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Transmission getting hot, slipping in overdrive.

SKNOT9

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Hi guys. Just recently i went on a long trip with the vs. About 2 hours into the trip going 110km/h in 4th gear with cruise control, all of a sudden the car starts revving out to 6500 rpm! pulled over and checked the fluid while it was still running, and it was boiling (bubbles all up the stick). Let it cool down and went out on the road and i saw the revs start to creep up again about 5 minutes later, so i ended up just driving in third gear and then it was fine. my car has only done 95000kms so its hard to believe the tranny is stuffed, i have checked error codes and there are none. Im wondering, is the transmission getting hot, and causing it to slip, or the transmission is slipping, causing it to get hot. Around town the trans feels perfectly fine, but i checked the fluid last night after a half hour of city driving and it was boiling again! anyone know what is going on? fluid is slightly brown but still reasonably clear.
 

hako

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It may not be boiling - it may be frothing due to being low or overful. If it was overheating it should have left a fault code. Are you sure the engine actually revved to 6500-----they should not rev this high as there is a limiter fitted I think from memory that stops it at about 5500rpm. I'd take it to a transmission specialist and get a service done on it - get the oil flushed and the filter changed - flushing is more expensive but replaces all the fluid. May cost about $220. Hopefully that's all it needs.
 

SKNOT9

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haha yeh the 6500 was a bit of an overstatement, it was on the limiter i should have said. I have checked the fluid when it is at normal temp and it is perfect, sitting on the hot. But when i checked it when i believe it was boiling, was half way up the stick and was frothing.
 

VR38

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Maybe it is the wrong fluid?
 

hako

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It would have to be frothing - if the fluid was boiling the temperature would have to be in excess of the boiling point of Dexron3 which is 315 degrees which is very very hot - over 3 times the boiling point of water. The frothing would have aerated the fluid which then cannot act as a hydraulic fluid as it is now compressible.
 

CRCinAU

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Contaminates? Any chance of water getting into it? Maybe pull the pan off, replace the filter & seal and put new fluid of the correct type in there and see what happens... It shouldn't froth at all - so either way, something is up with it. Also, while you have the pan off, clean up the magnet in there...
 

1SIKR8

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so it only does it in over drive? was just thinking in earth moving you test the slippage of the tranny by stalling it out ( putting the brakes on as hard as you can, put into drive and put the throttle at %100 ) you take note of the engine RPM and ( hopufully there in there ) compair to specs in the workshop manual, if the revs are above spec, its slipping.

but thats just what we do in earth moving, dunno if its the same for cars ?
 
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