86, E350 Diverter valve
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Freshman User
Joined: Jul 2003
Posts: 46
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From: S.D. CA.
86, E350 Diverter valve
I've got an '86 Econoline with a 460 c.i. engine. 4180 Holley carb. It's backfiring thru the exhaust on long periods of decelaration, (down grades). No exhaust leak, no intake manifold leak, so I suspect a diverter valve per my Chiltons. Only problem is the only time the Chiltons uses the term diverter valve is in the troubleshooting section, no where else in the manual. Does this also go by the name bypass valve?
thanks in advance
thanks in advance
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Originally Posted by tdbudman
I've got an '86 Econoline with a 460 c.i. engine. 4180 Holley carb. It's backfiring thru the exhaust on long periods of decelaration, (down grades). No exhaust leak, no intake manifold leak, so I suspect a diverter valve per my Chiltons. Only problem is the only time the Chiltons uses the term diverter valve is in the troubleshooting section, no where else in the manual. Does this also go by the name bypass valve?thanks in advance
Valve, Air By Pass
Valve, Anti Backfire
The Ford Basic Part Number (9B289) is the same for both valves, but the valves are different.
Sorry, I can't give the the part number without the Calibration Code.
Elder User
Joined: Mar 2004
Posts: 517
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From: Texas
If this is a California emissions vehicle I would suspect the EGR passages are loaded and the backfire you hear is detonation caused by carbon deposits at the tops of the cylinders.
I would remove the carburetor first to inspect that passage. If clogged, I would next pull the crossover tube at the back of the engine. This is a coat hanger job if clogged.
Next I would investigate the two valves aforementioned for proper operation, prior to buying replacements.
I would remove the carburetor first to inspect that passage. If clogged, I would next pull the crossover tube at the back of the engine. This is a coat hanger job if clogged.
Next I would investigate the two valves aforementioned for proper operation, prior to buying replacements.
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Freshman User
Joined: Jul 2003
Posts: 46
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From: S.D. CA.
It's without doubt backfiring in the exhaust as flames are present at the tail pipe when backfiring. Most often occurrs after climbing a long grade and then descending. So I assume the build up of unburned fuel in the exhaust system is igniting. By the way this is a 26 ft Minnie Winnie with no cat. converter, and yes this is a CA emissions vehicle. That's the part number I got from my local Ford dealer too. At least I'm on the right track. A good parts guy is more valueable than a good mechanic IMHO. Thanks for your input. 
Last edited by tdbudman; Jan 18, 2007 at 05:02 AM.
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