External tranny filter
 

Has anyone added an external transmission filter to their TCH? I was thinking of adding one. Thoughts anyone

Re: External tranny filter
 

Filter or cooler?

I've never heard of an external filter. I thought most traditional automatics have internal filters.

Of course the 2G+ Prius and TCH don't have one at all. Just a bunch of gears in oil.

I thought too that most of the reason for the oil going bad is simply heat related breakdown. It's not like engine oil where you have combustion by-products and other crud getting into the oil.

Re: External tranny filter
 

It was done on a Prius a while ago. Limited benefit. Just change out the Type WS ATF periodically (my suggestion at 30k miles then every 60k miles thereafter in normal use).

Metallic wear particles build up as the gears lap in to each other (slows as the gears mesh better). Since the M-G windings are exposed to the ATF, this is not a good thing.

JeffD

Re: External tranny filter
 

The only thing I have EVER found in the sump of a non-failed automatic transmission is the "fines", small ground up "lead-pencil" looking particles, from frictional surface wear. Most have small magnets in the bottom of the sump and if those have collected a substantial level of metallic particles....then...WORRY.

Does the FEH's e/CVT even have the small cooling heat exchanger section through the radiator...?

Re: External tranny filter
 

Not exactly - the TCH has a second rad (above the A/C condenser) for cooling the trans, electric motors, and the inverter. The transaxle cooling is primarily via oil - the coolant is a 'pad type' where the coolant picks up heat from the trans fluid and is circulated through that second rad via an electric pump. According to the analysis done by DOE:The electric motors are primary sources of heat build-up - unlike the conventional automatic, where the torque converter and friction clutches contribute heat. This cooling system setup, as well as the battery cooling limitation, are likely the reasons for towing prohibition with the TCH.

Re: External tranny filter
 

The biggest issue you face is the lack of an external oil circulation loop. The TCH transaxle uses a combination of internal trochoidal oil pump coupled with splash oiling - it's explained in the service manual.

Given the lack of friction elements in the TCH transaxle, the normal source of particulate contamination is not there - thus there is less value to a filter. 30-60K trans oil change interval should keep the fluid pristine, and virtually eliminate risk of oil-related failure. FWIW, Toyota doesn't have specific interval for trans fluid change; my consideration is to deal with the (very small) contamination risk - if stuff like water, even condensation from temp cycling, ever gets by the seals, periodic changes get rid of it.

Re: External tranny filter
 

I drained and refilled at about 48k miles. The stuff looked like new. Not sure when I'll do it again.

Re: External tranny filter
 

Ed_T,

Questrions if you don't mind:

Where do I find the drain for the tranny?

What fluid did you use, Toyota, Amsoil, etc.?

Where did you refill the tranny?

I have about 36000 on my '08 hybrid and am thinking of changing the fluid even though they say 100,000 miles.

Thanks for the help.

Re: External tranny filter
 

Hi, there should be a pdf of the tranny refill process somewhere on this board, I don't have that link.

You MUST use Toyota WS fluid.

There is a piece that fits on your ratchet wrench you will need to be able to uncork the refill and drain holes. Under $10. Be sure to uncork the refill first, just to be sure it will come out, heh. You should notice that there is a vacuum when removing the plug. Someone on a Prius board mentioned it, and the HyCam has it too.

I used a funnel with a long flexible tube to reach the refill hole. The trick is to set it up so that it will not pop out while refilling. I refilled until there was a light dribble from the hole.

The car should be level during the procedure, but I just ramped my front end, and it still took about 4 quarts. The old came out looking just like the new.

Also, to avoid massive splashing, elevate your drain pan as close to the drain as you can -- otherwise plan on some moderate cleanup.

I re-used the original "gaskets" - they looked fine and just like new.

I feel sorry for anyone with the new sealed transmissions who want to change out their old fluid. This is such a piece of cake in comparison, they would shed tears of joy.

Re: External tranny filter
 

Thanks for the info. I have not had a good look at the bottom of the car, that is whay I was asking about where the plugs were located. I will look around and see what else I can find on this. The plugs you remove, are they allen wrench heads, star heads, regular socket heads? Just trying to know what to look for. Pull the top plug first, like changing the fluid in a transfer case. The fluid refills on the side of the tranny?

Toyota fluid only, thanks.

Thanks again for the info.