Last Wednesday, I began the task of servicing the cooling system on my father’s 1992 Toyota Previa with 64,300 miles. As evident by its low mileage, the vehicle was an infrequently driven “garage queen” until several years ago. As a result, little maintenance was done aside from an annual oil change and the occasional air filter change. The cooling system was no exception to the various neglected maintenance items.
The first coolant service on this vehicle was done at 12,000 miles and six years from the original in-service date. A quick lube flushed/filled the system using conventional 50/50 coolant/water using an exchange machine. No cleaning chemicals were used. Then, two years ago (six years after the first service) at 45,000 miles, the van received a “major service” at the local dealership. As part of the service, the radiator and engine block were both drained and refilled with Toyota RED 50/50 mix. No cleaning chemicals were used either. Bear in mind, the recommended coolant for this vehicle is plain ethylene-glycol/distilled water 50/50 carrying a 3-yr/45k (initial) and 2-yr/30k (subsequent) service interval.
As I began taking over the maintenance of the various family vehicles, I opened the surge tank on this van in horror to discover a nasty smelling, brown colored coolant. I was not expecting to find such a nasty mess of discolored coolant and floating sediment given the short time since the last coolant replacement.
So, I immediately headed to the local Walmart and bought two gallons of Prestone All Makes All Models Extended Life coolant and a 1L container of Prestone Super Radiator Cleaner designed for neglected cooling system. I wanted to replace the original radiator cap, hoses, and thermostat as well, but my father did not approve those purchases as he argued that the system was fine.
My local high school auto shop has a RobinAir 75700 Coolant Exchange machine. You can look up more information about it if you’re interested. The machine works by attaching step adapters between the upper radiator hose and the radiator neck. With the engine hot, heater valve open, but engine turned off, 120 psi of compressed air is used to push new fluid into the radiator and simultaneously vacuum the old fluid from the upper radiator hose.
As a result, I took the van into the shop to use the machine. I hooked up the machine as directed, and ran 32 quarts of clean, drinkable water through the system. The old coolant was brown, but the fluid exiting out of the machine was clear water when I finished. After reconnecting the lines, I dumped the Super Radiator Cleaner into the surge tank, topped up with water (and over the course of several days) and proceeded to drive the van normally for the next week, totaling the three to six hour runtime as directed by the instructions.
After one week and a little more than six hours of runtime, the fluid in the surge tank was now brown, almost identical in color to the old coolant I had drained out the previous week. (Note that merely driving the van two blocks home after adding the cleaner already turned the fluid in the system light brown)The machine was hooked up yet again, and 16 quarts of water was run through the system. The fluid exiting looked clean, so I hooked the hose back up and idled the engine for 15 minutes as called for by the Super Radiator Cleaner’s instructions. Then, I hooked the machine up yet again to exchange another five gallons of water…but after about 6 quarts, I noticed that the color of the fluid looked like clean water, so I stopped and hooked the hose back up.
In order to add the correct concentration of pure antifreeze to the system, I could either premix the concentrate and water and exchange the system…or I could merely drain the radiator and add enough concentrate. I chose the latter in this case, as I knew that the radiator holds 7-8 quarts on this van. After draining almost eight quarts from the radiator, I (in horror) was only able to add 3.5 quarts of concentrate before the surge tank overflowed. Stumped, I put the cap back on and idled the engine for 30 min before the level finally dropped (while temps nearly skyrocketed), allowing me to add 6.5 quarts of concentrate (12.3 qt system). After returning home (two blocks away), the surge tank was empty yet again and forced me to add 1 qt of water. After two hours in traffic today, I had to add another 0.5 quart of water. This cooling system sure takes a long time to bleed!
On a more positive note, the coolant appears to be clean now, of a very light green color. No odor yet…and I’m seeing no signs of discoloration. The chemical cleaner appeared to have some effect…not just complete snake oil. Hopefully, no leaks will develop in the coming weeks and the coolant will stay clean. (fingers crossed)
The first coolant service on this vehicle was done at 12,000 miles and six years from the original in-service date. A quick lube flushed/filled the system using conventional 50/50 coolant/water using an exchange machine. No cleaning chemicals were used. Then, two years ago (six years after the first service) at 45,000 miles, the van received a “major service” at the local dealership. As part of the service, the radiator and engine block were both drained and refilled with Toyota RED 50/50 mix. No cleaning chemicals were used either. Bear in mind, the recommended coolant for this vehicle is plain ethylene-glycol/distilled water 50/50 carrying a 3-yr/45k (initial) and 2-yr/30k (subsequent) service interval.
As I began taking over the maintenance of the various family vehicles, I opened the surge tank on this van in horror to discover a nasty smelling, brown colored coolant. I was not expecting to find such a nasty mess of discolored coolant and floating sediment given the short time since the last coolant replacement.
So, I immediately headed to the local Walmart and bought two gallons of Prestone All Makes All Models Extended Life coolant and a 1L container of Prestone Super Radiator Cleaner designed for neglected cooling system. I wanted to replace the original radiator cap, hoses, and thermostat as well, but my father did not approve those purchases as he argued that the system was fine.
My local high school auto shop has a RobinAir 75700 Coolant Exchange machine. You can look up more information about it if you’re interested. The machine works by attaching step adapters between the upper radiator hose and the radiator neck. With the engine hot, heater valve open, but engine turned off, 120 psi of compressed air is used to push new fluid into the radiator and simultaneously vacuum the old fluid from the upper radiator hose.
As a result, I took the van into the shop to use the machine. I hooked up the machine as directed, and ran 32 quarts of clean, drinkable water through the system. The old coolant was brown, but the fluid exiting out of the machine was clear water when I finished. After reconnecting the lines, I dumped the Super Radiator Cleaner into the surge tank, topped up with water (and over the course of several days) and proceeded to drive the van normally for the next week, totaling the three to six hour runtime as directed by the instructions.
After one week and a little more than six hours of runtime, the fluid in the surge tank was now brown, almost identical in color to the old coolant I had drained out the previous week. (Note that merely driving the van two blocks home after adding the cleaner already turned the fluid in the system light brown)The machine was hooked up yet again, and 16 quarts of water was run through the system. The fluid exiting looked clean, so I hooked the hose back up and idled the engine for 15 minutes as called for by the Super Radiator Cleaner’s instructions. Then, I hooked the machine up yet again to exchange another five gallons of water…but after about 6 quarts, I noticed that the color of the fluid looked like clean water, so I stopped and hooked the hose back up.
In order to add the correct concentration of pure antifreeze to the system, I could either premix the concentrate and water and exchange the system…or I could merely drain the radiator and add enough concentrate. I chose the latter in this case, as I knew that the radiator holds 7-8 quarts on this van. After draining almost eight quarts from the radiator, I (in horror) was only able to add 3.5 quarts of concentrate before the surge tank overflowed. Stumped, I put the cap back on and idled the engine for 30 min before the level finally dropped (while temps nearly skyrocketed), allowing me to add 6.5 quarts of concentrate (12.3 qt system). After returning home (two blocks away), the surge tank was empty yet again and forced me to add 1 qt of water. After two hours in traffic today, I had to add another 0.5 quart of water. This cooling system sure takes a long time to bleed!
On a more positive note, the coolant appears to be clean now, of a very light green color. No odor yet…and I’m seeing no signs of discoloration. The chemical cleaner appeared to have some effect…not just complete snake oil. Hopefully, no leaks will develop in the coming weeks and the coolant will stay clean. (fingers crossed)
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