changing out vacuum lines on a 30 year old car

[steven]

we recently purchased a truck to mess around with on the weekend and take to the local cruise night its a 4 cylinder iron duke s10 from 89. we are contemplating rebuilding the whole vacuum system with silicone hoses and zip ties at all connections to make sure we seal good. first off the condition of the stock vacuum system is shady at best but the truck does run and drive as is but are tought is that all these lines are almost 30 years old anyways most of them are probably cracked and or dry rotted and brittle and most likely not sealing good. so where contimplating rebuilding the whole system and starting over fresh are question is: will doing so yield any performance or fuel mileage gains the truck originally got about 18 mpg in town driving new according to what we found on the web a recent mileage calculation revealed only 12 mpg in town and 15 on highway at 65 also would swapping the plugs wires and 02 sensor help to recover or improve on are mileage lose? i look forward to seeing your replys

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[Its me]

In my humble opinion, you are overdoing it with the hoses. Just replace with good old regular vacuum hoses and they will last for years…. The O2 sensor in this vehicle is probably not electronically heated, so replacing it may yield better gas mileage….

Many 80’s vehicles were a spaghetti mess of vacuum lines and fuel economy could suffer if all do not seal properly… You had a baro sensor, MAP Sensor, Purge valves all running off vacuum lines… Not to mention an AIR system most likely (w/smog pump) and a computer controlled carb that just reacts to the fluctuations of the lean/rich mixture the O2 sensor was sending….

Ensure the timing is set properly and a new distributor cap and rotor with new spark plugs also can’t hurt.

-Karl

[Bill]

I agree with Karl. Silicone hoses collapse under high vacuum and heat. Just don’t use windshield washer hose. A new o2 sensor is a good idea.

[steven]

also i dont think heat would really be an issue silicone hoses are rated at about 330 degrees for there max temp so im pretty certain that a 4 cylinder pickup isnt getting that hot lol

[Bill]

I’m just saying that the combination of both tends to make them collapse. The hotter silicone hose gets the softer it gets.

[Author]

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