The Combine Forum banner

Fendt 920 trans filter problems

7K views 11 replies 3 participants last post by  Dieselpower1466 
#1 ·
I'm having problems with my 920 the filter contamination light coming on. I recently did a service on it and changed all the filters and oil. Shortly after that the filter contamination ligh came on. Changed filter again. Same thing changed the sensor and tested the wiring new filter a couple hours later light comes on again. When I cut the filters open they look clean except the outer paper layer looks "mushy". The hyd filter does not look that way just the trans. Any ideas?
 
#2 ·
Generally that is a sign of the brakes needing to be replaced as they are failing and contaminating the system. I would take one of the filters to the Fendt tech at the dealer and see what he thinks. If it doesn't appear to be actually plugged then look into electrical.

The hydraulic filter should have nothing to do with the trans filter, they are completely seperate systems with their own oil and filters.
 
#5 ·
4.1.50. Trans high pressure filter contaminated. I can't see any contamination in the filter at all. I just cut open the hyd filter to compare the trans filter to. I think we have ruled out electrical as being the problem. Is there any chance moisture could deteriate the filter?
 
#7 ·
The switch that is on top of the transmission filter housing should have a long finger that goes down into it. The way it works is simple. The filter plugs which increases the pressure and in turn moves a bypass valve up to let the dirty oil through. When the valve pushes up it uses a small magnet inside the top part under the spring to trigger the code.

You can change the filter half a dozen times and also replace the sensor but it will still think the filter is plugged. What you need to do is unplug the sensor, remove it from the housing, and take the small plunger out. Clean this piece with some brake clean or starting fluid and blow it off with compressed air.

What happens is the metal shavings in the oil work their way into the top part and stick to the magnet. Then even though the valve is closed, the metal triggers the switch anyway.

Let me know what you find. If needed I should be able to find some pictures in my service manuals that may help.
 
#8 ·
Ok I have a service manual. I already replaced the sensor, spring, and plunger. It ohms out correctly and the signal wire has 8v unplugged and the correct voltages when plugged in also. I will try cleaning the sensor again though and see what happens.
 
#9 ·
The next thing you can try is pulling the small drain plugs down by the brake housings. If your brake discs are deteriorating you will find metal shavings there. If memory serves it is a 5mm allen plug. The oil in this area must be drained when you do a transmission oil change, as it is trapped by the brakes because of the way the housings are setup. The trans oil spills into this area when you refill it, so pull the plugs out and drain a bit of oil into a canister and see what it looks like.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top