Where does the vacuum modulator on a TH400 go????

1989 R3500 · Sep 20, 2020

I was rooting around under this truck I just bought and found the vacuum modulator line is off. I thought they connect to a hard line and go somewhere to the intake manifold. But I can't find any lines going down from the engine. It's a 454, TBI.

Does anyone sell the hard line?

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Frankenchevy · Sep 20, 2020

Full manifold vacuum, sometimes teed into the same port as the brake booster.

Blue Ox · Sep 20, 2020

I'd almost bet money that when yoi get it reconnected your going to find your engine smoking on decel and a loss of transmission fluid.

The only rational reason I can think of for not having it connected is that the modulator is blown. Still would have made more sense to replace it than disconnect it though.

Craig 85 · Sep 20, 2020

Inline Tube sells the hard line. Page 16 of the Chevy Truck catalog #CTT8105 standard $25 or stainless $35. First link is direct to the parts.

https://www.inlinetube.com/pages/product-list?itemNumber=ctt8105

http://online.flipbuilder.com/wmmk/wlho/

Where does the vacuum modulator on a TH400 go????

1989 R3500

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Frankenchevy

Proverbs 16:18

Blue Ox

Turning Diesel Fuel Into Fun

Craig 85

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