Vacuum Warning Switch

[genscripter]

My vac sensor hasn't worked for 6 years. Last year, I installed an old mechanical boost/vac gauge that I had sitting in the garage. I had it on an old TDI from years ago. I tee'ed it in on one of the vac lines on the hub, and ran the nylon hose to the cab, putting the gauge on the dash. Now I know the vac pressure at any given moment. If the vac pressure ever gets too low, I know it right away.

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[Cubey]

Haha!!! Me too! On my third since I got it...

The one that was in the truck when I got it was on it's way out when I got it in Feb 2017. It's had the Cardone one from O'Reilly's since around May/June of 2017 and it's still working fine.

 

[Justin B]

Good news, she fired up after getting all the air out!

I didn't bother with the switch, main focus was getting her started. The brake light didn't illuminate even though the switch wasn't connected to vacuum. I haven't tested the switch yet, but I'm assuming the contacts are stuck. Maybe next weekend I'll dive into that can of worms.. in the mean time I've got to figure out why my filter head is leaking (looks to be coming from the heater port) and get her timed. Thanks for the info guys.

 

[MR.T]

<snip> The brake light didn't illuminate even though the switch wasn't connected to vacuum. </snip>

That's how they seem to fail. There's a time delay inside and I think that's what actually gives up. Last one I got was in a wrecking yard, but it was off a Dodge diesel pickup, circa 1995. They are exactly the same, and usually newer. Tested about 5 bad ones out of Fords while at wrecking yards before finding this one.

Every so often I'll repeatedly pump the pedal and check that light comes on. Like having it, been through at least three vacuum pumps and that little bit of advance warning helps.

 

[BioFarmer93]

Dry vacuum pumps tend to crap out with no warning. I've had many vacuum pump failures in aircraft. they work fine for years, then just die mid-flight. A lot of people replace them at 500 hours

I don't doubt that you are correct, I was fortunate enough to get a good 48 hour warning from my gauge.

 

[renjaminfrankln]

I don't doubt that you are correct, I was fortunate enough to get a good 48 hour warning from my gauge.

I should probably test my factory warning system at least.

How many inches of vacuum does a good pump pull?