Tesla Coolant Seal Lip Thickness Analysis (see updates in description)

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In this episode, I show that the Tesla Large Drive Unit coolant seal lip was proably not "worn out" at all. Instead, it probably already had a smaller thickness from the start (in the region where it contacts the shaft) due strains induced by manufacturing and installation.
Previous video about coolant seal: • Tesla Motor Coolant Se...
PTFE forming example (a pipe flange, not a seal): • PTFE lined pipe flarin...
UPDATES
● This video should not be generalized to other seals. Maybe wear can still play a role, for example in triple-lip seals installed by Tesla.
● For improved readability, Δt should have been denoted as Δt_min and Δt_max for the minimum and maximum ν values of 0.3 and 0.5, respectively.
Timestamps
0:00 intro
0:39 seal lip production process
1:18 strain identification
1:43 analytical strain model
2:44 measurements and numerical results
3:38 outro
See also
sites.google.com/view/teslald...
Disclaimer
This video is for entertainment purposes only. All work you do on your car is at your own risk.
Keywords
Toyota RAV4 2012 2013 2014 Mercedes B-class Electric Drive Tesla Model S large drive unit LDU motor BEV glycol coolant fluid Zerex G48 automatic transmission fluid ATF Dexron VI leak battery aegis ring bearing bearings grinding noise CAD model PTFE teflon rotary lip seal failure drain housing rotor shaft repair common mode grounding runout eccentricity fluting wear axial radial play speed sensor check rebuild assemble disassemble vent reluctor ring expensive cheap repair DIY out of warranty

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Опубликовано:

16 июл 2024

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Комментарии : 22

@zachwak Год назад

This is great content! love to see it

@user-zk6mx3fm7y Год назад

Thanks

@Star3 Год назад

Dang if it’s not wear then this problem will be continuous

@DevinGrosz Год назад

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.

@diyEVguy Год назад

Yes that is one good cause candidate, thank you!

@christophhominger8062 Год назад

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.

@diyEVguy Год назад

Yes good point thanks.

@ScotGraham Год назад

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!

@diyEVguy Год назад

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?

@ScotGraham Год назад

@@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?

@diyEVguy Год назад

@@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.

@diyEVguy Год назад

@@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.

@diyEVguy Год назад

@@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.