So why did THIS vaccum line failed?
Thread Starter
Burning Brakes
Joined: Dec 2008
Posts: 1,021
Likes: 7
From: Morgan Hill and Marina California
So why did THIS vaccum line failed?
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
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
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
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.
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.
Pro
Joined: Dec 2010
Posts: 704
Likes: 1
From: Shillington PA
Thread Starter
Burning Brakes
Joined: Dec 2008
Posts: 1,021
Likes: 7
From: Morgan Hill and Marina California
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Michael S. Palmer
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
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.
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.
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
BTW While your replacing that line consider replacing all the lines.
Because at next years smog test another will fail
Because at next years smog test another will fail
Advanced
Joined: Nov 2009
Posts: 93
Likes: 0
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.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
