Two Water Pumps — Check Before You Order

This is the one thing to get right on this page. There are two 5VZ water pumps and they are distinguished by a cooler tube, not by a year:

Look at the pump that is on the engine before ordering. It takes a moment and there is no way to make the wrong one fit.

Do it with the timing belt

The 5VZ water pump is driven by the timing belt, which means the labour to reach it is the labour you are already paying for during a belt service. Replacing a belt and leaving an original pump behind it is how a truck ends up back on the ramp a year later with the same job to pay for twice. See Timing Belt Components.

Radiators

Two core sizes, shared with the 3RZ: 21" x 25" x 1" and 23" x 25" x 1".

Measure the core in the truck. Model year is not a reliable guide across Tacoma, 4Runner and T100, and the two sizes are close enough that guessing is a real risk.

All-aluminium options

Four aftermarket radiators are also listed, split by vehicle. These are heavier-built units aimed at trucks working hard — larger tyres, heavy overland loads, towing, sustained low-range crawling, desert heat:

  • CSF Heavy-Duty All-Aluminum — 1995-2004 Tacoma and 1996-2002 4Runner. Tig-welded aluminium end tanks in place of the factory plastic ones, B-shaped tubes that CSF states increase heat transfer by around 15%, and a built-in transmission cooler.
  • Koyorad All-Aluminum Racing — 1995-2004 Tacoma and 1996-2002 4Runner. A 36mm HyperCore, which Koyorad states is 44% thicker than the factory core.

One difference matters more than any of the specifications, and it decides which of the two you can use. Koyorad deliberately leaves out the internal automatic transmission cooler. On a manual truck that is a non-issue, and it removes any chance of coolant and transmission fluid mixing. On an automatic it means the transmission needs its own cooling arranged separately — the Tacoma unit is listed for manual transmissions for that reason. If your truck is an automatic and you want a drop-in, the CSF is the one with the cooler built in.

The factory-style radiators above remain the straightforward like-for-like replacement, and on a standard truck that is all the cooling system needs.

Radiator caps — two sizes

The cap is worth replacing with the radiator; one that no longer holds its rated pressure drops the boiling point of the whole system. Measure the outer diameter rather than ordering on the year: small, 1 3/4" and large, 2 1/4" (57mm).

Hose Kits

Three silicone radiator hose kits are listed: our TG silicone kit, and HPS reinforced silicone kits for the 1996-2002 4Runner in standard and blue.

Prefer the factory rubber? Moulded OEM-pattern upper and lower radiator hoses are listed for the 1996-2002 4Runner, and they use your existing factory clamps.

Do both ends at once. The two hoses are the same age and sit in the same heat, and the access is the same whether you change one or both. A hose that has gone hard cracks at the ends first, where you cannot see it until it lets go.

Heater hose kits and the rest of the hose range are on Hoses. The OEM coolant bypass hose clamp is here because it is the fastener nobody has spare and everybody needs.

Fans

The 5VZ flex fan comes on its own at 18.25" or with the billet spacer kit, and the spacer kit is sold separately for anyone already running a fan.

The spacer is not optional in the way it looks. It sets the fan at the correct depth in the shroud, and a fan sitting in the wrong plane moves far less air than its diameter suggests.

The 5VZ fan pulley bracket and the electric fan replacement blade complete the range.

Thermostat

The 180 degree thermostat opens earlier than the factory unit, which suits an engine working hard, towing, or running in heat. Fit it with the round rubber housing gasket.

One caution worth stating. A cooler thermostat is a useful tool on a hot-running truck, but it is not a fix for a cooling system that is actually failing. If a truck overheats towing, look at the radiator, the fan and the water pump first — a 180 thermostat will mask an early symptom rather than solve it.

Not sure which pump or radiator your truck takes? Send us the year and model and tell us whether the pump has a cooler tube and we will confirm it.

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