Chugging/sucking sound when cold
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Elder User
Joined: Jan 2004
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Chugging/sucking sound when cold
In the morning when I start my 94 Aero w/3.0 up it makes a sort of chugging sound...like it's sucking air or something. It tends to go away once it gets warmed up. Would this be a head gasket issue? How to I find/isolate the noise...with all that crap in the way under the hood? I'm at a loss on this one. It does burn about 2 quarts of oil between changes...but no drips or puddles can be found in the driveway. That doesn't mean it doesn't leak...maybe it only leaks when running, who knows. But this new chugging sound has me a bit worried, the van only has 102,000 miles on it.
Lead Driver
Joined: Sep 2003
Posts: 7,015
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From: SoCal
There were a couple of times when my engine would make a racket just after starting. I found it it would do this after long periods of non-use, and it seemed like all the oil had somehow left them engine. I think what I heard was the aweful sound of metal on metal contact due to no oil in the bearings. The noise would slowly go away as the engine ran more. I've learned to just crank the engine by shorting the posts on the starter relay for a few seconds after a long idle period. I can hear the sound of the cranking change as the oil finally gets into everything. Then when I start it, there is no "chugging" sound.
I've heard that some oil filters do not have an effective anti-drain-back valve, which allows this kind of oil drainage from the engine. But since I've only used Fram and Motorcraft filters, and the problem has happened with both types. One of these has been claimed to be the worst, while the other has been claimed to be among the best in dealing with the oil drain-back problem. I can't tell if there is any truth to this.
I've heard that some oil filters do not have an effective anti-drain-back valve, which allows this kind of oil drainage from the engine. But since I've only used Fram and Motorcraft filters, and the problem has happened with both types. One of these has been claimed to be the worst, while the other has been claimed to be among the best in dealing with the oil drain-back problem. I can't tell if there is any truth to this.
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Joined: Sep 2006
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Originally Posted by wresleu
It runs just fine cold or hot. I wish I was techno savvy enough to record the sound and post it. It's really tough to describe exactly what the sound is.
Post Fiend
Joined: Apr 2005
Posts: 5,720
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From: Washington state
I vote for defective IAC valve
the IAC on cold start and cold run ECU mode is almost the total controller of air fuel mix after the default ECU injector cold run tables....must be able to open totally and is what ECU is programmed to expect on cold start cold run
plugged IAC== too rich mix...not enough air
ECU has no way of knowing since O2 sensor is out of the loop....ECU in open loop mode until 145>155d F. at ECT
IAC after engine is up to temp just about drops out of the fuel/air mix algorithm except at idle and then it is only partially openning in short pulses...AC on and pwr steering switch on will increase IAC opening and idle
change the IAC or try cleaning first...sometimes works
Ford IAC's also have a unique failure mode that involves loud buzzing pulsing noise....original design problem...supposedly corrected in newer later replacement aftermarket designs...
only cure=new
the IAC on cold start and cold run ECU mode is almost the total controller of air fuel mix after the default ECU injector cold run tables....must be able to open totally and is what ECU is programmed to expect on cold start cold run
plugged IAC== too rich mix...not enough air
ECU has no way of knowing since O2 sensor is out of the loop....ECU in open loop mode until 145>155d F. at ECT
IAC after engine is up to temp just about drops out of the fuel/air mix algorithm except at idle and then it is only partially openning in short pulses...AC on and pwr steering switch on will increase IAC opening and idle
change the IAC or try cleaning first...sometimes works
Ford IAC's also have a unique failure mode that involves loud buzzing pulsing noise....original design problem...supposedly corrected in newer later replacement aftermarket designs...
only cure=new
Last edited by 96_4wdr; Sep 17, 2006 at 10:36 PM.
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Elder User
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IAC valve or IAC motor? What is the difference? I did a search on napaonline and found both....now I'm confused. Is it just the sensor looking thing with a receptacle? If so I have replaced that before on another Aero.
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Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
sensor/motor.....same same wresleu
different auto manuf.s call it different name....same function....control idle and coast down air flow and thus rpm
depending on engine, mounted on side or top of throttle body/plenum intake, electrically controlled by ECU/PCM
on ur 4L mounted on driver side of plenum behind throttle body
also check and change PCV valve if older than 20k, they leak and on 4L the oil mist goop gets sucked right thru the IAC....a little dust and we have IAC gumbo
even with a new PCV, with high mileage high blowby engine the PCV valve goop soup goes thru the IAC, not good
different auto manuf.s call it different name....same function....control idle and coast down air flow and thus rpm
depending on engine, mounted on side or top of throttle body/plenum intake, electrically controlled by ECU/PCM
on ur 4L mounted on driver side of plenum behind throttle body
also check and change PCV valve if older than 20k, they leak and on 4L the oil mist goop gets sucked right thru the IAC....a little dust and we have IAC gumbo
even with a new PCV, with high mileage high blowby engine the PCV valve goop soup goes thru the IAC, not good
Last edited by 96_4wdr; Sep 22, 2006 at 12:29 AM.
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