tach cable adapter

[Pappa-G]

My tach cable on my 250 Cummins M818 mounts verticaly on the injector pump, about 2" above and forward of that is the air compressor out put line. Well needless to say the tach cable is "geeked" and wont turn because of the interferance with the air line. I got a replacement cable from "M.E" and it has a taller sholder on the attach line than the original. I have heard of a 90 degree adapter that allows you to clear this. Has any one heard of this or know a source where i could get one?
Thanks

 

[Hammer]

What did you end up doing about this one?
My tach worked for about 600 or so miles, then slowed down, then stopped.
The cable is ok, and has the same issue you are describing.

 

[Hammer]

Here is a picture of how mine looks.

 

[grounded]

Hammer mine did the same thing. On the way to KY the other day it just flat stopped working. Otherwise my tach has always worked.

 

[319]

Would a brass 90 or 45 degree fitting installed on the compressor, instead of coming straight out, solve the problem?

 

[Hammer]

Not really, it doesn't look like you could get the fitting flush enough to make enough of a difference. It would just push the cable off to the front of the fitting.

 

[Hammer]

Hammer mine did the same thing. On the way to KY the other day it just flat stopped working. Otherwise my tach has always worked.

Does it look like it has the same interference like mine?

 

[Pappa-G]

Yep same as mine I haven't gotten around to repairing yet. I saw a 90 deg adapter for the tach cable in a PM magazine or a TM but I haven't been able to locate it.

 

[Hammer]

I think it is a universal speedometer cable.
One of these days I will buy a REAL tach cable.

 

[Pappa-G]

I bought a NOS cable from M.E. and it had the same interference issues. Big wrenching weekend coming up maybe Ill devise a solution.

 

[Hammer]

Not good news with the stock cable not working.
But if you figure it out, PLEASE post up!
Right now my tach AND speedo don't work on my 818.

 

[WillWagner]

The pump can move a 1/4 inch or so. Maybe try loosening the mount bolts and turn it CCW and see if it will give you enough room. If that doesn't do it, speedo shops can get 1:1 offset drives.

 

[Hammer]

Hmm, rotating the pump sounds like a worth while effort.
The deuce uses a 1:1 angle drive, but the drive that goes into the front of the motor is too large for the 5 ton setup.
Almost looks like that part is a somewhat simple part to replace, so maybe a speedo shop could replace just that part as well.

 

[Hammer]

Fixed mine!
Updates coming soon, no pictures yet.

 

[Pappa-G]

I'm telling ya that WillWagner is a Rocket Surgeon wheen it comes to those 5 ton Cummins trucks!

 

[Hammer]

Ok, I rotated my pump, but that wasn't enough to fix it. It might have fixed it if the cable of mine was brand new, but I cannot be sure.
I replaced the rubber washer in the end of the tach cable with a washer from a rubber hose.
Yup, a regular old washer from a garden hose. You have to MAKE it go into the setup, but it works good. And their CHEAP!
STILL didn't work.
So I started looking very close, and it would seem that the tach cable drive, which is a round piece of metal that was clamped on one side to create the flat 'drive' area, was worn down.
The flat part wasn't the part that was worn down though, it was the backside of it. And because it is round, it was harder to notice that it was worn down.

My quick answer?
I took a pair of vice grips and started squashing the main shank of the drive. It was worn on the back, but the sides were relatively ok. So squashing them moved enough material to the back side to force the flat area to engage the slot from the IP.
I also smashed out the flat drive area a little more, but not too much.
The tach WORKS!
I let it idle, I drove it around, and I put over an hour on the meter, and it's still working perfectly!

So, if your tach stops working, but the cable still feels good, this might be a way to help gain a few thousand more miles.
If your NEW tach cable doesn't work, this still might be the answer. But I think that clocking the IP is all that would be needed.
And the cheap washer idea is a nice bonus.

 

[Pappa-G]

Hey, I found the adapter in the TM library about 7 rows back. Look in TM 9-2320-260-20P fig. 534
http://old.steelsoldiers.com/index.php?module=pagesetter&type=file&func=get&tid=1&fid=file&pid=20
Called M.E. but they didn't show the NSN. Thier Cummins guy will be out till next week. I'll try back then.

 

[cessnatwin]

Ask memphis equipment if the 90 angle from a deuce would fit, try Ed at extension 113, or maybe a service guy. I swear ford uses the same angle adapter that is on an m 35a2, worth a try.

 

[Hammer]

The 90 degree from a deuce does NOT fit.
I already tried that

Btw, clocking the IP gained enough clearance that a new tach cable should work fine. Mine was worn down, so I had to work it over to make it work. But a new cable should work ok.
Seems that the amount of flex the cable is under if it is hitting the air line fitting, causes the cable end to wear down over time/rpm. And the smaller outside diameter allows it to disengage from the IP drive.
I think that clocking the IP would be the ticket. If it still hits the air line, I think you can gain a little bit of clearance there with a more appropriate fitting coming out of the compressor.