Why my van lost its power in the Rockies ?

Think about it
the higher you go the less air you have there for the less power you have
the higher you go the less pressure you have there for more pressure
leaks ie transmission and oil leaks
for every 1000 ft up you should drop top speed by 5-10mph

have fun next time


aa wrote:
Hi folks


Maybe someone know the answer for the question:
why my van lost its power in the Rockies ?



Shortly:

Van: 1992 Ford Aerostar, 3.0 litre engine, automatic
transmission, usually driven in Ontario, Canada
(altitude: ca 500 ft above sea level).
Trip: Ontario - Yellowstone - Grand Canyon - Ontario
+ sidetrips.
Load: 5 people (total 750 lb) and their camping gear.
Van loaded pretty full, but no trailer.

Observations:
Leakages of transmission fluid during hard driving
(climbing up hills, speeding, accelerating).
No leakages, when less power was neccessary
(driving with moderate speed at flat highway).
No leakages during stops and overnights.
End of above problems after return to lower altitudes.

Hypotesis: when driven at higher altitudes
the van used to significally lose its power (why ?).
That caused increasing in tranny workload (?),
hence tranny overheatings.

Anybody to confirm / negate / explain ?



Details:

Problems started in SD. It was transmission fluid leakage
during climbing hills at I-90 west from Missouri crossing
with 75-80 mph at the speedometer.
After cooling down and refilling the fluid, the van run
smoothly (however cautiously, at 50 mph) without any leak.
Also there was no leak overnight.

Problem returned in Black Hills, SD. Again tranny leaked.
But that time I noticed I could climb a hill (quite steep,
however) at 30-40 mph only. Above that speed
engine temperature gauge started to climb quickly to
a red mark. After slowing, temperature felt down.
If not slowed, tranny leaked.
Again, no leaks after cooling down and refilling.

Spoke to a tranny mechanic. He tested the van
and diagnosed that tranny is OK. 'Do not press
too hard' was his advice.

Third episode:
climbing Bighorn Mountain on WY-14, heading to
Yellowstone. Elevation ca 9000 ft. Really steep.
It took 1,5 hours to make 10 miles. Speed 20 mph,
seemed that the engine wasn't able to provide more
power to speed up. Every other mile or so there was
neccessity to stop and cool down the tranny.
Also: I used 3 qts of tranny fluid for refills.

Then I returned to Sheridan, WY, to speak with
a Ford dealership. Their diagnosis: tranny to replace
or rebuild. Mere $1900 or $2600. I declined both
solutions. After all, tranny functioned properly
except overheating. And I believed the new tranny
would not solve this problem.

Spoke to another tranny specialist. He test-drove
the van and confirmed, tranny is OK.
Also he suggested to test the engine, stating
it is too weak.

Spoke to engine specialist. He tested it carefully,
test-drove the van and found nothing wrong.
And it seemed to me, also, that the engine power
was OK during the test. So I started to think that
the problem is not permanent, but random.

Stripped from full faith in my van, I decided not
to try WY-14 again but to reach Yellowstone by northwest
entrance. I did it, however the climb on 191 was tough.
The van was able to make only 30-50 mph without engine
temperature gauge going to red. But it did it. Later
I drove all Yellowstone without a problem, regardless
of altitudes 7000-9000 ft. Slower speeds probably helped.

During the remain of the trip, several other episodes
showed me, that sometimes the van drives just great,
but there are numerous times, when it is incredibly
weak. For example, it was unable to drive 75 mph on
flat highway 20 in ID without a cloud of white smoke.
Or unable to accelerate quickly when entering a I-80
near Wells, Nevada. Or tranny fluid leakage because
of its overheating near Bryce Canyon (speed: 30 mph)
and in many other places.

However, what wondered me mostly, was: all the
weak-engine-and-leaking-tranny problems just vanished
after leaving Colorado during the return leg of our trip.
I.e., after driving down the 3000 ft altitude line.
Since then, I drove over 3000 miles without any problems
with engine power or tranny fluid refilling. So, it seems
obvious to me, that my van had a kind of mountain sick.
Who knows, what was it ? Who had similiar problems ?



Regards
Tadeusz

On Fri, 12 Sep 2003 02:42:49 -0400, "aa" wrote:


Hi folks


Maybe someone know the answer for the question:
why my van lost its power in the Rockies ?

You don't say what sort of carburetion it has, or whether it is
fuel inected, but the simple fact is that in the thinner air at
high altitudes engines lose power. There simply isn't as much air
in a cubic foot to mix with the fuel, resulting in an over-rich
mixture. Airplane pilots compensate for this by having a nice
manual choke, or mixture control, which has to be adjusted with
altitude. Presumably, a computerized fuel injection system will
also be able to compensate.

But the compensation with choke or computer can only result in a
proper air-fuel mixture ratio; because of the reduced air density
at altitude, that mixture will have less fuel in it per cubic
foot, and power will still be lower.

Crooked cas stations in heavily traveled high altitude locations
are famous for taking advantage of this by telling complaining
motorists they need the likes of an engine overhaul. I had a
friend that this was tried on in Flagstaff.


************* DAVE HATUNEN ) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *

Keith Willshaw wrote:



How does this provide a mechanism for explaining a lower O2 percentage
in thinner air ?


Who said anything about lower percentage of oxygen?
We are dealing with density, the number of molecules of gas in a given
volume. The reason that there is less oxygen at, say, 10,000 feet, is that
there is less air. There is a corresponding reduction in the amount of
nitrogen, hydrogen, helium CO2 and other gases in the same air. The engine
needs a certain amount of oxygen for proper combustion and it gets that
sucking air into the carburettor.

The turbocharger, which is driven by the exhaust gases, compensates for the
thinner air by pumping a larger volume of air. From that larger volume of air
there is be the same amount of oxygen that would have been found at low
altitude.

"alohacyberian" wrote in message ...

It's not a good idea to take an older lowlands
car into the high Rockies, you're lucky it didn't die up there! KM

You must be joking. I live in Kansas City (750 feet) and go on yearly
trips above 10,000 feet, often in cars with ~200k miles, without a
single problem. It depends on the car's overall reliability and
mechanical condition, which can still be quite good in a car 10-15
years old.


Kaleb

That will get less air. The claim was that the air has a lower
percentage of oxygen. FFM

Dave Smith wrote:
A turbocharger. The turbo charger in most engines runs of the
exhaust, and since
there is less resistance in the thinner air, it will force more volume
through the system than can be done with a naturally aspirated
carburettor.

"Frank F. Matthews" wrote:
I agree that there is less quantity of oxygen at altitude but what
mechanism do you propose to produce a lower percentage? FFM

To quote Keith's original post

therefore, you can expect a little more leakage. The percent of
oxygen in
the Colorado Rockies is quite a bit less than it is at sea level,

The discussion is therefor a challenge to the concept that there is a
lower percentage of oxygen. -- See title. FFM

Dave Smith wrote:

Keith Willshaw wrote:

How does this provide a mechanism for explaining a lower O2 percentage
in thinner air ?

Who said anything about lower percentage of oxygen?

snip

On 12 Sep 2003 11:15:45 -0700, Kaleb Axon wrote:
"alohacyberian" wrote in message ...

It's not a good idea to take an older lowlands
car into the high Rockies, you're lucky it didn't die up there! KM

You must be joking. I live in Kansas City (750 feet) and go on yearly
trips above 10,000 feet, often in cars with ~200k miles, without a
single problem. It depends on the car's overall reliability and
mechanical condition, which can still be quite good in a car 10-15
years old.

and the existance of a MAP sensor, something that's been common since the
early 80's.

Cars before then used to have to be retuned for high altitude operation.

"Dave Smith" wrote in message
...
Keith Willshaw wrote:



How does this provide a mechanism for explaining a lower O2 percentage
in thinner air ?


Who said anything about lower percentage of oxygen?

The post you replied to did

I agree that there is less quantity of oxygen at altitude but what
mechanism do you propose to produce a lower percentage? FFM


We are dealing with density, the number of molecules of gas in a given
volume. The reason that there is less oxygen at, say, 10,000 feet, is
that
there is less air. There is a corresponding reduction in the amount of
nitrogen, hydrogen, helium CO2 and other gases in the same air. The
engine
needs a certain amount of oxygen for proper combustion and it gets that
sucking air into the carburettor.

The turbocharger, which is driven by the exhaust gases, compensates for
the
thinner air by pumping a larger volume of air. From that larger volume of
air
there is be the same amount of oxygen that would have been found at low
altitude.


Yes I know that

Keith

aa on Thursday 11 September 2003 23:42 wrote:

Maybe someone know the answer for the question:
why my van lost its power in the Rockies ?

Shortly:

Van: 1992 Ford Aerostar, 3.0 litre engine, automatic
transmission, usually driven in Ontario, Canada
(altitude: ca 500 ft above sea level).
Trip: Ontario - Yellowstone - Grand Canyon - Ontario
+ sidetrips.
Load: 5 people (total 750 lb) and their camping gear.
Van loaded pretty full, but no trailer.

Observations:
Leakages of transmission fluid during hard driving
(climbing up hills, speeding, accelerating).
No leakages, when less power was neccessary
(driving with moderate speed at flat highway).
No leakages during stops and overnights.
End of above problems after return to lower altitudes.

Hypotesis: when driven at higher altitudes
the van used to significally lose its power (why ?).
That caused increasing in tranny workload (?),
hence tranny overheatings.

Anybody to confirm / negate / explain ?

Even without a 1000 lb payload (people + gear), pulling mountain
grades at altitude is a strain on any engine, especially since most
engines made for "family" cars are underpowered, which compounds the
problems.

Your fluid leakage is most likely due to your transmission seals
"breaking" because of excessive differential heating between the
engine and transmission: one expands faster than the other, "breaks"
the seals, fluid leaks, the other then "catches up" (maybe) and the
seals reset cutting off the leakage. I've had this problem with a
couple of cars, but with engine oil leaks due to the engine being
cast iron and the timing chain cover or valve cover being aluminum.
Aluminum expands faster when heated, than iron etc., etc. Nothing
much you can do about this. It's a design problem. Just make sure
you have a good gasket and the bolts are torqued to specs.

Other points to consider:

Don't overload. Know the max payload of your van and don't exceed it.
It exists for a reason.

When climbing grades, manually shift to a lower gear. Automatics are
notorious for staying in the highest gear they can, even if it's not
beneficial, and only down shift, when you hit the gas to pass, etc.
Using a lower gear will help climbing grades and keeps the engine
RPMs up, which means the fan turns faster, increasing engine cooling,
and lessening the possibilty of overheating. Most people, who live
in mountainous terrain, have heavy duty radiators and transmission
coolers on their vehicles to combat the overheating problem when
pulling long grades. If you plan on doing such mountainous trips
frequently, a transmission cooler is an inexpensive upgrade.

You might consider putting a couple of thermostatically controlled
electrics fans on your radiator in addition to the regular one to
improve engine cooling at low speeds like when pulling a long hill.

If your engine is running hot, turn off the air conditioning, if all
other techniques fail to alleviate the problem. The a/c condenser on
most cars is usually placed in front of the lower part of the
radiator, so very hot air from the condenser blows directly onto the
radiator reducing engine cooling efficiency. Stupid. I moved the
a/c condenser on my 4x4. BIG improvement on engine temp during those
hot summer months in the desert southwest US.

Driving at altitude with an engine tuned for sea level (or there
abouts) results in a too rich mixture, which reduces performance and
wastes gas. The engine runs hotter, too. If you have an engine that
automatically adjust to changes in altitude, so much the better, but
if you don't, there's not much you can do, unless once you're above
5000 feet, you retune it.

Good Luck on your next trip.

--
Stefan Patric

"Dave Smith" wrote in message
...

"Frank F. Matthews" wrote:

I agree that there is less quantity of oxygen at altitude but what
mechanism do you propose to produce a lower percentage? FFM

A turbocharger. The turbo charger in most engines runs of the exhaust,
and since
there is less resistance in the thinner air, it will force more volume
through the
system than can be done with a naturally aspirated carburettor.

Actually, in the United States very few of the newer vehicles have
carburetors, almost all are fuel injected nowadays. KM
--
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