Transmission fluid question. - JeepForum.com

 
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post #1 of 6 Old 01-30-2016, 10:36 PM Thread Starter
blu3fan
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1992 XJ Cherokee 
 
Join Date: Jun 2008
Location: california
Posts: 128
Transmission fluid question.

Hey guys.
So I am almost done rebuilding my whole engine.
And I came across something a little worrying....
I have a 92 Laredo. 6-4.0
automatic with the xfer case. and the transmission lines run from the side up to the radiator.
When I pulled the lines off there was no fluid. I expected it to leak everywhere.

The radiator was new. (2years)

Ive put close to 25k on since the transmission was replaced by P.O. with receipts from a shop. (sure its bytime I changed the fluid and filter)
but it has been 10 years since that was done (yes don't laugh at me for putting 25k on a car Ive owned for almost 10 years)

I know when I pulled the motor years ago the old radiator leaked fluid everywhere.

automatic Transmissions. I know very little about.
I'm assuming there would be a pump of some sort
Anyone else ever ran into this ?
No transmission problems at all prior to rebuild of engine.
Fluid levels are good as well.

Any suggestions.
I mean it hadn't given me a problem until now those lines could have been empty for a while its been driven for 2 years since the rad swap. But it is something I believe needs to get fixed.
Any info would really be helpful.

My best guess is one of a 3 things. but correct me if Im out of the ball park on any of them.
Blocked filter
blocked line (I replaced the lines 6 years ago)
blocked radiator


Thank you.


jeepstroker moneypit
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post #2 of 6 Old 01-31-2016, 11:34 AM
ECL
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1998 XJ Cherokee 
 
Join Date: Dec 2005
Location: Easton
Posts: 490
Simplified answer:
An automatic transmission has a pump. It is usually located inside the casing, right behind the torque converter. You don't have access to it from the outside. It only pumps when the engine is running. It draws fluid from the pan on the bottom of the transmission casing, sends it to the cooler in the radiator and then to the bands in the transmission via the valve body. Pressure on the various bands force their respective clutch packs to engage, which effectively "engages" the various gears.

So, when you pull a trans cooling with engine off, you SHOULD get a LITTLE fluid - there is usually a check valve in the valve body that prevents all the fluid from running back to the pan when the engine is off. The cooler in the radiator is a little higher the the cooling lines so gravity will push some out. If none comes out, don't freak out. The check valve ( basically a little metal ball in the trans valve body with a spring behind it) might be just getting a little "lazy" after all these years and has allowed all the fluid to run back into the pan. Don't freak but it is something to note.
Check the fluid level on the trans dip stick. I have a manual trans in mine so I don't recall the specifics for a Cherokee but generally this should be done engine running and up to operating temperature (fluids expand when they get warm - check it cold it will show low). Since you are finishing a rebuild, I'd just check to see that there is fluid on the dipstick. Maybe put a half pint in just to cover what probably got lost somewhere along the way, and the continue initial startup. Check again once the motor is warmed up and before you drive somewhere.
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post #3 of 6 Old 01-31-2016, 11:40 AM
ECL
Registered User
1998 XJ Cherokee 
 
Join Date: Dec 2005
Location: Easton
Posts: 490
Simplified answer:
An automatic transmission has a pump. It is usually located inside the casing, right behind the torque converter. You don't have access to it from the outside. It only pumps when the engine is running. It draws fluid from the pan on the bottom of the transmission casing, sends it to the cooler in the radiator and then to the bands in the transmission via the valve body. Pressure on the various bands force their respective clutch packs to engage, which effectively "engages" the various gears.

So, when you pull a trans cooling with engine off, you SHOULD get a LITTLE fluid - there is usually a check valve in the valve body that prevents all the fluid from running back to the pan when the engine is off. The cooler in the radiator is a little higher the the cooling lines so gravity will push some out. If none comes out, don't freak out. The check valve ( basically a little metal ball in the trans valve body with a spring behind it) might be just getting a little "lazy" after all these years but it is something to note.
Check the fluid level on the trans dip stick. I have a manual trans in mine so I don't recall the specifics for a Cherokee but generally this should be done engine running and up to operating temperature (fluids expand when they get warm - check it cold it will show low).
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post #4 of 6 Old 01-31-2016, 11:43 AM
ECL
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1998 XJ Cherokee 
 
Join Date: Dec 2005
Location: Easton
Posts: 490
Well I messed that up! Ignore the second posting - sorry! ...
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post #5 of 6 Old 02-03-2016, 07:05 PM
wyowalsh
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1999 XJ Cherokee 
 
Join Date: Sep 2015
Location: casper
Posts: 106
I would just get it all back together and see what happens, definitely drop the pan see how it looks replace screen and pan gasket and service the ATF . run it and see......
you may be ok.
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post #6 of 6 Old 02-03-2016, 09:43 PM Thread Starter
blu3fan
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1992 XJ Cherokee 
 
Join Date: Jun 2008
Location: california
Posts: 128
Started her up for the first time. And Lo and behold fluid came out. on the rad side.
Im going to monitor it. But it is possible somethig is blocking the filter So I am going to do a transmission fluid+filter change

jeepstroker moneypit
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