exhaust sucking in air

exhaust sucking in air

Postby chevyastro [OP] » July 20th 2011, 1:41am

hey me with the 88 v6 tbi... what does it mean when air is being sucked in through tailpipe? the idle is also bad. i held a dollar bill up to the tailpipe and it got sucked in and out, sucked in then out, etc. its not rhythmic, its sporadic, its worse when warm. thanks for the help....
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Re: exhaust sucking in air

Postby doyoulikeithere » July 20th 2011, 1:48am

I would guess theres another hole somewhere in your exhaust pipe besides the one at the very end...
Does the exhaust sound bad?
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Re: exhaust sucking in air

Postby chevyastro [OP] » July 20th 2011, 1:52am

actually a friend on here, paintdrying, has already answered this. it was due to worn valve spring and the valves not seating properly. I was just wondering if anyone could elaborate more on this so i can understand how and why this happens. and if there are other possible reasons why air gets sucked in through exhaust and the popping sounds please let me know
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Re: exhaust sucking in air

Postby chevyastro [OP] » July 20th 2011, 1:53am

i do have a leak either at the manifold or the gasket
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Re: exhaust sucking in air

Postby chevyastro [OP] » July 20th 2011, 1:58am

just curious how would i go about fixing the gasket leak? i heard the studs usually break, whats the probability of this happening, how would i fix the studs if they did break? and if its the manifold that's leaking...would i need a new exhaust manifold?
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Re: exhaust sucking in air

Postby Leeann_93 » July 20th 2011, 2:20am

Mine didn't break. Soak with plenty of PB, often, for a day or so. Tap every once in a while; that seems to help the capillary action.

If you break a stud, you drive or drill it out and put in a new one.

If it's the manifold, yep, you'll need to replace the manifold gasket.
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Re: exhaust sucking in air

Postby WoodButcher » July 20th 2011, 2:23am

Look at your donut gasket, Use lots of pb blaster, days before you plan to do the work start spraying the bolts / studs, 2-3 times each day until you do the job. Work the nut off the stud like you were tapping a new hole, a little forward a little back, don't just crank them off. If you break one or more you will be tapping holes. The manifold is not likely cracked, a bad gasket maybe but I would bet dollars to dough nuts on the donut :lol:
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Re: exhaust sucking in air

Postby chevyastro [OP] » July 20th 2011, 3:37am

so how do i tell if the popping noises and the sucking in air is from the exhaust leak or from a valve problem?
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Re: exhaust sucking in air

Postby WoodButcher » July 20th 2011, 3:42am

If you find an exhaust leak and fix it you'll know what the problem isn't.
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Re: exhaust sucking in air

Postby maximus7001 » August 1st 2011, 8:12am

Does this van have flat tappet lifters?

The popping and sucking into exhaust you are describing can be a symptom of a collapsed lifter and/or a round cam exhaust lobe. Is there any lifter tick? This can still happen to hydraulic roller lifters.
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Re: exhaust sucking in air

Postby T.Neff » August 1st 2011, 9:52am

A rounded cam lobe would mean that lobe isn't providing lift and therefor isn't opening the valve.Because of that,it couldn't be sucking air.A burnt valve on the other hand staying open would or one the possibly has bad guides/seals would suck air.Thing is the valve has to be staying open for whatever reason.
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Re: exhaust sucking in air

Postby chevyastro [OP] » August 8th 2011, 5:25am

there does seem to be some ticking out of the engine 1 person said it was the lifters other say they dont know what it was
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Re: exhaust sucking in air

Postby chevyastro [OP] » August 11th 2011, 3:00am

i believe i have hydraulic lifters. When engine is cold it does kinda have a tapping sound. it happens when in drive and at a very low speed, 1-15 mph, and when engine warms up it goes away. The van still really does drive good, theres just alot of smoking and loss of power after 45 mph, i just have to push in on accelerator alot trying to keep at 60 mph or more and especially going up hills. I got a code 43 at wot a few times so i look down at knock sensor and wire was all chewed up, i just spliced a wire in between, hopefully it'll work. everything down there is oil soaked. I have been to weary about going to wot, just dont like to kill engine any faster lol. uncle says going to wot wont hurt it.
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Re: exhaust sucking in air

Postby T.Neff » August 11th 2011, 3:24pm

Sure does sound like bad valve guides/seals solely because of it smoking .It doesn't exclude the possibility of a lifter miss-adjusted or lifters that are bad as well or a valve is burnt on the exhaust side of it.I suggest it is time to take it apart and start looking for these problems.Once it is apart,take those heads into a machine shop to have them checked out/pressure tested and repaired.
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