Thanks for posting this content. I just had my Drive Unit replaced and am awaiting the time when the new unit begins to leak. The replacement unit has a part warranty of 2 years from Mercedes, but we'll see how they feel if it begins leaking. As a prevention, I'm looking into running Evans waterless coolant and zero pressure (open coolant cap) or even a negative pressure similar to the "leak shield" system for water cooled desktop computers. Any thoughts of prevention? Thanks!
Actually I just started researching the effect of coolant additives. The current coolant is Zerex G48 which contains silicates as additives. These seem to form nasty deposits right next to the seal lip on the shaft. So a different coolant may help. But.... What additives are in EWC exactly?
@@diyEVguy Not really sure what sort of additives the Evans has. What I was looking at is that fact that it doesn't rely on pressure to keep the boiling point low. Seems like a lot of folks run it in notoriously leaky (under pressure) cars at zero pressure. Google "zero pressure coolant system". What is your intuition about the role of coolant / air pressure differential across the seal and its contribution to leaking? One other question: My B250e has two chambers in the coolant overflow tank leading me to believe that the battery coolant circuit and the motor coolant circuit are separate. Is that true of the Rav?
@@ScotGraham Ah I see your point. Interesting. I have to do some research before I can answer because for example I assumed that EV cooling systems are generally not using pressure for boiling point elevation bc not needed bc battery goes to max 55degC and rotor 85degC but I could be wrong.
@@ScotGrahamUpdate: EWC is reportedly pure glycol plus additives, which is an order of magnitude more viscous ("thick") than water, so EWC can increase friction at the seal/shaft interface w.r.t. 50/50 glycol/water (Zerex G48), in turn increasing the temperature at that interface, which is not good. Also the heat capacity of glycol is significantly lower than water, meaning that the coolant temperature increase is significantly higher than water per unit of injected (frictional) heat energy. Also for pumping a more viscous liquid, a higher pumping pressure is required (independent from the pressure increase due to expansion in a closed system). So I doubt that EWC is an improvement in this case.
@@ScotGraham Yes, the RAV4 has separate circuits for drive unit and battery. I want to replace the battery coolant soon too. May make vid about that too.
This is great content! love to see it
Thanks
Dang if it’s not wear then this problem will be continuous
Thanks for posting this content. I just had my Drive Unit replaced and am awaiting the time when the new unit begins to leak. The replacement unit has a part warranty of 2 years from Mercedes, but we'll see how they feel if it begins leaking. As a prevention, I'm looking into running Evans waterless coolant and zero pressure (open coolant cap) or even a negative pressure similar to the "leak shield" system for water cooled desktop computers. Any thoughts of prevention? Thanks!
Actually I just started researching the effect of coolant additives. The current coolant is Zerex G48 which contains silicates as additives. These seem to form nasty deposits right next to the seal lip on the shaft. So a different coolant may help. But.... What additives are in EWC exactly?
@@diyEVguy Not really sure what sort of additives the Evans has. What I was looking at is that fact that it doesn't rely on pressure to keep the boiling point low. Seems like a lot of folks run it in notoriously leaky (under pressure) cars at zero pressure. Google "zero pressure coolant system". What is your intuition about the role of coolant / air pressure differential across the seal and its contribution to leaking? One other question: My B250e has two chambers in the coolant overflow tank leading me to believe that the battery coolant circuit and the motor coolant circuit are separate. Is that true of the Rav?
@@ScotGraham Ah I see your point. Interesting. I have to do some research before I can answer because for example I assumed that EV cooling systems are generally not using pressure for boiling point elevation bc not needed bc battery goes to max 55degC and rotor 85degC but I could be wrong.
@@ScotGrahamUpdate: EWC is reportedly pure glycol plus additives, which is an order of magnitude more viscous ("thick") than water, so EWC can increase friction at the seal/shaft interface w.r.t. 50/50 glycol/water (Zerex G48), in turn increasing the temperature at that interface, which is not good. Also the heat capacity of glycol is significantly lower than water, meaning that the coolant temperature increase is significantly higher than water per unit of injected (frictional) heat energy. Also for pumping a more viscous liquid, a higher pumping pressure is required (independent from the pressure increase due to expansion in a closed system). So I doubt that EWC is an improvement in this case.
@@ScotGraham Yes, the RAV4 has separate circuits for drive unit and battery. I want to replace the battery coolant soon too. May make vid about that too.
I would look at the shaft. You could have a bad surface finish lead. This would result in fluid being pumped across the seal interface.
Yes that is one good cause candidate, thank you!
Hi, nice video.
If you have two different delta t, i would suggest you name one delta t_min and the other delta t_max.
Yes good point thanks.
всё это не актуально , не нужно там никакое охлаждение :)