Steering - Steering Gear Leakage Information
Date: June 21, 2007
Order No.: T-B-46.20/58
Supercedes:
Group: 46
SUBJECT:
All 163, 164 and 251 Models
Equipped with Rack-and-Pinion Steering
Steering Gear Leaking Under Dust Cap on Control Head
During inspection of returned power steering racks, we have encountered cases where steering racks have been replaced due to "leaking" but
which prove to exhibit merely "sweating" or a film of grease under the dust cap on the top of the control head.
If during power steering complaint diagnosis, moisture on the surface of the steering gear under the dust cap is noticed in a localized section,
this is considered sweating due to grease liquefying and not leakage.
This moisture can be caused by:
^ Grease under the dust cap to keep dirt (dust) away from the steering system.
^ Heat from the engine causes some of the grease under the cap to liquefy which produces a slight but noticeable moisture/grease film on the
surface and does not indicate leakage, nor is it a cause for power steering complaints.
2000 Mercedes Benz Truck ML 55 AMG (163.174) V8-5.5L (113.981) 317
Figures 1, 2 and 3 contain examples of steering racks that are "sweating" in this area. It can be seen that, on the sweating steering gear, only
the top of the control head is wet on one side (i.e. not all round). No droplets form (no run marks etc.) that run down the steering gear/control
head. For this reason, do not expect any contamination with grease/oil in the surrounding area or on the ground. The grease (film) adheres to
the steering gear housing.
In contrast, if the steering is genuinely leaking, the steering gear housing appears very wet, even when combined with dirt, and sometimes
droplets are formed.
Note:
Another form of leakage in the steering system is a drop in the oil level in the reservoir of the power steering pump. For this reason, the oil
level must always be checked with the dipstick when ascertaining findings.
Therefore, when assessing whether a steering gear is merely "sweating" due to liquefying grease in the area of the control head or whether it is
actually leaking, strictly adhere to the procedure described below:
1. Clean steering gear.
2. Spray or coat steering gear with a suitable leak detector spray.
2000 Mercedes Benz Truck ML 55 AMG (163.174) V8-5.5L (113.981) 318
3. Warm up the steering system by turning the steering wheel from lock to lock several times and, if necessary, perform a test drive and observe
the oil level in the power steering pump reservoir.
4. Assess steering for leaks
Note:
If leakage is found at the screw connections of the internal/external lines or at the power steering valve, repair parts are available. Steering
Date: June 21, 2007
Order No.: T-B-46.20/58
Supercedes:
Group: 46
SUBJECT:
All 163, 164 and 251 Models
Equipped with Rack-and-Pinion Steering
Steering Gear Leaking Under Dust Cap on Control Head
During inspection of returned power steering racks, we have encountered cases where steering racks have been replaced due to "leaking" but
which prove to exhibit merely "sweating" or a film of grease under the dust cap on the top of the control head.
If during power steering complaint diagnosis, moisture on the surface of the steering gear under the dust cap is noticed in a localized section,
this is considered sweating due to grease liquefying and not leakage.
This moisture can be caused by:
^ Grease under the dust cap to keep dirt (dust) away from the steering system.
^ Heat from the engine causes some of the grease under the cap to liquefy which produces a slight but noticeable moisture/grease film on the
surface and does not indicate leakage, nor is it a cause for power steering complaints.
2000 Mercedes Benz Truck ML 55 AMG (163.174) V8-5.5L (113.981) 317
Figures 1, 2 and 3 contain examples of steering racks that are "sweating" in this area. It can be seen that, on the sweating steering gear, only
the top of the control head is wet on one side (i.e. not all round). No droplets form (no run marks etc.) that run down the steering gear/control
head. For this reason, do not expect any contamination with grease/oil in the surrounding area or on the ground. The grease (film) adheres to
the steering gear housing.
In contrast, if the steering is genuinely leaking, the steering gear housing appears very wet, even when combined with dirt, and sometimes
droplets are formed.
Note:
Another form of leakage in the steering system is a drop in the oil level in the reservoir of the power steering pump. For this reason, the oil
level must always be checked with the dipstick when ascertaining findings.
Therefore, when assessing whether a steering gear is merely "sweating" due to liquefying grease in the area of the control head or whether it is
actually leaking, strictly adhere to the procedure described below:
1. Clean steering gear.
2. Spray or coat steering gear with a suitable leak detector spray.
2000 Mercedes Benz Truck ML 55 AMG (163.174) V8-5.5L (113.981) 318
3. Warm up the steering system by turning the steering wheel from lock to lock several times and, if necessary, perform a test drive and observe
the oil level in the power steering pump reservoir.
4. Assess steering for leaks
Note:
If leakage is found at the screw connections of the internal/external lines or at the power steering valve, repair parts are available. Steering
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