What The Hose Does
The 56120251 upper hose carries hot coolant from the engine block outlet to the radiator core inlet. It sees the highest coolant temperature in the loop and the most pressure spikes, which is why it usually fails before the lower hose does. On a loaded truck pulling grades, that hose is working every minute the engine is running.
Molded silicone is used here instead of straight rubber because it holds its shape through repeated heat cycles. It resists oil mist off the engine, resists vibration chafe where it passes near chassis and bracket points, and does not go soft and spongy the way an aged rubber hose does after a few hundred thousand miles.
Rated service range is -40F to +500F. That covers cold starts in winter and heat soak sitting in traffic with the fan cycling. The hose is molded to the factory bend pattern, so it follows the original routing without kinking at the elbow or rubbing a hard point once the clamps are torqued.
Why These Numbers Cross
Two numbers show up for this hose: 56120251 and Automann 29-070200030. They cross because they describe the same molded part geometry — same overall length, same bend angles, same inside diameters at both cuff ends, same wall construction. A radiator hose is defined almost entirely by its shape and its cuff sizes, so when those match, the numbers are interchangeable.
The Automann number 29-070200030 is an aftermarket catalog number. It is listed here for identification only. PartStop is not affiliated with, endorsed by, or authorised by Automann or Kenworth, and their numbers appear so you can match what is printed on the box or stamped on the hose you pulled off.
Cross-reference is a starting point, not a fitment promise. Kenworth built several cooling package variants across 2014 to 2024, and the upper hose changes with radiator position and engine outlet location. Confirm by VIN, or measure the old hose — cuff ID at each end and overall run — before you order.
Before You Order
Pull the old hose and read it. Molded numbers are often on the cuff or along the outer wall, sometimes under road grime. Wire brush it and check. If the number matches 56120251 or 29-070200030, you are on the right part. If it does not, measure both cuff IDs and the leg lengths and compare before committing.
Check the clamps and the fittings while you are in there. This hose uses the stock clamp diameter and installs with the T-bolt clamps already on the truck, so no special tools. Inspect the radiator inlet neck and the engine outlet flange for scoring or corrosion — a pitted sealing surface will leak on a new hose too.
56120251 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 56120251. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| Automann | 29-070200030 |
Frequently asked questions
Does 29-070200030 replace 56120251?
They cross to the same molded silicone upper radiator hose. Automann lists 29-070200030 as their number for this application. Numbers are shown for identification only. Verify against the number on your old hose or by VIN before ordering, since Kenworth used more than one cooling package across these model years.
How do I know my upper hose is bad and not the water pump?
Squeeze the hose cold. A good silicone hose is firm and springs back. If it feels spongy, or you see swelling near the cuffs, weeping at the clamp, or oily softening on the outer wall, replace it. If the hose is sound and you still lose coolant, look at the pump weep hole, the radiator seams, and the head gasket.
Do I need new clamps with this hose?
The hose matches the stock clamp diameter, so the existing T-bolt clamps will work if they are in good shape. Check the band for corrosion pitting and the bolt threads for galling. A clamp that will not pull to spec torque will leak no matter how good the hose is, so replace anything questionable while the system is drained.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
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Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.