Checking ZF trans oil level

[steveadil]

New owner here so please indulge a dumb question: when I pull he dipstick to check trans fluid I get one reading. When I put it back in and read it again it's always higher. It seems like there's pressure that gets released when I pull the stick.

Which reading is correct? Has anyone else experienced this?

Many thanks!

 

[fwebster]

Each transmission make and model has a specific procedure for checking the oil level. For example, I have had to replace one transmission……the replacement is the exact same type, both ZF, only a later version and I have to check mine warm, one with the dip stick inserted all the way; the other is checked warm with the dip stick threads just making contact and not inserted.

You might get a more precise answer if you post the make and model of your transmissions. Generally, however, always check your gear oil after running when the transmissions are warm and if you have an expandable rubber plug on the dip stick, the fluid is checked with the plug all the way inserted in the dipstick tube. Transmissions have oil pumps, oil coolers and fluid lines in them so checking cold can give erroneous readings because the oil usually partially drains back out of the pump, coolers, etc. and into the gear case while the engine is sitting and not running.

 

[steveadil]

Frank, thanks for the input - I have since contacted the po and he told me to check after shutting down and after releasing the pressure. Another question: are there simple causes for mushy engagement? Both transmissions engaged with a positive bump but now there is no detectible engagement on the port side. The oil looked dirtier than the starboard. There is no slippage, just the mushy engagement. They are IRM-301M's.