bowtye8

Running twin 496HO in my Baja. My Drivers side engine oil pressure flutters between 40 and 55 PSI. This happens at WOT and normal drving conditions.

I replaced what I thought was the oil Pressure sending unit. This was located near the bottom of the block where a standard car/truck oil filter would be. The sending unit from my local mercury was $85.00
Been running a few weeks and still have the flutter. At idle both engines dead on. 20 PSI. under WOT or above 4000PRM the port is 60PSI the starboard(bad one) 40-55.

Today I unplugged the sending unit(What I thought was at least) Fire up the engine and it dieplayed 40 PSI while on the muffs. Engine was cool from sitting some.
I plan to dig into this more deep tommorow. Just asking if for some advice and the location of the sender. I did search and found a location for a 502. not the 496.

Thanks
Dennis

bowtye8

After some more research on the net. I found the location. Its right where most factory Chevys are. Near the factory distributer location would be.
Cleaned up the contact and did a quick couple of blitz and it displayed 60 PSI.
Still going to buy a new sender. Maybe swap after a true water test.

turnerrd

60 Seems kind of high. What oil are you running? I think the guage that reads 40-55 is more like it.

Raylar

On the Mercury 496 engines there are two oil pressure snesors/senders. One is for your helm guage and is located at the back of the block on top of the ledge just behind back of the intake mAnifold base. This has a single push on wire plug. The other oil sensor is located on the left side of the block, over the top of the oil filter adaptor pad. this sensor has three wires and is the one that connects to the ECM and records the oil pressure readout for the computer ECM. It is common for these two different sensors/senders to read slightly different pressures because of where they connect in the pressurized oil system and just the differences in sensor/sender types. Generally on stock 496's the oil pressures will be between 40-60 psi cold and 35-55 warm at idle or thereabouts. At high rpms/WOT they should read between 50-70 psi cold and 45-60 hot. Thes are approximate numbers and remeber diffent helm guage installations and brands of guages can read differently. Differences will also show up depending on the oil type and weights you may be using as well as ambient temperature and water system temperature. If there is any real low or over high oil pressure on these motors the Guardian system will beep and note it as a fault.

Ray @ Raylar