If your diesel engine is starting to shut off very slowly or maybe not at all and you know your vacuum system is ok, it may be time to replace the vacuum fuel shutoff valve located at the rear of the injection pump. You can check its operation with a hand vacuum pump or you can pull the rubber hose off the back for visual inspection. If there is black oil in the hose, it's time to change the valve (the diaphragm has started to leak) the rubber hose AND the switch under the dash. Removing it is a tight squeeze but not a difficult job for the do-it-yourselfer. You will be amazed at how nice it is to have the engine shut right off again right after turning the key off. Also, the switch under the dash on top of the steering lock could be faulty. We have included that switch and 1/2 meter of high-quality vacuum hose.
Product Details
The under-dash vacuum switch looks like this and is located under the dash on top of the steering lock. You will need to remove the steering lock to replace it. General instructions are included to help you remove the steering lock. Be sure to replace the vacuum hose. WARNING: DO NOT SWITCH THE HOSES OR YOUR ENGINE WILL NOT START RIGHT AFTER TURNING IT OFF. Keep track of which nipple goes to which hose color.
This is an aftermarket part and may not be as cosmetically pretty as the original Bosch part, but Bosch no longer makes it, so your options are limited.
We vacuum test each one in our shop before we ship them to make sure they pull fully back ( fuel off) before reaching 10 inches of vacuum. NOTE: a very slow, gradual leak down is acceptable and does not affect operation in turning off your diesel engine.
PLEASE NOTE: If your engine does not shut off, the problem may not necessarily be this shutoff valve. You could have a bad vacuum pump or leaks elsewhere in the system. I have two resources to help you troubleshoot this problem properly BEFORE you start purchasing parts.
- Look below in related products to read more about my manual "Vacuum Source Troubleshooting and Repair."
- Look below in related products to see the vacuum tester we offer to help you find the problem fast.
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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:
Diesel 616 617 Vacuum Source Troubleshooting and Repair - by Kent Bergsma
Applies to 240D 300D 300CD 300TD 300SD Diesel This guide is written specifically for owners of 123 and 126 diesels from 1977 up to 1984. There are some sections that apply to the 115 and 116 chassis but it is not specific to those models.
Service: Vacuum Hand Pump Testing Kit w/ Extras