MCI Engine Manual, Oil pressure sending unit location

[trig123]

Originally Posted by JPonLKN

Does anyone have a 4 cycle Robbin engine tech manual specifically for the MCI engine? I have one that I used for a pre-mci rebuild, and most of the differences are identified with pop out windows labeled as "Newer Model". One of the differences that is not identified in the manual is the placement of the oil pressure sending unit. Both of the MCI engines I have here have the sending unit on the side of the engine case cover. The manual shows it on top of the case side cover. If anyone has a newer manual that shows the set up for the oil sending unit on the side of the case side cover, can you please post a clip of set up? Better yet, if someone has an MCI engine case side cover off the engine and can photograph what the pathway is between the old oil sending unit location on top of the case cover to the side. Did the check ball and spring move as well, or is there simply a passage that extend over to the side from the original check ball location?

Also, can we re-use the head gasket on these engines? Has anyone done it with success? This engine may have to come apart several times....had to have to buy a bunch of head gaskets for it if it isn't needed.

Thanks

Even though you may not need this now here is the inside of a MCI cover.

You should have at least 40 psi if you test it with a manual gauge at the sending unit if that engine is rebuilt. I think it takes around 4 psi to put the light out.

Maybe use two jump wires and just use a taillight or something similar to do this with if I you think the wiring is messed up. Power one side and connect the other to sending unit.

[JPonLKN]

Thanks Trig123. Looks like the check valve remains the same location and there is a passage to th top left of the bearing to the new sending unit location.

[trig123]

Originally Posted by JPonLKN

Thanks Trig123. Looks like the check valve remains the same location and there is a passage to th top left of the bearing to the new sending unit location.

You welcome. Let us know how things go.

[JPonLKN]

Originally Posted by CP241

...Despite being in that (and other) mci engines more times than I can count, I still have absolutely no clue how that cam gets lubrication...

Well...it looks like it simply sprays it across the top of the head just above the cam shaft. You can see how it works with the engine turning over and not starting. It doesn't look like it makes it all the way across without the engine running, but when you remove the cap on the valve cover and start the motor...what a mess. I tried to take a photo of the spray of oil across the top of the head, but the engine started and covered the phone in oil...picture came out blurry.

To that end...I definitely have oil pressure. Sending unit isn't working, or the passage to the sending unit is stopped up. Good news is that there isn't any issue with oil pressure at present. Now to fix the electrical issues and figure out if the sending unit is simply bad. I'll pop one in from one of the other motors tonight and find out. Either way...tonight should be the last night working on the two machines going back to the course. I'll have one more, but that one needs the engine re-built first. My two carts are pretty close too...seats for one of them, and a few cosmetic issues to resolve later this week. Four carts in two months on after hours work...not bad for a newbie.

[JPonLKN]

Well, update. The issue is most definitely inside the engine. Tried a different oil sending unit...same problem. Light won't go off. I tried a separate test light directly to the sending unit and same issue, so it isn't a wiring issue. Just no oil pressure in the passage behind the sending unit which means the check valve isn't opening to get to the sending unit. Either way, I have oil pressure, and it runs good. Looks like this will be like most TXT's and run without an oil pressure idiot light.

I did find a wiring issue with the gas gauge though. There has to be something messed up, as when I replace the two wires from the sending unit to the gauge, both sending unit wire and ground, I get 100 Ohms at empty, and around 40 when full at the gauge. When using the cart wiring, I get around 3, and no change on empty or full. Either way, the gas gauge doesn't work even with the jumpers. Not sure what the resistance values between empty and full should be. At least now it doesn't jump to full as soon as I press the pedal...just stays at empty. This problem will also remain with the cart...Oh well.

[CP241]

That’s the best I can figure also. Oil sprays across the head and hopefully goes into that little notch at the top of the journal. What a terrible design. It’s no wonder that’s the first thing to seize when there’s any lubrication issues...

The pre mci was a much better design. There was actually a path/tube inside the valve cover that carried pressurized oil through the valve cover to an oil hole directly into that cam journal. Needless to say, I’ve never seen a pre-mci cam seize in the head.