Hi there

a fellow owning a brand new ute with Turbo engine hasd a timer put on it.
When i asked why, he told me ALL Turbo Engines, old or new, should have a
timer to avoid turbo damage, something to do with oil in the lines etc

However the dealer says not needed. so do I need a timer for my GT subaru ?

A timer is not that expensive - is this cheap insurance like frequent oil
changes or using 98 petrol ?

Thank you

AdvarP wrote:
If it needed it, wouldn't you think that Subaru
would have installed one at the factory?

Subaru turbos seem to be trouble-free without it.

AdvarP wrote:

I think they were more important in the 'old days' when oil formulations
were less sophisticated and turbos had no coolant lines.


Carl


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Allright, thanks for the answers...

So I don't need to let the engine idle a little anyway before stopping, you
reckon ? Normally if I do that the cooling fan kicks in for a while and then
stops (well normal, no air flow so fan must kick in I guess).

Thank you



"Carl 1 Lucky Texan" <alckytxn (AT) swbell (DOT) not> wrote

In article <134a00fmf42881b (AT) corp (DOT) supernews.com>,
advarp (AT) hotmail (DOT) com says...
Your friend is correct, with regards to ALL
older, simpler designs.

Doesn't your Forester have the same design as a
WRX---a coolant supply line, and a catch tank
higher than the turbo...that lets coolant
continue to flow thru the bearing housing by
convection, even when the engine is off?

;-)

Your friend is right about older designs...they
will benefit from a turbo timer.

I know it's no fun but, read the manual for your car. (-; Subaru puts
proper care instructions in there if you really want to know.

Your electric cooling fan(s) are temperature based, but also come on if the
air conditioner compressor is in use to keep air flowing over the condenser.
It's not unusual for a cooling fan to kick on when your car stops moving so
I wouldn't recommend using your cooling fan(s) as an indicator of whether
your turbo is hot or not.

To try and help explain what is happening, your turbo uses the oil to
lubricate and cool the turbine bearings that tend to spin at extremely high
speeds. Yes, there is also water cooling in there which can help circulate
the heat away from the turbo even after the motor is off, but it's not in
the same direct contact with the hot bearings as the oil is. When a lot of
boost is produced by a turbo, it naturally ends up with more heat in the
bearings needing to be dissipated. When you turn your motor off, the oil
stops flowing. So, instead of distributing the heat into oil flowing
through the bearings, the oil sits in the bearings and pretty much gets
cooked by all that heat. The term used is "coking", which is your oil
forming deposits as it breaks down in the hot turbo. Eventually this can
lead to clogged oil passages, but even if they never clog entirely, would
you really want to decrease oil flow to your turbo?

I doubt it eliminates coking entirely, but synthetic oil tends to coke much
less. Also, consider having a turbo as severe service for your motor oil
and change it accordingly.

From all I've ever heard and read, letting the motor idle for 30 to 60
seconds before shutting it off should be sufficient to prevent coking under
most conditions. But, use your own judgement. If you were driving 30 mph
without producing boost for say a minute or more before parking, there would
be little reason to idle longer than about 10 seconds to give the turbine
long enough to spin down to it's idle speed, but if you just went up a steep
hill with full boost, sure, idle the motor before you shut it down.

All the turbo timer is going to do for you is keep the motor idling for a
specific amount of time after you take the ignition key out, somewhere
between say 30 seconds and 5 minutes, depending what you set the timer for.
If you have the money and don't like to idle the motor yourself, might be a
good investment, otherwise, is it really that big of a hassle to idle your
car for a minute before you shut it off?

Wikipedia has a more in-depth article on turbochargers, with pictures, if
you want further reading:

http://en.wikipedia.org/wiki/Turbocharger

~Brian

"AdvarP" <advarp (AT) hotmail (DOT) com> wrote

Great! Thank you for the info... Some timers even recognize if you drove
hard or not and idle the engine for the appropriate period of time. And shut
off the engine if you release the handbrake to prevent theft :-)\

Of course I meant the fan kicks in with A/C off, but yeah you are right.

Sometimes it IS a hassle for me to sit in the car waiting for a minute (I'm
a rather hectic guy) , so I guess a timer would do it for me..

Many thanks for the answer, now it is a bit clearer :-)



"strchild" <strchild (AT) hotmail (DOT) com> wrote

I honestly have NO idea :-( I can't get an engine manual for the 2.0l turbo
Forester unless I buy the factory one and I'm told that'll cost a lot for a
few pics i may need.

I suspect the timer won;t do any harm... will think abt it. I wonder if any
other Subaru GT owners have put timers on...

AdvarP wrote:
it at 100k. I had no problems with the timer, the turbo, the car.
It was just a bit un-nerving to walk away from the car leaving the
engine running.

It was concerning that when I drove to the supermarket and the timer had
the engine idling (using fuel)for the preset 90 seconds when I hadn't
been going fast enough for the turbo to kick in, let alone get hot. Most
of the time, when commuting or long distance, there was usually 5 miles,
10 miles, 5 minutes, 10 minutes of suburban driving which was sufficient
for the engine to cool down.

When I replaced with an 02 GT Legacy I didn't bother getting a timer.

Think about it............would Subaru (or any auto company for that
matter) sell you a vehicle which is going to cook the turbo every time
you switched off ????

Bugalugs wrote:

I think on modern subes, to increase longevity, I'd be less concerned
about a turbo timer BUT train myself to give the car 15 seconds of
idling before pulling away from a cold start AND avoid HAMMERING the
accelerator for 15 minutes/a few miles - till normal operating
temperature is reached.
Don't jump in your car in the morning, start it, slam it into gear and
start redline shifting it.
I suppose it isn't a bad habit to let it 'cool down' for a few seconds
if you parked it immediately after a freeway run - but a turbo timer is
probably un-needed by 99% of owners.

Carl


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