FITS THE FOLLOWING: ALL 123 and 126 chassis 240D, 300D, 300TD, 300CD, and 300SD 1980 to 1985 with later style vacuum pump (only one line coming out of top). In 1980, Mercedes changed the design of its diesel vacuum pumps. Instead of a rubber diaphragm pumping action, they designed a piston with a 0-ring seal to replace the diaphragm. This design is inherently more reliable, but there seems to be a common weakness in thee- pumps installed on four and five cylinder diesel built from 1980 to 1985 (excluding the 190D).
Product Details
To determine which type of pump you have, check the following: Older pumps have two large vacuum lines attached to the top of the pump, while this newer style only has one.
From my experience, the most common reason for a total loss of vacuum from these later-style engine-driven pumps is the disintegration of the external main check valve. When that happens, the pump cannot build up vacuum pressure, and you will have all the symptoms of a complete pump failure, i.e., hard and ineffective brakes, diesel engine won't shut off, hard automatic transmission shifting, door locks inoperable, etc. As of July 2024, I also have a kit that can replace the three internal check valves. These are also now failing and need to be replaced. See related products below
This kit includes a brand-new OEM check valve and complete PDF installation instructions.
Here you can see the location of the check valve, and it is accessible without having to take the vacuum pump apart.
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How to view the PDF digital instructions:
Once you complete the purchase of this product you will be able to download the digital instructions immediately when you are logged in and on your personal account page (click on My Account). Any PDFs will show up under My PDF Manuals. You will be allowed three downloads, so please save the file on your machine for backup.
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Related Products:
Single Hole Diesel Vacuum Pump Partial Overhaul Kit
I have chosen to call this a "partial" overhaul kit because full rebuild kits have been NLA for years. However, many of these pumps still need help, so I have assembled this kit to help owners restore some of their lost vacuum output.
615 616 617 Diesel Healthy Vacuum Exam Kit
Is your diesel suffering from hard brakes, poor or no engine shut off, climate control problems, or even funky transmission shifting??