Manitou mlt 731 hydraulic issue

[Massey 6470]

On my 731 the hydraulics are doing an awful droning when operating the boom, took the filter off on the hydraulic return line and there’s a lot of gold coloured filings through the oil that came out of the filter. I know it’s going to hurt the pocket at lot, what’s people’s thoughts

 

[Nearly]

@ACEngineering

 

[ACEngineering]

On my 731 the hydraulics are doing an awful droning when operating the boom, took the filter off on the hydraulic return line and there’s a lot of gold coloured filings through the oil that came out of the filter. I know it’s going to hurt the pocket at lot, what’s people’s thoughts

Has it been making air cavitation noises on first start up or after being stood for awhile?

 

[Massey 6470]

Not really it only started making the funny noises yesterday it’s like tipping a trailer and the oil gets scarce and starts to drone, it’s been messing about for a wee while stalling the engine every now and again while working with no revs, like a pressure relief valve issue

 

[ACEngineering]

Not really it only started making the funny noises yesterday it’s like tipping a trailer and the oil gets scarce and starts to drone, it’s been messing about for a wee while stalling the engine every now and again while working with no revs, like a pressure relief valve issue

PM sent.

 

[jd6820]

Swash plate bearings on the pump?

 

[Pistonbroke]

While youve all got hydraulic problems on your mind,what is the right way to lift a boom to replace the lift hose on the main ram. Hose burst when boom was right down ?

 

[del_boy]

Has it been making air cavitation noises on first start up or after being stood for awhile?

@ACEngineering our 741 14 plate elite does this. Can go for months and not do it then it might do it several times a day. Usually on start up the forward reverse drives but no brake pedal and no hydraulic function. Restart and it'll make an almighty groan like its starved of oil then it'll work perfect. When it does play up the little red steering light is on on the dash.

 

[ACEngineering]

While youve all got hydraulic problems on your mind,what is the right way to lift a boom to replace the lift hose on the main ram. Hose burst when boom was right down ?

On what model? something like a MLT 634/735 or 741 with boom right down will be a absolute arse hole of a job IMO

ideally if the boom is up a couple of foot, you use another machine to take weight of boom, then undo the 4 cap screws or bolts holding the lock out valve/check valve to the side of the lift ram. then slowly lift the boom up with the other machine and try and catch some of the oil!

once at a height you can work with refit the valve but the ram will be full of air so you still need the other loader to hold it up while you work.

If the boom is right on the deck you wont be able to get at the valve. in this case your only option is to struggle like feck and get the top lift ram pin out from underneath, working blind over the top of the gearbox! be very careful to support the ram so it dont drop down and smash your fingers between it and the gearbox

When this type job comes in i'm normally VERY VERY busy

 

[Pistonbroke]

On what model? something like a MLT 634/735 or 741 with boom right down will be a absolute arse hole of a job IMO

ideally if the boom is up a couple of foot, you use another machine to take weight of boom, then undo the 4 cap screws or bolts holding the lock out valve/check valve to the side of the lift ram. then slowly lift the boom up with the other machine and try and catch some of the oil!

once at a height you can work with refit the valve but the ram will be full of air so you still need the other loader to hold it up while you work.

If the boom is right on the deck you wont be able to get at the valve. in this case your only option is to struggle like feck and get the top lift ram pin out from underneath, working blind over the top of the gearbox! be very careful to support the ram so it dont drop down and smash your fingers between it and the gearbox

When this type job comes in i'm normally VERY VERY busy

2004 630-120 lsu. The other hose( pushing down ) went in December and wasn't too bad because the boom was up. I toyed with the idea of changing both while I was at it but it looked too good. Other than oil escaping,will the check valve let the boom be lifted if the joystick is in the lift position?

 

[ACEngineering]

2004 630-120 lsu. The other hose( pushing down ) went in December and wasn't too bad because the boom was up. I toyed with the idea of changing both while I was at it but it looked too good. Other than oil escaping,will the check valve let the boom be lifted if the joystick is in the lift position?

if the hose is blown then it likely will not develop the 110bar needed to open the check valve and just pee oil out everywhere.

 

[Pistonbroke]

if the hose is blown then it likely will not develop the 110bar needed to open the check valve and just pee oil out everywhere.

Well you haven't really cheered me up but thanks for your time.

 

[e5c0rt.mk1]

2004 630-120 lsu. The other hose( pushing down ) went in December and wasn't too bad because the boom was up. I toyed with the idea of changing both while I was at it but it looked too good. Other than oil escaping,will the check valve let the boom be lifted if the joystick is in the lift position?

We have the exact same problem on the exact same machine, i've been putting it off since last year lol.

I was thinking of putting a chain hoist on the headstock and over a couple of days slowly, bit by bit, pull it up. Hoping it has an internal leak somewhere and the oil can escape out of the ram over a few days. Dont have a clue if it will work, but i cant think of another way to do it.

 

[Pistonbroke]

We have the exact same problem on the exact same machine, i've been putting it off since last year lol.

I was thinking of putting a chain hoist on the headstock and over a couple of days slowly, bit by bit, pull it up. Hoping it has an internal leak somewhere and the oil can escape out of the ram over a few days. Dont have a clue if it will work, but i cant think of another way to do it.

Fecking snail and garlic eating,onion selling lazy stinking stupid French b@stards

 

[ACEngineering]

We have the exact same problem on the exact same machine, i've been putting it off since last year lol.

I was thinking of putting a chain hoist on the headstock and over a couple of days slowly, bit by bit, pull it up. Hoping it has an internal leak somewhere and the oil can escape out of the ram over a few days. Dont have a clue if it will work, but i cant think of another way to do it.

worth a try if you have the time, i would try it gently though. the reason for that is the move force you use the tighter the piston seals will seal and the harder the valve will be held closed. so just take some weight but not so the wheels are off the ground.
Also attach the chain to the box section of the boom not the headstock, 735 and 741 booms do crack underneath when you reverse the normal working stress.

 

[ACEngineering]

Fecking snail and garlic eating,onion selling lazy stinking stupid French b@stards

JCB and merlo would be similar arse of a job too IMO

 

[Pistonbroke]

Bush fix!! Only to get the boom up to get the hose off. Oil still pouring out but revved her up and it got the boom up to the top. Result!!!

 

[ACEngineering]

Bush fix!! Only to get the boom up to get the hose off. Oil still pouring out but revved her up and it got the boom up to the top. Result!!!View attachment 869070View attachment 869068

if thats the bigger 5/8 pipe thats blown get a genuine one, normal 2 wire will likely blow again. working pressure is 270bar.

 

[Pistonbroke]

if thats the bigger 5/8 pipe thats blown get a genuine one, normal 2 wire will likely blow again. working pressure is 270bar.

Heading off to a Manitou dealer to get it made up so hopefully a decent spec. This one doesn't look original anyway,it's only rated 3250psi.

 

[ACEngineering]

Heading off to a Manitou dealer to get it made up so hopefully a decent spec. This one doesn't look original anyway,it's only rated 3250psi.

i only like to use genuine manitou hoses most of the time. the bog standard 2 wire hose people use to make up to pattern is often poor.

a lot of 5/8 hose will only have a working pressure of 210bar, fitting multi spiral isn't an option as its too stiff.