Self level suspension hose warning
 

This is intended as a word of advice to those with models fitted with self-levelling suspension of a similar age to mine. I recently took my family on an interstate vacation where we covered around 3000km in our well laden 1990 300TE. Around 1000km into the journey I decided to check under the bonnet (hood). I was alarmed to see my previously perfectly clean engine covered in oil. Much of the engine and engine bay was contaminated but particularly the right side of the engine block. Some oil had also been thrown from the pulleys at the front leading me to initially think the front crankshaft seal had failed. On closer inspection I noticed that the oil was very light. This made me look at the SLS reservoir which was low.

It turns out that the high pressure hose leading from the pump (part of steering pump on 300TE - shown "A" in attached pic) under the engine and up to the rigid line (shown "B") at the rear of the engine bay on the oposite side of the engine had begun to leak. The leak was in the area between the engine block and alternator (shown circled) where the hose is exposed to the greatest amount of heat.

The hose had failed during the journey possibly due to the greater pressures experienced as a result of the extra load in the rear of the wagon. The hose only carries high pressure while raising the suspension to compensate for additional load and as a result of suspension movement while driving. Fortunately, I was able to purchase a replacement hose (at great expense) from a Mercedes dealer and fit it before continuing our journey. Had I not been able to do this, I had intended to disconnect the control rod at the control valve at the rear of the car. By then setting the valve in the neutral position, the hose would not have been exposed to high pressure for the remainder of the journey, thus preventing further fluid loss and the risk of the reservoir emptying and causing the pump to run dry.

I have posted this to alert other owners of a fault that can catch you out at an inconvenient time. In my case, the car is very well maintained, however the failing area of the hose was not visible until the hose was removed. Fortunately, I was able to replace the hose and we did not experience excessive inconvenience to our vacation.

Greg
Thanks for your post. I went through the same recently. I am curious, did you also have a hard time removing that long bolt that attaches the hose to the pump housing/engine block? In my case (1992 300TE) there was a silly plastic shield in the way. I guess I would have quite some problems to replace the hose "on the road" like you. So is there a trick?
Regards, Bruno

I am having similar problem with my 87 560SEL (very minor leak) and has to be fixed. The pressure hose on the 560 is really hard to get to since it's snaked around and behind the main pulley, water pump and other stuff. I am not sure about your car, but mine is a ***** to get to and I have not yet found an easier way to remove the hose without removing the main pulley and other stuffs. Maybe there is no other ways.

I posted a thread regarding this issue and no one has yet to reply. :(

Bruno,
Yes, the long air-con compressor mounting bolt that also mounts a bracket for the hose also gave me trouble. To extract that bolt, I had to remove the plastic panel at the lower left side of the engine bay. To remove the plastic panel, I had to drop the front sway bar! Usually the 124 is easy to work on but this complicated this job somewhat. The other end of the hose presented a problem too. The pipe nut was extremely tight and took quite some time to loosen. Fortunately I carry tools with me on long journeys.

newr,
I cannot offer advice relating to this hose on your 560. Apart from the issues above, replacing the hose on the 300TE was straight forward. Even though it fits between the engine block and alternator, it was not difficult to feed it through without removing the alternator. The rubber grommet in the bracket for the hose near the alternator was hard and crumbled when trying to remove it. The new hose only included the lower bracket and grommet but fortunately the grommet from this bracket for the old hose was still good and could be used in the upper bracket.

Greg

Thanks for the post. I just removed my oil pan from my 1990 300TE, and now would be a damn fine time to inspect that hose. Check my pic in the how do you remove the oil pan thread :eek:

Saint, I would not replace it unless it is leaking. It costs 200$.

Greg, many thanks for your reply. I wass less patient with the plastic shield and just cut it somewhat with the angle grinder to be able to bend it out of the way. Probably not the best practice.
Bruno

I'm guessing the hose on these cars is very similar to the one on my 85 300TD. If so, it can be replaced with ordinary high pressure hydraulic hose, reusing the original fittings using the procedure outlined in this thread:

http://www.peachparts.com/shopforum/diesel-discussion/192973-repairing-hydraulic-hose-sls-hydropneumatic-suspension-td.html?highlight=sls+hose