“THIS RESTRICTOR FITS THE FOLLOWING UZ ENGINES WITH THE WATER INLET HOUSING SHOWN IN THE PHOTOS ABOVE. THIS SHOULD CONSIST OF 1UZ NON VVTI, 2UZ VVTI, 3UZ VVTI.”
The Coolant Bypass Restrictor for the UZ family of engines was created to help push the performance capabilities of the engine. It is not solely about lowering temperatures but controlling the engine temperatures. The coolant range is still at OEM operating temperatures but never getting to a point that could damage the engine. It is a solution to many while being simple and effective. What is included is a Billet Aluminum restrictor that is designed to be tolerance fit into the thermostat housing.
The 1UZ while being a great engine, was never designed for prolonged periods of performance-based driving. The original cooling components are adequate for its intended use from factory but under severe stress coolant temperatures tend to climb up to or surpassing 220 degrees Fahrenheit (104C +) which can put the engine in dangerous territory leading to damage due to overheating. The coolant bypass restrictor is used to alleviate this problem.
The modern cooling system utilizes a bypass port. This bypass port is intended to allow coolant to flow straight from the exit of the block back into the rear section of the thermostat housing to be cycled through the engine again bypassing the radiator. This bypass port allows coolant to cycle through the engine during the warmup period because the thermostat is closed not allowing coolant to cycle through the radiator.
When the engine warms up to operating temperatures the thermostat finally allows coolant to flow through the radiator and enter the water pump delivering cooled coolant from the radiator. However, the thermostat is supposed to not only open and allow coolant from the radiator at operating temperatures but also limits the flow of the bypass circuit. In this case we find that the bypass circuit is allowing an immoderate amount of bypassed coolant back into the engine reducing the coolant systems effectiveness. Under normal driving conditions this is not an issue but under spirited driving or track conditions the coolant temperatures can climb into unsafe territories.
In testing the coolant bypass restrictor (paired with the OEM thermostat) has placed the operating range of the coolant temperature of the engine at 190-200F (88-93C) in cruising, spirited driving, drifting or track sessions while still retaining a quick warm up time like OEM.
WARNINGS:
1) A colder thermostat ALONE will not have the same result as the coolant bypass restrictor but using a 170F (76C) thermostat WITH the restrictor will maintain your temperatures in the 183-193F (84-89C) range.
2) Corrosion in your coolant system may cause fitment issues when installing the restrictor. Lightly sanding and cleaning the inlet is highly recommended before installing.
3) A Dead Blow Hammer is highly recommended when installing the restrictor into the housing to prevent damage to the restrictor or the housing. The restrictor should be pushed in by hand as much as possible before using the Dead Blow Hammer to get a flush fitment.
The Coolant Bypass Restrictor fits the following models:
-1UZ-FE Non VVTI
-2UZ-FE VVTI
-3UZ-FE VVTI
*If you have the housing with a removable 2 bolt side barb (as pictured below) then this WILL NOT FIT. (which has been found on 1UZ VVTI and 2UZ Non VVTI engines). Please replace water inlet housing and use part number 16032-50110.
Reviews
There are no reviews yet.