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Overland travel comes with the occasional mechanical problem. Here’s the story of a Mercedes Benz clutch cylinder with a sudden oil leak – meaning no clutch.
Mercedes Clutch pedal cylinder leaking oil
Many 70’s and 80’s Mercedes Benz trucks, like the 1017, 1719 and 1222 have a hydraulic operated clutch. This means at some point in time the rubber seals start to leak – after all there is aggressive DOT4 brake fluid in there. As it did with our 1719;
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| Clutch pedal oil leak - brake fluid gushed from the top of the clutch cylinder |
The first symptom is a pedal that won’t fully return to it’s original position. It’s a subtle sign but it means there is a brake fluid oil leak in the making. Normally there’s no reason for panic – they can last many miles more before a total breakdown without clutch.
However in our case – it was a very sudden leak and quite large too. The floor was covered with oil in just a few minutes. Luckily we were just about to park our rig.
Broken clutch pedal seal and piston
Because the leak was large, a replacement clutch pedal cylinder was ordered regardless of the precise cause. In the meanwhile the leaking pedal was opened;
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| Clutch pedal oil leak - the plastic pistion is broken |
The plastic piston was cracked. After nearly 7 years, we haven’t seen this sort of malfunction. The clutch pedal pin has come out of it’s normal position and settled itself on the edge of the plastic cylinder.
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| Clutch pedal piston and seal broken |
It cracked, splitting the rubber seal. A sudden oil leak was the result and the clutch pedal stuck to the floor. No clutch – 12 tons stuck on the road. We got lucky, we were just about to parked our rig.
Mercedes replacement clutch cylinder
The replacement clutch pedal cylinder was already improved from this version. The alloy piston can’t break like the plastic version did.
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| Clutch pedal piston - old plastic and new alloy piston |
But there was another subtle difference – the feed pipe diameter of the new clutch cylinder was a bit smaller;
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| Clutch pedal piston - old plastic and new alloy piston |
With a bit of a fight the old tube was re-used – and as a precaution, the rubber hose clamped with a simple hose clamp.
Clutch cylinder bleeding technique
The newer clutch pedal cylinder has no bleed nipple – so removing air bubbles is by opening the bottom notch. A very handy device is a handpump;
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| Handpump to pressure the brake fluid canister to bleed the clutch line and cylinder |
With this pump the brake fluid canister can be pressured so fluid is pressed through the hoses removing any air from the clutch pedal cylinder.
Overland truck parts list – looking back
Would this have happened in the middle of no-where, it’s a good thing to have a few repair kits at hand. Here’s the list of Mercedes Benz parts to take with you on long distance overland journeys;
- Clutch pedal cylinder repair kit
- Clutch pedal cylinder
- Clutch cylinder actuator (no repair kit available)
- Rubber hose
- DOT 4 brake oil
- Hose clamps
- Handpump
And for those with a hydraulic brake pedal
- Repair kit brake pedal cylinder
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| Mercedes Benz Clutch pedal cylinder |
