1985 300i6 vacuum issues?
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From: Donora, Pennsylvania
1985 300i6 vacuum issues?
Hey guys I'm new to the forum and looking for some help.. I have an 85 carbureted 300i6 and I am stumped. My truck normally runs around 900-1000 rpms and idles good but when I hit the brake my rpms die down to about 300-400 rpms and if I let off back up to normal again lol I pulled the vacuum line off my brake booster and put my thumb over the check valve and it does the same as if I'm pressing my foot on the brake it bogs down and if I let off it goes back to normal there seems to be good suction. I can't figure out what the problem is and honestly i don't even know where to start so any help would be greatly appreciated! If a video would help I will gladly record one but anyways thank you to anyone in advance.
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From: Donora, Pennsylvania
I can't recall at the moment but I will keep my ears open in the am when I check it. I replaced the master cylinder not to long ago and I didn't have that problem before that so its a good possibility.
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Clarify something for me; You pulled the hose off the check valve on the booster, and if you put a bolt in the hose to plug it, and then start the truck, it still tries to die when you hit the brakes?
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From: Donora, Pennsylvania
No if I pull the hose off the booster at all then it makes no difference when I hit the brakes and if I plug the hose it does the same thing that it would if I were to press the brakes in with the hose connected.
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