ABC Hose Rebuild
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Senior Member
Joined: Sep 2012
Posts: 411
Likes: 23
2011 E550 Coupe, 1992 Corvette ZR-1, 1991 368ci ZR-1, 1990 ZR-1, 1987 Callaway TT, 05 SL600, CLA45
ABC Hose Rebuild
I see some people have rebuilt their ABC system hoses....wondering if anyone can comment on longevity of the rebuild?
Thanks
Thanks
Senior Member
Joined: Apr 2019
Posts: 428
Likes: 96
From: Houston
001 s600, 94 sl600
ABC Pump noise and low pressure, hoses
The following comments come from over 45 years in owning and maintaining hydraulic suspension systems, including 23 years with my 1973 Citroen SM. I was 'the go-to guy for over 10 years for the Lexus LX-4xx and 5xx series luxury SUV's. I manufactured new accumulators and repaired other parts for owners worldwide. I support other makes and models with adjustable height suspensions such as the Mercedes '100' series like the 450-6.9, Porsche 959 'supercar 'and others. The comments below are based on my experience, engineering development of and manufacturing of parts for these systems. They are not intended as criticism or demeaning on anyone, including MBZ. Like all thing, designed and built by MAN, the ABC system implemented by Mercedes is not perfect (whatever that is.) The significant 'shortcomings, in my own personal opinion are:
1) The pressure pulsation dampening feature. Using a short length (+/_ 3 ft) of high pressure hydraulic hose with a closed end to absorb and dampen pressure pulses from the system high pressure pump is not a good choice. The ABC system operates at about 3000 psig--which is typical of automotive type hydraulic systems. It is not 'high.' Higher pressure hydraulic hoses are usually constructed with 1 or more steel mesh layers (depending on hose diameter and pressure rating) separated by synthetic 'rubber' and and high strength textiles (such as Nylon mono-filament) wound around the fluid retaining core (nitrile for oil service). These steel mesh layers are subject to fatigue type failures caused by repetitive bending and flexing. Pressure pulsations are not desirable and can cause rapid failures. This service is a 'high cycle application', meaning lots and lots of and frequent pressure fluctuation. Then to route that hose underneath the hot engine oil pan with very little separation or heat protection exacerbates the misapplication. Most all other hydraulic applications with pressure pulsation concerns use hydraulic accumulators appropriately sized for the application. For example, Citroen, Nissan, Toyota all have successful hydraulic suspension systems using accumulators for pulsation management, as do the 'hydro-dynamic' suspensions by others,
IMHO, MBZ should have used a small (0.2 liter) bellows type accumulator (or a different design pump like Nissan's) for pulsation/vibration management.
Replacing this hose with one that is more flexible (no steel layers,re- routing it away from hot surfaces, insulating where necessary, and at least doubling the length should more than double the expected life of this failure prone, inexpensive part that has very costly potential damage.
Retro-fitting a small accumulator is not difficult or costly and would 'cure' forever the most frequent failure in the ABC system. I will do so before that recently replaced part in my newly purchased 2001 S600 exhibits any signs of failure by leaking.
2) The biggest 'enemy' of hydraulic system is DIRT any kind of particle. More frequent replacement of the ABC system filter should be included in scheduled maintenance as should fluid replacement.
3) HEAT Heat dramatically shortens the service life of hydraulic oils. For any temperature above about 180F, the life shortens by HALF for every 20 F increase. If even a small portion of the oil/system is HOT, the entire fluid volume is damaged by the degradation products. The 'rubber' hoses, seals, O-rings and other components made with 'synthetics' are also damaged by heat. Mercedes has routed the numerous ABC system hoses and components such that some are exposed to very high radiant (and conductive) heat loads and subsequently high temperatures. Industry best practices is to PROTECT hydraulic system and components from high heat sources and exposure---using radiant heat shields and oil resistant insulation. All the hoses, control valves, and accumulators SHOULD be so protected. IF Owners or Dealers would retrofit radiant heat shields and insulation(aluminum foil? and aircraft 'fire-wall insulation" That would prevent the vast majority of the remaining component failures of the ABC system. I have already installed such heat protection.
Member
Joined: Jun 2019
Posts: 200
Likes: 26
2005 R230 SL-500 / 2017 E300
The ABC system as implemented by Mercedes is a simple and reliable suspension system. It is a moderate pressure (+/- 3000 psig) hydraulic system with electronically directly actuated solenoid valves that send high pressure oil to the individual struts (or exhaust it back to high pressure flexible reservoirs (accumulators), in order to control the car body movements when moving over bumps and dips in the road surface. Like other automotive 'semi active suspension' systems the ABC struts support about 40% of the vehicle weight with conventional coil springs supporting the rest. The system removes more than 50% of body movements that a conventional suspension system would transmit to the auto chassis/body. However, like any system, it has 'weaknesses.'
The following comments come from over 45 years in owning and maintaining hydraulic suspension systems, including 23 years with my 1973 Citroen SM. I was 'the go-to guy for over 10 years for the Lexus LX-4xx and 5xx series luxury SUV's. I manufactured new accumulators and repaired other parts for owners worldwide. I support other makes and models with adjustable height suspensions such as the Mercedes '100' series like the 450-6.9, Porsche 959 'supercar 'and others. The comments below are based on my experience, engineering development of and manufacturing of parts for these systems. They are not intended as criticism or demeaning on anyone, including MBZ. Like all thing, designed and built by MAN, the ABC system implemented by Mercedes is not perfect (whatever that is.) The significant 'shortcomings, in my own personal opinion are:
1) The pressure pulsation dampening feature. Using a short length (+/_ 3 ft) of high pressure hydraulic hose with a closed end to absorb and dampen pressure pulses from the system high pressure pump is not a good choice. The ABC system operates at about 3000 psig--which is typical of automotive type hydraulic systems. It is not 'high.' Higher pressure hydraulic hoses are usually constructed with 1 or more steel mesh layers (depending on hose diameter and pressure rating) separated by synthetic 'rubber' and and high strength textiles (such as Nylon mono-filament) wound around the fluid retaining core (nitrile for oil service). These steel mesh layers are subject to fatigue type failures caused by repetitive bending and flexing. Pressure pulsations are not desirable and can cause rapid failures. This service is a 'high cycle application', meaning lots and lots of and frequent pressure fluctuation. Then to route that hose underneath the hot engine oil pan with very little separation or heat protection exacerbates the misapplication. Most all other hydraulic applications with pressure pulsation concerns use hydraulic accumulators appropriately sized for the application. For example, Citroen, Nissan, Toyota all have successful hydraulic suspension systems using accumulators for pulsation management, as do the 'hydro-dynamic' suspensions by others,
IMHO, MBZ should have used a small (0.2 liter) bellows type accumulator (or a different design pump like Nissan's) for pulsation/vibration management.
Replacing this hose with one that is more flexible (no steel layers,re- routing it away from hot surfaces, insulating where necessary, and at least doubling the length should more than double the expected life of this failure prone, inexpensive part that has very costly potential damage.
Retro-fitting a small accumulator is not difficult or costly and would 'cure' forever the most frequent failure in the ABC system. I will do so before that recently replaced part in my newly purchased 2001 S600 exhibits any signs of failure by leaking.
2) The biggest 'enemy' of hydraulic system is DIRT any kind of particle. More frequent replacement of the ABC system filter should be included in scheduled maintenance as should fluid replacement.
3) HEAT Heat dramatically shortens the service life of hydraulic oils. For any temperature above about 180F, the life shortens by HALF for every 20 F increase. If even a small portion of the oil/system is HOT, the entire fluid volume is damaged by the degradation products. The 'rubber' hoses, seals, O-rings and other components made with 'synthetics' are also damaged by heat. Mercedes has routed the numerous ABC system hoses and components such that some are exposed to very high radiant (and conductive) heat loads and subsequently high temperatures. Industry best practices is to PROTECT hydraulic system and components from high heat sources and exposure---using radiant heat shields and oil resistant insulation. All the hoses, control valves, and accumulators SHOULD be so protected. IF Owners or Dealers would retrofit radiant heat shields and insulation(aluminum foil? and aircraft 'fire-wall insulation" That would prevent the vast majority of the remaining component failures of the ABC system. I have already installed such heat protection.
The following comments come from over 45 years in owning and maintaining hydraulic suspension systems, including 23 years with my 1973 Citroen SM. I was 'the go-to guy for over 10 years for the Lexus LX-4xx and 5xx series luxury SUV's. I manufactured new accumulators and repaired other parts for owners worldwide. I support other makes and models with adjustable height suspensions such as the Mercedes '100' series like the 450-6.9, Porsche 959 'supercar 'and others. The comments below are based on my experience, engineering development of and manufacturing of parts for these systems. They are not intended as criticism or demeaning on anyone, including MBZ. Like all thing, designed and built by MAN, the ABC system implemented by Mercedes is not perfect (whatever that is.) The significant 'shortcomings, in my own personal opinion are:
1) The pressure pulsation dampening feature. Using a short length (+/_ 3 ft) of high pressure hydraulic hose with a closed end to absorb and dampen pressure pulses from the system high pressure pump is not a good choice. The ABC system operates at about 3000 psig--which is typical of automotive type hydraulic systems. It is not 'high.' Higher pressure hydraulic hoses are usually constructed with 1 or more steel mesh layers (depending on hose diameter and pressure rating) separated by synthetic 'rubber' and and high strength textiles (such as Nylon mono-filament) wound around the fluid retaining core (nitrile for oil service). These steel mesh layers are subject to fatigue type failures caused by repetitive bending and flexing. Pressure pulsations are not desirable and can cause rapid failures. This service is a 'high cycle application', meaning lots and lots of and frequent pressure fluctuation. Then to route that hose underneath the hot engine oil pan with very little separation or heat protection exacerbates the misapplication. Most all other hydraulic applications with pressure pulsation concerns use hydraulic accumulators appropriately sized for the application. For example, Citroen, Nissan, Toyota all have successful hydraulic suspension systems using accumulators for pulsation management, as do the 'hydro-dynamic' suspensions by others,
IMHO, MBZ should have used a small (0.2 liter) bellows type accumulator (or a different design pump like Nissan's) for pulsation/vibration management.
Replacing this hose with one that is more flexible (no steel layers,re- routing it away from hot surfaces, insulating where necessary, and at least doubling the length should more than double the expected life of this failure prone, inexpensive part that has very costly potential damage.
Retro-fitting a small accumulator is not difficult or costly and would 'cure' forever the most frequent failure in the ABC system. I will do so before that recently replaced part in my newly purchased 2001 S600 exhibits any signs of failure by leaking.
2) The biggest 'enemy' of hydraulic system is DIRT any kind of particle. More frequent replacement of the ABC system filter should be included in scheduled maintenance as should fluid replacement.
3) HEAT Heat dramatically shortens the service life of hydraulic oils. For any temperature above about 180F, the life shortens by HALF for every 20 F increase. If even a small portion of the oil/system is HOT, the entire fluid volume is damaged by the degradation products. The 'rubber' hoses, seals, O-rings and other components made with 'synthetics' are also damaged by heat. Mercedes has routed the numerous ABC system hoses and components such that some are exposed to very high radiant (and conductive) heat loads and subsequently high temperatures. Industry best practices is to PROTECT hydraulic system and components from high heat sources and exposure---using radiant heat shields and oil resistant insulation. All the hoses, control valves, and accumulators SHOULD be so protected. IF Owners or Dealers would retrofit radiant heat shields and insulation(aluminum foil? and aircraft 'fire-wall insulation" That would prevent the vast majority of the remaining component failures of the ABC system. I have already installed such heat protection.
Mike.
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Newbie
Joined: Jul 2013
Posts: 5
Likes: 1
From: Elkhart Lake, Wisconsin
2002 CL500, 02 Grand Cherokee, 63 Avanti, MGB, 09 ES350, (ex 66 250S, 70 280SE, 85 500SEC EURO, etc)
Not sure who to ask but ...The flex hose section of the rear accumulator line from the valve body failed. Since the accumulator is the only thing on the line, I'd like to disconnect it from the valve body and plug the valve temporarily while I get the line repaired so I can at least top off the system & move the car without damaging the pump.. My question is what size are the fittings ?
Super Member
Joined: Dec 2007
Posts: 963
Likes: 224
2005 S500 Designo
The ABC system as implemented by Mercedes is a simple and reliable suspension system. It is a moderate pressure (+/- 3000 psig) hydraulic system with electronically directly actuated solenoid valves that send high pressure oil to the individual struts (or exhaust it back to high pressure flexible reservoirs (accumulators), in order to control the car body movements when moving over bumps and dips in the road surface. Like other automotive 'semi active suspension' systems the ABC struts support about 40% of the vehicle weight with conventional coil springs supporting the rest. The system removes more than 50% of body movements that a conventional suspension system would transmit to the auto chassis/body. However, like any system, it has 'weaknesses.'
The following comments come from over 45 years in owning and maintaining hydraulic suspension systems, including 23 years with my 1973 Citroen SM. I was 'the go-to guy for over 10 years for the Lexus LX-4xx and 5xx series luxury SUV's. I manufactured new accumulators and repaired other parts for owners worldwide. I support other makes and models with adjustable height suspensions such as the Mercedes '100' series like the 450-6.9, Porsche 959 'supercar 'and others. The comments below are based on my experience, engineering development of and manufacturing of parts for these systems. They are not intended as criticism or demeaning on anyone, including MBZ. Like all thing, designed and built by MAN, the ABC system implemented by Mercedes is not perfect (whatever that is.) The significant 'shortcomings, in my own personal opinion are:
1) The pressure pulsation dampening feature. Using a short length (+/_ 3 ft) of high pressure hydraulic hose with a closed end to absorb and dampen pressure pulses from the system high pressure pump is not a good choice. The ABC system operates at about 3000 psig--which is typical of automotive type hydraulic systems. It is not 'high.' Higher pressure hydraulic hoses are usually constructed with 1 or more steel mesh layers (depending on hose diameter and pressure rating) separated by synthetic 'rubber' and and high strength textiles (such as Nylon mono-filament) wound around the fluid retaining core (nitrile for oil service). These steel mesh layers are subject to fatigue type failures caused by repetitive bending and flexing. Pressure pulsations are not desirable and can cause rapid failures. This service is a 'high cycle application', meaning lots and lots of and frequent pressure fluctuation. Then to route that hose underneath the hot engine oil pan with very little separation or heat protection exacerbates the misapplication. Most all other hydraulic applications with pressure pulsation concerns use hydraulic accumulators appropriately sized for the application. For example, Citroen, Nissan, Toyota all have successful hydraulic suspension systems using accumulators for pulsation management, as do the 'hydro-dynamic' suspensions by others,
IMHO, MBZ should have used a small (0.2 liter) bellows type accumulator (or a different design pump like Nissan's) for pulsation/vibration management.
Replacing this hose with one that is more flexible (no steel layers,re- routing it away from hot surfaces, insulating where necessary, and at least doubling the length should more than double the expected life of this failure prone, inexpensive part that has very costly potential damage.
Retro-fitting a small accumulator is not difficult or costly and would 'cure' forever the most frequent failure in the ABC system. I will do so before that recently replaced part in my newly purchased 2001 S600 exhibits any signs of failure by leaking.
2) The biggest 'enemy' of hydraulic system is DIRT any kind of particle. More frequent replacement of the ABC system filter should be included in scheduled maintenance as should fluid replacement.
3) HEAT Heat dramatically shortens the service life of hydraulic oils. For any temperature above about 180F, the life shortens by HALF for every 20 F increase. If even a small portion of the oil/system is HOT, the entire fluid volume is damaged by the degradation products. The 'rubber' hoses, seals, O-rings and other components made with 'synthetics' are also damaged by heat. Mercedes has routed the numerous ABC system hoses and components such that some are exposed to very high radiant (and conductive) heat loads and subsequently high temperatures. Industry best practices is to PROTECT hydraulic system and components from high heat sources and exposure---using radiant heat shields and oil resistant insulation. All the hoses, control valves, and accumulators SHOULD be so protected. IF Owners or Dealers would retrofit radiant heat shields and insulation(aluminum foil? and aircraft 'fire-wall insulation" That would prevent the vast majority of the remaining component failures of the ABC system. I have already installed such heat protection.
The following comments come from over 45 years in owning and maintaining hydraulic suspension systems, including 23 years with my 1973 Citroen SM. I was 'the go-to guy for over 10 years for the Lexus LX-4xx and 5xx series luxury SUV's. I manufactured new accumulators and repaired other parts for owners worldwide. I support other makes and models with adjustable height suspensions such as the Mercedes '100' series like the 450-6.9, Porsche 959 'supercar 'and others. The comments below are based on my experience, engineering development of and manufacturing of parts for these systems. They are not intended as criticism or demeaning on anyone, including MBZ. Like all thing, designed and built by MAN, the ABC system implemented by Mercedes is not perfect (whatever that is.) The significant 'shortcomings, in my own personal opinion are:
1) The pressure pulsation dampening feature. Using a short length (+/_ 3 ft) of high pressure hydraulic hose with a closed end to absorb and dampen pressure pulses from the system high pressure pump is not a good choice. The ABC system operates at about 3000 psig--which is typical of automotive type hydraulic systems. It is not 'high.' Higher pressure hydraulic hoses are usually constructed with 1 or more steel mesh layers (depending on hose diameter and pressure rating) separated by synthetic 'rubber' and and high strength textiles (such as Nylon mono-filament) wound around the fluid retaining core (nitrile for oil service). These steel mesh layers are subject to fatigue type failures caused by repetitive bending and flexing. Pressure pulsations are not desirable and can cause rapid failures. This service is a 'high cycle application', meaning lots and lots of and frequent pressure fluctuation. Then to route that hose underneath the hot engine oil pan with very little separation or heat protection exacerbates the misapplication. Most all other hydraulic applications with pressure pulsation concerns use hydraulic accumulators appropriately sized for the application. For example, Citroen, Nissan, Toyota all have successful hydraulic suspension systems using accumulators for pulsation management, as do the 'hydro-dynamic' suspensions by others,
IMHO, MBZ should have used a small (0.2 liter) bellows type accumulator (or a different design pump like Nissan's) for pulsation/vibration management.
Replacing this hose with one that is more flexible (no steel layers,re- routing it away from hot surfaces, insulating where necessary, and at least doubling the length should more than double the expected life of this failure prone, inexpensive part that has very costly potential damage.
Retro-fitting a small accumulator is not difficult or costly and would 'cure' forever the most frequent failure in the ABC system. I will do so before that recently replaced part in my newly purchased 2001 S600 exhibits any signs of failure by leaking.
2) The biggest 'enemy' of hydraulic system is DIRT any kind of particle. More frequent replacement of the ABC system filter should be included in scheduled maintenance as should fluid replacement.
3) HEAT Heat dramatically shortens the service life of hydraulic oils. For any temperature above about 180F, the life shortens by HALF for every 20 F increase. If even a small portion of the oil/system is HOT, the entire fluid volume is damaged by the degradation products. The 'rubber' hoses, seals, O-rings and other components made with 'synthetics' are also damaged by heat. Mercedes has routed the numerous ABC system hoses and components such that some are exposed to very high radiant (and conductive) heat loads and subsequently high temperatures. Industry best practices is to PROTECT hydraulic system and components from high heat sources and exposure---using radiant heat shields and oil resistant insulation. All the hoses, control valves, and accumulators SHOULD be so protected. IF Owners or Dealers would retrofit radiant heat shields and insulation(aluminum foil? and aircraft 'fire-wall insulation" That would prevent the vast majority of the remaining component failures of the ABC system. I have already installed such heat protection.
There are decisions in there that just leave me scratching my head. Hydraulic lines running in ways they probably shouldn't, their weird decision to call the hydraulic fluid "lifetime" - even beyond the shelf life on the bottle, running an extra hose off the pump as a dampener (seriously?!), hydraulic lines and accumulators that don't last...
I just finished swapping out all high pressure hydraulic hoses with fresh rebuilds. This should be at the top of every ABC owner's maintenance priority, and should become common practice (like cooling systems on BMWs every 70k miles).
Hopefully my rebuilt hydraulic hoses last a good long time.
