Not dealing with Series I'm afraid, but this subject was discussed awhile
back so I thought those of you with Range Rovers might be interested. Some
time ago there were some comments about the tendency of ZF automatic
transmissions to damage their clutch packs when revved up in Park, say
during an emissions test. Apparently, the transmission can develop a fault
which prevents the fluid from draining out of the clutch packs when the
transmission is shifted from Drive into Neutral or Park. Or at least
draining completely out.
Several people who know more about these things than I said the solution
they use is to shift the transmission into Park, switch off the engine for
a minute or so, which apparently allows the fluid to drain from the clutch
packs, and then re-start the engine. As long as the transmission is not
put into any gear, which I guess fills the clutch packs with fluid again,
the engine can be revved without endangering the packs.
Incidentally, the owner of the shop that works on my BMW told me today that
BMWs of the same era, which use basically the same ZF transmission, can
develop exactly the same problem.
Well, I had to take our '91 Range Rover through an emissions test today,
and being mindful of the discussion on this list, I intended to use the
"switch off the engine" process even though we have so far had no
indication of any problems with our transmission. But better safe than
sorry. Given the "follow the rules no matter what" attitude at places like
emissions test centers, I figured this would give the testers fits and I'd
have to explain over and over why I was doing what I was doing.
But it dawned on my that there was a much easier way. The Range Rover,
unlike a BMW car, has a transfer case. The solution seemed so simple to
me, there's probably something wrong with my reasoning.
When I was in position in the test bay (after explaining to the testers why
a full-time 4wd vehicle couldn't be put on their rolling road), I put the
transmission in neutral, not park, and put the transfer case in neutral.
So now, if the transmission had by chance developed this no-drainback
problem, it wouldn't matter. Since the transmission was in neutral, not
park, the clutch packs were free to spin up with the engine if they were
inclined to do so. But since the transfer case was in neutral as well,
there would be no resistance against the packs, even with the parking brake
applied.
No need to switch off the engine, no need to argue with the emissions test
people. When one of them told me to put the transmission in Park not
neutral, I simply told him I couldn't do that in this vehicle and rev the
engine, and that was the end of it. The downside is you have to sit there
during the test and listen to the transfer case neutral alarm the whole
time.
After the rev part of the test was over and the gearbox had settled back
down, driving away was just matter of pulling the transfer case back into
high and shifting the transmission to drive.
________________________
C. Marin Faure
(original owner)
1973 Land Rover Series III-88
1991 Range Rover Vogue SE
Seattle, WA
marin.faure@boeing.com
faurecm@earthlink.net
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