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EGR Solenoid Bleed?
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Author:  pickle84 [ Thu Oct 24, 2013 11:18 am ]
Post subject:  EGR Solenoid Bleed?
I have a 1985 d100 with a straight 6 below is the vacuum hose routing diagram.
My question is what is the bleed?
I've been to partsourse and people have no idea I've asked around and no one knows what its is or means.

I have one open nipple on the solenoid do i just leave it open? Everything else is hooked up correctly.

Image
Author:  Reed [ Thu Oct 24, 2013 11:22 am ]
Post subject: 
Hello and welcome.

The bleed is just that- a vacuum bleed. Leave it uncapped on the solenoid, and get a factory service manual for your truck.
Author:  pickle84 [ Thu Oct 24, 2013 11:32 am ]
Post subject: 
So just leave the open nipple?
Author:  Reed [ Thu Oct 24, 2013 11:36 am ]
Post subject: 
Yes.
Author:  pickle84 [ Thu Oct 24, 2013 11:39 am ]
Post subject: 
[/img] http://i1293.photobucket.com/albums/b59 ... 88ab67.jpg
Pic of the orig hook up of the solenoid the far left one is now open
Author:  Reed [ Thu Oct 24, 2013 1:21 pm ]
Post subject: 
From my 1984 Factory Service Manual:

EGR Delay System

Some vehicles are equipped with an EGR delay system having an electrical timer mounted on the dash panel in the engine compartment which controls an engine mounted solenoid (!). The solenoid is connected by vacuum hoses between the carburetor venturi signal nipple and the vacuum amplifier. The purpose of this system is to prevent exhaust gas recirculation for approximately 60 seconds after the ignition is turned on.



So, it sound like you have the EGR timed delay system on your truck and this is the solenoid you have found. Where does the hose that was hooked to the nipple on the far left in that picture go? If it was hooked to the nipple then something else is not getting or supplying the vacuum signal it should.
Author:  ceej [ Thu Oct 24, 2013 9:06 pm ]
Post subject: 
The bleed on that system may be a restrictor. It limits flow so that the EGR works, then when the vacuum amplifier removes vacuum from that part of the circuit, it allows the EGR to close by bleeding off vacuum. Without it, there is a vacuum leak in the system when the EGR should be operating.
As Reed points out, the correct vacuum amplifier circuit diagram is needed for the specific emissions package that came on your truck.
Some of the bleeds were just small plastic restrictor fittings. I don't have experience with the timed bleed that he refers to.
It still should be a restrictor of some sort, otherwise vacuum isn't available at the EGR diaphragm to operate the EGR valve. Without the EGR, you will need to limit vacuum advance, or detonation can occur at partial throttle settings.

2¢

CJ
Author:  Reed [ Thu Oct 24, 2013 9:11 pm ]
Post subject: 
The service manual passage I quoted leads me to believe that the solenoid is normally closed an allows vacuum to go form the carb to the vacuum amplifier. For the first 60 seconds after the car starts the solenoid is energized by the EGR timer delay and vents the vacuum to atmosphere, creating a small vacuum leak but eliminating the operation of the EGR. That would be my guess as to the function.
Author:  ceej [ Fri Oct 25, 2013 6:15 am ]
Post subject: 
That makes sense. What used to be controlled by the Radiator temperature switch is cut over to a start up timer. Gotcha.

CJ
Author:  Reed [ Fri Oct 25, 2013 7:07 am ]
Post subject: 
Actually, there is still a CCEGR valve in the EGR system, too. The mid 80s was an absolute nightmare of a time for emissions controls. Lots of switches and vacuum hoses. Unfortunately, it is getting harder to find replacement parts. I know the EGR timers are no longer available new, and they aren't all the same. Different timers had different delay periods.
Author:  pishta [ Sun Oct 27, 2013 7:13 pm ]
Post subject: 
Here's a little help pickle.

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