I got that clogged hydro filter light that stays on the display. Changed the filter and the sending unit but it still comes back on? Anyone know of anything else that can set this warning light off? If I remove the wire of the sending unit on the filter housing it doesn't come on. So that tells me that can't have a short. The wire is grounded also when the warning light comes on.
That's a pressure switch. If the light goes off when you disconnect the wire then the logical conclusion is that the switch is defective. The light comes on when the 499 Grey wire sees ground through the switch body. Suggest you replace the switch. Part Number is 7X-8549.
Yes that is the correct part number but I had the whole filter assembly replaced with a new switch on it. Besides a restricted filter I don’t get what could make the switch go off. Could any restriction in the hydro tank cause this? The machine doesn’t get hot just the warning light and the indicator for hydro filter goes off. The switch is grounded by the filter body assembly when the pressure rises at the filter.
How about some details of the oil you use in the hydraulics, and what filter you are using..? Did this problem develop suddenly or has it been building up for a while..? Lastly, was there some reason for replacing the whole filter housing rather than just the pressure switch..?
Using the same oil we used all the time 15-40 oil. The filter was the correct one from caterpillar. The problem just popped up recently never had the issue before. The pressure switch was replaced first then had bought the correct filter from cat but they ended up sending the whole filter assembly with the pressure switch again. So this would be the second new pressure switch and same issue. With the wire on switch disconnected warning light stays off just don't get what's making it come on with it connected?
As Nige says need more information, but on a completely different Cat loader back in I believe 2009/2010 I had a problem that appeared to be a plugged transmission filter switch intermittently acting up but after living with the problem for months found the problem to be a temperature sender going bad. Do I understand on this machine you can get the warning light to come on by grounding the #499 Grey wire but if the grey wire is removed the warning light always goes out? Also just to be sure did you post the serial number of the 950G?
Yes if I manually ground the grey wire to the frame warning light and indicator pic comes on like it's supposed to. If I remove the wire they go away all day. Once I put the wire back on the sending unit after some time the warning light comes back on. When My transmission indicator flashes i do replace my transmission filter and the light goes away for that. Only Serve code on monitor is engine oil temp sensor erratic but that's been on with no warning light buzzing.
I am still not clear on how this is behaving, and your mention of the transmission filter is only muddying the waters. Let's concentrate on the hydraulic filter warning. First - machine serial number please......... 1. With the machine running and the hydraulic oil at normal operating temperature, if you have the wire not connected to the plugged filter pressure switch and you connect it, does the plugged filter light come on immediately..? 2. If you have the wire connected to the plugged filter pressure switch and you install a new filter element, from first start-up is always on with the machine running..?
Don’t have serial # right now but the parts book being used is for AXX1-UP will post seriel # soon. When I had the new cat filter and new filter assembly with the new pressure switch the hydraulic warning light didn’t come on right away with the pressure switch wired up. After like 3 hrs the warning light beeped and the indicator flashed. When I took off the wire to make it stop beeping and put it back on the pressure switch the warning light didn’t come back on right away. The warning light just comes and goes randomly. This filter seems to be installed on the return side of the hydraulic oil so I can’t make of what’s making the switch ground out randomly even with a new filter installed. This machine has one oil line from the filter going to the tank and the other oil line comes from the hydraulic oil cooler with a one way check valve installed at the cooler and goes to the filter where it has a tee there for another small oil line. But this oil travels from the cooler through the one way check valve goes through the hydraulic oil filter and then goes through the other oil line at the filter back to the hydraulic oil tank.
Have you cut open any of the old filters that you have removed to check for debris in them..? It could be that the system is working exactly as it should do and that something somewhere in the machine is creating debris.
Sorry about muddying things with mention of transmission filter. My bad! Agree 100% on cutting open and inspecting old filters! If nothing else seems to help explain the problem would it be possible to Tee in a 30 psi pressure gauge to the port the sender is mounted in? Spec's for the 7X-8549 switch call for 16-20 psi to activate and it should deactivate at 12.5-15 psi. At least you would then be able to have a "second opinion" that the pressure is the problem and not a wire rubbed through and going to ground somewhere giving a false indication of plugged filter.
I did cut open one of the filters but didn’t see anything. Took a sample anyway just to send it in.
KSH's idea of installing a 30psi pressure gauge where the plugged filter pressure switch goes is a good one. It would let you see exactly how mush pressure you have in the return to tank line.
One more idea off top of my head. Would it be possible if the breather on the hydraulic tank was plugged for it to cause enough pressure in the tank to actuate the sensor? As it only needs to see 16 psi to turn on the warning light it might be possible. The tank is already under some pressure but not sure what the spec's are for those relief valves in the breathers. Most of the ones I ever dealt with were mounted on the side of the tank so dirt would just fall away. This one appears on top of the tank and could get dirt build up around it. I always made it a point to remove disassemble them and wash out the brass filters several times a season.
I will clean out the breather and look into installing pressure gauge. Also could it be also possible that the screen inside the tank might be plugged causing this issue? I see in the parts book there is like to screens inside the tank.
Where is the warning horn located so I can unplug it and see if the light comes off and on while operating. Also that file is the same loader because the breather is on top.
Best as I can tell from looking in parts breakdown and wiring schematics is it should be in the cab in the right rear corner as you are sitting in the seat. I know that is were the ones were located on some of the bigger machines I worked on. Might have to remove some panels to access it. It looks like this drawing from parts book: Not sure I would run machine too much with it unhooked because if there is something else going wrong you won't know it! This same warning alarm sounds for all serious problems.
A couple of comments: - 1. Without a Serial Number it's impossible for those of us who have online info to be sure we're looking at the same thing you are. 2. If you don't know the S/N how can you be sure the Parts Manual you have is the correct one for your machine..? Just sayin'. As a comment there are no less than 15 different Parts Manuals for 950G of different Serial Number prefixes. 3. I'm with KSH. You can disconnect the warning horn for a short test but remember it's the warning horn for everything related to the machine Monitor System. 4. If you have sent off an oil sample for analysis post the results when you get them. 5. If you went to the expense of buying a complete new filter head then I would personally buy a new breaker relief valve for the top of the hydraulic tank and have done with it. On loaders we used to replace those valves on a 2000hr PM. They suffer a lot more than you would imagine.
Not to belabor this point but with all the running changes Cat and others make on a machine the serial numbers is about the most important piece of information when looking for help and information, I as well as Nige try to push this point not just for you but the next guy who needs help. To go off on a tangent, which I tend to do too often. Just the other day on a walk-behind snow blower form a guy was asking how to change a belt on a ST824 machine(no, not a Cat). Well I looked up that number and found that the manufacture uses the same "sales" model for at least two very different machines! One had one belt to drive auger and the wheels and another that had separate belts for the auger and the drive wheels. Just imagine how upset this guy would be if I or someone else went into details on the project but it was for the wrong version on the machine! This also is an excellent idea, especially if like many machines the people taking care of them don't know the part even exists so it has been covered with six inches of dried mud for years! Also at times even Cat does not have engineers who have a good understanding of the conditions these machines work under. More than once I found it important to relocate a breather to get it to a place one could actually reach and not get buried in dirt and dust in the matter of a couple weeks,
PIN CAT0950GHAXX01087 model 950G
Have you replaced the breaker relief valve on the tank yet..?
Yes but no change the breather I got was 507-0646 cat# it didn’t have the push down to relief the air. But it had the same nipple to screw down on the tank. Parts book show a screen on the inside of the tank where the return line from the filter goes through the tank. Not sure if that screen could be plugged? Haven’t put a gauge on the sending unit either.
SIS does show the original breaker/breather 133-1963 changing over to the 507-0646. Not saying the return line screen can not be the problem but the screen in the return lines for most systems have fairly large holes in them. Now I could see if someone had worked on the machine and stuffed a rag in a fitting or line to keep dirt out and forgot to remove it before hooking up hose there could be enough in the screen to cause back-pressure. Getting to the return line screens means splitting the tank so I would eliminate everything else first! I still would recommend trying to test with an actual pressure gauge teed into the port the send er is mounted in just to know 100% sure you are seeing too much pressure there. Then I would be trying to move the pressure gauge from the inlet side of the filter to the outlet side of the filter. This will tell you if the pressure is high because of the filter or some problem in the tank. One more idea/question what filter are you using on this machine? I see you mention it was the "correct" one from Cat but what is the actual part number on it? The more information the better chance of an answer.
1g8878 cat filter the tranny filter is the same also. Also when that pressure switch alerts the operator that the filter is plugged. Does the oil bypass in that filter head to make up for the plugged filter?
One more thing the filter am seeing in parts book dosent show the big holes for the screen on the hydro filter return side. But the other screen inside the tank that goes to the pump I believe does show the big screen holes. That's why I was thinking the filter screen could be kinda plugged.
Removed the pressure sending unit on the hydraulic oil filter base and I am getting 20-21 psi at idle. And at high idle roughly around 24psi. I tried putting the gauge on the quick connect fitting near the pressure sending unit first to leave the sending unit connected but the pressures were not the same at that quick connect. Now am thinking the problem might be in the screen inside the tank?
An idea from left field. Could there be a loose piece of the inner liner of the hose between the filter and the tank that is restricting the flow and causing back pressure..? Another thing you could try is unscrewing or removing the tank cap as a test. That would be the last throw of the dice before pulling the tank apart, which iirc requires the tank to be removed from the machine. I haven’t looked at it for your machine but usually the return line has a baffle (cylinder full of big holes) in the tank rather than a screen to disrupt the flow as the oil returns to the tank. I’d be surprised if that was causing a restriction unless something has collapsed.
I have to apologize. It is a screen in the tank. Attached the parts breakdown for information. I think I would still look at the return hose from the filter housing to the tank to make sure it's not partially blocked inside before ripping the tank off the machine.
Even if the return flow has to go through a screen and not just a pipe with large holes in it something has to be plugging that screen! But I agree I would start it up with the gauge connected then loosen the cap to see if there is a drop in pressure. Just be ready if there is a rush of oil out of the tank! If that does not drop the pressure then check the return hose like Nige says, it might as well be the first thing off when getting ready to drop the tank. And please be sure to take lots of pictures of what you find. Both for your self and those of us here who are dying to know what the problem ends up being!
If that sender is reporting differential pressure across a filter, what difference does a restriction in the tank make? The pressure will just backup and the filter will show the same pressure on both the inlet and outlet ends of the filter housing. Find a way to put a gauge in both sides of the filter to see what you actually have and troubleshoot from there.
Wish I could see that pressure switch/Sender. Not sure if it is a differential pressure switch like say the 988H transmission filter we had at work or if it is just a straight pressure switch. Kind of sounds like a straight pressure switch because of the way the schematic refers to the open/close pressure and does not have the word "differential" in the specification. But then we all know what happens to those who "assume" anything. Lewis12, if you are reading this can you maybe post a picture or two of the switch to help us understand what it is for sure??
It's a straight pressure switch Ken, #2 in the illustration. It's plumbed into the filter inlet port and when the pressure in the incoming line rises high enough (as it would if the filter was plugged) it sets off the filter change warning.
That's what I was thinking but I was just responding in reference to John C's post. Trying to be positive about the way the thing works and not send someone down a rabbit hole trying to fix something that is not broke. After my experience with a certain 988H to say I don't trust Cat schematics or description of operation writings would be an understatement! At least my cheapness and stubbornness saved me from replacing an expensive ECM that was working perfectly despite what the tech expert at the dealer had said the problem was!
The switch could be a pressure switch but the manifold could be ported in such a way as to only show a differential. Filter restrictions I've worked on in the past were always set up to show differential across the inlet and outlet. What does the schematic show?
Not much John. It doesn't even show the pressure switch although other pressure switches (e.g. brake accumulator pressure) are shown. #61 is the hydraulic filter, I assume HH is the test port that the OP mentioned earlier.
NIGE your solution is always good....but a properly sized piece of black tape over the light is better for u guys....win win so to say...you get to really fix it...and he doesnt see the.light lol
Personally I'm hoping that it is something inside the return line between the filter and the tank, because removing the tank in order to disassemble it in order to get at the return screens is not an easy job.
The HH is the oil sample port. I was looking into the schematics myself but got called away to visit Grandson in Hospital, appendix operation yesterday, only five years old and not a happy camper, but doing OK. E3 is the location in the schematic drawing in case anyone is wondering!
The service Manuel appears to show the pressure setting of the hydraulic oil filter bypass valve to be at 25psi. So does this mean when the pressure at the pressure switch on the filter housing reaches 25psi it sets of the hydraulic filter plugged warning light? Before I think about opening the hydraulic tank I do see the screen in th3 tank does have big holes which would be hard to plug up. So instead I am looking into first flushing out the tank and adding new oil and new filter. I think the oil may have a little containmintion and need to be replaced. Because when I had the wire connected and buzzer disconnected the light wouldn’t always be on but when it would come on it would come and go. But sometimes stay on for like 10 min then go away.
Update i got the light to go away. The hydraulic fan motor stopped working so the machine got hot. Once I replaced the hydraulic fan pump with the new one I also drained the hydraulic tank and added new oil. Now the hydraulic filter indicator on the monitor with the tattle tail lights doesn’t come on and everything is functionaling normally. Not sure if the pump was causing the issue or if the draining and adding of the hydraulic oil fixed the problem but it’s work8ng now. I really think it was probably the oil being contaminated in the tank. But anyways just wanted to make an update.
Very interesting that repairing an over heating problem solved a plugged filter indication problem. If you go way back to my #5 post you can see that the machine I was chasing a similar problem with was fixed once I stumbled on the fact that I had a bad temperature switch sending in my case a false over heating message to the ECM! Not sure what to make of this as it would probably take talking to who ever designed the warning panel in these machines to understand how this could happen. Could be just one of those times you have to just be happy the "problem" is gone and just live with it.
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