Big Cam Cummins reliability

I'm also unsure of the cam on the N14 vs the big cam, but just to look at one inside and out, the only visual difference is the IP and the injectors have wires going to them. We have both a big cam 400 and a N14 Celect+. As far as performance, the N14 wins. The N14 does have some electronic issues from time to time, but most issues are pretty easy to self-diagnose, and they are nothing complicated compared to the newer electronic stuff. Lots of people complain of N14 wiring harness pin connections, and I could understand where that would be hard to diagnose and repair, but we haven't experienced and pin connection problems.

We did have a Cummins C-brake issue with the N14. Apparently Cummins had some faulty adjustment screws that they issued a service bulletin about. We didn't figure this out until we broke 2 adjustment screws. Luckily, on both of the adjustment screw breaks, the broken piece stayed in the rocker box out of harms way. If those broken screws had fallen into the engine, they could cause all kinds of problems if they got it the wrong spot. In other words, if you are running a N14 with C-brake, you need to make sure you have the updated adjustment screws.

 

I guess I could look on quickserve to see if the bulletin matches our eng serial # or cpl. I’m wondering if ours has C-brakes, I know it has engine brakes on top of the heads, with Jacobs casted into it. Idk if there’s a difference between jakes and compression brakes. I know they are both considered compression brakes, but don’t know if they are termed different.

I think they call it the slave piston with the locking nut or jam nut around it. If it is the Jacobs brake you spoke on, is the slave piston also the adjusting screws spoke on in your post?

Edit: just looked on quickserve, the adjustment screw wasn’t included on our list.

 

It's been awhile since I've been into it, but it's the adjusting screw that adjust the lash clearance for the C-Brake. Of course, the C-brake is the Cummins compression brake, but I think it is of the same design as the Jacobs. For whatever reason, it is a hollow screw, they break right where the jam nut meets the top of the piston. Even with the updated screws, you need to adhere to the proper torque spec as to not stress the screw too much.

When I went to the Cummins dealer after the second one broke, he said "I think there is a service bulletin on that", and then told me about the updated screws. When the first one broke, I thought it was just a fluke, but when the second one let go, I knew something was going on. I replaced all the screws and torqued to the proper spec, and haven't had any future problems.

 

Ten four, even though I didn’t see the bulletin on ours, I just ran the overhead about 2 months ago, and need to pull the covers off to take a look, to make sure I didn’t tighten the jam nut too tight . Can you tell with the covers off if a screw has broken? Thanks for this info, very good to know

 

Yes you can tell with the covers off, the adjuster is right on top of the brake. It requires a special tool to properly torque the jam nut, because you need to keep the screw from turning while you tighten the jam. I used a crows foot socket and some math to use our standard torque wrench.

 

I'm look at old trucks right now and found a
1989 International 9300 steel single frame with a 855NT 400HP
379 rears
9 speed
I would like some of your opinion on this truck and how you think it would do pulling 80000+ in the Midwest and how reliable it is while doing 3500 mile+ a week mpg doest really matter to me right now I'm in a 2016 truck and only geting about 5.5 on good weeks.
But the most important thing is how reliable it is would it have problem going 1000+ mile at one time with minimum stops

 

They did it every week in the 80’s and 90’s. No reason they can’t do it now. Remember the speed limits were only 55mph back then though. Guessing it’s not going to like doing 70mph all day though?

beret find someone that can still wrench on them though. Petro or TA won’t be much help in the engine department.

 

An 89 is probably a big cam 4, which has low flow Cooling. A lot of people had problems with the low flow.

It can be changed over but I don't think it's cheap to do that.

As far as reliability, that just really depends on the condition of the engine. If the engine is in good shape, the big cam is 100% reliable.

 

The 4s were fine as long as you didn't try turning them up any.

 

A big cam is just as reliable as a newer motor as long as you know how to drive it. My dad has been running an 84 Pete with one and he says it has about the same power as his fleet garbage N14 does, doesn't get the quite as good of fuel mileage.