Transmission (auto) grinding while in gear

J

justfixedthat...

TJ Enthusiast
Joined
Jan 20, 2020
Messages
152
Location
Texas
2002 TJ 4.0
I first noticed it at red lights. A grinding/rattling sound coming from beneath me that disappears when I go into neutral. And it's not noticeable when I'm driving, probably drowned out. I've been leaking ATF for a while but I thought it was just a bad pan seal and now it has low ATF, but I put fluid in it and it still grinds. Am I looking at a new transmission or something I can fix in my driveway? FYI I don't want to drop and rebuild my transmission in my driveway.

Thanks for any advice
 
Cant say Ive ever heard a auto trans "grind",but I suppose a disintegrating converter would do it. Does it still shift/work correctly? Can you tell exactly where is the leak coming from? Have you tried letting it idle in gear,E brake on and wheels blocked or have somebody hold the brakes on and climbing underneath to try to pinpoint the noise? May be a rattle from something else,exhaust,cat or ?? and not the trans.
 
How are you checking the ATF level? The engine must be running and the transmission must be in Neutral while checking it with the dipstick. It's far better for it to be slightly overfilled than be slightly underfilled by even a little. Make sure you only add ATF+4! No other type of ATF is correct!
 
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Gilaguy23 said:
Cant say Ive ever heard a auto trans "grind",but I suppose a disintegrating converter would do it. Does it still shift/work correctly? Can you tell exactly where is the leak coming from? Have you tried letting it idle in gear,E brake on and wheels blocked or have somebody hold the brakes on and climbing underneath to try to pinpoint the noise? May be a rattle from something else,exhaust,cat or ?? and not the trans.
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I say it's the transmission because it doesn't grind when I put it in neutral. But, when I start it and shut if down, for a split second I hear a bad grind as well so it must not be the transmission and I should have figured that out myself...
It shifts/drives fine. I hear it grind at red lights until I start driving.
The ATF seems to be coming out of the rear of the pan because it's tilted back. That's why I thought (hoped) it was just the seal/loose bolt.
I have crawled under there while it's in gear but I can't quite pinpoint the noise. I'll try that again.
I shouldn't have used the word "rattle" it's definitely a grinding sound. Would I hear a disintegrating converter upon starting/stopping the engine?
When I start/shut down, the sound is only there for a split second, very similar to someone shifting a manual trans and missing the gear. Then the sound goes away except for later at red lights, fast food lines, etc. Again, it disappears in Neutral.
 
Jerry Bransford said:
How are you checking the ATF level? The engine must be running and the transmission must be in Neutral while checking it with the dipstick. It's far better for it to be slightly overfilled than be slightly underfilled by even a little. Make sure you only add ATF+4! No other type of ATF is correct!
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I did notice the other day when I started up and put it into gear, the Jeep wouldn't quite 'giddy up' without a little gas, which told me it was low on ATF. And after putting more in ATF today the grinding has lessened so it seems the sound was is indeed the transmission and hopefully it was just low. Thanks Jerry.
 
justfixedthat... said:
I did notice the other day when I started up and put it into gear, the Jeep wouldn't quite 'giddy up' without a little gas, which told me it was low on ATF. And after putting more in ATF today the grinding has lessened so it seems the sound was is indeed the transmission and hopefully it was just low. Thanks Jerry.
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Good, just be sure to check it's actual/real ATF level as described above. It can't be checked accurately unless done while the engine is running and the transmission is in Neutral.
 
Perhaps the guys will chime in on this, but I had a flex plate crack apart on one of my Ram diesels. It rubbed on the bell housing and you could feel it in the floor board when sitting in it. I dont think its very common on TJ's but who knows. On the other hand Im thinking in N the converter is free wheeling a bit easier so to say, but once in gear there is more of a differential in rpm's of inner vanes and outer shell. Just a far off thought. It may be a PITA but worth dropping the pan to see what kind of metal if any is in there. If the fluid and pan is clean at least you can install a new pan gasket if nothing else.
 
justfixedthat... said:
Please elaborate. Where would I find these bolts?
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They're in the very front of the transmission where they face forward and are what holds the transmission's input shaft to the engine's crankshaft. Their bolt heads have to spin inside a very shallow area so their bolt heads have a very low profile. That's why if one of them backed out it could cause a racket.
 
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