2001 Mercury XR6 150 Oil Injection Removal

[DeudeMann]

I just completed removal of the oil injection system on my 2001 Mercury XR6. So I am adding to the info on screamandfly to help those who choose to do this later.

This engine came to me used, runs great, has good compression (115 psi +/- 2 psi across all 6 cylinders) and has enough power for my current needs (19' fish and ski - 95% fish). It is stock except for this mod.

The information here is only from me in part; a lot also comes from other posts here, the Mercury manuals and parts diagrams for this engine, and posts on other forums. In my opinion all of the information I have below is important for this job. The information I have bolded is really important.

Why am I removing the oil injection? There are tons of discussions (arguments) about whether or not this is a good idea. I myself planned on leaving it on until I figured out this particular XR6 does NOT have the warning system for an inactive (not rotating) oil pump; if the plastic driving gear on the crankshaft fails (apparently it's common) the oil pump stops pumping and there is no warning system for this failure mode.

Why Mercury had this rotation sensor on previous XR6 motors, and then later removed it, I have no idea. I myself cannot come up with a good reason.

What fails exactly? The oil pump is driven by a gear set that meshes in the crankcase at the crankshaft. The removable oil pump shaft (driven) gear is metal, but the crankshaft (driving) gear is plastic. It wears over time, and/or it can overheat and melt. If this happens, then the oil pump is no longer rotating and 'injecting' oil into the fuel; the engine runs unlubricated, and really bad things happen. Again, for MY XR6 motor, there is no warning system for this failure mode. The plastic gear on the crankshaft cannot be removed (AFAIK) without accessing the crankcase (significant engine teardown) so periodic, preventive replacement of the gear is not really feasible.

[DeudeMann]

Is it hard? So removal is pretty basic as long as you are reasonably familiar with general engine mechanics and are comfortable with wrenching on your own stuff. I've been building/modding/working on motorcycle/car/racing engines and vehicles for decades so for me, and with the info available on this site, it was straightforward and not intimidating. In any case, if you do this, read up on why you are doing it, how to do it, and look through the engine diagrams available at the Mercury web site and elsewhere. Make sure you verify your engine design based on the serial number; as stated previously, not all of the XR6 150s are the same.

WARNING: BE SURE you add the proper amount of premix (50:1) to your fuel tank now and forever after this mod. I only mention this because it is the silly sort of thing I would forget to do. Until you do, hide your keys, put tape across the ignition and on the steering wheel, tattoo it on your forehead, whatever it takes to remind you to premix the fuel in the tank after this mod.
ALSO be sure to flush out the fuel line from the tank all the way to inside the cowl since it will not have premix in it. The carbs (and everything else downstream of the injection system) will have premix in them but drain them if you want to be safe.

NOTE: As mentioned above, my version of the XR6 does NOT have the oil pump rotation sensor on the oil pump assembly. Your XR6 may have it. If so you will need to research what to do with these sensor wires to keep the oil injection alarm from alarming. Everything else (AFAIK) is the same. Also, if you do have the rotation sensor you may want to rethink whether you want to remove the oil injection system. Some still do it, your call.

[DeudeMann]

So first step is removal of the oil tank located on the top front of the motor above the carburetors. There are three bolts/isolators that attach it to the motor, the inlet hose from the remote tank, the outlet hose to the oil pump, and the two wires from the float switch on the cap on top of the tank.

I clamped off the oil outlet hose before I disconnected it; this keeps the stuff in the tank in the tank.

Here is the tank after removal:
520398

Here is the motor after removal of the tank:
520397

I left the two wires from the cap sensor disconnected and wire tied them out of the way; see the two connectors in the photo below. On MY XR6 the cap float switch is off (not on) when the tank is full. So, with the wires disconnected, the oil injection warning system will think the tank is always full and will stay quiet (no warning).
520400

[DeudeMann]

There are two large hoses on the right side of the engine that need to be dealt with:
The hose (black) from the bottom of the motor (crankcase) to the external oil tank.
The hose (black with blue stripe) from the external tank to the top of the oil tank.

How I did it...
- I cut the black hose from the crankcase to the external tank; leaving about 2-3 inches of hose attached to the motor end. I then plugged (tightly) both of the cut ends of the hose. This seals off the crankcase and the line to the external oil tank.
- I plugged (again, tightly) the black-with-blue-stripe hose that was disconnected from the top of the motor oil tank and laid it down in the lower cowling next to the block.

So, when finished, I had three hoses, all plugged, all laying down on the right side of the motor. The black line has two caps (on the two ends from the cut). The black-blue line has one cap. If this seems nonsensical it is really simple and will make more sense when you dig into it.
520402

[DeudeMann]

Now it is time for removal of the oil pump. NOTE: In the following images I have also removed the fuel pump for servicing. This is not necessary, just noted for clarity.

Remove the oil pump from the motor. There are two bolts holding it in place, as well as the hose that was connected to the oil tank, and the hose that runs to the brass tee on the fuel line (disconnect it from the pump).

The arm that attaches the pump to the throttle assembly also needs to be removed. Carefully pop the black plastic sockets off of the brass ball ends. I did this by hand, no tools required.

Here is what the motor looks like after the pump is removed. Again, I have also removed the fuel pump which is not necessary for this.
520404

Disconnect the hose that runs from the oil pump to the brass tee on the fuel line and plug it (very tightly - it is a fuel line after all). NOTE: Later on I removed the tee and replaced it with a two-ended metal (brass) barb fitting to join the fuel line from the fuel tank to the line to the fuel pump; the oil injection tee is no longer needed so removing it leaves fewer connection points that can leak.
520403

There is an o-ring, a brass bushing, and a slotted shaft in the motor that are now visible. Carefully remove all of these. The shaft can be tricky to grab but I managed it with needlenose pliers.

Here is what all of the oil pump parts look like after removal. From left to right: oil hose and tee, throttle arm, oil injection pump, gear-shaft-bushing assembly, the two retaining bolts, and the o-ring.
520405

When finished, all of the oil injection lines will be removed. The fuel line will run from where the tee used to be, directly to the fuel filter, and then onto the carburetors (as normal).

[DeudeMann]

Finally there is a plug that needs to be installed into the hole where the oil pump gear-shaft-bushing assembly used to be. This reseals the crankcase, which of course has to be sealed for the motor to operate. The plug also holds a small bushing in place that supports the other end of the oil pump shaft. If you look in the hole where it used to be you will see the bushing in the motor block (see below). Holding this bushing in place is very important because if it falls out into the crankcase it could (will) trash your motor.

520406

Mercury sells this plug as part# 43453T (this is the plug for MY XR6 so again check it for your serial number).
520407

There are also aftermarket plugs available on places like ebay and Amazon. Others have reported that on some motors these plugs are a very tight fit into the motor bore where the pump shaft bushing used to be. If so the plug, not the motor(!) will need to be sanded to fit.

NOTE: Unexpectedly, the Mercury plug did not come with an o-ring or the retaining bolts. I used one of the seal rings and the retaining screws from the oil pump. I cut the longer of the two screws to the length of the shorter one so it would fit. The lesson here is order the o-ring and the screws for the plug. I do not know these part numbers.

Install the plug. Recheck all of your work. If something looks wrong, figure it out before running your engine.

FINALLY...
- DRAIN ALL THE OLD FUEL FROM THE TANK.
- ADD PREMIXED FUEL TO THE TANK (50:1 is recommended by most).
- PURGE ALL OF THE OLD FUEL FROM THE FUEL LINE ALL THE WAY TO THE FUEL FILTER
- ALWAYS PREMIX THE FUEL FROM NOW ON.
If you fail to do this, you will kill your engine, your spouse, your children, your grandparents, puppies and kittens, and all cute innocent forms of life across the planet. You have been warned.

Now you are finished.

[DeudeMann]

If I missed anything let me know. I am sure y'all will.

[James45157]

If I missed anything let me know. I am sure y'all will.
great job wish everyone would do that good showing how things are done thanks jim 45157

[tlwjkw]

If I missed anything let me know. I am sure y'all will.

excellent presentation... u asked so.... oiler module?

[LakeFever]

Great write up! I can attest to ditching oil injection immediately when buying a Merc and paying the hard price.

[DeudeMann]

excellent presentation... u asked so.... oiler module?

Do you mean the oil warning module on the motor? After checking the parts diagram and looking over the motor I do not see an oil module on the engine anywhere. I know there is one on some of the XR6 motors so I suspect it is for the versions that have the oil pump rotation sensor; mine does not.

It is possible that function was integrated into the ignition module though I do not have a wiring diagram to confirm that.

[tlwjkw]

it very well could be.. from '00 up we kinda refer to them as "lectronic" motors 'cause of tha changes to tha ign. system.. coulda changed tha oiler warnin' module also... i can't remember for sure?.. we didn't keep much of tha 'lectronic stuff around.. we pretty much used switch box stuff on everything... 'lectronic stuff (ecm mostly) was way to limiting for what we did..........

where did tha two wires from tha cap terminate???

[25two.stroke]

Oil injection warning was integral to the control module that ran the CDMs or the rev-limiter module (or both). I believe his XR6 is the first year of this. As you notice there is no rotational sensor on the front half of the block to sense the shaft rotation. Unlike the previous 16 or so years of oil injection that most of us deal with, this system does not back-check the rotation of the shaft to the firing of a single cylinder to verify oil injection system operation. Not sure exactly why mercury got rid of that rotational sensor: probably because they almost never sounded an alarm in time. The motors blew up before that alarm rang.

[25two.stroke]

520435
3 wire sensor would be right above above the oil pump in this pic. On the cdm blocks they made 2 major changes in the casting that I know of: they added a second boss for a grounding bolt under the starter and they removed the well for the rotational sensor above the oil pump.

[tlwjkw]

yeah, i knew tha got rid of tha rot. sensor when tha cdm motor came out, jus never paid any attention to tha oiler module when we would strip all tha 'lectronic junk off... we were more concerned with tha extra 40 thous. deck height... back then wasn't anyone cuttin' o-ring heads.. well no one we could afford.......:reddevil:

[DeudeMann]

where did tha two wires from tha cap terminate???

I did not trace them, just left them unplugged as shown.