Finding a 6.7 Cummins serpentine belt diagram no AC can be a real headache when your compressor locks up on the side of the road and you just need to get the truck moving again. It's one of those situations where the factory sticker under the hood is suddenly useless because it only shows the standard configuration. Whether you're dealing with a seized bearing in the middle of nowhere or you're intentionally deleting the AC for a dedicated track build, knowing how to route that belt without the compressor is a lifesaver.
The 6.7-liter Cummins is a workhorse, but like any engine, it has its weak points. One of the most common "get stranded" scenarios is when the AC compressor clutch or bearing decides to quit. Since the AC pulley is part of the main accessory drive, a seized compressor usually means a snapped belt, which means no water pump, no alternator, and no power steering. You aren't going anywhere until you bypass that pulley.
Why you might need to bypass the AC
Most of the time, people are looking for this specific routing because of a mechanical failure. AC compressors on the Ram 2500 and 3500 trucks take a lot of abuse. If the internal bearings go, they can create enough friction to literally melt the belt off. If you don't have the cash for a new compressor right away, or if you're waiting on parts, bypassing it is the only way to keep the truck on the road.
Some guys also do this for weight savings or to "clean up" the engine bay, especially on dedicated pull trucks or drag setups. Whatever your reason, the main hurdle is that the belt path changes significantly. You can't just use the stock belt and leave the AC out; it'll be way too long. You need a shorter belt and a clear understanding of where it needs to wrap to keep everything spinning in the right direction.
The routing logic for a bypass
When you look at a 6.7 Cummins serpentine belt diagram no AC setup, the biggest thing to watch out for is the water pump. On these engines, the water pump is driven by the back side (the flat side) of the belt. If you route the belt incorrectly, you might end up spinning the pump backward or, worse, not spinning it at all.
In a standard setup, the belt comes off the top of the alternator, goes down to the AC compressor, then over to the water pump. When you remove the AC from the equation, you're basically taking a shortcut. You'll go straight from the alternator pulley down toward the water pump or the idler, depending on your specific year and whether you have a dual alternator setup (though most people looking for this have the single alternator).
The belt should still go around the crankshaft pulley at the bottom, up over the fan hub, across the top to the alternator, and then you have to bridge the gap. Usually, you'll drop the belt down from the alternator and wrap it under the water pump pulley before heading back toward the tensioner.
Getting the right belt length
This is where most people get stuck. You can't just guess at the belt length, or you'll be making five trips to the parts store. For a standard 6.7 Cummins (non-chassis cab) where you are bypassing the AC, you're generally looking for a belt that is about 10 to 12 inches shorter than the stock one.
A common part number that guys use for this bypass is the Gates K081021 or something very similar in length. The "08" in that part number refers to the number of ribs (8 ribs), and the "1021" refers to the length (102.1 inches). Stock belts are usually around 126 inches, so you're cutting out quite a bit of material. Always double-check your specific year, as tensioner designs changed slightly over the years, which can affect the exact length you need by a fraction of an inch.
Tools you'll need for the job
Working on a Cummins engine bay is relatively straightforward because there's actually some room to move, but it's still a tight squeeze near the radiator. You won't need a massive toolbox for this. * 1/2-inch drive breaker bar: This is for the tensioner. Don't try to use a short ratchet; that spring is incredibly stiff, and you'll want the leverage. * A long screwdriver or pry bar: This helps "guide" the belt onto the lower pulleys where your hands won't reach. * The new (shorter) belt: Make sure it's an 8-rib belt. Using a 6-rib in a pinch might work to get you home, but it won't last under the torque of the 6.7.
Step-by-step installation without the AC
Before you start, make sure the engine is cool. You're going to be reaching deep into the bay, and those coolant lines stay hot for a long time.
- Clear the old debris: if your previous belt snapped, make sure you pull all the "spaghetti" out from behind the crank pulley. Leftover belt ribs can ruin your front crank seal, which is a much bigger job to fix.
- Locate the tensioner: It's on the passenger side of the engine. Insert your 1/2-inch breaker bar into the square hole and rotate it to release the pressure.
- Start at the bottom: It's usually easiest to loop the belt around the crankshaft pulley first. Since it's the largest and lowest, getting it seated there early prevents it from slipping off later.
- Route the fan and water pump: Bring the belt up over the fan hub. Then, loop the flat side of the belt against the water pump pulley.
- Hit the alternator: Pull the belt up and over the alternator pulley. This should be the highest point of your routing.
- The final stretch: Pull the tensioner again and slide the belt under the idler pulley or onto the tensioner pulley itself. This is usually the hardest part because you're fighting the spring tension while trying to align the ribs.
Common mistakes to avoid
One thing I see a lot is people forgetting to check the alignment on every single pulley before starting the truck. It's very easy for the belt to be one "rib" off on the crank or the fan hub. If you fire up the engine like that, the belt will either shred instantly or jump off and take out a sensor wire.
Another thing: check your tensioner. If your AC compressor seized, it might have put a lot of sudden stress on the tensioner arm. Give it a wiggle. If it feels loose or if the pulley on the tensioner feels "gritty" when you spin it by hand, you should probably replace that too while you're in there.
Is this a permanent fix?
Honestly, you can run a 6.7 Cummins serpentine belt diagram no AC setup indefinitely if you don't mind the heat. The engine doesn't "need" the AC compressor to function properly. The ECM (engine control module) might throw a soft code because it can't find the AC clutch, but it won't put the truck into limp mode or cause any performance issues.
That said, remember that the AC compressor also acts as a dehumidifier for your defroster in the winter. If you live in a rainy or cold climate, your windshield might fog up more than usual without the compressor cycling. But for a quick fix or a budget-friendly way to keep the truck running, bypassing it is a totally valid move.
Just keep that shorter belt part number written down in your glove box. If that belt ever fails, a parts store counter person is going to look at you like you have three heads when you ask for a belt for a 6.7 Cummins but tell them "it's the short one without the AC." Having the exact length or part number on hand will save you a ton of frustration later on.