installation
Warning: The air conditioning system is under high pressure. DO NOT loosen any fittings or remove any components until after the system has been discharged. Air conditioning refrigerant should be properly discharged into an EPA-approved container at a dealership service department or an automotive air conditioning repair facility. Always wear eye protection when disconnecting air conditioning system fittings.
Note: Camshaft and tappet replacement in the diesel engine is a very involved process. The diesel engine tappets have a head that is larger than the tappet body, and they must be inserted into their bores from the bottom of the bore. This is a specialized procedure which requires several special tools. There are two methods for retaining the tappets for camshaft removal; read through the entire Section and obtain the special tools before beginning the procedure.
1. If the vehicle is equipped with air conditioning, and you’re planning to remove the camshaft with the engine installed in the vehicle, have the air conditioning system discharged by an automotive air conditioning shop before proceeding (you will have to remove the grille, radiator and condenser to remove the camshaft).
2. Remove the crankshaft damper and gear housing cover (Crankshaft front oil seal and gear housing cover – replacement). Remove the radiator and the upper radiator support panel, then remove the intercooler and the air conditioning condenser (see Chapters 3 and 4B).
3. If you’re planning to retain the tappets using Method Two, remove the fuel transfer pump, the fuel filter/water separator and the fuel injection pump (see Fuel and exhaust systems – diesel engine).
4. Position the engine at TDC for cylinder number 1 (Top Dead Center (TDC) for number one piston – locating).
5. Remove the valve cover, rocker arms and pushrods (see Sections Valve cover – removal and installation and Rocker arms and pushrods – removal, inspection, installation and adjustment).
Note: There are access holes with rubber plugs in the cowl for the removal of the pushrods for the rear cylinders.
Tappet retention
Note: The tappets must be retained up in their bores, away from the camshaft lobes, in order to remove the camshaft.
Method one
6. A set of 12 wooden dowels, four inches longer than the pushrods and the correct diameter to just fit snugly into the top of the tappets, will be necessary for the procedure. If you make your own and size them to fit, make sure that they are well-sanded with fine sandpaper and cleaned of sanding residue before use, so that no wood chips or sawdust contaminates the engine.
7. Insert the dowels down through the pushrod holes until they lodge firmly in the tappets. For each cylinder, pull up the two dowels (intake and exhaust) and secure them to each other with large rubber bands. There must be enough tension on the rubber bands to keep the tappets raised as far as they can go up in their bores.
8. When all of the tappets are secured at the top of their bores, the camshaft can be removed.
Method two
9. A somewhat easier method of tappet retention can be accomplished if the engine is out of the vehicle for overhaul, or in-vehicle, if the fuel filter/water separator and fuel injection pump are removed allowing removal of the engine side cover (see illustrations).
9.9a Remove the crankcase vent tube and the two screws, then pull off the plastic cover
9.9b Remove these six bolts and pull off the side cover and its gasket
10. Slip a small hose clamp over each tappet. Pull up the tappet to the top of its travel with a magnetic tool and tighten the hose clamp to keep the tappet at the top of its bore. Repeat this procedure for all of the tappets, tightening the clamps only enough to retain them at the top (see illustration).
9.10 With the side cover off, use a magnetic tool to lift each tappet up, then tighten a small hose clamp around the tappet to keep it there
Camshaft removal
11. With the engine positioned at TDC, remove the two bolts retaining the camshaft thrust plate (see illustration).
Caution: DO NOT let the thrust plate fall into the crankcase.
9.11 Remove the two bolts retaining the camshaft thrust plate
12. Pull the camshaft out as straight as possible. Be very careful not to nick any of the camshaft bearings in the block with the lobes or journals. Work slowly – it’s a long and heavy camshaft.
Tappet removal
13. A special tool is necessary to extract the tappets from the block. The tool is a long 1/2-section of pipe slightly smaller than the camshaft bore. The top of the pipe is removed, lengthwise, and one end capped. This trough may be available through your local dealer, or you can fabricate your own from copper tubing.
14. Insert the trough-like tool the full length of the camshaft bore, with the open side up (see illustration). Remove the rubber bands from two of the dowels, pull the dowel out of one tappet, and re-tie the other dowel with rubber bands to the valve spring or other nearby component. As the dowel is pulled out, that tappet will fall into the trough. Look through the trough with a flashlight to ensure that the tappet is lying on its side in the trough. If not, jiggle the trough to make it fall over and then extract the trough and retrieve the tappet.
9.14 Insert the trough-like tool into the camshaft bore with the open side up – then pull the dowels or, as shown, release the hose clamp from one tappet at a time until it falls into the trough and can be withdrawn from the engine
15. Repeat this procedure for each tappet, keeping the tappets in order so they can be reinstalled in their original locations, until all of the tappets have been removed for inspection.
Inspection
16. After the camshaft has been removed from the engine, cleaned with solvent and dried, inspect the bearing journals for uneven wear, pitting and evidence of seizure. If the journals are damaged, the bearing inserts in the block are probably damaged as well. Both the camshaft and bearings will have to be replaced. Note: Camshaft bearing replacement requires special tools and expertise that place it beyond the scope of the average home mechanic. Although the tool for bearing removal/installation is available at stores that carry automotive tools and can possibly even be found at a tool rental business, if the bearings are bad and bearing replacement is beyond your ability, remove the engine and take the block to an automotive machine shop to ensure that the job is done correctly.
17. Measure the bearing journals with a micrometer to determine if they are excessively worn or out-of-round. Measure the camshaft lobe height (see illustration). Compare your measurements with this Chapter’s Specifications to determine if the camshaft is worn.
9.17 Measure the camshaft lobe at its greatest dimension to determine the lobe height
18. Check the camshaft lobes for heat discoloration, score marks, chipped areas, pitting and uneven wear. If the lobes are in good condition and if the journal diameters and lobe height measurements are as specified, the camshaft can be reused.
19. Check each tappet wall, pushrod seat and foot for scuffing, score marks and uneven wear. Each tappet foot (the surface that rides on the cam lobe) should be perfectly flat, although it may be slightly concave in normal wear (see illustration). If there are signs of uneven wear or scoring, the tappets and camshaft must be replaced. If the tappet walls are damaged or worn (which is not very likely), inspect the tappet bores in the engine block as well, using a small inspection mirror with a long handle. If the pushrod seats are worn, check the pushrod ends.
9.19 Examine the foot of the tappet for uneven wear or pitting – it should be perfectly flat
20. If new tappets are being installed, a new camshaft must also be installed. If a new camshaft is installed, then use new tappets as well. Never install used tappets unless the original camshaft is used and the tappets can be installed in their original locations.
21. Measure the thickness of the camshaft thrust plate with a micrometer. Refer to the Specifications listed in this Chapter. If the camshaft thrust plate is too thin or thick, replace it with a new one.
Camshaft and tappet installation
22. A special tappet installation tool is needed to fish the new tappets up into their bores before the camshaft is installed. The installation tool is basically a long wire attached to a short plug that fits inside the tappet. This special tool is available through your dealer, or you can make your own. Insert the tappet trough tool fully into the camshaft bore and drop the tappet retrieval tool down through the pushrod hole from above until it hits the trough. Using the hooked retrieval tool (included with the tappet installation tool kit), pull the tappet installation tool out of the trough, then push the plug into the tappet, lubricate the sides and foot of the tappet with engine assembly lube and pull the wire back out the tappet hole until the tappet is seated in its bore. If you don’t have the factory installation tools, make your own (see illustration). You can get by without the hooked retrieval tool; instead, carefully pull the trough out of the engine until the tappet installation tool is exposed.
9.22 You can make your own tappet installation tools: Our trough was made from a length of copper tubing, and the retrieval tool is a short section of hose that just fits into the tappet and is attached to a long piece of wire (you can get by without the hooked retrieval tool – simply pull the trough out to retrieve each tappet)
23. Push the trough back into the engine fully, if removed, then from above, pull up on the wire until the tappet is at the top of its bore.
24. Now rotate the trough around until its closed side is UP, which will keep the tappet from falling out of its bore. The fishing tool can now be pulled out of the tappet and the dowel inserted and secured, retaining that tappet in place. If the side cover is off, secure the tappet with a hose clamp, as in Step 10.
25. Repeat Steps 22 through 24 for the remaining tappets until all are held high in their proper bores with the dowels and rubber bands, or hose clamps.
26. Lubricate the camshaft lobes and journals thoroughly with camshaft installation lubricant (see illustration) and insert the camshaft into the block, again being careful to insert it straight without nicking the bearings with the lobes or journals.
9.26 Lube the camshaft thoroughly with camshaft installation lube
27. As the camshaft is close to being fully inserted, align the timing marks on the camshaft gear with the timing mark on the crankshaft gear (see illustration). When the camshaft is fully inserted and the gears properly meshed, install the camshaft thrust plate bolts and tighten them to the torque listed in this Chapter’s Specifications.
Caution: Do not push the camshaft any further into the block than is necessary, or the camshaft plug at the back of the block could be loosened, creating an oil leak.
9.27 Align the timing marks on the crankshaft and camshaft gears
28. All of the tappet retaining dowels or clamps may now be removed, and the push-rods, rocker arms and other components installed. Adjust the valve clearance (Rocker arms and pushrods – removal, inspection, installation and adjustment).
29. The remainder of installation is the reverse of removal. If the side cover had been removed, install it with a new gasket. Change the engine oil and oil filter (see Tune-up and routine maintenance).
30. Have the air conditioning system evacuated, recharged and leak tested by the shop that discharged it.