GM 88891774 Seal Asm,Intake Valve Stem Oil

Internal lash lifters can be replaced while the crankshaft is still in the engine, while the more complicated and time consuming substitute jobs that involve the replacement of free or broken valve springs or a defective valve stem seal seldom call for more than the removal of the cylinder head which normally demands two special tools and a source of compressed air. Under circumstances where compressed air is not possible, a piece of nylon string may be utilised to keep the valves from falling into the cylinder. Start with the dismantling of the spark plug from the cylinder having a defective part, and if all the valve stem seals are being replaced at one go, then apart from the spark plug, both the camshaft housings should also be removed. Next, it is necessary to take out the ignition coil assembly and the camshaft or camshafts and lifters as well as the housing or housings. Rotate the crankshaft until the piston of the cylinder that needs to be tested is on the TDC of the compression stroke and if replacing all the valve stem seals begin with cylinder No, 1 in the firing order. Insert an adapter in the spark plug hole and attach the other end of an air hose to a source of compressed air. Using compressed air blast the cylinder while seeing to it that the piston is not moving in the wrong direction. This should keep the valves seated to the air pressure; if not the valves may need to be ground. If compressed air cannot be used then place the piston slightly before TDC, thread a nylon rope into the combustion chamber, turn the crankshaft until one feels slight resistance. Push shop rag into other cylinder head holes, use valve spring compressor to compress the spring and take off the keepers. When the retainer and the valve spring have been taken off, look for signs of wear of the valve stem. Apply pressure to the air to maintain the valve shut; undo the tape or rubber band if used. Engine oil should then be applied on the valve stem, a new guide seal fitted and placements of the spring the of the valve done properly. Place the valve spring retainer again, and by compressing the valve spring, place the keepers rightly in position. However, turn off the air hose, retract the adapter, replace the camshaft(s), lifters and housing(s), as well as spark plug(s) and coil assembly then starting the engine and examine there and then for oil leaks or unusual noise.

Looseness of valve springs and damaged valves stem seal can be remedied without having to take off the cylinder head; it requires only two special tools and a compressed air. If compressed air is not available a piece of nylon rope can be used to keep the valves from falling into the cylinder. To start, one will have to take off the valve cover and the spark plug from the side of the cylinder which is affected or all spark plugs if changing all valve stem seals. When the piston is at the TDC on the compression stroke turn the crankshaft and using an adapter attach an air hose from a pressurized air source to the spark plug hole. Take off the nut, pivot ball and rocker arm in respect of the defective valve to have the valves compressed by applying some air pressure. In case of air pressure failure, valve job may be required. A worse solution is to partially insert the piston in front of the TDC, through the intake valve, stuff nylon ropes into the combustion chamber, and start to turn the crankshaft until some resistance is met. It is advisable to use shop rags so that the parts will not fall into the engine, and then compress the valve spring using valve spring compressor and remove keepers. After that, unscrew the spring retainer and the valve spring, and then examine the stem to determine if it is worn out, and if the stem can move smoothly within the guide. Pressurise the air to lock the valve back in place, then grease the stem of the valve, and replace the valve guide seal. Position the spring and retainer, then compress the spring to put the keepers on, if grease is needed it should be applied at this stage. Turn off the air hose, take off the adapter and the return of the rocker arms and the pushrods and put the spark plugs and the valve cover back on. Last of all, switch on the engine and observe areas such as the oil drips and abnormal sounds.