Hello everyone, I have question about the rear mounted camshaft sensor/ oil pump drive #840982A 1. I had some valve train problems on my 572's so I've got both motors out and heads off. Now it's time to put things back together and I'm having a hard time finding info on installing the cam sensor. Also I would like to know it anyone knows of an aftermarket sensor? The High-volume oil pump is very hard on that plastic housing. Just for your info the motors are custom built and they have the Mercury Racing 555 ECM just like what's on the EFI 525's along with all the same sensors. Happy Holidays.

Pm me your e-mail and I will send you the mercury install instructions. The drives are Ac Delco's off 1999 454 efi's.

Not as hard as it seems to install but somewhat very hard to write & describe all the details to correctly install this. Here is the old college try..

Merc calls this "cam position sensor pickup setting".

Rotate crank to the # 1 cyc TDC position and make sure damper is align at 0 degrees.

make sure the slot on the oil pump drive is pointed to the 1 and 7 clocked position while viewed from back of engine facing forward, If this is not you can rotate the drive with a screwdriver to achieve the position. Align the cam sensor connector as close to that position as well before installing.

Take the sensor cover off beforehand then install the sensor and make sure using a new gasket or the gasket is in perfect condition.Heads up 1 st when correctly installed make sure the sensor assembly is flush on the intake manifold. Most of the times you have to rotate the rotor a tad bit counter clockwise (CCW) beforehand. As installing, the sensor rotor it will slightly move clockwise as it meets up with the cam teeth hence this is why most of the times you have to rotate the sensor rotor slightly CCW to obtain the position and again making sure it completely flush mounted into the intake manifold. All the way down in position.

Next align the center of the cam sensor pickup block with falling edge of the outer ring, if it is close the lower body of the assembly can be rotated to align the falling edge. This is hard to explain so I hope I am making senses here. I can picture this my head but if you have the manual I believe there is drawing of this alignment of the cam sesor pickup block and the cam sensor rotor falling edge. Important if the alignment is way off then the whole procedure will need to be taken out and start over again.

When it is correctly position and installed correctly next is secure the cam sensor assembly shaft hold down and do not forget to put the cam sensor assembly cover back on.

Hope this is understandable on my part as I tried to write how Merc teaches the install. It might be a good idea to buy the correct OEM service manual for your app especially if you are going to work on it. I do not have spare hp 525 manuals at this timeframe but maybe later on down the road..

Forgot the CAM sensor here is NLA - Merc did have a later part number change for it but that is very hard as well to find as well. You might get lucky as a place or dealer might have one left on the shelf. The price range for the newer part # range from 700 to 925 dollars.

here was the lastest part # 8M0085070 - again very hard to find this.

Thank you for all the info. The two I have work fine it's just plastic and I'm afrade that the high volume oil pump being so much harder to turn is going to break them. I was hoping to find a aftermarket one made from something a little stronger. I'll keep looking thanks again!!

The can sensor is made by Ac delco part # 213-350, available on line for around $200.00.

Like above said you can find them for a price range of 200 to 400 not including shipping. At one time I looked into carry them as Merc kept raising the price and the stock was getting very limited to none. I know the available stock for the aftermarket ones is somewhat limited currently but still around to grab one here and there. If you can not find one nor trust the seller let me know because I can still get them / sell for around the 260 dollar mark plus they are brand new 100%. Maybe add 10 to 15 bucks from that price with shipping included. FYI

contact Eddie Young,,he has a billet piece.

I will consider this my own head but when there is an guide I think there may be attracting with this alignment of your cam sesor pickup prevent.