GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Another Lesson About Cascading Problems: Power Steering Fluid Eats Rubber

Old Nov 22, 2022 | 07:39 PM
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2007 GL450
Another Lesson About Cascading Problems: Power Steering Fluid Eats Rubber

If you replace the alternator without verifying the battery and starter, you run the risk of the whole system crashing right back down. A bad alternator can destroy the battery by undercharging it; a bad starter can drain the battery, loading the alternator to recharge it, and so forth. Ditto with the air bags and pump; leaking air bags consume the pump's lifetime, which can also lead to pumping moisture into the valve block, which corrodes the solenoid valves, which ... you get the picture.

After changing my radiator, I noticed power steering fluid was disappearing. There was also a mysterious coolant leak, which I perhaps incorrectly attributed to the o-ring that self shredded when removing the petcock plug. It turned out this leak was from the heater hose that runs transverse under the radiator. The hose had failed in a completely unnerving fashion, its exterior getting all gummy and loose. At the time I simply chalked it up to one of the many mysteries.

The power steering fluid leak has been troublesome lately, so I gritted my teeth in the rapidly onsetting Idaho winter and jacked up the front to investigate. I traced it to the line coming from the steering to the radiator. This is a puzzle, because I put regular hose clamps on both those fittings, and besides they are not very high pressure.

When I wiped the fluid away from the new hose I had installed under the radiator, I noticed it was sticky. This is a sign that rubber is dissolving.

Here is the hypothesis: Slight failure on the line going to the radiator led to a slow drip of fluid (I had noticed gradual loss of fluid, plus wetness in the belly pan). Replacing the radiator disturbed this line, increasing the leak. That fluid led to me chasing a coolant leak which may not have been an issue in the first place. I could fix the symptom - leaking coolant - and not address the root cause.

Note if the power steering fluid eats rubber, it is probably dissolving the swaybar bushings, which are downwind.

The replacement power steering hose is cheap. Kinda wish I had changed it when I was swapping the radiator.

Watch out for cascading effects.
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Old Nov 22, 2022 | 10:54 PM
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