Hunting Down Vacuum Leaks On A Carbureted Oldsmobile

so one of the things we've wanted to do with the new shop here is have people bring their cars and we're going to help walk them through the issues kind of like as if you had a problem with your car and you brought it in so uh meet james james is a local guy from here in murfreesboro and he's got an old cutlass so what's what's going on with this guy uh no i don't vacuum leaks uh the carburetor no idle and vacuum yes what if he's done with it uh took it out the box put it on that carburetor that's right yeah okay yeah but you're a body guy correct yes yes well put a paint job on it uh made it look nice so mechanically you're just not not familiar with carburetors no no fuel injection so tell them what you give them the details on the cards what year is it it's an 85 uh code it's got a 77 350 rocket um it's rebuilt trans it's nice okay and the carburetor and all that is uh rochester rochester yeah okay it's called yeah okay all right so let's go over to the car and let's start you ready ready let's do this all right come on that sounds a bit choppy a little bit it is okay [Music] so we had uh we've got a new hydrogen on here manufactured right so the first thing i'm seeing here is that the choke is closed you're driving around with the choke closed which would make it run really rich how did it run besides idling oh it runs up on yeah the one's fine yeah you got to get on it you got it yeah you gotta always be yeah yeah okay that's probably because of this okay so on this carburetor we're missing yeah it doesn't have a vacuum for this it doesn't have anything for the choke does it okay i didn't know after it's warm it is open well no it's warm this engine is hot and this choke is closed because there's there's no not available i have to find a zip tie okay lots of luck right yeah i don't there's no way you know see we're still moving in here right so i still have all my stuff scattered to the wind um let me see what i got here all right so this is i mean this is definitely not permanent right we're just sure come on now she would have been easier with a zip tie here yeah see if that's tight enough okay that'll hold that open all right so fire it up [Music] [Music] we have a massive vacuum leak of biblical proportions yeah i think it might be the gasket between the carbon the intake no i don't think so no it's way too much for that generally speaking if it's the gasket you'll get like a a minor vacuum leak so if you okay you cut off some of the air uh it'll like just smooth out so you'll have it'll run rough but then it'll smooth out this thing takes up a thousand rpm as soon as you which means you've got a massive mess of vacuum leak so i'm looking at the the vacuum lines here you are you are definitely not familiar with carburetor this is all like it was i stuck this on and went off of what was there okay all right well these these are the heat but you've got you know uh joined over here yeah those are those are the heat lines for the choke thermostat which is missing on this so that's not that's not it um okay this line here is for your vacuum modulator and this is loose yeah so you've got that's that's going to be somewhat of a vacuum leak that'll give you like a little bit of roughness but not what we're looking at here we're looking at massive vacuum leak uh your brake line is hooked up do you have uh the power brakes feel a little weird like there's no pedal it has no back brakes only run out front right now okay um and yes they it takes a lot of pedal effort to make it work most times yes sometimes now all right well that could be it could be a leak at the power brake booster not likely but uh before if i break out a wrench these these are tight right to my knowledge okay but again see big difference in rpm another thing i think is this one that runs to what used to be the pvc valve okay we found it we found it okay fire it up [Music] [Music] oh [Music] all right that's not all of it but that's some of it so what you've got here let me see there's a breather with a nipple breathe it with a nipple and this has got to have a pcv valve in it they make nipples like this you know breathers like this that have the pc viva pcv valve built into it but this isn't one of them so you're just you're sucking constant constant so uh yeah so let's block this thing off let me throw a uh throw a bolt in there all right so you got it jumped off here you know what you need something more substantial in a bolt spark plug let me find a spark plug i'm still putting stuff away things are still in a state of uh total disorganization here we'll just throw a brand new sparkle we're gonna down again okay perfect all right now let's knock this idle down some is it a regular screwdriver yes it is so i'm gonna what i'm gonna do is i'm gonna lower this until it's wow you really have this thing cranked open somebody get it when i try to adjust it okay so we're gonna back this off until it's completely closed wow okay and now i'm going to go i'm going to go two full turns all right let's start it up see what it does [Music] [Music] take out one full turn take it out yeah i want to establish the idle rpm the throttle position for the idler rpm we're looking for it still has a vacuum leak but we're moving closer to the problem so start up again all right one more time have you put the breather on it no no it's still we've we've got where i mean we have less of a vacuum leak but we've still got a crazy kind of vacuum leak all right so the next thing i'm going to do is uh let's see if it's sealing around the intake i'm going to take some gasoline and just trickle it around if we hear it smooth out so okay fire it up again [Music] all right so we have something back here at the back of the carburetor all right um i can't really see so this is where the power brake line hooks up okay and that's loose it's actually really loose i had to find an adapter that goes in this adapter because it was different than the so i see that fire it up again [Music] all right i'm i'm pouring gas i'm squirting guests right on this series of adapters and that's where it wants to run the best so uh and that would also explain why you've got a weird feeling brake pedal you got a pretty big vacuum coming from right over here so uh let's see that's a half inch it looks like a 916 sounds like a 5 8. you got them stacked up yeah yes the only one i can figure out the auto store yeah so yes okay this is stripped i don't really think it's the right thread teacher yeah all right this is we found our problem here that's just barely hanging in there oh yeah okay let's put that out of the way i'm gonna block this off with my finger fire it up ready yeah [Music] that that's a man you got a lot of leaks here that was uh that was blocking that off completely but we're still we still got a vacuum so we need to figure out some way to cap this off motor sounds good otherwise when i opened it it's pretty clean in there yeah valve's everything yeah it sounds really solid okay so hmm what can we uh block that off with a regular bolt that said thread well i've got a little little hole in the center so i'm thinking like a uh like a soft tapping screw would probably work right here see how all my hardware is still in the old place i have containers full of nudge balls washers right right right right right right right right right right right right right right right right right right right right right right right right right right right right right right right right right results in yours i don't have any of that here so let's uh let's see if we can improvise with i got trim screws you got trim screws perfect let me see if one fit in there smallest one probably do it yep i'll do it all right let me get a screwdriver screw this back in you know the threads seem like they might be a little boogered on the back of the carburetor possibility all right back in the first one i got from there was a chunk of the float missing and it wouldn't work at all all right let's try it again okay [Music] fire it up one more time [Music] we still now did you screw around with these idle mixer screws down here at all ah not a whole lot now okay but you did did yes okay so let's try let's see what we got here i think the flight is flatheads right oh that's closed completely all right so we're going to go i'm going to go two turns open that's closed all right so that's one turn come on and that's two turns all right and now this this one's a little more difficult to get it i do have a very long screwdriver do you really i can't even see in there oh wait wait wait dude [Music] this was this is like awkward like yeah five different ways there we go okay that one's closed too okay try it out [Music] all the way good [Music] [Music] okay we're finally narrowing this down um you've got a vacuum leak at the back of the carburetor now when you first started out you said that you thought it was leaking from correct gasket yeah and i think that's what we have here because as i was squirting gas around the normal reaction here and as soon as i got to the back corner that's where she smoothed out so let's uh let's see it's a half inch yeah okay um that's tight oh yeah okay all right let's try it again [Music] [Music] that's pretty damn close it is a lot better yeah i think that gasket is still pulling a little bit of air okay and this line here that you got the vacuum modulated to this is loose so we got a little bit of a vacuum leak from here too i think that's the wrong size fitting kind of like the same way you had with the uh but we've got this thing to where it's like it's close enough for government work right so what you're gonna have to do is uh a get yourself one of these breather caps that has a pcv valve built into it and uh also you're gonna have to uh do something with with uh that line the power brake line so because the fitting that's in there now and that trim screw isn't really in there in there so there might be a little bit of a vacuum from that also but you're gonna have to find the right combination of uh fittings to work with that so we're gonna leave just leave this off to the side now drive it home you're gonna not have any power brakes at all right right you probably didn't have very much power brakes to begin with but i mean other than that it sounds good i mean the cardboard is great the motor sounds fantastic but i can't get an adjustment we can't get it adjusted until you fix all those smaller vacuum lengths okay so you're going to take it from here yeah yeah all right cool appreciate you i think that's it go did you guys get anything out of that i hope this is the first time we've tried this so that's it he'll straighten this out he'll bring it back by we'll check it out uh uh a couple days yeah sounds good sounds good see yes sir meeting you thank you that's it guys i'll see you tomorrow

Channel: Uncle Tony's Garage

Views: 35,255

Rating: 4.9374747 out of 5

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Id: r9SwBulkt40

Length: 23min 32sec (1412 seconds)

Published: Fri Apr 02 2021