Cummins air compressor


For you lovers of the Class 8's and bigger.

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Mon Dec 31, 2012 9:23 pm

Cummins air compressor

Had a broken bolt in in the mount for the air compressor on my '83 9670. The P/O had tried to drill it out and broke a drill off in the stub. I went to Cummins to get a new front case for the compressor, Cummins said they don't sell compressor parts, only complete compressors.
I found the part nmber for the piece I needed in an old Interstate Mc Bee cat. Fast forward 6 months and look what I found:
http://www.ebay.com/itm/160835538844?ss ... 1439.l2649
Got one in the mail today. Still had over 30 of them. I would bet from a gov auction somewhere.
All's well that ends well.
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Golden Jubilee
Golden Jubilee

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Location: Wichita, Kansas

Post Tue Jan 01, 2013 10:06 pm

Re: Cummins air compressor

CB89,
Congratulations on your find! Often, patience pays off.

Dean
Lifelong Kansan
Grew up with red paint
Moved off the farm 26 years ago.

Golden Jubilee
Golden Jubilee

Posts: 3493

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Thu Jun 13, 2013 6:51 pm

Re: Cummins air compressor

I know it has been awhile. I got the piece on, re-rung the engine, replaced the liners added a jake brake an a different turbo. Rebiult the clutch linkage, and am in the process of installing an Eagle overhead console in it. Put new radius rods on the rear suspension and have moved back to driveing it. As much as I enjoy the space in my '92 Marmon conventional, there will always be a soft spot in me for a 9670. It was the 1st truck I owned, and I put over 1M miles in one before I moved to the Marmon. The Marmon is show some age and needs some work. So I'm back in one of my 9670's.

Golden Jubilee
Golden Jubilee

Posts: 3493

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Wed Jun 04, 2014 11:01 am

Re: Cummins air compressor

I figuar it is time for an update. I ran the 9670 for a while, even pulled some oversize loads with it. Last winter right around the 1st of the year, I was on my way to load when the rear end started howling. It lasted for 5 miles then quieted down again. I am a firm believer that things don't fix themselves. I turned around and came home. Pulled the powerdivider section off the front diff, and found a missing thrustwasher. Looked a little further and found 3/4 of a tooth missing off the pinion. Rebiult diffs are going for $2100 around here, $100 more then I paid for the truck.
I kept my eye out for some way to fix this truck. A "core" diff showed up on the website of my local yard. It had a blown powerdivider section and case but was only $321 out the door. I went and looked at the ring and Pinion and it look ok. I took a chance and bought it. When I got it home and apart I got a suprize. The powerdivider "nest" had not blown but the unit was a fresh rebiuld failure due to being assembled wrong. The preload on the carrier was non-existant and the ring gear had been forced against the rubbng block. Something had caused the imput shaft to snap and break the PD case. All of the non-damaged parts look practically new. I was going to swap my used parts into this diff, but have since decided to swing for a new input shaft and go back with the undamaged and amost new parts. I set the carrier bearings and rolled the tooth pattern, and installed the chunk in the houseing. I should come away with a practially new diff for $450!
Although I will not be driveing it regularly, It will be nice to have it ready to go as a back-up again. Cheap "insuarnce"
Part of my problem was the ratio, the orignal rear was a 3.70 or ten tooth pinion on a 37 tooth ring gear. Soon after they went to an 11 tooth pinion on a 41 tooth ring gear for a ratio of 3.73 I needed to find and exact replacement and had to wait until one showed up.

Golden Jubilee
Golden Jubilee

Posts: 3493

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Mon Sep 21, 2015 5:38 pm

Re: Cummins air compressor

Well its been another year and half. I am trying to get to some "quality of life" improvements in the old 9670. On my other trucks I have air start and deep cycle batterys. With these I can run an Espar all night and fire it up in the morning. There just isn't room on the short cabover frame for an air start tank. Unless I get real lucky and find an old "CF" Freightliner from the '60's with the vertical "hot dog" air start tank, I'm SOL for air start. I think I am going to go with a Maxwell Super Capacitor for starting, leaving enough room in the battery box for 3 deep cycles.
http://www.maxwell.com/products/esm/esm-ultra-31-1800
Next I ordered new window weather strip, both belt line "wiskers" and full weather strip. I replaced the door lock mechanism (a real problem area on IHC's big trucks) and modified the latch so it will open more reliably.
Last I dug out the original trans that came on my 89 9600. It started out as a RTF11609A but I put a "kit" in it to make it a RTOF 11613A years ago, but swapped in a RTOF14613A that came in a truck I broke up for parts. The lighter 13 never gave a bit of trouble even though I was doing "heavy haul" at the time. When I get done with all the changes/upgrades, I hope to move back to driving it over the winter.
I had a slight dilemma, the period correct shift knob would have been the old chrome knob with a two position (direct/overdrive), with the range being a button lower down on the stick. These are plentiful on E bay but are most are imports that have a bad rep for leaking. There was one guy sell NOS Eaton units but the price with shipping was over $100. I don't need it that bad. There are many selling the newest Eaton style, but that wouldn't look right on this truck, so I settled on the older "squared off" style aftermarket.
For me, the advantage of the original style is I could leave my range control alone, as the truck has a nine speed now. I just couldn't part with $100 to do so. My '89 had the "squared" knob, so these two will "match".
One good thing about cabovers, changing the transmission (or doing a clutch) is an easy day job.
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Golden Jubilee
Golden Jubilee

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Location: SW Washington

Post Tue Sep 22, 2015 10:16 pm

Re: Cummins air compressor

Your mentioning a CF truck made me think of this. Been on craigslist for maybe a year now. Can't understand why no one wants a V-8 Cummins ;)

http://seattle.craigslist.org/skc/hvo/5236406002.html
Last edited by Jared on Thu Sep 24, 2015 10:12 pm, edited 1 time in total.
'52 L-160 dump truck
'57 RD-405
'58 Allis Chalmers D grader

Golden Jubilee
Golden Jubilee

Posts: 3493

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Wed Sep 23, 2015 4:51 pm

Re: Cummins air compressor

If it weren't 1/2 way across the country, and him mentioning a problem with the air start, I jump on it for the air starter, tank and parts, then break the rest up, sell what I could and scrap the rest. No one likes the V-8 but down under they have a better rep. Also a day cab cabover is kind of pointless, as the trailer can only be so close as the engine sticks out behind the cab.
My air start can sit for weeks at a time and still have enough air to start. Chasing air leaks is a lot easier then chasing bad connections! The whole system is simple too. If the relay valve (on the tank) doesn't leak (easy to check) there is only one line that has system air to it at all times, Make sure this line is one piece (don't use a bunch of small sections of line spliced together) and your good to go.
If he is having problems, he might have a rusted out tank, which is what I'd be buying it for. Wouldn't surprise me as the tank is almost 40 years old, and likely wasn't drained every day when in use. It was built in a time before air driers were common, so draining was a must.
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Golden Jubilee
Golden Jubilee

Posts: 515

Joined: Sat Oct 26, 2013 10:11 am

Location: SW Washington

Post Wed Sep 23, 2015 11:03 pm

Re: Cummins air compressor

My dad who ran a service truck with a big air compressor on the back always says he'd rather hook up an air hose than jumper cables. He just did some work on a big Massey Ferguson articulated tractor with eight good tires for a farmer who bought it for 4 grand. It has a 903 in it and he figures that's why it was so cheap. I heard it out in the field the other day and I'd rather listen to an inline 6 all day.
'52 L-160 dump truck
'57 RD-405
'58 Allis Chalmers D grader

Golden Jubilee
Golden Jubilee

Posts: 3493

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Thu Sep 24, 2015 8:31 am

Re: Cummins air compressor

I guess the 9-0 nothing's had a better rep in ag and marine then they did in trucks. Down in OZ they pulled road trains with them, and were much better received there than here in trucks. One of the big problems in trucks was they operated at a higher rpm then the 6's. If you wanted to replace one with an NTC six, you had to change the rears as well.
Add to that the crowded engine bay, and they really would be a pain in a truck. I've never owned one, but that's what I hear about them. I guess they were also a bigger "hit" down in Mexico where they were put in DINA trucks. I know of one guy down there that had one.

Golden Jubilee
Golden Jubilee

Posts: 3493

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sat Oct 10, 2015 9:44 pm

Re: Cummins air compressor

Well I finished the install (little stuff like running air lines and putting in a shunt for the ammeter) and took it for its 1st test drive. Shifts great and I like the ratios. Should top out about where My Marmon does, but with a little less HP to get it there. I never drive much faster the 65 anyway so that will keep it right at the powerband.
The next question is which Maxwell Super capacitor to use. The make a 12 and also a 24 volt unit. Both will fully charge off a 12 volt system, but the 24 volt unit stores more total power (50Kw vs. 38 Kw for the 12 volt model). I would need to change the starter but considering the age of the one in there now, it might not be a bad idea anyway. So far the best price I've got is still $350 more for the 24 volt unit. When you factor in another $250-$300 for starter, that a lot of money for 12 KW. I'm going to call a few more dealers and see if anybody can beat Bosselmans's price. The 1st hurdle is finding a dealer who will admit they even make a 24 volt unit. I had to educate a few before I could get a price quote.
Like 12 vs. 6 volt, the advantage of a 24 volt cranking circuit is the amp draw is 1/2 of 12 volt and anything you can do to reduce high amp cables and connections will increase reliability. I know I preach 6 volt is fine, but unlike a 6 to 12 volt change, where the whole truck electrical system is being changed, I am only changing the cranking circuit, the truck will remain a 12 volt system. I wouldn't consider it otherwise. Now if they only made a 12 volt unit that could charge off a 6 volt system....
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