Vacuum system

pctghost · Feb 11, 2018

I just got a 1984 ranger 2.8L V6 4x4. There is a newer motorcraft carb in place. My vacuum diagram is not matching up with the hoses in my engine compartment. I am trying to find out about a WOT VLV on my vacuum diagram. It seems to be missing from my engine compartment. I also have exhaust gas coming from my oil cap/breather hose to the air filter compartment. I have changed out the PCV valve and the hoses are clear and not stopped up. I can't find anything online about this WOT VLV part. Any help would be appreciated. I have posted the diagram also for reference.

AndyB. · Feb 12, 2018

WOT VLV—I belief this is a wide open throttle cutout that disengaged the air conditioning compressor clutch under wide open throttle conditions.

The blowby (exhaust gas venting from crankcase) is not likely related to the vacuum issue. You can do a leak down test to tell you the rings/cylinder are worn—but if you’re not prepared to do a rebuild, you might as well just live with it.

pctghost · Feb 13, 2018

I was looking at the vacuum diagram and it shows the WOT VLV as being part of the system, but we're it says it is hooked up I have nothing there. Most of my vacuum hoses are routed according to the diagram except the WOT VLV which the vacuum hose for that goes from the main vac to the carb. I am just not sure if this is due to the newer carb that is on it or I am missing something that I need to have hooked up.

enginepaul · Feb 13, 2018

That's an Air Conditioner valve, so if you don't have AC, you don't need the valve.
It may have broken when the previous owner had you truck and couldn't get a replacement. If it runs good with out it, don't worry; just take your time finding one.

litleblue · Jun 22, 2018

Guys this valve cancels the the air cleaner diverted valve. It is the WOT VLV (wide open throttle valve). You notice this three way valve Is teed in to the aircleaner diverter valve and is operated by manifold vacuum. When the throttle is opened the vacuum decreases, this normally open valve cancels the “stove”heat for the carb (air cleaner stove heat or (A/CL DV) air cleaner diverter valve. When the manifold vacuum is high the valve is closed and the thermostat (A/CL BI MET) air cleaner bi metal thermostat controls the carburetor air intake temperature. When you step on the throttle and need more power the valve cancels the carb heat delivering cooler air (higher density) to the carburator this has nothing to do with the air conditioning. The only thing The EEC IV system has to do with the Air conditioning is the input to the engine control module. When the air conditioning is on the idle control is reset a little higher for the additional load on the engine.

enginepaul · Jun 24, 2018

LitleBlue is right; I took a bad guess.

kimcrwbr1 · Jul 13, 2018

Just use the diagram under the hood if it dont show it it aint there. More than likely the excess blowby is from the valve guide seals. You can replace the seals without pulling the heads there is a section in the tech library. I bet your engine blows black smoke on a restart after it sits 1/2 hour or so? The old seals just turn to owder when you touch them. Once you replace the seals then give it a good decarb with seafoam that will clean the pistons and rings from carbon buildup from the oil dripping down the valve guide seals. Your cat is probably shot as well from the oil in the exhaust.

Vacuum system

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