843 Question

[bigmackerel1]

Have to remove the pressure/temp sensor under left seat. It has three wires, yellow/blue & yellow (yellow terminal is broken off at post) My question is, if I unscrew the sensor is it under hyd pressure with the engine turned off? Or, do I have to do something else. This is a great Forum, Great people, enjoy reading every message.

 

[7LBSSMALLIE]

no it is not under pressure. but tank is elevated so you will have drainage.

 

[donald73d]

Its not under pressure with engine off. I just replaced mine. What symptoms are you having? Does the hour meter still work? Does the trans warning light come on with key on engine off? Have you replaced the bulbs for oil and transmission warning lights? Is it towards the outside or kind of in the middle, just a little to the side? I have an 843B with Isuzu engine. If you have an 843 it might be slightly different. If the sender has 2 contacts (not wires, but contacts) its the pressure switch. If it has one contact its the temp switch. The pressure switch has a NO and a NC contact. They need to go back correctly. There is another "hydraulic filter plugged" sender in the engine bay, next to the very large hydraulic filter in the engine bay.

 

[bigmackerel1]

Its not under pressure with engine off. I just replaced mine. What symptoms are you having? Does the hour meter still work? Does the trans warning light come on with key on engine off? Have you replaced the bulbs for oil and transmission warning lights? Is it towards the outside or kind of in the middle, just a little to the side? I have an 843B with Isuzu engine. If you have an 843 it might be slightly different. If the sender has 2 contacts (not wires, but contacts) its the pressure switch. If it has one contact its the temp switch. The pressure switch has a NO and a NC contact. They need to go back correctly. There is another "hydraulic filter plugged" sender in the engine bay, next to the very large hydraulic filter in the engine bay.

donald73d. Both red lights work (Oil & Temp) temp light comes on at low idle, but goes off when I increase throttle, has Perkins engine. I was power washing the inside, getting ready to change the chaincase oil. I noticed the yellow wire going to pressure sensor was pulled away from post. The slotted screw was rusted and I was unable to unscrew it. I will remove the sensor and try to get the screw out, if not, I will go Bobcat and buy another one. When I get rid of all of the Crud inside, I might find more items like you stated. This 843 works great, just TLC. I will keep you posted. Great Forum, Great people. Thanks to all of you for the help.

 

[donald73d]

donald73d. Both red lights work (Oil & Temp) temp light comes on at low idle, but goes off when I increase throttle, has Perkins engine. I was power washing the inside, getting ready to change the chaincase oil. I noticed the yellow wire going to pressure sensor was pulled away from post. The slotted screw was rusted and I was unable to unscrew it. I will remove the sensor and try to get the screw out, if not, I will go Bobcat and buy another one. When I get rid of all of the Crud inside, I might find more items like you stated. This 843 works great, just TLC. I will keep you posted. Great Forum, Great people. Thanks to all of you for the help.

OK, I looked on the schematic. The all yellow wire attached to the trans charge pressure switch under the cab is for pressure. Does the trans light come on with key on, engine off? Have you changed the large hydraulic filter in the engine bay? I think the light you are seeing is a filter clogged light. The trans charge pressure is not in the circuit with the yellow wire not connected. These senders ground to complete the circuit. I would also suggest you remove the seat, even if you snap the bolts, they can be replaced. EBAY has nice seats at a decent price. Under the seat tends to collect stuff that stays wet and rusts that area. You find all kinds of odd things under the seat. One guy found a live bullet. Clean the area and treat for rust and repaint.

 

[donald73d]

OK, I looked on the schematic. The all yellow wire attached to the trans charge pressure switch under the cab is for pressure. Does the trans light come on with key on, engine off? Have you changed the large hydraulic filter in the engine bay? I think the light you are seeing is a filter clogged light. The trans charge pressure is not in the circuit with the yellow wire not connected. These senders ground to complete the circuit. I would also suggest you remove the seat, even if you snap the bolts, they can be replaced. EBAY has nice seats at a decent price. Under the seat tends to collect stuff that stays wet and rusts that area. You find all kinds of odd things under the seat. One guy found a live bullet. Clean the area and treat for rust and repaint.

The two lights you have are "engine oil pressure" and "hydraulic oil temp and/or hydraulic oil filter clogged and/or hydraulic charge pressure". For the hydraulic it can be any or all.

 

[Fishfiles]

The two lights you have are "engine oil pressure" and "hydraulic oil temp and/or hydraulic oil filter clogged and/or hydraulic charge pressure". For the hydraulic it can be any or all.

I have not had to work on an 843 in a long time , but from what I remember I would think that if the light is on at idle and goes off when rev'ed then the light must be for the charge pressure and not the temperature .....

 

[bigmackerel1]

The two lights you have are "engine oil pressure" and "hydraulic oil temp and/or hydraulic oil filter clogged and/or hydraulic charge pressure". For the hydraulic it can be any or all.

Will be out of town for many days, will get back to you. Thanks for the help.

 

[donald73d]

Will be out of town for many days, will get back to you. Thanks for the help.

My point is if you do not know the history of the maint. then change all filter especially the hydraulic oil filters. Fix the one sender where the connector is off the screw and see where you are.

 

[7LBSSMALLIE]

My point is if you do not know the history of the maint. then change all filter especially the hydraulic oil filters. Fix the one sender where the connector is off the screw and see where you are.

843 had three senders 1TEMP 2pressure differantial(clogged filter) and charge press. eisest way is to follow scchematics. detirmene which. is setting light.most likley a sender but if you have (actual low charge) it needs to adressed sooonest. or loo.ssing the unit. stop and think .before you shoot youre foot. (change the filter) eximne the oil that comes out.no shiny stuff. ground temp wire does light go out? and always put guage in and check charge press. could probally be bumped up to high side of spec. 843 old wear in stat and motors is going to decrease flushing and cooling, so ,change hyd oil. replace hyd filters including case drain every 1000. hrs 3 senders on hyd 1`(temp) 2press differantial.(indicating clogged filter) 3 low charge. charge can be shimmed to increase press,(springs get worn) i hope this helps and does not add to youre worrys.

 

[donald73d]

843 had three senders 1TEMP 2pressure differantial(clogged filter) and charge press. eisest way is to follow scchematics. detirmene which. is setting light.most likley a sender but if you have (actual low charge) it needs to adressed sooonest. or loo.ssing the unit. stop and think .before you shoot youre foot. (change the filter) eximne the oil that comes out.no shiny stuff. ground temp wire does light go out? and always put guage in and check charge press. could probally be bumped up to high side of spec. 843 old wear in stat and motors is going to decrease flushing and cooling, so ,change hyd oil. replace hyd filters including case drain every 1000. hrs 3 senders on hyd 1`(temp) 2press differantial.(indicating clogged filter) 3 low charge. charge can be shimmed to increase press,(springs get worn) i hope this helps and does not add to youre worrys.

All three senders supply ground. Grounding the temp wire will always turn on the bulb assuming no wiring problem or burned out light.

 

[7LBSSMALLIE]

All three senders supply ground. Grounding the temp wire will always turn on the bulb assuming no wiring problem or burned out light.

sounds like you have done the homework, so which one is it can we isolate?

 

[donald73d]

sounds like you have done the homework, so which one is it can we isolate?

I think we kind of have isolated it. Get the wire connected back to the hydraulic charge pressure switch. What about filter maint? Then does the hour meter work? Does the trans light come on with key on, engine not running. Either of those would point to hydraulic charge pressure switch.