As not only a VAG service and performance shop, but a group of enthusiasts as well, WCAVD feels itโs our duty to bring light to failures on platforms that are becoming alarmingly common (especially current model gens.) Just as we did with our EA839 Rocker Arm PSA some time ago, we want to bring light to a new issue plaguing the EA839/825 platforms, coolant migration. **Photo slides below are numbered and referenced in the PSA**
๐ช๐ต๐ฎ๐ ๐ถ๐ ๐ฐ๐ผ๐ผ๐น๐ฎ๐ป๐ ๐บ๐ถ๐ด๐ฟ๐ฎ๐๐ถ๐ผ๐ป?ย
As suggested by the name, this issue highlights the migration of coolant, namely to places it shouldnโt be going as a symptom of cooling system failure.ย
๐๐ผ๐ ๐ฑ๐ผ๐ฒ๐ ๐ถ๐ ๐ผ๐ฐ๐ฐ๐๐ฟ?
Due to the fundamental design of the EA839/825 cooling system, the significant majority of its components are vacuum-actuated (they function via vacuum); for instance the water pump uses vacuum to slide an internal sleeve forward and back to either allow or block the flow of coolant through the system, this is done to promote a rapid rise in coolant temp. on cold starts. When the water pump fails (slide 5), and the coolant begins to seep out internally, coolant then travels into the same vacuum-tree system that actuates/controls the water pump. This vacuum-tree system is a series of vacuum connections, lines, and solenoids that are shared by the cooling system and other components that function off of vacuum; as a result of the migration from the water pump section, the entire vacuum-tree system now houses coolant impeding the delivery of vacuum to components that need it (sls. 2,3 & 5.)ย
๐ช๐ต๐ฎ๐ ๐ฎ๐ฟ๐ฒ ๐๐ต๐ฒ ๐๐ถ๐ด๐ป๐?
Since coolant is migrating and no longer staying within the cooling system, itโs common to see coolant loss or frequent topping off; you may even see coolant (residue or small pools) build-up on the bank 1 cylinder head (sl.4.) Additionally, because coolant is now migrating through the shared vacuum-tree system and impeding flow of vacuum, you may also see a โDrivetrain Malfunctionโ error present during operation, with a fault stored in the ECU, namely a P0299.
๐๐ผ๐ ๐ฐ๐ฎ๐ป ๐ ๐ฝ๐ฟ๐ฒ๐๐ฒ๐ป๐ ๐ถ๐?
Unfortunately there is no preventative course of action that can be taken against these failures, there is also no correlation between strict maintenance and coolant migration occurrences. Over the course of this year weโve performed several of our CM (coolant migration) Services on vehicles ranging from stock D5 A8s to Stage 2+ S5s across varying mileages, some of which were believed to be preventative by the owners until we began teardown and found signs of seepage and migration.ย
๐ช๐ต๐ฎ๐โ๐ ๐๐ต๐ฒ ๐๐ผ๐น๐๐๐ถ๐ผ๐ป?
If youโre experiencing any of the above symptoms or just want to be proactive, schedule an inspection with WCAVD or your local Euro/VAG shop. The solution is to replace the gamut of revised components (sl.1), included are a new Genuine: water pump, thermostat, Thermo-pneumatic valve, vacuum-tree w/ solenoids, 2 coolant pipes, and coolant.ย
๐๐ผ๐ ๐บ๐๐ฐ๐ต ๐๐ถ๐น๐น ๐ถ๐ ๐ฐ๐ผ๐๐?
Pricing will vary, we recommend reaching out to your local shop for more information. If youโre planning to visit WCAVD for the service, send us an email or give us a call for pricing and information.ย
We hope this PSA has helped clear up some questions and confusion regarding coolant migration. This post was intended to help educate those who own an Audi platform with these drivetrains or those who are experiencing any of these symptoms. Donโt hesitate to contact us with any questions or if youโd like to schedule an inspection/CM Service for your EA839/825 powered Audi.ย
ย ย ย ย ย ย ย ย ย ย ย -WCAVDย
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