Hydraulic clutch in the winter.

[Jedd]

So, I'm looking for some information.

The 05 and up 6 speed standard Tacomas use the brake fluid resevoir to supply the hydraulic clutch. The problem that I've been running into for the last couple years is that the fluid viscosity starts getting very thick by -25 celsius and by -30C i can push my clutch pedal to the floor take my foot off and watch it return slowly....not good for clutch life.

I'm myself a heavy duty mechanic and cant seem to dig up any information on brake fluid viscosity versus ambient temperatures. Toyota has been no help to me, they just stare with jaws dropped in amazment whenever I bring it up.

I'm starting to think that Toyota hasn't taken into account that their trucks do still get used in harsh climates.....

So any takers?

 

[java]

hmmm, i run motul rbf600 in my car for high temps but never worried about low temps, i do know its a little lower viscosity than a DOT3/4

 

[sargeek]

Contact the NZ Antarctic Program

If you really want to know, contact the New Zealand Antarctic program. They use Toyota HiLux Trucks at their stations for transportation.
http://www.antarcticanz.govt.nz/about-antarcticanz/7201

 

[Jedd]

sweet thanks for the link.

 

[ExploringNH]

Each DOT regulation has its own standards.

DOT 3 = 1500 Centistokes @ -40° F
DOT 4 = 1800 Centistokes @ -40° F
DOT 5 = 900 Centistokes @ -40° F.

DOT 5 is supposed to be able to mix with DOT 3 and 4 fluids. With a 40% decrease in vicosity, there is a chance that it could make a significant difference.

 

[Jedd]

DOT 5 is absolutly not compatible with DOT 3 & 4 brake fluids, it will destroy the seals in your brake system. Being that 5 is silicone based and 3 & 4 are a polyglycol. They just flat out dont mix.

There is however (and I just learned this) a DOT 5.1 that is a polyglycol base and is fully compatible with DOT 3&4, it would also seem that it is even more stable then DOT5, So if I can find out the availability of this stuff and the price I may go with it, or at least give it a shot.

 

[ExploringNH]

DOT 5 is absolutly not compatible with DOT 3 & 4 brake fluids, it will destroy the seals in your brake system. Being that 5 is silicone based and 3 & 4 are a polyglycol. They just flat out dont mix.

There is however (and I just learned this) a DOT 5.1 that is a polyglycol base and is fully compatible with DOT 3&4, it would also seem that it is even more stable then DOT5, So if I can find out the availability of this stuff and the price I may go with it, or at least give it a shot.

My mistake. You re correct. It is 5.1 that is compatible. The viscosity number still stands, per the standard. Depending on brand, you can most likely find some that are lower viscosity than others. A lot of sportbikes use 5.1, and it can be expensive.

 

[RU55ELL]

It may be pricey, but is worth not accelerating the wear of your clutch.

 

[Jedd]

I've spent the afternoon looking around for DOT 5.1 fluid, not the easiest stuff to find. Found it online for $7 per 250ml not the cheepest for sure.

 

[Christian]

As brake fluid is hydroscopic ( pics up water over time) you might just need to change your clutch fluid. I had a similar problem on a HJ60, and changing the fluid helped a lot! Many car manufacturers describe that brake fluid must be changed every other year. no reason to suspect clutch fluid being different. So start by changing the fluid and see if that doesn't help.

 

[Jedd]

As brake fluid is hydroscopic ( pics up water over time) you might just need to change your clutch fluid. I had a similar problem on a HJ60, and changing the fluid helped a lot! Many car manufacturers describe that brake fluid must be changed every other year. no reason to suspect clutch fluid being different. So start by changing the fluid and see if that doesn't help.

My Tacoma is under 2 years old, and the problem has been there since I drove it off the lot (two winters now). But If I can get a hold of some DOT 5.1 then I will definatly be flushing the entire system.

 

[Christian]

Sorry, I did not realize that! IMO it should not behave like that and it is a the dealers problem to fix it. I am sure that it cannot be blamed on DOT 4 fluid as DOT 4 fluid is widely used here and I suspect on Iceland and Greenland too. It should not freeze!
I could be sorely mistaken, but we get warnings here that we have to remember putting snow tyres on etc. before going to Norway or Sweden in the winter, but not a word on brake fluid though.
Sorry I couldn't be of more help...

PS DOT 5.1 is readily availiable here, but only used on newer cars (3 years old and newer... But not neede according to the mechanics)

 

[Jedd]

No problem Christian, thanks anyways for the pointers

 

[007]

Use a dot 3 fluid, it will help your problem as it did mine. It won't be perfect, but its much better than stock. (better cold weather viscosity than Dot 4)

Also, two years is enough time for water to effect the fluid, thats when I began really noticing mine had a problem.

I'm with you on this one though, my 01 takes to the cold much better than my 06. Left me wondering whats going on in the testing department!

The next option would be a heating pad for the clutch/brake res.

 

[Harald Hansen]

I live in Norway and have owned a few vehicles with hydraulic clutches, and have never noticed the problems you have. If you don't have the same problem with the brakes, and the brakes use the same type of fluid, maybe your clutch fluid has been contaminated? I would try to just change it first.