Any problem with Hi altitude driving in T?

I've never driven higher than 12,000 feet but didn't notice any such problem.

I wonder if some combination of really hot brakes and water in the brake fluid was the culprit. Hydraulic brakes don't run very well on steam!

Enough water contamination and you don't need a mountain to deprive you of brakes when they get hot, but dimming memories of chemistry make me think high elevation makes it happen at a lower combination of temperature and water content.

It's additionally possible that the system had not been bled of air as well as it should've been.

I'm also told that darkening of brake fluid is not a sure diagnostic of water content, though by the time it gets dark it probably happens to also have absorbed water. (The darkness comes from tiny suspended rubber particles, apparently.) The stuff is hygroscopic (absorbs water from its surroundings, including the air) and 'tis said that just a few percent water content is enough to bite'cha under extreme conditions... and this doesn't necessarily change the color enough to notice with the naked eye.

So I just preventively change the brake fluid every few years or in the course of other brake work, whichever comes first, per the procedures in the ship manual. Refill using new fluid from a sealed container (the half-full container that's been on the shelf in your garage for years should basically go to the household hazmat place with the used stuff that you pull out of the system).

Be sure to slap "Wolf Creek Pass" into the CD player for inspiration and test out your brakes under very forgiving conditions after doing any such work, of course, before heading into traffic and/or the mountains.

Cheers,

--Joe

No problem. Some people forget just how risky just being in business for yourself generally is or can be. Risks associated with your actions, that of any employee or agent and that of outright nutty opposing law firms. If you attempt to insure around this then there is no possible profit left. If you do not insure around risks - then any fight is "to the finish". The LLC and other corporations set up to protect the owners are typically closely held (with few owners) and are both extremely costly, cumbersome and worthless as liability protection. If there are many owners then you are really nothing more than just another employee (typically the W-2 variety) with a very limited upside even if the business does well. Ray - It is my wild guess that you have never had a business (and risks) of your own . I have and therefore view risk as something to be avoided or at least controlled if the outcome appears to justify the risk. Getting off the soapbox. j

I am one of 3 principals in a real estate brokerage firm.

I have and therefore view risk as

It sounds like we're thinking along the same lines. Getting back to the original topic in this thread, I minimize the risk of a brake or mechanical failure in my vehicles by performing periodic maintenance and inspection.

Surely A) Extended use at high revs is un-necessary wear that would be better put on the brakes with greater use of them, its a tradeoff really. B) your rev limiter will only work if you're the one causing the engine to over-rev with the throttle and gears, if you're ramming it into 2nd on a steep incline you will total your engine as its cutting of fuel and spark will do jack all? Mis-shift at 100mph and you'll experience this like i did lol.

My thoughts also - I lacked the "experience" to argue since I had no first hand facts at hand. Do tell us the details of your "experience" please. Mine was with a small two cycle antique 50 years ago - the magneto/flywheel blew in a spectacular manner that could have killed people. j

Nissan 200sx turbo (240 over the pond?). I was a passenger, driver was new to the car and at ~100 went to drop a cog, missed and dropped 3 instead. Driving in a rather nippy manner the box went right in and the clutch came right up. Rev counter pegged out for about 1 second and it was like hitting a brick wall with a banshee as an airbag. Blew the rings on at least one cyl - engine had a nasty rattle and oil eating problems from then on until it was sold to someone as a project.

Without a physical brake mechanism, which im not aware of, its not possible to prevent over-rev due to innertia and the fact that there will be fuel cut for a long period you'll also be reducing the lube and cooling to teh back of the valves/seats and somewhat in the chamber.

I'm just always aware that engine braking is the time my engine sounds most unhappy, moreso than when it has a bar of boost forced through it and dragging 1400Kg of car up to scratch.

I think what he means is how it would help reduce rpm's when going downhill.. It won't prevent rpm's to go to high when going downhill. The RPM limiter cuts off fuel, but going downhill you don't need fuel to get the engine to rev high. Just stay in a lower gear and tap the brakes once in a while and you'll be just fine.

Only for 2 strokes. 4 strokes don't use any significant lubraication from the fuel. (especially since we no longer have lead in the fuel)

As far as A) above, there is more wear on the engine, however, it is insignificant compared to the problems that result from brake fade and loss of braking ability.

For B), since the OP's Sienna has an electronically controlled transmission, the transmission will not downshift if the engine RPM/vehicle speed combination are too high.

The best course of action would be to downshift before picking up speed on the downhill grade and then tapping the brakes as needed.

Ahhh thats where I'm always missing out - we dont do autos over here lol.

So assuming one has downshifted at a slower rpm and still is accelerating because of a steep hill with no apparent end (such as in CO) - will the electronically controlled transmission limit the speed/rpm in any way? Is so by what mechanism? j

Hey, you do not have to rub it in! My LS 400 and my wife's Sequoia would be much more fun to drive with a manual transmission!

No. The transmission will not limit speed or RPM other than normal frictional losses. When you downshift, the engine is what provides braking, not the transmission. Here is a pretty good explanation of engine braking: