Sold "as is" and is not returnable. This is a special sale of 2 3/2 valves with an extra lever and is priced accordingly. The used one looks good but has not been tested. These special vacuum switching valves are found on most Mercedes diesels from 1980 to 1984 240D, 300D, 300CD, 300TD and 300SD. Some 85 models do not use this type of valve. On most turbo diesel engines, there are two of these located under the black plastic cover on the center top of the valve cover. Most of the time, you will find the lever arms worn off. Others may be full of vacuum leaks due to heat and age.
Product Details
These valves control important functions related to the EGR valve and the automatic transmission shifting. If yours look aged or worn I would recommend you replace them. If the lever is worn out I have found that in over 80 percent the entire valve is worn out as well. Just replace the whole valve. They are subjected to a lot of heat and vibration and I don't think they are good for more than 8 to 10 years because of this.
THEORY OF OPERATION:
To diagnose problems related to these valves, it is important to understand their function. Many believe that they exist solely for the purpose of shifting the transmission. While others believe their only function is to control the EGR. Not so. They actually serve a dual purpose. Their primary function is to control the operation of the EGR valve. Their secondary function is to work in conjunction with the vacuum control valve on top the fuel injection pump (VCSV) to aid in transmission shifting.
Some argue that you should just remove the 3/2 valves, plug off the EGR, and plug the two vacuum lines going the the VCSV. I strongly argue against that. I will agree it is possible to get some transmissions shifting better by doing this - especially if there were vacuum leaks at multiple locations in the 3/2 valve assembly as well leaks in the EGR itself. But this is a “bandaid” repair. If you want to get your engine burning clean (who likes to ride behind a smoking diesel) and get the maximum performance out of your transmission, then I say repair the 3/2 valve assemblies and associated connections. Come on, we are not talking about big bucks here!
Some early 1980 models only had one valve open on the valve cover. Later models had either two or three valves located under the black plastic lid on top of your valve cover. Remove this lid inspect your assembly before ordering.
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