Hydraulic pump rebuilds?

scoffcruddle

Well-Known Member
The Pump3 on my Volvo is weak (well I think it is) this means the hydraulic fan slows when you brake and on heavy work it gets hot and throws up error codes for low brake pressure,I’ve replaced a lot of parts after advice from an American forum but now I think it can only be the hydraulic pump for the brakes/fan.

I’ve got prices for a new pump and they are all about the 2k mark but I can have a rebuilt pump from the USA for about £1k including import tax and carriage,what’s the general thoughts on a pump rebuild? Normally I’d buy new but not 100% it’s the pump.

It’s a bosch rexroth by the way.

tia Scoff....
 
The Pump3 on my Volvo is weak (well I think it is) this means the hydraulic fan slows when you brake and on heavy work it gets hot and throws up error codes for low brake pressure,I’ve replaced a lot of parts after advice from an American forum but now I think it can only be the hydraulic pump for the brakes/fan.

I’ve got prices for a new pump and they are all about the 2k mark but I can have a rebuilt pump from the USA for about £1k including import tax and carriage,what’s the general thoughts on a pump rebuild? Normally I’d buy new but not 100% it’s the pump.

It’s a bosch rexroth by the way.

tia Scoff....
Piston pump is it?
 
Yes,axial piston pump.
Not yet,I see they test and re-build so worth a try.
Tested pressure but it seems to be a flow issue.
L70F
Almost sounds like a charge pump problem, Don't think any firm would test it without rebuilding it first, was talking to a guy at Linde a few years back and he said everything is stripped down first for fear of contaminating the test rig, understandable when you hear prices for the test gear!
 
Almost sounds like a charge pump problem, Don't think any firm would test it without rebuilding it first, was talking to a guy at Linde a few years back and he said everything is stripped down first for fear of contaminating the test rig, understandable when you hear prices for the test gear!

It has 3 accumulators it charges in the system to allow the brakes and hand brake to work if the engine fails,I’ve replaced all 3 and a none return valve,only other thing other it could be is a crack in the control manifold or pump.

Trouble is Volvo loaders aren’t the most common machine around and finding someone who knows them is hard going.
 
It has 3 accumulators it charges in the system to allow the brakes and hand brake to work if the engine fails,I’ve replaced all 3 and a none return valve,only other thing other it could be is a crack in the control manifold or pump.

Trouble is Volvo loaders aren’t the most common machine around and finding someone who knows them is hard going.
Does temperature make a difference or is it the same all the time? Does engine temperature control the pump in any way if its driving the fan?
 
Does temperature make a difference or is it the same all the time? Does engine temperature control the pump in any way if its driving the fan?

Sorry Win never saw you’d posted,no temp doesn’t make any difference,engine temp alters the speed of the fan,one of these great ideas to save fuel:rolleyes2: you pump oil around a system then it gets hot and you need the fan to go even faster!

Anyroad I’ve done a couple of YouTube clips showing what happens when I press the brakes,in service mode it shows the pressures,I press the brakes and the warning comes on.

2nd clip,if I press the brakes slowly the pressure lifts and the warning doesn’t come on,end of clip I press the brakes normally and the warning comes up:scratchhead:


Before anyone comments :yes: alternator light on dash is faulty,a known problem with the F series.
 
Sorry Win never saw you’d posted,no temp doesn’t make any difference,engine temp alters the speed of the fan,one of these great ideas to save fuel:rolleyes2: you pump oil around a system then it gets hot and you need the fan to go even faster!

Anyroad I’ve done a couple of YouTube clips showing what happens when I press the brakes,in service mode it shows the pressures,I press the brakes and the warning comes on.

2nd clip,if I press the brakes slowly the pressure lifts and the warning doesn’t come on,end of clip I press the brakes normally and the warning comes up:scratchhead:


Before anyone comments :yes: alternator light on dash is faulty,a known problem with the F series.
You would think oil temp would make a difference in some way if it was a crack or pump/ controller fault, your new accumulators were definitely pre- charged were they?
 
You would think oil temp would make a difference in some way if it was a crack or pump/ controller fault, your new accumulators were definitely pre- charged were they?

Yes accumulators were pre charged,I’m thinking it’s possibly a fault with the footbrake valve.
 
Yes accumulators were pre charged,I’m thinking it’s possibly a fault with the footbrake valve.
It does point that way, suppose there's seals or 'o' rings or something in it? Would it have some form of priority valve I wonder? :unsure: After all the amount of flow required to put the brakes on would be pretty low!
 
It does point that way, suppose there's seals or 'o' rings or something in it? Would it have some form of priority valve I wonder? :unsure: After all the amount of flow required to put the brakes on would be pretty low!

Is there an easy way to check an accumulator?

When I’ve got my gauge on the pressures on the dash are the same so I know it’s reading right,500psi on the brakes near puts you through the windscreen.

found a bit online regards the footbrake valve,seems it 2stage,I reckon I’ve a fault with the 2nd stage.81126EB0-B113-4AE3-9647-E74338B0C6C2.png602A7B6F-0FC2-4913-B4DF-036EE090285A.png
 
Your accumulator for the brakes probably reserves pressure for when the engine cuts out?do you have more than a few pedal presses if you switch the engine off?
 
Had a quick drive and pressure seems to drop fast once stopped,didn’t have gauge hooked up and once you turn the key off you lose the pressure readout off the dash.

The book of words says 4 full presses of the pedal then pressure should be 1305psi,faulty accumulator,cracked accumulator manifold or foot brake valve?

One thing for sure it’s frustrating.F160E21A-A204-4589-A732-CE8CB0A58492.png
 
I'll check when I next get on it.

Using hydraulics doesn't seem to alter anything.
Ours does the same is your brake pressure actually low? Once you start it does that but if you dead end the 3rd service it will knock out the light.
Most volvos I've driven have been like that
 
Ours does the same is your brake pressure actually low? Once you start it does that but if you dead end the 3rd service it will knock out the light.
Most volvos I've driven have been like that

Yes the pressures low,continually recharging the brake circuit means it slows the fan,this in turn means it gets hot.
 
Had a quick drive and pressure seems to drop fast once stopped,didn’t have gauge hooked up and once you turn the key off you lose the pressure readout off the dash.

The book of words says 4 full presses of the pedal then pressure should be 1305psi,faulty accumulator,cracked accumulator manifold or foot brake valve?

One thing for sure it’s frustrating.View attachment 80128
Well start with accumulator, the reason I said were they definitely charged was a mate had one for his forager and that came not charged.
 
Well start with accumulator, the reason I said were they definitely charged was a mate had one for his forager and that came not charged.

The type they are don’t have a charge cap at the rear,have you come across them?
How do you charge them?
D4648889-2338-424B-A843-F8393C80E999.jpeg
 
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