How To Repair A Vacuum Leak On A 2008 Chrysler Sebring

Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.

A decal showing a vehicle vacuum hose routing.

Photo courtesy of James A O on Flickr.

A vacuum leak can crusade a myriad of drivability problems, as it introduces extra, unwanted air into the engine, leaning out the air/fuel mixture. Modern internal combustion (multi-port fuel injection) engines employ intake vacuum to operate sensors, actuators, and power brakes (on some vehicles). Older engines also use information technology to operate some emission command devices and to pull fuel into the combustion chamber.

So even a modest vacuum leak can play a joke on you, and your car computer, into believing a particular sensor or system needs fixing. So you showtime replacing components hoping you lot'll ready the problem, unsuccessfully.

Often, a vacuum leak makes an audible hissing audio, which makes it easy to discover; other times, though, you lot won't hear annihilation. Automobile shops employ special, costly equipment to observe hard to find leaks. But before yous head to the shop, you tin apply unproblematic techniques used to rail most common vacuum leaks.

This guide non merely helps you detect a vacuum leak or an obstructed vacuum hose and gives you useful repair tips, but it also tells you lot what engine performance problems may point to a potential vacuum leak. And then let'southward get-go there.

Index
I. When Should I Troubleshoot for a Potential Vacuum Leak?
Vacuum Leak Symptoms
Vacuum Leak Related Trouble Codes
II. How to Find a Vacuum Leak
Using a Vacuum Gauge
Three. Checking the Intake Manifold for Vacuum Leaks
4. Using a Mitt Vacuum Pump to Test Devices for Vacuum Leaks
V. Vacuum Hose Repair Tips

Throttle torso and intake manifld gaskets can develop leaks also.

Photo courtesy of James A O on Flickr.

I. When Should I Troubleshoot for a Potential Vacuum Leak?

Vacuum hoses are a common source of engine functioning bug. After miles of service, vacuum hoses wear out, harden, split or soften; and vacuum tubing deteriorates, turns brittle, and breaks, causing all kinds of engine performance bug.

And then whenever you notice an engine operation trouble and tin't seem to find the source, include a vacuum leak diagnostic into your repair strategy.

Depending on your particular vehicle brand and model, you may discover various sensors and actuators that depend on a good vacuum source to operate. For example, some engines use a Manifold Accented Pressure (MAP) sensor that requires vacuum to measure outside air pressure.

A MAP sensor vacuum leak can upset ignition timing and engine stability and efficiency. A vacuum leak tin also prevent an EGR valve from opening, cause engine overheating, and increment harmful emissions. This type of leak can as well affect the Positive Crankcase Ventilation (PCV) arrangement.

Vacuum Leak Symptoms

Here is a list of functioning problems to keep in mind, every bit they might maybe be related to a vacuum leak:

• Backfiring
• Hesitation
• Hard starting
• Low engine power
• Misfiring (ordinarily random. Y'all may get trouble code P0300)
• Poor fuel economic system
• Poor acceleration
• Crude idle
• High idle or very low idle, depending on vehicle model.
• Stalling
• Stumbling
• Check Engine Low-cal on
• Oxygen sensor reports a lean mixture continuously.
• Poor restriction functioning (on vacuum-blazon power brakes)

Proceed in mind that these symptoms are not exclusive to a vacuum leak. For case, a bad EGR valve, bad pinch, or ignition timing problems may cause one or more than of these symptoms as well.

The following diagnostic trouble codes (DTCs) may be triggered by unlike types of faults, including a vacuum leak.

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Read More from AxleAddict

Trouble Code	Description
P0505	Idle command system malfunction
P0301-8	Cylinder specific misfire
P0170	Fuel trim malfunction (bank one)
P0171	System too lean (bank i)
P0173	Fuel trim malfunction (bank 2)
P0174	System too lean (bank 2)

Check vacuum hose connectors for cracks that may leak vacuum.

Photo courtesy of James A O on Flickr.

Two. How to Find a Vacuum Leak

OK. Yous accept an engine performance problem and you lot want to do some vacuum leak checking, where do you start?

Start, locate the vacuum diagram for your vehicle. Y'all may discover a re-create of the vacuum diagram on your car owner'due south transmission, simply most car manufacturers include a diagram inside the engine compartment. Raise the hood and look around the front of the engine compartment for a decal.

If you lot tin can't find one on your manual or in the engine compartment, you lot can buy one at your dealer service section. Some other source is your vehicle repair manual. Yous can buy an inexpensive aftermarket vehicle repair manual at your local auto parts store or online. The repair manual has all kinds of useful data your tin can use for maintaining and troubleshooting many auto systems. So you'll make a proficient investment.

The vacuum diagram shows the different vacuum controlled devices and how they interconnect. Newer vehicle models describe the components resemblance and their location.

OK. Now that you accept the vacuum diagram for your vehicle, yous can starting time troubleshooting for a potential vacuum leak. However, even if you don't have the diagram correct at present, you still tin follow the next steps.

(Notation: If y'all are trying to find a potential vacuum leak because of a trouble code yous retrieved after your Cheque Engine Lite came on, your auto computer may be adjusting the air/fuel ratio to compensate; so the engine might not sound as if it had a functioning problem. If so, unplug the throttle position sensor [mounted on the throttle trunk] or oxygen sensor, to force the computer to run the engine in "hard code" fashion [open loop], so you tin can hear the engine rough idle. This will make it easier to detect the vacuum leak source during your diagnostic.)

If you suspect a particular device (or several), you can start with that device. Otherwise, follow the diagram and start checking each hose. If you don't accept the diagram, check each vacuum hose equally you become around the engine. Almost vacuum hoses are sparse and soft, except for the one used on the brake booster, which is thicker and more than sturdy in pattern, and perchance the PCV hose.

Troubleshooting vacuum leaks requires a shut visual inspection of the hose, making sure it's properly continued, and listening for the telltale hissing sound of the vacuum leak.

Merely dissonance from a running engine tin can make it impossible to hear a hissing sound coming from leaky vacuum hose or gasket. For this you lot have two options: You tin use a mechanic's stethoscope that helps to amplify the sounds in your ear, or yous can utilize a length of hose for the aforementioned purpose.

How to Check Each Vacuum Hose

Follow the side by side steps to check each vacuum hose, keeping a reasonable distance from moving components during your inspection:

1. Start the engine and let it idle. Set the transmission to Park (automatic) or Neutral (manual) and apply the emergency brake.
2. Make sure the hose is properly connected, not loose or hanging free. Information technology'south easy to knock a hose loose inadvertently when doing maintenance or replacing a component. You may need to use a small mirror and a flashlight to bank check on difficult-to-reach places, like behind the intake manifold, throttle trunk, or exhaust manifold.
3. Unplug and inspect both ends of the hose. If the inside stop of the hose is torn, worn, or widened, cut off the damaged office and plug the hose back to the fitting.
4. Trace the length of the hose with your fingers to feel for rough, hardened, splitting, softened, or out-of-shape spots, especially effectually the hidden, underside of the hose. Likewise, attempt to feel for vacuum at those rough or uneven spots.
5. Check if the hose is near or touching a hot surface.
6. Also, cheque hose connectors, tees, and unions for cracks and looseness. Supervene upon them equally necessary.
7. Pay special attending to the check valve that connects the restriction booster to its vacuum hose. If leaking, you lot may hear a hissing sound.
8. Y'all can check a leaking brake booster at idle by blocking the vacuum hose with a pair of Vice Grip pliers. Utilise a shop rag between the pliers and hose to foreclose damage. If the rough idle improves, check the brake booster and valve.
9. Check the hose for contamination equally well, like oil, coolant, or another substance. Disconnect the hose from the device it connects to and check within the device connector. If you lot discover a foreign substance inside the hose, contamination has potentially reached inside the device as well, probably not performance properly. Yous may demand to test the device for proper operation.
10. As part of your visual inspection, include the devices the vacuum hoses connect to. Check the devices for harm like cracks, dents, and loose parts. These may create a vacuum leak besides. Pinch the vacuum line leading to the device, and spray soapy water on it and hear for a change in idle speed.
11. If y'all observe a hose with a softened, hardened, or damaged spot, supervene upon it.

You lot tin also spray water on a hose, ports and connectors to aid you lot check for leaks.

Using a Vacuum Gauge

You can besides use a vacuum judge to farther ostend the presence of a vacuum leak, if necessary. If yous don't ain a gauge or don't want to buy one correct now, your local auto parts store may loan yous ane.

Follow the instructions that come with the tool and the tips included in the post linked above.

Pay special attending to needle movement patterns. A steady low or very low reading may point to a gasket (intake or throttle) leak, among other potential faults.

Supersede the intake manifold gasket if information technology develops a vacuum leak.

Photo courtesy of scottt on Flickr.

III. Checking the Intake Manifold for Vacuum Leaks

Although you're more likely to come across a vacuum hose leak, intake manifold gasket leaks also happen. If your previous check didn't turn out anything wrong, bank check the intake gasket between the manifold and cylinder head, and the base of operations gasket located between the intake manifold and throttle torso or carburetor.

To cheque these gaskets y'all can use ane of two simple culling methods:

• Soapy water in a spray bottle.
• A length of hose (or mechanic's stethoscope).

Whatever one of these methods is practiced.

1. Apply the emergency brakes.
2. Gear up your transmission to Park (automatic) or Neutral (manual).
3. Block the wheels to exist safer and prevent the vehicle from moving.
4. Start the engine and allow information technology idle.
5. To use the soapy water, spray a piffling around the intake manifold where it mates with the cylinder head and around the base of operations of the carburetor or throttle trunk. Don't forget to visually cheque the intake manifold itself for cracks and spray water on doubtable spots.
6. Listen for any changes in the engine idle.
7. If the engine smooths out every bit y'all spray water, y'all've found the vacuum leak; you may also see bubbles on the location of the vacuum leak.

Note: To utilise a hose (or mechanic's stethoscope), place one terminate of the hose confronting your ear and move the other terminate of the hose around the edge of the intake manifold gasket and carburetor or throttle body gasket. If there's a leak, you lot'll hear a hissing audio.

If you institute a vacuum leak either at the intake manifold or at the base of operations of the throttle body, first try tightening the intake or throttle torso mounting commodities:

• Tighten the bolts gradually, following a crisscross design—when tightening a manifold, start at the center and work your way out.
• Tighten the bolts to the torque listed in your vehicle repair manual using a torque wrench.
• Check again for the vacuum leak.
• If the leak is still present, yous'll need to supercede the intake manifold gasket or throttle body gasket.
• Follow the instructions in your vehicle repair manual to replace either gasket.

Watch the video below see how the guy uses water to diagnose a misfire on cylinder one.

Locating a Vacuum Leak With Water

IV. Using a Hand Vacuum Pump to Test Devices for Vacuum Leaks

Often, a careful visual and manual inspection like the 1 described above is enough to observe a vacuum leak. Just not all the time.

Some components that operate with vacuum may endure internal impairment (a diaphragm may rupture, for example). And yous tin can't diagnose this type of harm past touch or sight.

So, if you suspect a vacuum leak simply tin can discover the source, this is the next pace in your troubleshooting strategy.

For this, y'all'll need to employ a hand-operated vacuum pump. You may buy one at most auto parts stores or online. The vacuum pump helps in troubleshooting emission systems. But if you don't want to buy the tool right now, your local auto parts store may loan y'all one.

Follow the instructions that come with the vacuum pump for operation instructions and the repair manual for your item vehicle for the steps in troubleshooting the device you need to examination.

Some times you demand to troubleshoot a device under specific operating conditions, or in conjunction with some other tool. Although this type of troubleshooting may sound complicated, yous don't need special training. You do still need to follow the tool operating instructions, however, and the repair manual troubleshooting steps.

Besides, follow these tips when using a vacuum pump:

• Brand certain the connection between the pump and the device is tight—use the correct diameter connector or hose to make the connection.
• Only apply the right amount of vacuum for the device you are testing (usually 10 to 15 in Hg; consult your repair manual).
• The fewer connectors, adapters, and hoses you use to connect your mitt pump to the device you lot want to test, the ameliorate.

You tin utilize a union to repair pocket-sized vacuum hose leaks.

Photograph courtesy of James A O on Flickr.

V. Vacuum Hose Repair Tips

Dealing with damaged vacuum hoses doesn't necessarily mean you need to replace them. Often, a vacuum hose only requires a simple repair that tin take you a couple of minutes or so.

• Y'all tin repair a damaged vacuum hose finish in a minute. Most of the time you can get away with cut off about half an inch at the end and reconnecting the hose.
• Be careful when dealing with impairment located between the ends of a vacuum hose. If you just need to repair a minor hole less than half an inch, cutting out the damaged area and use a spousal relationship to reconnect the two pieces back.
• Repair one vacuum hose at a fourth dimension to avoid confusion. Some vehicles, particularly Asian brands, come with several vacuum hoses that can make it disruptive to repair when they interconnect in diverse ways. For these cases, y'all can find 1-, 2-, three-, 4-fashion, and elbow connectors to deal with nearly any kind of hose routing and repair.
• Always characterization hoses and their respective connectors or fittings, so that you reinstall repaired or new hoses to their corresponding fittings.
• If y'all find i or more asunder hoses, use your vacuum diagram to reconnect the hose to the correct fitting.
• After making a repair, route and secure the vacuum hose away from hot surfaces and moving components.
• Ever replace a vacuum hose with i of the same diameter and length, and for the application intended (PCV, restriction booster, or regular vacuum).

This content is accurate and truthful to the best of the author'due south knowledge and is not meant to substitute for formal and individualized communication from a qualified professional.

Questions & Answers

Question: My check engine light came on, and I went to the mechanic who said information technology was a P0171 error. Depository financial institution 1 arrangement 2 lead too lean. I cleaned the mass air flow sensor and all was fine for around 800 miles and ii weeks. However, it returned with the same code. I pulled out the MAF sensor to see if it was dirty and it looked fine. What is my next step?

Answer: This other post may assistance:

https://axleaddict.com/auto-repair/Trouble-Lawmaking-P0...

Question: When fixing a vacuum leak, how long afterward resetting the p071 code will it revert if non fixed?

Answer: In general, if y'all are dealing with an intermittent trouble, it may take a while for the light to come back on, until the part fails once again and the reckoner detects the problem. If there's a failed, monitored part, it probably will take a few hours for the computer to detect it once more.

Question: How do yous fix an air leak on a box stock get-kart motor?

Answer: Cheque the gaskets; the one betwixt the carburetor and air box might exist leaking.

Question: What are the most common vacuum leaks on the manifold?

Answer: Check vacuum hoses condition and connectors. Then bank check for intake gasket leaks. Sometimes spraying some carburetor cleaner on suspected leaks helps to detect damaged hoses and leaks.

Question: If I disconnect a vacuum hose and hear a hissing sound, does that indicate that my vacuum is good? Meaning, if there is a leak, at that place wouldn't be a proper seal to keep that pressure/vacuum on the line and no hiss would emit when the line is disconnected.

Answer: It is difficult to find a minor leak but past disconnecting a vacuum hose. You'd recollect the hose and fitting are perfectly adept. A vacuum may leak through damaged hoses, gaskets, and faulty valves. If you lot are suspecting a leak, attempt using a vacuum gauge. It'll be more accurate. This other post may assistance:

https://axleaddict.com/car-repair/Use-a-Vacuum-Ga...

Question: I'm restoring a fifty-twelvemonth former Jeepster 258-half-dozen. I have replaced the intake manifold gasket and put on headers. My jeep starts up but within three seconds, the RPM sounds like it shoots upward to nearly 2500 and dies. Could information technology be the gasket? The jeep will only run for iii seconds.

Answer: It seems similar a huge vacuum leak. It could be the intake manifold or base carburetor gasket. Your local auto parts store may loan you a smoke machine. Hook information technology upwards to the brake booster hose. Hope this helps.

Question: What could my trouble be? My 2001 Chevy Blazer has constant air audio. Noise is within the cabin and rises at idle only while break is pressed. No fluid loss but with the ignition off, I pump the brakes, they don't get harder, and nonetheless they sink if held while starting, feel spongy and pedal almost sink to the floor. Merely beginning to acquire well-nigh diagnosing for a vacuum leak. I will bank check the hoses tomorrow. And your assist would be greatly appreciated. Any ideas?

Answer: Information technology sounds like yous may have a vacuum leak in the brake booster. This other post may help you diagnose the problem:

https://axleaddict.com/machine-repair/Bad-Brake-Boost...

© 2022 Dan Ferrell

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