Yellow Three-Prong Vacuum Plug
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Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
Yellow Three-Prong Vacuum Plug
I found what looks like a broken vacuum plug at the back of my engine. It is yellow, sticks up about an inch from the very back of the engine on the right (driver's) side, and has three prongs that stick out of it. The previous owner had cut and plugged all three ports with screws, and I just found that the whole yellow vacuum plug had broken off. Can someone tell me what these three ports went to?
There is another similar one on the front of the engine, where the water pump is. Same yellow color, three prongs that stick out of it, only this one is in good shape with a top vacumm line running to the back and the engine and the last two are comnnected to each other with a half inch piece of hose. Can someone tell me what these bottom two ports once led to?
I do not understand the vacumm diagrams, so if anyone has any pictures, that would be a big help. THANKS!
There is another similar one on the front of the engine, where the water pump is. Same yellow color, three prongs that stick out of it, only this one is in good shape with a top vacumm line running to the back and the engine and the last two are comnnected to each other with a half inch piece of hose. Can someone tell me what these bottom two ports once led to?
I do not understand the vacumm diagrams, so if anyone has any pictures, that would be a big help. THANKS!
Thread Starter
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Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
Of course, how stupid of me! I can't believe I forgot to post what I had!
1985 Ford F-150 XLT Lariat
302 2-Barrel V-8 (original rebuilt Motorcraft)
THANKS!!
P.S. Did most 302 V-8 F-150's in 1985 come with a carburetor, or did most have the fuel injection?
1985 Ford F-150 XLT Lariat
302 2-Barrel V-8 (original rebuilt Motorcraft)
THANKS!!
P.S. Did most 302 V-8 F-150's in 1985 come with a carburetor, or did most have the fuel injection?
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Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
YES, I mean the left side. This always confuses me. I was going by standing in front of the hood; in which case it would be to the right, and on the driver's side. I guess if I were to sit INSIDE the truck, it would be the left side.
Thanks!
Thanks!
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
Without a vacuum diagram, and picture of the part, I wouldn't even hazard a guess to what it could be for. Almost anything really. EGR system, Thermactor system, Evaporation system, spark advance, air duct heat riser system, etc.....
A thermal vacuum switch sounds acurate. Manifold vacuum goes into one side, and depending on the tempurature, switches the vacuum between the other two ports.
Does part of it go into the water jacket?
A thermal vacuum switch sounds acurate. Manifold vacuum goes into one side, and depending on the tempurature, switches the vacuum between the other two ports.
Does part of it go into the water jacket?
Senior User
Joined: Jun 2004
Posts: 141
Likes: 0
From: Coal Creek CO
on my 84 w/460 the rear vacuum port has 3 different sized ports on the one fitting, one goes to the pwr brake, one goes to the cruise control, and the third??? I guess I will find out when I get to that point of reassembly.
The front ones go to the polution crap, egr and air pump devices via a temp switch on the coolant outlet fitting.
Jeff
The front ones go to the polution crap, egr and air pump devices via a temp switch on the coolant outlet fitting.
Jeff
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