delco1946 Posted September 2, 2019 Share Posted September 2, 2019 I’m trying to double check the vacuum lines on my engine because somethings wrong. Although in looking at all my resources I have no idea what the vacuum line connecting into the back of my Motorcraft 2140 carburetor is or where it supposed to go to ? It’s not a part of the EGR and it’s the top most vacuum line at the back . Also In line with the vacuum are two different colored cylinders -how do they differ? One is gray and black and the other is teal black and white . I am assuming one is a vacuum delay valve and the other is a vacuum retard delay valve but I don’t know which is which . Link to comment Share on other sites More sharing options...
delco1946 Posted September 2, 2019 Author Share Posted September 2, 2019 Link to comment Share on other sites More sharing options...
delco1946 Posted September 2, 2019 Author Share Posted September 2, 2019 Argh. Thoroughly frustrated. Anyone have or know of photographs of what a 1981 351M vacuum line system should look like? That would be so much more helpful than a schematic. My engine seems to be running worse now. Not better. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 2, 2019 Share Posted September 2, 2019 Argh. Thoroughly frustrated. Anyone have or know of photographs of what a 1981 351M vacuum line system should look like? That would be so much more helpful than a schematic. My engine seems to be running worse now. Not better. I have some '81 351M vacuum diagrams here: Underhood/Vacuum/Vacuum Systems/Vacuum Diagrams/351M & 400. Is that one the same as yours? If so, we can figure it out. Are you keeping all the emissions stuff? Link to comment Share on other sites More sharing options...
LARIAT 85 Posted September 2, 2019 Share Posted September 2, 2019 The hose in your hand is not connected to the right place. Do you still have the stock air cleaner? That hose is supposed to be connected to the vacuum motor on the snorkel part of your stock thermostatic air cleaner. And, the colored check valve is turned backwards. The teal-colored end should face the snorkel, where it is connected on one end by a short section of vacuum hose. The cream-colored end should have a longer vacuum hose that connects it to the air cleaner lid. Remove the hose from the carburetor. The port on the carburetor it is currently connected to is the fresh air port that is supposed to be used for a "fresh air tube" for the stock thermostatic choke. It should have a small section of rubber hose connected to it, and then a metal line is connected to the the other end that routes down to a chamber on the passenger-side exhaust manifold. This chamber should have a second insulated tube - called the "hot air tube" - in it that connects back up to the carburetor, right behind the choke cap. If you don't have a thermostatic choke, you should cap that off, as it will let unfiltered air into the filtered side of the air cleaner. Link to comment Share on other sites More sharing options...
delco1946 Posted September 2, 2019 Author Share Posted September 2, 2019 I have some '81 351M vacuum diagrams here: Underhood/Vacuum/Vacuum Systems/Vacuum Diagrams/351M & 400. Is that one the same as yours? If so, we can figure it out. Are you keeping all the emissions stuff? It’s similar but I don’t have air-conditioning, I have the thermactor system, and a thermal valve switch Sticking out horizontally out of my thermostat housing, and then a 4 pronged vacuum tree sticking vertically out of the thermostat housing. I was tempted to take my EGR valve out to look at it and maybe just replace it assuming that it’s probably that gets old . I had multiple systems including the thermometer connected to my cold weather switch in the air cleaner housing ( I don’t see any evidence that anything should be connected to that except for the snorkel ) . I disconnected everything from that and reconnected the vacuum motor in the snorkel which had been abandoned. Link to comment Share on other sites More sharing options...
delco1946 Posted September 2, 2019 Author Share Posted September 2, 2019 It’s similar but I don’t have air-conditioning, I have the thermactor system, and a thermal valve switch Sticking out horizontally out of my thermostat housing, and then a 4 pronged vacuum tree sticking vertically out of the thermostat housing. I was tempted to take my EGR valve out to look at it and maybe just replace it assuming that it’s probably that gets old . I had multiple systems including the thermometer connected to my cold weather switch in the air cleaner housing ( I don’t see any evidence that anything should be connected to that except for the snorkel ) . I disconnected everything from that and reconnected the vacuum motor in the snorkel which had been abandoned. Lariat- the The tubing in my hand was originally connected to the top of my stock air cleaner, however the other connection points within the air temp switch simply connected to a vacuum tree in the back of the manifold. This means there was nothing connected to my snorkel. Said differently- manifold vacuum was going to the air temp switch and then to the back of the carb via the large diameter tube in question. From other diagrams I’ve looked at intake manifold should connect to the air temperature switch On top of the air cleaner, which should then connect to the side of the air cleaner to the cold weather switch, which should then connect to the snorkel. Correct? Regarding the thermostatic choke/your second paragraph it’s going over my head currently. So I’m off to the store to get a lot more vacuum line and then I’m going to study up so I can get this right! Link to comment Share on other sites More sharing options...
delco1946 Posted September 2, 2019 Author Share Posted September 2, 2019 Lariat- the The tubing in my hand was originally connected to the top of my stock air cleaner, however the other connection points within the air temp switch simply connected to a vacuum tree in the back of the manifold. This means there was nothing connected to my snorkel. Said differently- manifold vacuum was going to the air temp switch and then to the back of the carb via the large diameter tube in question. From other diagrams I’ve looked at intake manifold should connect to the air temperature switch On top of the air cleaner, which should then connect to the side of the air cleaner to the cold weather switch, which should then connect to the snorkel. Correct? Regarding the thermostatic choke/your second paragraph it’s going over my head currently. So I’m off to the store to get a lot more vacuum line and then I’m going to study up so I can get this right! Here’s some new pictures after I reassembled everything just to test it. So this isn’t how I am planning on leaving it, but I only messed with things that I felt more comfortable with which is why you see weird tubing on the air cleaner. One line of the tee on the air cleaner now goes to the CWS which I am pretty darn sure is correct, and the other goes to the tubing I originally held in my hand in that first picture as that is what it was connected to originally and I know at least at that point in time my truck ran so I left it. In my hand below is The other change I made which was in splicing the thermactor air bypass. Per The radiator label, after the temperature valve switch on my the thermostat, vacuum goes to both the EGR and the thermactor. It first passes a vrdv enroute to the thermactor (Which I assumed was the teal thing) and ( via tee in my hand) separately passes a vdv enroute to the egr, (which I assumed was the gray and black thing). Link to comment Share on other sites More sharing options...
LARIAT 85 Posted September 2, 2019 Share Posted September 2, 2019 Here’s some new pictures after I reassembled everything just to test it. So this isn’t how I am planning on leaving it, but I only messed with things that I felt more comfortable with which is why you see weird tubing on the air cleaner. One line of the tee on the air cleaner now goes to the CWS which I am pretty darn sure is correct, and the other goes to the tubing I originally held in my hand in that first picture as that is what it was connected to originally and I know at least at that point in time my truck ran so I left it. In my hand below is The other change I made which was in splicing the thermactor air bypass. Per The radiator label, after the temperature valve switch on my the thermostat, vacuum goes to both the EGR and the thermactor. It first passes a vrdv enroute to the thermactor (Which I assumed was the teal thing) and ( via tee in my hand) separately passes a vdv enroute to the egr, (which I assumed was the gray and black thing). I don't think the way you have it is correct. That looks way too complicated. Look at the connections on the air cleaner in the video below: I think the temperature switches on the side of the air cleaner are for emissions devices. Can you post a picture of your vacuum diagram under the hood? Link to comment Share on other sites More sharing options...
delco1946 Posted September 2, 2019 Author Share Posted September 2, 2019 I don't think the way you have it is correct. That looks way too complicated. Look at the connections on the air cleaner in the video below: I think the temperature switches on the side of the air cleaner are for emissions devices. Can you post a picture of your vacuum diagram under the hood? So what I have set up is quite similar to the YouTube video. Only with the cold weather switch, that appears to take the place of that blue cylinder thingy in the video. I followed the cold weather switch document on this website, which also aligns with my Haynes manual (or at least I’m pretty sure I did ). My understanding is that the CWS basically holds a vacuum below 55° so that if you accelerate it the cold, the vacuum motor stays open. *Edit * maybe I’ll just switch to you design Lariat- the cws stuff doesn’t show on my label so perhaps I’m getting carried away. The only reason I stuck a temporary tee on the air cleaner is that I don’t know where that tube in the first pic goes to. That unknown tube is I. The first pic, and its not coming out of the manifold, which I think would indeed go to the snorkel via air temp switch and cws, rather it’s coming from the back of the carburetor. Link to comment Share on other sites More sharing options...
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