Chuck Tribolet

My '87 went in for California smog inspection today. It passed, but
one item was just barely. The pressure test on the evap systems
was marginal. The problem was likely a vacuum line that runs past
the base of the power steering pump. This one line had gotten all
mushy. All the other lines seem good as new.

Any ideas why THIS one line failed?


Chuck

Muffin

Cause it is 25 years old.

kimmer

Daah yeah.

Chuck Tribolet

But all the others are just fine. Why THIS one?

Churchkey

SWAG: Due to its location it may have some oil on it = soft (er) hose.

Might be time to freshen things up. Brake booster & PCV hoses deteriorate on the inside.

If the brake hoses are original suggest replacing them first.

383vett

That line was sucking fuel vapors from the canister to the motor. Try doing that for 25 years and see how mushy and soft you look like.

popo8

AGREED!!!

Chuck Tribolet

Now that's a reasonable explanation.

BTW, the hose wasn't oily.

BTW, it's relatively low mileage, 38,000.

leesvet

Cause....

Its attacked from both sides. Inside its full of gas fumes if its the evap system. The outside is likely subjected to some PS leakage and PS fluid is just higher refined hydraulic fluid that is loaded with acid, anti wear agents, and temp stabilizers that do strange things to plastics and some forms of rubber. Its ok in hyd hoses designed for hyd fluids, but expose a windshield wiper to hyd fluid and watch it wrinkle like a crinkle cut french fry.
All hydraulic fluids are full of acid to clean the super tight tolerance control valves and metering devices in a hyd system. The ultimate is aircraft hyd fluids and then brake fluids that have to clean even though they age, lubricate, resist boiling and maintain a very specific viscosity.

I ended up replacing those evap hoses with EFI fuel hose so there was no more plastic line to crack or break and the EFI hose would handle the fuel and oils. For the smaller vac line I just used the rubber vac line instead of the plastic. Tie straps and its good.

JrRifleCoach

BTW While your replacing that line consider replacing all the lines.

Because at next years smog test another will fail

Davejs

Plastics deteriorate over time period, now add on the heat cycles and vapors or liquids. Pressure or vacuum on lines is another factor to enter into the equation. That they are only designed to last about 7 years or 100,000 miles by mfg to meet emissions.

JackDidley

Best answer.