Summer and the towing season are in full swing. With the temps getting ready to go even higher across the nation, we figured it’s a perfect time to talk about some cooling system components: water pumps, hoses and fan clutches. Lets start with the pumps, but first lets discuss one thing.

We're going to use the phrase "mass-produced aftermarket." By this, we mean the high-volume, often overseas-made parts found at big chain auto stores and Amazon. Smaller, specialized shops (like Riffraff) commonly offer superior quality parts. Our discussion here will focus mainly on these mass-produced parts versus OEM.

Water pumps for the 7.3L Powerstroke have an odd reputation. The debate over which is better (mass-produced aftermarket, International/Navistar, or Motorcraft) has been ongoing for decades and is often marred by misinformation. Let's clear that up.

The Aftermarket: This will not apply to all, but this does apply to a good majority of mass-produced aftermarket pumps. Unlike OEM (Motorcraft or International), most mass-produced aftermarket 7.3L water pumps suffer from inferior bearings, seals, and casting quality, often leading to premature failure. Improper impeller sizing or even loose impellers are also common. Can you get a mass-produced aftermarket pump that will last a decade or more? Of course you can. But by the numbers, it’s less likely to happen than with the next two we’ll discuss.

Motorcraft or International? Believe it or not, the pumps offered by these two companies are the exact same pump. And they’re the highest quality pumps on the market today. Long story short, these pumps have: higher-level, more consistent machining; better, more consistent castings; better bearings; and better seals; with amazing reputations for quality, fitment, and reliability. As for the battle between which is better, Motorcraft or International, they both win, because they're the same part.

Hoses, to go with the Aftermarket hose, or the Motorcraft version? The difference between the two is pretty much the same as we discussed with the pumps. With Motorcraft, you’re guaranteed a certain level of quality. With mass-produced aftermarket parts, it’s a gamble. So with the same conclusion as with the pumps, lets discuss the different routing options (around the belt or through it) and what the performance aftermarket (not the mass-produced aftermarket) has done to improve upon OEM.

OEM radiator hose routing was chosen, of course, due to manufacturing costs and ease of installation (on their end, not ours), but also for variations in parts used between models (like intercoolers). The performance aftermarket stepped in when an upgrade was needed for quality and for ease of use. Some hoses, like ours, reroute the radiator hose around the accessory drive belt as opposed to through it. This means that when you’re removing a belt for any reason, you won’t have to drain the coolant or remove the hose. Significantly simplifies the belt removal chore.

If you have an OBS Powerstroke truck, another option is upgrading to the more robust thermostat housing found on the Super Duty trucks. This style has a larger performance aftermarket backing, for things like billet aluminum thermostat housings or upgraded thermostats, so changing to it allows for more upgrade options, better sealing ability, as well as a cleaner engine bay.  

The introduction of silicone hose construction used by the performance aftermarket allowed for a few things to happen. The silicone is much stronger than OEM materials, they look eons better and because of how they’re made it allowed companies like us to manufacturer smaller batches with much higher quality than if we went the OEM style route. At a much cheaper cost too.

Fan Clutches. The 7.3L's factory thermal-viscous fan clutch uses silicone fluid and a bimetallic spring to engage with heat. The hotter it is, the more the clutch engages. Like the other parts, OEM offers guaranteed quality, while mass-produced aftermarket is a gamble. So as with the hoses, let's discuss something more valuable: Failure symptoms. They’re not all as obvious as you’d think.

Fan Clutch Failure Symptoms.

Permanent engagement. When the 7.3L Powerstroke's fan clutch gets stuck in the "ON" position (often due to a failed bimetallic spring), your truck will develop a loud, constant roar – it's not a quiet fan, and you'll hear it all the time, even on cold starts when the clutch should be cold, or at highway speeds when airflow is high. This constant engagement creates significant parasitic drag, directly leading to a noticeable drop in your fuel economy, a frustrating decrease in horsepower and acceleration, and a much slower engine warm-up time, especially in colder weather.

Stuck Disengagement: This is the opposite of the previous. Not enough engagement. This commonly happens when the fluid inside the clutch has leaked out (which would be visible around the clutch and on the fan). Symptoms include the following: poor air conditioning (A/C) performance; visible fan freewheeling when hot; no noticeable fan noise when hot (or when the A/C is engaged); and engine overheating (or temperature spikes), especially when stopped or at low speeds.

Performance Aftermarket Upgrades: The OEM clutches from Motorcraft are the best options for daily drivers in our minds. And they have been upgraded to heavier-duty units since these trucks were first produced. Full electric fan upgrades are available and fine for many. They allow for less parasitic draw on the engine which means slightly better acceleration and increased horsepower. However, these fans do not cool as well as the factory fan does in stressful situations. So, if you tow frequently or live in a hot climate, these may not be the best option for you.

Related Parts:

Navistar Water Pump 1996-2003: https://www.riffraffdiesel.com/water-pump-oem-7-3l-96-03/

Motorcraft Water Pump 1996-2003: https://www.riffraffdiesel.com/water-pump-7-3l-96-03/

Coolant Silicone Radiator Hose (SD Thermostat) - Upper 1994-1995: https://www.riffraffdiesel.com/coolant-silicone-radiator-hose-sd-thermostat-cover-upper-94-95/

Coolant Silicone Radiator Hose (SD Thermostat) - Upper 1995-1997: https://www.riffraffdiesel.com/coolant-silicone-radiator-hose-sd-thermostat-cover-upper-95-97/

Coolant Silicone Radiator Hose (Around The Belt) - Upper 1999-2003: https://www.riffraffdiesel.com/coolant-silicone-radiator-hose-around-the-belt-upper-99-03/

Coolant Silicone Radiator Hose - Lower Straight Inlet 1999-2003: https://www.riffraffdiesel.com/coolant-silicone-radiator-hose-lower-straight-inlet-99-03/

Mechanical Fan Clutch 1994-1997: https://www.riffraffdiesel.com/mechanical-fan-clutch-94-97/

Fan Clutch 1999-2003: https://www.riffraffdiesel.com/fan-clutch-99-03/