Oil Priming a Mercruiser496
04-15-2007, 05:01 PM
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Oil Priming a Mercruiser496
What's the best way to oil prime a Mercruiser 496? This engine is distributorless isn't it (no hole to drop down something to turn the oil pump)?
04-15-2007, 08:15 PM
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Priming a 496 Mercruiser
If this is a newly assembled block and motor then priming should be a MUST! Mercruiser 496's have a oil pump drive assembly in the block below the intake manifold that takes the place of the distributor that used to be there in older 454-502 earlier generation big blocks. You can remove the intake (this is a lot of work) ,the oil pump drive assembly and use a drill and primer tool here to prime the system.
An alternative, if carefully done, is to make sure the valve train under the valve covers is pre-lubed with oil or assembly lube and the oil pan is filled to the correct level. Disconnect the wiring plug connector at the top left side of the manifold that connects to the fuel injector harness.Then using the starter motor in short durations of 10 seconds or so with a wait of 30 seconds or so between cranks, turn over the motor until an oil pressure guage hooked to the motor registers about 20-30lbs consistently during each crank period and there is engine oil appearing out of some of the rocker arms during cranking. Feel the starter motor after a few cranking periods and if gets hot to the touch, wait for it to cool to warm before proceeding. When it appears that the system is properly primed, reconnect the injector harness plug and fire the engine, monitoring the oil pressure carefully to make sure it stabilizes at about 45-65lbs on most system guages cold. Sometimes the roller lifters and rockers will clatter slightly until all of them prime, but this should only take less than a minute and the clatter should stop.
Hope this helps.
Regards,
Ray @ Raylar
An alternative, if carefully done, is to make sure the valve train under the valve covers is pre-lubed with oil or assembly lube and the oil pan is filled to the correct level. Disconnect the wiring plug connector at the top left side of the manifold that connects to the fuel injector harness.Then using the starter motor in short durations of 10 seconds or so with a wait of 30 seconds or so between cranks, turn over the motor until an oil pressure guage hooked to the motor registers about 20-30lbs consistently during each crank period and there is engine oil appearing out of some of the rocker arms during cranking. Feel the starter motor after a few cranking periods and if gets hot to the touch, wait for it to cool to warm before proceeding. When it appears that the system is properly primed, reconnect the injector harness plug and fire the engine, monitoring the oil pressure carefully to make sure it stabilizes at about 45-65lbs on most system guages cold. Sometimes the roller lifters and rockers will clatter slightly until all of them prime, but this should only take less than a minute and the clatter should stop.
Hope this helps.
Regards,
Ray @ Raylar
04-15-2007, 08:33 PM
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Michael,
Another alternative is to use a pressurized oil primer tank. The one I have came from NAPA. You fill it with oil, then pressurize it with about 50Lbs of air pressure, then hook the hose up to the oil pressure fitting on the block and open the valve. It pumps the oil into the block under pressure. It is a must have for the newer distributorless ignition engines and those that run the oil pump off the front of the crankshaft like the LS1's
If you dont want to go to that much trouble, Ray's method works too !
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Another alternative is to use a pressurized oil primer tank. The one I have came from NAPA. You fill it with oil, then pressurize it with about 50Lbs of air pressure, then hook the hose up to the oil pressure fitting on the block and open the valve. It pumps the oil into the block under pressure. It is a must have for the newer distributorless ignition engines and those that run the oil pump off the front of the crankshaft like the LS1's
If you dont want to go to that much trouble, Ray's method works too !
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
