PeachParts Mercedes-Benz Forum - View Single Post - The joys and sorrows of removing oil cooler lines

JimSmith · #10 04-29-2003, 09:59 AM

This is becoming an odd thread. I thought the recommendation by rwthomas1 was pretty good.

The small section of hose length is needed to provide flexibility between the cooler mounted to the car body structure and the connections to the oil filter housing, mounted on the engine. The engine shakes and bounces around enough that a solid metal line would not work. This bouncing, the heat and the pressure cycles are what eventually lead to hose failures.

MB hoses are not designed to last the life of the car without replacement any more so than the aircraft hoses. In fact, the five year replacement periodicity for hoses in general is intended to ensure there is never a hose failure in service, under any normal operating conditions. There is also usually a shelf life for critical application hoses after which the hose is not allowed to be installed for the full five years. This periodicity is common in all military applications as well as the commercial aircraft applications where "normal operating conditions" can be pretty strenuous and the consequences of a failure can be catastrophic.

If asked, I believe the MB engineering advice would be to replace them at the five year period as well. There is nothing to be gained for MB to suggest the hoses should last longer on their cars when the industry standards for rubber hoses makes it clear the 5 year period is the safest way to go. We, as owners elect to wait until we see visual signs of a failure taking place before we change them. So we elect to exceed the industry standard on our own. Our motivation is usually first that we tend to be frugal, and second the job is such a PIA.

The features of rwthomas1's recommendation that I found of particular merit were that he addressed both of the big problems. Once you decide to do the job and scrap the old hoses, you can cut them up to get them out. The replacements can be lower cost, and they can be easier to remove and replace. If the new parts are mostly hose, they can be more easily manipulated to get into position. You can still wait for them to fail like the MB units and the replacements will in all likelihood last a similar length of time provided you buy a quality grade of hose, or you can elect to perform a preemtive strike on the hoses and replace them just because they are five years old. But you can do it yourself and if you make the design so replacement of the hose section is inexpensive, the job won't cost an arm or a leg.

I find this argument a lot like the "Topsider" oil change issue. If the job is easier to do you are more likely to do it at a reasonable interval. I think it is more important to replace the hoses before they fail catastrophically than to use OE hoses, if that would be a barrier to doing the job. Same with the "Topsider" issue. It is more important to replace 99% of the oil at reasonable intervals than it is to get 99.5% out but do it less frequently.

Hope this helps, Jim