What This Hose Actually Is
This is the upper radiator hose on a Cascadia with a DD13. It carries hot coolant out of the engine to the top of the radiator. The Z-bend is not cosmetic — it routes around hard points in the engine compartment and holds the hose off the charge air piping and belt path. A straight length of bulk hose will not do the same job.
The two ends are different sizes. One is 2.50 in inside diameter, the other 2.37 in. Measure the necks on your truck before you order, not the old hose, because a hose that has been on for years swells and reads large. Put a caliper or a tape on the radiator inlet and the engine outlet.
PartStop sells this as an aftermarket direct replacement, premium quality, backed by our 6+ month warranty. It is not an OE product and we are not affiliated with or authorised by any original equipment manufacturer. The numbers here are for identification only.
Why These Numbers Cross
0521797001 and F02521S352 describe the same molded hose in different numbering systems. The first is the part number most shops have written on the old hose or pulled off a parts ticket. The second is a Freightliner-side reference that shows up in dealer lookups for the same Cascadia cooling circuit. Same bend, same end sizes, same routing.
Molded hoses cross cleanly when three things match: end IDs, overall developed length, and bend geometry. Change any one of those and the hose either will not seat on the neck or it kinks under vibration. That is why this cross holds — both numbers point to the same Z-shape tooling with a 2.50 in and a 2.37 in end.
Treat any cross-reference as a starting point, not a fitment guarantee. Confirm by VIN, or read the number stamped or printed on the hose you are pulling off. If your truck has had a radiator or engine swap, the routing may not match what the VIN says it should be.
How These Fail And What To Check
Upper hoses die from the inside. Heat cycling and coolant additives break down the tube, so the hose feels soft and squishy near the ends, or hard and glassy with cracks in the bend. Squeeze it cold. If it collapses easily or you feel grit moving inside the wall, it is done. A hose that has swelled over the neck and will not slide off is also finished.
Look for staining and white or green crust at the clamp lines — that is a slow seep that will become a blowout on a hot grade. Check the necks themselves while you are in there. A pitted or scored radiator inlet will keep leaking no matter how good the new hose is, and constant-tension clamps that have lost spring should be replaced with the hose.
0521797001 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 0521797001. 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 |
|---|---|
| Freightliner | F02521S352 |
Frequently asked questions
Will 0521797001 fit my Cascadia?
It is listed for Freightliner Cascadia with the DD13 engine. Cooling packages vary by build, so confirm with your VIN or by matching the number on the hose you are removing. Check that your radiator inlet is 2.50 in and the engine outlet is 2.37 in before ordering.
Can I use straight bulk hose instead of the molded Z-shape?
No. The Z-bend keeps the hose clear of surrounding components and prevents kinking as the engine rocks on its mounts. Bulk hose flexed into that shape will collapse under vacuum on cooldown or chafe through where it touches. The end sizes also differ, 2.50 in to 2.37 in, which bulk hose will not give you.
How does F02521S352 relate to 0521797001?
They are two references for the same molded upper radiator hose. F02521S352 is the Freightliner-side number, listed here for identification only. Either number should lead you to the same 2.50 in to 2.37 in Z-shape hose, but verify against the old part before you install.
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.