Home » Public Forums » GMCnet » [GMCnet] tranny dipstick calibration
| [GMCnet] tranny dipstick calibration [message #186013] |
Sun, 30 September 2012 18:41  |
KB
Messages: 1262
Registered: September 2009
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I'm trying to figure out how to effectively calibrate the tranny
dipstick. I've seen a few different approaches, the easiest seeming
to be pulling the vacuum modulator and filling the tranny until fluid runs
out the hole, replace the modulator, then marking the dipstick "full" line
at that level. I assume we also need the tranny pan level in order to do this right.
My questions though: does the tranny have to be hot
(ie, just driven) and does the engine have to be running
while checking this? Can I pull the modulator before starting
the engine, start the engine to fill the torque converter, add fluid
until it flows out the modulator hole, then mark the "add" (cold)
line on the dipstick instead?
I'm really not looking forward to lying in close proximity to
the underside of a hot, running, engine in order to reach the modulator...
Details on how to do this safely and correctly would be greatly appreciated.
thanks
Karen
1973 23'
1975 26'
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1975 26'
San Jose, CA
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| Re: [GMCnet] tranny dipstick calibration [message #186020 is a reply to message #186013] |
Sun, 30 September 2012 19:56  |
armandminnie
Messages: 864
Registered: May 2009
Location: Marana, AZ
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| KB wrote on Sun, 30 September 2012 16:41 |
I'm trying to figure out how to effectively calibrate the tranny
dipstick. I've seen a few different approaches, the easiest seeming
to be pulling the vacuum modulator and filling the tranny until fluid runs
out the hole, replace the modulator, then marking the dipstick "full" line
at that level. I assume we also need the tranny pan level in order to do this right.
My questions though: does the tranny have to be hot
(ie, just driven) and does the engine have to be running
while checking this? Can I pull the modulator before starting
the engine, start the engine to fill the torque converter, add fluid
until it flows out the modulator hole, then mark the "add" (cold)
line on the dipstick instead?
I'm really not looking forward to lying in close proximity to
the underside of a hot, running, engine in order to reach the modulator...
Details on how to do this safely and correctly would be greatly appreciated.
thanks
Karen
1973 23'
1975 26'
_______________________________________________
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http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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I think the process is to get the tranny warmed up, park the coach and shut it off, and then pretty quickly drain the fluid from the modulator opening before the torque converter drains down. Just the oil that comes rushing out - don't let it drain. Somewhere near level would be good.
Armand Minnie
Marana, AZ
'76 Eleganza II TZE166V103202
visit my gmc blog
click here to visit gmcws.org
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| Re: [GMCnet] tranny dipstick calibration [message #186038 is a reply to message #186013] |
Mon, 01 October 2012 03:39 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
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| KB wrote on Sun, 30 September 2012 16:41 |
I'm trying to figure out how to effectively calibrate the tranny
dipstick. I've seen a few different approaches, ...
...
My questions though: does the tranny have to be hot
(ie, just driven) and does the engine have to be running
while checking this? ...
|
My thought on this do not seem to match what most think, but I'll explain my thinking.
While checking the fluid level "normally," you DO need to have the transmission, and fluid, hot. BUT if all you want is to know where on the stick is the LEVEL that is considered "good" it can be done hot or cold. If you are going to change the fluid and filter, why not calibrate the dip stick while you are at it?
Place the coach where you can get to the transmission while the coach is level. With the engine off, wait long enough to ensure the fluid has drained out of the torque converter. Check the level on the stick, it should be well above the "full" mark.
Put something under the modulator to catch the fluid and pull it. When the fluid stops draining from the modulator hole, the level is level with the bottom of the modulator hole. This is the proper level for the fluid. Check the fluid level on the dipstick... this is your "new" full mark.
Drain the fluid pull the pan and replace the filter. Reinstall the pan, and fill the transmission with new fluid... then you need to check it on level ground, HOT, idling in park but using your "NEW" full mark.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] tranny dipstick calibration [message #186092 is a reply to message #186013] |
Mon, 01 October 2012 14:51 |
KB
Messages: 1262
Registered: September 2009
Karma: 0
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Senior Member |
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> My thought on this do not seem to match what most think, but I'll explain my thinking.
>
> While checking the fluid level "normally," you DO need to have the transmission, and fluid, hot. BUT if all you want is to know where on the stick is the LEVEL that is considered "good" it can be done hot or cold. If you are going to change the fluid and filter, why not calibrate the dip stick while you are at it?
>
> Place the coach where you can get to the transmission while the coach is level. With the engine off, wait long enough to ensure the fluid has drained out of the torque converter. Check the level on the stick, it should be well above the "full" mark.
>
> Put something under the modulator to catch the fluid and pull it. When the fluid stops draining from the modulator hole, the level is level with the bottom of the modulator hole. This is the proper level for the fluid. Check the fluid level on the dipstick... this is your "new" full mark.
>
> Drain the fluid pull the pan and replace the filter. Reinstall the pan, and fill the transmission with new fluid... then you need to check it on level ground, HOT, idling in park but using your "NEW" full mark.
>
Good thinking! It's only the level of the hole that matters, relative
to the dipstick. The actual measurement still has to be done hot, but
we'd at least know what that level should be on the stick. thanks!
I'm not pulling the pan again. This is a freshly rebuilt tranny done
by the master. We're having trouble going into gear sometimes, which
is most likely a fluid level problem, hence my questions.
On further measuring, the levelness of the coach is a lot more
important than we thought. The dipstick is in the front corner of the pan.
If the coach (and hence pan) are out of level by only two degrees, the level
will be off by the better part of 1 pint. I've also found our '75 coach
dipstick is at least 1/4" longer than our '73 coach stick, measured from
cap to marks. I don't know if the dip tube is also different, but
that 1/4" would mean another 1/2 pint error. Add it up and pretty soon
you're talking a lot of fluid. I wonder how much low (or high) is too much.
The manual cautions against over filling, so I think we've been running
chronically low by being too paranoid and measuring when insufficiently level.
Makes me wonder if the level front to back is as critical as left to right,
or if they took into account the typical nose-up attitude of the coach.
thanks
Karen
1973 23'
1975 26'
_______________________________________________
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Karen
1975 26'
San Jose, CA
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