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I learned something new! Again!

KVH

Obi Wan
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My engine idle has been very poor and inconsistent, so I thought I'd check the PVC valve. It's clean, and I suspect no problem there. But the hoses are both very flimsy and worn, so I took them into the local parts store to replace.

The parts guy looked at them and said he didn't have anything that would work. I thought he had to be joking because they sell all sizes of hose by length. He said that PVC Valve hose is a special oil resistent hose that is carried only by the serious auto shops and that other hose will deteriate with oil residue and collapse on itself.

I think he's right, because my hose was collapsed, even to the point of causing a whistling when the engine was idling. I'm en route to another parts house.

[Next, I'd like to know why my horn relay switch works fine, but two new ones from Moss won't work. They look different, but what the hey is going on? Don't they all do the same thing?]
 
PCV hose should have a reinforcing braid going through it to prevent it's collapse from vacuum drawing through it. You can see it in the wall when it's cut.

Power brake booster hoses should be the the same material.
 
I agree, PCV hose is made from a special material that resists the blowby gases better than ordinary vacuum or fuel line. It's not just a matter of withstanding vacuum, and brake booster vacuum lines don't need to be the special material.

What's a "horn relay switch"?
 
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