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  #1  
Old 09-21-2009, 01:45 PM
VunderBob VunderBob is offline
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Bypassing an EGR valve

I have a 1985 F150 pickup, and over the weekend, it began running funny. It ran fine with the revs up, but if the engine slowed to Idle, it would not remain running; while revving down, it would also backfire.

Long ago, I had a Mercury Zephyr that did something similar, and the EGR valve needed replacing. After trying to help my neighbor recently with an EGR problem, I know parts are no longer available.

The current fix is to bypass the EGR system. I know that the vacuum line from the carb needs to be pulled and capped. What else is involved?
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  #2  
Old 09-21-2009, 02:01 PM
engineer_comp_geek engineer_comp_geek is offline
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Are you sure it's not available? I checked auto zone's web site and found an EGR valve for most of the common engines for that year.

There are other things that can cause those symptoms. What makes you think it's the EGR valve?
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Old 09-21-2009, 02:01 PM
Gary T Gary T is offline
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I find it very surprising that EGR valves for an '85 F150 are not available.

If the cause of the problem is a faulty EGR valve, then the passage from the EGR valve to the intake needs to be fully blocked. The simplest way to do this is to find or fabricate the equivalent of an EGR valve gasket with no holes in it, to act as a restrictor plate. Alternatively, you may be able to block/seal one of the holes in the EGR valve, perhaps by wedging a ball bearing into it. Note that with the EGR not working, engine ping is likely.
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Old 09-21-2009, 03:26 PM
Kevbo Kevbo is offline
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You might find that a penny is a nice fit in the line coming from the exhaust manifold. (worked in a 86 Bronco-II until I could get a replacement valve)
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Old 09-21-2009, 04:28 PM
VunderBob VunderBob is offline
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I made the claim on the EGR unavailability based on trying to find the control solenoid (separate piece) for an '81 351 Windsor. The recommendation from my mechanic was 'bypass the EGR, and make sure you plug the vacuum line to the carb'.

Or, I could say screw it, limp the truck to his place, and let him deal with it.
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Old 09-23-2009, 01:50 PM
zwede zwede is offline
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Problem is your engine is designed to operate with EGR. With it disabled you will probably find that it pings. EGR cools the combustion which is why NOx emissions decrease, but it also allows more part throttle timing advance.

Like others said, they made millions of the things, parts should be easily available.
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  #7  
Old 09-23-2009, 02:51 PM
Gary T Gary T is offline
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Quote:
Originally Posted by VunderBob View Post
I made the claim on the EGR unavailability based on trying to find the control solenoid (separate piece) for an '81 351 Windsor.
It's a whole different kind of part than an EGR valve. The fact that the solenoid and the valve are both parts of the EGR system has no bearing on parts availability.

The pertinent factor is that control solenoids (for whatever system on the car) are low volume items of some complexity. The aftermarket never had any incentive to make them because the engineering costs were too high in comparison to the pitifully low numbers of the things they'd ever sell. And Ford is very good about purging low sales volume parts as soon as they can get away with it.

Conversely, EGR valves are fairly common failure items. In some designs, the aftermarket was able to design a fits-many-applications valve that comes with different orifice plates. This reduced engineering costs over a wide range of part numbers, and that combined with relatively good sales volume makes the parts readily available.

Your symptom suggests a stuck open EGR valve. It may well be that replacing the valve will solve your problem. Bypassing the EGR to eliminate the symptom is easy to say, but not so easy to do.

Quote:
Or, I could say screw it, limp the truck to his place, and let him deal with it.
This may be your best bet.
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  #8  
Old 09-24-2009, 08:19 AM
Translucent Daydream Translucent Daydream is offline
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Have you tried taking it off and cleaning it? I have cleaned a few and gotten some more miles out of them.
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  #9  
Old 09-24-2009, 08:21 AM
Translucent Daydream Translucent Daydream is offline
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I don't know if this link will work but you can order one at Auto Zone.

http://www.autozone.com/autozone/cat...ll&totalPages=[I@121cc73&currentPage=1&vehicleNValue=&navValue=16100214&parentId=61-0&fromString=&fromWhere=null&filterByKeyWord=&categoryNValue=&categoryDisplayName=Exhaust&_requestid =2163654




ETA: It doesn't.

Last edited by Translucent Daydream; 09-24-2009 at 08:22 AM..
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