Engine speed sensor question

[Awesomeness]

On the Cat 3116, there is an engine speed sensor (part 4) screwed into the driver's side of the bell housing (TM 9-2320-365-20-3, 7-38, Page 406). Two questions...

1.) Are replacements available? Is it a military or civilian part?

2.) What does it do? Is it only used for a tachometer (which I don't have), or does it do other things too?

I'm replacing the engine, and mine appears broken (fine copper wires unraveling out the nose of it). I'm curious if I'll be able to get the new engine running without one, or do I have to get it replaced before I can start it up.

Thanks!

 

[DiverDarrell]

I believe it feeds the transmission ecu rpm info.

 

[DieselInfantry711]

If it is the Allison automatic then yes this is correct. This part would also be available through a CAT dealership. Usually just need engine info. Serial number and some times ratings.

Sent from my Moto G Play using Tapatalk

 

[Awesomeness]

I called the Cat dealership, and it's not an engine part. Does anyone know anything about it that might help me track one down (military or civilian part? part number? etc.)?

I'm trying to get this engine swap done to be in the parade on the 4th, so I need to move quickly.

 

[Suprman]

I have a used one. When installed too far in they end up like yours. Its one of the trans ecu input signals.

 

[DieselInfantry711]

My apologies I overlooked the same fact that I already stated that it was for the transmission. I was thinking of a 3126 this is used for the fuel injection. Got them crossed.

Sent from my Moto G Play using Tapatalk

 

[coachgeo]

What engine your swapping in?

 

[scottmandu]

My apologies I overlooked the same fact that I already stated that it was for the transmission. I was thinking of a 3126 this is used for the fuel injection. Got them crossed.
Sent from my Moto G Play using Tapatalk

3126 and C7 don't have that sensor.

 

[DieselInfantry711]

I'm just going to keep quiet as my brain must not be functioning correctly today. You are correct sir. Those are under the compressor on the back of the timing cover. Obviously I am malfunctioning.....

Sent from my Moto G Play using Tapatalk

 

[Awesomeness]

What engine your swapping in?

Just another 3116. It happens to be a 290HP out of an MTV, but that wasn't really intentional.

 

[samsneed]

Did anyone ever identify the part number for the 3116 engine speed sensor? My transmission was throwing codes 22-15 and 54-33...I believe both of these are related to my engine speed sensor. It has copper coming out of it as well....

 

[Suprman]

If it has the copper coil coming out of it then its bad. Got too close to the flywheel. I might have a good used one.

 

[samsneed]

It does have copper coming out of it. Definitely bad, hoping this is the root of my problems

 

[samsneed]

I'd definitely be interested if you have a used one. My lmtv is 1998 1078 A0 version I believe with the cat 3116

 

[Suprman]

Will look for one tommorrow. The trans uses that for input when shifting so you could get odd shifts if it was bad.

 

[samsneed]

my transmission is throwing codes, 22-15 is the speed sensor i think......

Researching this issue, i discovered that this is not an Allison part. Apparently it's not a Caterpillar part either. both dealers told me it is installed by whoever manufactures the chassis. That being the case, i'm wondering if this Freightliner magnetic pick up i found at napa would do the trick. for $22, i figured it's worth a try. I will need to splice my plug onto this sensor. Anyone know if the 24v vs 12v will be an issue? Also, will this fry something if i hook it up backwards?
keeping my fingers crossed!

 

[Guyfang]

Most of these Transducer, Motional, are about the same. About the only difference is the diameter of the shaft, and the plug. Normally you screw them in, bottom it out, and back it out 1/3 turn, ( at least) Lock it in place. Turn the engine over, ( without starting!!!!!!!) and measure at the plug, AC volts. Between 2.5 and 3 volts AC is good. The closer to 3 the better. If the volts are low, turn in the transducer. If it is higher then 3, turn it out. High volts is bad. That means you are about ready to see all those tiny wires hanging out. Always better to see low voltage. The general rule for the thing is, if it works, don't fool with it. 99% of the non-op parts, is due to someone " checking it" or fooling with it.

Do not worry about 12-24 volts. No voltage is sent TO the device. The device produces its own voltage. Like I said before, AC voltage.

 

[Suprman]

If it fits it should work. Screw in till it just touches the flywheel and then back off one turn and tighten down.

 

[samsneed]

Napa part number NHD 6569002 works, you just have to cut the plug and wire it to match it to the lmtv... Got my tachometer working. Now it's throwing code 56-22..... frustrating, thought I had it beat.

 

[Awesomeness]

Normally you screw them in, bottom it out, and back it out 1/3 turn, ( at least) Lock it in place. Turn the engine over, ( without starting!!!!!!!) and measure at the plug, AC volts. Between 2.5 and 3 volts AC is good. The closer to 3 the better. If the volts are low, turn in the transducer. If it is higher then 3, turn it out. High volts is bad. That means you are about ready to see all those tiny wires hanging out. Always better to see low voltage. The general rule for the thing is, if it works, don't fool with it. 99% of the non-op parts, is due to someone " checking it" or fooling with it.

I was doing this by myself, so I had to start the engine to measure. I had installed it to 2 turns back from bottomed out in contact, as the TM said. I was reading 0.025VAC, with the engine running. I turned it in to about 5/8 turn backed out, and am now reading 0.260VAC with the engine running. This was a used RPM sensor I bought from Suprman. Any idea if those readings are ok?