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Change SMT fluid

27K views 24 replies 14 participants last post by  cyclehead 
#1 ·
I finally changed the SMT system fluid out of the reservoir today. 1st Toyota (Tacoma Washington) shipped me a can of factory fluid for $110. (Dealers in Florida and Ohio refused, saying it was a hazardous material.) I removed the heat shield from the side of the HPU pump, but that was a waste of time. The only way to get access to the SMT reservoir is to remove the airbox completely. The SMT reservior is straight down below the air filter box. There are only two screws securing the airbox, but you have to fight with about six rubber lines to get the lower half of the airbox free. I sucked the fluid out of the reservoir with a vacuum oil-change tank/pump thing. Here's what I learned in the process:
- The reservoir holds about 1/4 can of Toyota SMT fluid
- The reservoir cap has a vent hole - so forget about any worries of "depressurizing the system" before changing fluid.
- SMT fluid sure tastes like brake fluid
- After you pump the reservoir dry and refill with fresh fluid, you can turn on the ignition (only) and cycle the shifter into 1st and back to neutral repeatedly. After about 8 shifts, the pump will come on and pump your nice fresh fluid around the SMT system. Then you can suck the reservoir dry and refill with fresh fluid again. This is kind of wasteful, but if you repeat it enough times, you’ll slowly get the whole system filled with cleaner fluid. (It’ll never be completely filled with fresh fluid, you’ll just approach complete cleanliness closer and closer…asymptotically.)

Two 10mm bolts hold the airbox in the car:


View Down with the air box removed:


Old fluid level was a little low, and the fluid was darker than the fresh stuff in the can:



Reservoir holds about 1/4 can of fluid:


New fluid:


Vented reservoir cap:

 
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#5 ·
Best information yet!

Thanks for your very informative post. I have been looking for this information, and was really getting disappointed. I don't understand why some folks are compelled to give 'I don't know' or even worse, flat wrong information. I guess that back of the little school bus was a nasty place. Again, thanks for your help.
 
#7 ·
I'm thinking it's more a function of time instead of miles. Factory manual says nothing about a fluid change interval - that I know of. To be anal, maybe change up the fluid every year or two? Regarding fluid - some guys are using straight DOT4. I've read DOT3 has slightly lower affinity for water. I've read on the Rolls Royce forums that some guys are mixing their own concoction of fluid - 90% brake fluid and 10% castor oil (not Castrol motor oil!!!). Rolls apparently used a similar fluid, that nobody can find any more.
 
#9 ·
I'd say use DOT4. And it can't hurt to mix in some castor oil (not castrol!!). I've seen and touched all the guts of the SMT system, and there's nothing magic in there except the swash plate pump. That thing is a marvelous piece of work! I don't think the Toyota fluid is necessary. I currently have straight DOT3 in one of my SMT cars, and DOT4/Castor oil mix in the other SMT. I intend to change out the DOT3 to DOT4/mix...when I get around to it.

I dug out copied notes below from my archives. Sorry I can't credit the author properly, but it was somewhere on a Rolls Royce forum. Glean what you can and form your own opinion.

=============
Excerpt from Rolls Royce forum:

"According to the 'experts' on the Australian RR website you should use something called 'propoxylated ethylated castor oil rather than the BP or edible stuff due to it staying miscible with the DOT4 for longer - allegedly. I couldn't say.


The percentage of castor oil depends on ambient temperatures the car experiences. In any part of the world where the temperature dips below 5C that should not exceed 10%. There is little advantage to using more unless you already change the fluid twice per year: Before and after Winter.

NB: The fluid should be changed at least EVERY 2 years. More often in humid climates as it is strongly hygroscopic.

DOT 4 brake fluid is good to use too, but it has a tendency to absorb water more quickly, so it loses it's boiling point quicker than DOT 3. Because it is open to the atmosphere, this is an important consideration in our systems.

. Model engine or aircraft suppliers are another. Castor oil is also available in health stores. In addition to its effect on lubricity the castor oil raises the viscosity to around 35 mPa.sec at 75 deg. Fahrenheit, the same as LHS (plain glycol brake fluid of DOT 3 has a viscosity at this temperature of 23.1 mPa.sec). This mixture has been used for some time without problems, except in cold climates. If the car is to be used while ambient temperatures are below the freezing point, the castor oil fluid should be drained and replaced with DOT 3 brake fluid. The simplest way to do this is to drain the reservoir, discard the fluid and refill it with pure brake fluid. When warm weather resumes, just add 4 oz of castor oil. For more information on this experiment, please go to Mark Bardenwerper's web site.

After learning that the first fluids utilized in these cars contained castor oil, I have tried to determine whether this lubricant could again be employed as an additive. After some reading and probing, I found that there is already a small group of owners who use castor oil, but the amount needed seemed to be, at best, conjecture.
I determined to find the matching ratio of castor oil to brake fluid to match the viscosity of pure LHS-2. After running a series of tests, I found it to be 9.25%. Using that percentage, therefore, one would add 3 oz of castor oil to 1 U.S. quart. Using metrics, one would add 92.5 ml to 1 liter of brake fluid.
To arrive at this figure, I sent a set of 12 samples, each one of an increasing ratio of castor oil to brake fluid, to an independent professional tester, Geoff Byrnes, ofThe Coatings Laboratorybanmepleasein Houston, TX. The samples were of 400ml. each. 200ml was the minimum sample size, but I chose the larger quantity because it allowed more precise mixing. On July, 2000 I received this data from Geoff:

If you look over the above chart, you will find that the viscosity of LHS-2 matches that of a sample somewhere between 8.75% and 10% castor oil/brake fluid. This data was further examined by a designer/engineer of rheometers, Jint Nijman. He agreed in principle to the findings but offered a correction to account for some deviations caused by the testing equipment.
It has been determined that use of DOT 3 fluid is perfectly acceptable. It is slightly less hygroscopic and though its boiling point is higher when fresh, as it ages the boiling point of DOT 4 fluid drops more quickly."
 
#12 ·
Ok, so il change the SMT fluid, I will also do the quick shift mod (cut the tab off the throttle body) Other than an exhaust or CAI, is there another common mod to do to these cars ? Something with the MAF ? Thanks.
MAF Mod is thought to slow shifting on an SMT.

Look into bracing. Corky's breast plate makes a big difference. Front strut tower is good too.
 
#18 ·
Changing the fluid.

Hi everyone, I'm new to the forum but have been visiting over the past week due to recently purchasing a 2000 (x) plate MR2 MK3. It's a Jap import registered in the U.K. In 2003 and is the SMT.

I paid a reasonable price for it knowing it needs a clutch change which is eveident during kick down or aggresive acceleration.

The day after I got it home however it development a problem with the cog illuminating on the dashboard. The research I did and found on here was excellent and it was the SMT hydraulic fluid that required changing. In addition the level in the reservoir was less than a third. I've used Dot 4 (Halfords) as mentioned In one of the posts and it seems to have done the trick and I followed this post to complete successfully.

My tip here was a £2 purchase of a large pipette (from Morrisons) to extract the old fluid and again to insert the new fluid as I don't have a funnel - Anyway works brilliantly.

Anyway a few mile test drive and all seems well with no lights and no stalling and jumping out of gear.
 
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