Kenworth T660 / W900 Radiator Replacement: Overheating Symptoms and a Heavy Duty Aluminum Core in Stock

Kenworth started in Seattle in 1923, and in 1961 it launched a conventional-cab truck called the W900. It is still being built. More than sixty years in continuous production makes it one of the longest-running vehicles of any kind in North America — a truck whose basic silhouette has outlasted whole car companies. Drivers do not buy a W900 because it is the cheapest way to move a trailer. They buy it because a well-kept one runs for a million miles and looks right doing it.

The Kenworth W900 — in production since 1961 and still on the road (photo: Wikimedia Commons).

Which is precisely why cooling matters more on a truck like this than on almost anything else you own. A million-mile chassis is only worth keeping if the engine underneath it survives, and the fastest way to destroy a big-bore diesel is to run it hot.

What an overheating truck actually costs

Not the tow. The tow is the cheap part. A heavy diesel run hot warps heads, cooks head gaskets, glazes liners and can crack an EGR cooler — and every one of those repairs is measured in days out of service, not hours. For an owner-operator, a week off the road is usually a bigger number than the parts bill. That asymmetry is the whole argument for replacing a marginal radiator before it strands you, rather than after.

Symptoms of a radiator on the way out

• Coolant loss with no visible puddle — often a seam or tank-to-core crimp weeping only when hot and under pressure.
• Temperature climbing on grades and recovering on the flat. Early core blockage shows up under load first.
• White crust or dye trails down the core face, or wet fins behind the bug screen.
• Bent, flattened or corroded fins across the face. Airflow is half the job; a core can be leak-free and still be finished.
• Fan running constantly because the coolant never comes down to where the clutch releases.

The radiator we have

In stock right now: a SCITOO heavy-duty radiator for the 2008-2010 Kenworth T660 and W900, $649.99. It is an aluminum core with plastic tanks, built to the original mounting points and hose connections so it drops into the factory location without fabrication, and the inlet and outlet necks are capped for transit.

Condition, stated plainly: it is open box. The shipping carton was opened and shows transit wear with one end flap torn. The radiator is still sitting in its original foam and packing, and the aluminum core and tanks are visible in the photos — judge the fin condition from those photographs before you buy. It was not removed for individual inspection or pressure-tested by us. Against what a new heavy-truck radiator lists for, that is the trade.

Verify your application first. T660 and W900 both ran multiple engine and cooling-package combinations, so measure your core and check your hose positions against the photos rather than assuming that year and model alone settle it.

The rest of the class 8 shelf

We buy heavy-truck stock in the same lots as everything else, so the shelf runs deeper than one radiator. For the International side we have a pair of ProStar headlight assemblies, 2008-2014, black housing, LH and RH, at $189.99 and a FLTRUCKTOP AF26103 + AF27958 engine and cabin air filter set for the ProStar at $65.99 (that engine filter also crosses to TranStar, WorkStar, 4400 and select LoneStar with C10 through C15, ISM/ISX and N9/N13/A26 power).

For Freightliner: a genuine Spectra Premium 99426 HVAC heater core for the 2008-2010 Cascadia at $114.99 — it has slight cosmetic damage, which is exactly why it is priced where it is, and it crosses to Four Seasons 938065/96116 and Navistar VCCT1000899G. Also a 6-pack of KOFIL LF17800 lube oil filters at $62.99 for 2020-and-newer Detroit DD13, DD15 and DD16 engines, roughly a full year of 15,000-mile services in one box.

And for the heavy-duty pickups

Different class of truck, same customer more often than not. We have a Delphi HFP1000 fuel lift pump at $169.99 for the 2011-2016 Ford F-250 through F-550 with the 6.7L Power Stroke — Delphi is an OE fuel-system manufacturer, and this crosses to Ford BC3Z-9G282-A through -E and FC4Z-9G282-A. It is listed used because it arrived loose in Delphi-branded packaging rather than a sealed carton, and it has not been bench-tested. And for the Duramax crowd, a Mishimoto MMBK-DMAX-11HBK hot-side silicone boot kit at $139.99 for the 2011-2016 6.6L LML — five-layer silicone boots that hold where stock rubber splits under boost. Read that listing carefully: the T-bolt clamps are not included, which is the entire reason it is priced below a complete kit.