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| stalling still...intake manifold leak? https://slantsix.org/forum/viewtopic.php?t=42826 |
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| Author: | bootsnbolts [ Thu Dec 09, 2010 8:51 am ] |
| Post subject: | stalling still...intake manifold leak? |
so it's been months of tracking down various stall issues: replaced timing chain and gasket, rebuilt holley 1920, new float, new ignition coil, new fuel pump, fuel filters (metal), lots of carb adjustments recently, timing check, you name it. acc. pump working fine. all vac hoses are new. vac is a tad low, off the carb or off the tree. plugs, rotor, etc., all new. recent oil change. i do have sludge in my tank but murray's said to just throw another fuel filter on before the fuel pump. lean? rich? we've adjusted it all. checked everything. yet she still stalls. sometimes with acceleration around right hand turns, often from a stop (warm) at a light or sign, especially when at a stop and accelerating uphill. sometimes just accelerating. she does it less when she has a full tank of gas and oil is topped up, and when i accelerate slowly, but when i punch accelerate or accelerate too quickly she goes out. it's become an art that keeps me on the edge of my seat every time i come to a stop. one of the last things i have yet to do with her is replacing the intake manifold gasket, the only thing i notice getting consistently worse while everything else is getting better. she's got leaks pretty much across the whole damn thing at this point....started as just a few spots. my book is not giving me much help, so i thought i'd sound off here. at this point, there's not much left to fix on her, but this stalling issue is making my daily kid/school runs really stressful as she tends to stall out in the worst, unavoidable places, like rush hour in the middle of powell street. of course i don't have hazards. The major symptom of a vacuum leak is very poor idle quality, stalling, Spitting back through the Intake, and a very lean condition at part throttle�. Read more: http://wiki.answers.com/Q/What_is_a_vac ... z17dPsaIgm the lean condition at part throttle is making a lot of sense...she doesn't do it at full throttle, EVER. http://wiki.answers.com/Q/What_is_a_vacuum_leak |
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| Author: | 4speed [ Thu Dec 09, 2010 9:13 am ] |
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Have you adjusted the valves? Have you pin pointed the leaks by spaying carb cleaner/wd40 around gaskets or carb? |
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| Author: | bootsnbolts [ Thu Dec 09, 2010 9:17 am ] |
| Post subject: | |
valves have been adjusted twice. new valve gasket. have not done the carb cleaner around gaskets but i can tell you right now that girl has got a massive intake manifold gasket leak, it's gotten really bad lately, to where i smell it constantly while driving and it just pours smoke with hood up at idle. i can see the holes in the gasket, and the underside of my hood is black with exhaust. carb is rebuilt and good to go, when we redo the IMgasket we'll also do the gasket to IM under the carb. pardon my lack of technical terms, i'm on a learning curve. compression is at about 90 straight across. |
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| Author: | 4speed [ Thu Dec 09, 2010 9:33 am ] |
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I know that the intake and exhaust gasket are on the same line (and same gasket cut from the same material) but if your exhaust is leaking it will not cause stalling-just extra noise and fumes. But if the spay test shows intake leaks then you found your problem. Do the test with the engine warm enough to open the choke. Ether way it sound like you need to change that gasket. |
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| Author: | bootsnbolts [ Thu Dec 09, 2010 9:46 am ] |
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i've got fumes, but not noise. she runs pretty damn quiet, one of the reasons i bought her is the rebuilt engine. as i said, fumes are just pouring out of the intake manifold gasket area, i can SEE the gaps, not sure i even need to do that carb cleaner test. a while back she had sealer thrown on the outer IM gasket leaks, but that didn't really fly either and it's exponentially worse than it was, as i can now see visible leaks all the way down the IM at the gasket. |
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| Author: | 4speed [ Thu Dec 09, 2010 10:14 am ] |
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If fumes are coming out it is ether the valve cover is leaking oil on to the exhaust manifold or the exhaust gasket is leaking. If the intake gasket is leaking you will not see fumes as the leak is sucking air into the intake manifold. Ether way it is the same gasket to change. You may want to take a light tug on the bolts to see if they got loose over the years. |
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| Author: | wjajr [ Thu Dec 09, 2010 2:03 pm ] |
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Do you have a torque wrench? Pull the carburetor, and check its bottom for any concave with a straight-edge condition from over torqueing. My old Holley had this problem, and no amount of carburetor cleaner sprayed around its base detected the condition because it was sucking air from all four sides. A big millbastard file can be used to file its base flat if needed. It looks as if a new intake-exhaust manifold gasket may be in order. Remove both manifolds as one unit, check them for trueness with a good straight edge, and also check the mating surface on the head as well. If needed have a machine shop true them up. When reassembling, be sure that the threads on all the manifold studs allow a nut to freely be threaded on by finger before attaching the manifolds in order to get a true torque reading. Also use a good grade of gasket, I have used a Fel-Pro, others like the Australian gasket as it will seal manifolds that may not be as true as they should be, and do not over torque the nuts. These manifolds are designed to expand & contract during heating & cooling cycles, and have to be able to move, or soon you will have a vacuum or exhaust leak. |
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| Author: | ESP47 [ Thu Dec 09, 2010 2:11 pm ] |
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Something just isn't adding up here. If you can just look and see holes between the intake and head, the car shouldn't even be able to run at that point. What is your vacuum gauge reading? The huge leak you explain and the "tad low" vac reading you're showing do not go hand in hand. Are you sure you aren't just burning a ton of goop off the gasket and manifolds? Also I would not recommend an extra fuel filter as a fix or even a short term fix for a gas tank that has sludge. Would you drink water out of a port-o-potty after two runs in your brita filter? If you have bad gas going to the engine, you're going to be chasing your tail until you get the tank cleaned out. |
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| Author: | kipamore [ Thu Dec 09, 2010 6:33 pm ] |
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Speaking from experience, doing the intake gasket isn't that hard. That's a article on this site that's helpful. I found that using a screwdriver to guide the washers on made it pretty easy to do. Even though I screwed it up! It says, cast right into the intake manifold itself no less, torque to 10ft/lbs which is almost nothing. I got about 1000 miles on it, then the gasket went out and caused all kinds of fun problems. I still haven't fixed it (it's cold outside) I just set my idle to 2000 and have been driving it that way. If it's as bad as you say it should be very easy to verify with a can of starting fluid. Squirt it at the gasket and the idle should change. It should be obvious. Even so, for that $14 gasket it's an easy one to rule out. Whatever this problem is, it's going to something pretty simple. Heck, the whole car is deceptively simple. But the symptoms you describe are about as vac leak as it gets. Kip |
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| Author: | bootsnbolts [ Thu Dec 09, 2010 11:30 pm ] |
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the gas tank is a huge expense i can't take on right now. i've already priced the labor, parts, and boiling. i'm doing it as a fix until i can, it will keep my fuel pump from getting sludged out and will be the primary one i change regularly until i've got that cool $750 for a proper tank drop, boil, SU, gasket, etc. she only stalls at partial acceleration, not at speed. the stalling is predictable, not a more random, fuel delivery performance. i have the gaskets and the job set to go this weekend for the intake manifold gasket +. in the manual, under diagnosis, the stalling can be at this point the intake manifold, as all else has failed (been replaced but didn't fix long term). i'm asking for a second opinion here before going on to the next step (intake manifold gasket) in case i missed anything. i'm prioritizing this as my next step fix because i think it is the bigger problem that is easier & more affordable to repair. i have a spare intake manifold and the gaskets i need, so we should be good to go. my oil leaks are from the oil pan gasket. a different, but well-read, story. checking the valve cover gasket is definitely something i want to do. it was replaced 6 months ago, but that means nothing. |
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| Author: | olafla [ Fri Dec 10, 2010 12:52 am ] |
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Hi, bootsnbolts, I fire some shots in the dark: I see you have new vacuum hoses, are you sure that the vacuum line to the distributor is hooked up to the correct vacuum port on the carburetor? If you observe the carb with hot engine at idle, is the choke completely off, and stay that way if you suddenly open the throttle? Have you checked that the timing mark on the balancer is correct, that the ring has not slipped? If you adjust your timing to give it a couple of degrees less initial advance at the time between short test drives, is the problem still there, better or worse? Olaf. |
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| Author: | bootsnbolts [ Fri Dec 10, 2010 11:30 am ] |
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thanks olaf, and everyone...we'll review all of the above when the time comes. i appreciate the input! and i'll let you know how it goes. |
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| Author: | bootsnbolts [ Mon Dec 13, 2010 9:53 am ] |
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we got the gaskets changed...went quite smoothly, actually. she started up and went vroom, then she died and wouldn't start again. yes i have gas, yes she is getting gas, and in the event she wasn't we threw some carb cleaner in her and NADA. so we're tracking an ignition issue. does anyone have the schemo for my rotor cap? it goes in and then has to be turned, so it seems like it's backwards. it's a '62 thing, cause she's narrower. they did a lot of weird stuff on my car when she was made, decided it was a bad idea, and changed it the next year, so i have some one-year-only oddities. love my dash panel. anyway i don't think it's the rotor, but that schemo would be a good thing to have. i called josh and he and mark had a couple long blab sessions so today we go back to it. yeeeeeHAW! |
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| Author: | wjajr [ Mon Dec 13, 2010 10:36 am ] |
| Post subject: | |
bootsnbolts: [quote]we got the gaskets changed...went quite smoothly, actually. she started up and went vroom, then she died and wouldn't start again.[/quote] Good job, Now you know that portion of intake system is good to go. After reassembly the engine started, than quit, and there is fuel. --- Where this was a rapid shut down, two places to check: ceramic resistor, and coil. It is not uncommon for these two devices to play tricks, working one minuet, and not the next. Cutting in & out could be caused by heat, vibration, or old age. Resistance of ballast resistor, should be 1 ohm or a little less to say around 0.7 ohm. A high number indacates a broken filament. To test coil, remove attached wires, than test resistance of coil’s primary circuit, between (+) & (-) low voltage terminals, should be somewhere close to 0.75 & 0.81 ohms, in other words a bit less than one ohm depending on which coil you have. Check high, or secondary circuit by probe on (+) or (-) low voltage terminal, and the other in “center†high voltage terminal, this should be in the 10,000 to 11,000 ohm range. A lot less indicates a short, a lot more an open circuit, time for a new coil. A third place to inspect is all the ignition circuit wiring for shorts, broken conductors, bad splices, and corroded connections. Pay particular attention to both sides of bulkhead connector. |
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| Author: | mopardean [ Mon Dec 13, 2010 12:39 pm ] |
| Post subject: | |
one thing that i have used over the years to evaluate manifold leaks is to pour a little seafoam down the carb. exhaust leaks at the manifold will appear as little puffs of smoke. a little spray on brake cleaner around the intake runner connection to the head will expose intake leaks by slowing the idle. careful not to pour so much seafoam down that it kills the engine |
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