Caterpillar 315c Hydraulic problem

[truecountry]

I'm really at wits end on this one Serial number is cjc01986
I get a call last week 315c had quit moving while digging ..15 mins later it would move but only for a few secs
When I get there it will not do nothing (engine runs no change in sound of engine moving hydraulic shift level ) I check fuses and all good I changed relays around and still nothing
I called and ordered a micro switch that is screwed to shutoff level ....repleaced them the next day still nothing ..Called Cat service Department and was tolded to check for voltage at solenoids System voltage is what I'm looking for and had 28 volts ...then I was tolded Top is lock out middle is swing third is travel all same part numbers so I can switch them around see if anything changes still nothing ...........I call Cat and have a tech come out next day
This is what puzzles me pilot pump is good psi 550 main pumps good 5800 and 5850
Now this is only thing he check and said Hey for ****s and giggles crank it up and see if she moves IT DID ...wtf....He hooked his computer up aND no codes...he did notice voltage a lil high and checked alternator 38.6 volts wow this is got to be it ...I unhooked alternator wire ( didn't want batteries or computer fried and loaded it on trailer got it to shop unloaded it and ordered a new alternator ...
Now after it was installed it ran 1 hour and stopped same thing ( voltage is 27.4 good )
Call Caterpillar back up and was tolded to check check valve in solenoid block for trash in lockout , swing ,travel block nothing .....
I know voltage is right I see it on meter I see nitro filled accumulator line move when level is moved down ..pressures are same on pilot and mains ..
Any thought on if it is trash where to look next
Are there any orfice fitting that could get plugged with trash ?
I under stand how this is designed level shut off hydraulic electric signal to solenoids but I cant see what hoses go to what and where before it goes to pilot pump

 

[Cmark]

On the pilot solenoid manifold there will be a hose to a port marked PIN. That is the line in from the pilot filter. You can check this pressure at the port marked P1.

The hose to the port marked PSA1 is the hose out to the pilot controls in the cab. You can check this pressure at the port marked PSA2. If you are getting pilot pressure here when the safety lever is in the operate position, then you should be getting pilot pressure at the pilot controls. As far as I can see, it is a straight run to a manifold under the cab which just splits the flow to the left, right and travel controls.

 

[truecountry]

On the pilot solenoid manifold there will be a hose to a port marked PIN. That is the line in from the pilot filter. You can check this pressure at the port marked P1.

The hose to the port marked PSA1 is the hose out to the pilot controls in the cab. You can check this pressure at the port marked PSA2. If you are getting pilot pressure here when the safety lever is in the operate position, then you should be getting pilot pressure at the pilot controls. As far as I can see, it is a straight run to a manifold under the cab which just splits the flow to the left, right and travel controls.

Got to work this morning and it cranked and ran fine .............igot ghost somewhere

 

[truecountry]

I don't know how to check but I think the accumulator is bad ....Once today while working it I stopped and locked and unlocked lever to engage hydraulics and it messed up once

 

[Cmark]

A faulty accumulator wouldn't cause the problems you're having. Its job is allow the implement to be lowered in the event of engine failure. It sounds more like you've got an intermittent electrical problem.

 

[truecountry]

Ok please explain engine runs but even off I couldn't lower implements with key on engine not running still didn't move....Hmmm Now Thinking ecm overcharged by alternator ?

 

[truecountry]

I can heard solenoids thump when I move lever and everything moves when I hear no thump nothing moves but I have 26 to 27 volts on the solenoid wire ....My caterpillar dealer has said it has to be broken down to fix ...not sending no one out now ...His Quote was ...Hmm How do I tell a tech it will work and don't sometimes ...My quote as I tolded him what am I paying u for?

 

[Cmark]

Ok please explain engine runs but even off I couldn't lower implements with key on engine not running still didn't move....Hmmm Now Thinking ecm overcharged by alternator ?

If the engine stops, the accumulator does the job of the pilot pump and provides pilot pressure for a short time to allow the implement to be lowered. If it's faulty it won't affect the operation of the machine at all while the engine is running.

I can heard solenoids thump when I move lever and everything moves when I hear no thump nothing moves but I have 26 to 27 volts on the solenoid wire ....My caterpillar dealer has said it has to be broken down to fix ...not sending no one out now ...His Quote was ...Hmm How do I tell a tech it will work and don't sometimes ...My quote as I tolded him what am I paying u for?

So you've got 26-27V to the solenoid, but have you checked the ground wire as well?

 

[truecountry]

No sir its a cluster of them under cab I will tomorrow

 

[truecountry]

If the engine stops, the accumulator does the job of the pilot pump and provides pilot pressure for a short time to allow the implement to be lowered. If it's faulty it won't affect the operation of the machine at all while the engine is running.



So you've got 26-27V to the solenoid, but have you checked the ground wire as well?

Thanks Cmark it was a broken ground wire going to the solenoid for hydraulic lockout
Again Thanks

 

[movindirt]

Thanks Cmark it was a broken ground wire going to the solenoid for hydraulic lockout
Again Thanks

Glad you found that ghost!! Its amazing what kind of trouble something as simple as a ground can cause, had a truck that was acting strange with the lights, replaced switches and fuses and stuff, came down to a faulty frame ground :Banghead

 

[Cmark]

Some years ago I was working on a loader, 988G maybe?, that was having all sorts of weird electrical problems which turned out to be a bad connection at the cab ground strap. How did I find it, you ask? Well I touched the connecting bolt and burnt my bloody fingers!