Methods of finding a vacuum leaks
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Methods of finding a vacuum leaks
So I have a vacuum leak. Diagnosed from AP data logs only (during MM Custom Calibration, I trust the diagnosis). There is no CEL, and there are no major problems with my engine operation. However I could see it explaining a few things about how my 8 runs, namely being quite rich all the time.
I have searched the site via Google and am only finding individual vacuum leak threads looking for a specific leak or known problem with physical symptoms. In none of these threads am I finding any method of how to look for a vacuum leak in the first place, other than "is X line attached" or "are your LIM nipples still on". Anything visual like that I have checked and rechecked several times. I have gone over the chart JON colored up, and everything is connected and in place.
I assume it is a cracked hose somewhere, but since assumptions are often not accurate, I can't rule anything out at this point. So rather than asking "what could it be?", I'm asking "give me methods to use to locate it"
The quick and easy one is CARB cleaner. Hose down stuff while the engine is running and look for bubbling /spurting (air exiting), or the engine starting to stumble as the carb cleaner is ingested (air entering).
I've done that. 2 cans worth in sprays here and there trying to find it (no, I didn't just empty 2 cans and hope for a reaction, anyone on here that knows me knows how thorough I am.)
So, what other options or methods? Sensor data, liquids, tools, etc...and what to do with them.
Tools at my disposal:
- AccessPORT
- common hand tools
- IR laser thermometer
- Flashlight
- Anything available at local autoparts stores
I have searched the site via Google and am only finding individual vacuum leak threads looking for a specific leak or known problem with physical symptoms. In none of these threads am I finding any method of how to look for a vacuum leak in the first place, other than "is X line attached" or "are your LIM nipples still on". Anything visual like that I have checked and rechecked several times. I have gone over the chart JON colored up, and everything is connected and in place.
I assume it is a cracked hose somewhere, but since assumptions are often not accurate, I can't rule anything out at this point. So rather than asking "what could it be?", I'm asking "give me methods to use to locate it"
The quick and easy one is CARB cleaner. Hose down stuff while the engine is running and look for bubbling /spurting (air exiting), or the engine starting to stumble as the carb cleaner is ingested (air entering).
I've done that. 2 cans worth in sprays here and there trying to find it (no, I didn't just empty 2 cans and hope for a reaction, anyone on here that knows me knows how thorough I am.)
So, what other options or methods? Sensor data, liquids, tools, etc...and what to do with them.
Tools at my disposal:
- AccessPORT
- common hand tools
- IR laser thermometer
- Flashlight
- Anything available at local autoparts stores
#2
Extraordinary Engineering
I'm assuming that you have listened for the telltale whistle of a leak?
Grab yourself a vacuum tester and check your actuators, vacuum accumulators, hoses, check valves etc. for leaks.
When visual checks fail then the vacuum tester is a great tool.
If you test the vacuum accumulator under the UIM then you know that the solenoids are holding.
Grab yourself a vacuum tester and check your actuators, vacuum accumulators, hoses, check valves etc. for leaks.
When visual checks fail then the vacuum tester is a great tool.
If you test the vacuum accumulator under the UIM then you know that the solenoids are holding.
Last edited by DarkBrew; 03-17-2011 at 01:23 PM. Reason: I re-read his post and saw that he had seen thae drawing I posted
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Sounds like a plan. How will I know when it is picking up a leak or not? Is there a manual/chart/data which shows that pressure each item should be at?
And yes, no whistle.
And yes, no whistle.
#6
Boosted Kiwi
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remove the air cleaner assembly and jam the end of a vaccum cleaner up the intake . Stuff a bunch of rags in there as well to block it off . Now get a spray bottle and put water and a little detergent in it .
Spray it all over the intake while pressurising with the vac. Watch for bubbles ...
Spray it all over the intake while pressurising with the vac. Watch for bubbles ...
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fistofmeat (11-18-2017)
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remove the air cleaner assembly and jam the end of a vaccum cleaner up the intake . Stuff a bunch of rags in there as well to block it off . Now get a spray bottle and put water and a little detergent in it .
Spray it all over the intake while pressurising with the vac. Watch for bubbles ...
Spray it all over the intake while pressurising with the vac. Watch for bubbles ...
Don't worry 9k, I only stopped so I could post that, I am continuing reading
#9
Extraordinary Engineering
If the unit you are testing holds the vacuum then there is no leak.
If you see no vacuum on the gauge or it drops over the next minute or so then it is leaking.
From what you are saying though about picking it up on AP logs then it must be a fairly large leak...
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Ah, understood.
Finished reading the link 9k, thanks for that, quite a few methods to use. Using smoke appeals to me the most, but probably the least viable without paying a shop to do it. (I get the feeling grabbing a smoke bomb from the local firework's shop probably isn't the best idea )
Finished reading the link 9k, thanks for that, quite a few methods to use. Using smoke appeals to me the most, but probably the least viable without paying a shop to do it. (I get the feeling grabbing a smoke bomb from the local firework's shop probably isn't the best idea )
#12
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The method my father taught me which has always worked is to use a can of carb cleaner. Start the car and then proceed to spray carb cleaner around the engine bay. Well really just the intake, vacuum lines, spark plugs, and such. If you spray a certain spot and hear the engine rpms increase thats where your leak is. Works wonderfully and engines are very responsive to carb cleaner. Its a great way to start an old lawn mower and such.
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The method my father taught me which has always worked is to use a can of carb cleaner. Start the car and then proceed to spray carb cleaner around the engine bay. Well really just the intake, vacuum lines, spark plugs, and such. If you spray a certain spot and hear the engine rpms increase thats where your leak is. Works wonderfully and engines are very responsive to carb cleaner. Its a great way to start an old lawn mower and such.
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+1 on pressurizing intake via vacuum cleaner or air compressor (make sure not to exceed 14psi or so). Starting fluid works ok but nothing beats knowing that your system can hold the pressure.
#16
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This is what SARX put together and it works perfectly.
RX-8 Hymee Supercharger Install - Smoke Tester
RX-8 Hymee Supercharger Install - Smoke Tester
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More proof I need to move to SARX area for my 8 ;-)
Fogger is what I used when trying to see if I had a crack in my air intake causing my rough idle. Foggers like this typically produce very thin smoke. If you run it through a cooling chamber it will produce a very thick easy to see smoke.
Fogger is what I used when trying to see if I had a crack in my air intake causing my rough idle. Foggers like this typically produce very thin smoke. If you run it through a cooling chamber it will produce a very thick easy to see smoke.
#18
Bumping because its relevant.
So I airsealed the throttle body and started blowing into the yellow marked hose, and it happened without any resistance (aside from the hose thickness that causes the resistance). Now I don't know if the intake and exhaust port were both open at the same time, which would explain why there was no resistance to begin with. In any case, when my car runs, I hear pretty much the same air puffing noise like a steamtrain would make and it's louder as the throttle opens and faster as the rpm's increase.
What is a truly reliable backyard test, if there is any?
So I airsealed the throttle body and started blowing into the yellow marked hose, and it happened without any resistance (aside from the hose thickness that causes the resistance). Now I don't know if the intake and exhaust port were both open at the same time, which would explain why there was no resistance to begin with. In any case, when my car runs, I hear pretty much the same air puffing noise like a steamtrain would make and it's louder as the throttle opens and faster as the rpm's increase.
What is a truly reliable backyard test, if there is any?
#19
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If you're trying to find a vacuum leak (?) just use the method below. Otherwise what you posted makes no sense.
The method my father taught me which has always worked is to use a can of carb cleaner. Start the car and then proceed to spray carb cleaner around the engine bay. Well really just the intake, vacuum lines, spark plugs, and such. If you spray a certain spot and hear the engine rpms increase thats where your leak is. Works wonderfully and engines are very responsive to carb cleaner. Its a great way to start an old lawn mower and such.
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Bumping because its relevant.
So I airsealed the throttle body and started blowing into the yellow marked hose, and it happened without any resistance (aside from the hose thickness that causes the resistance). Now I don't know if the intake and exhaust port were both open at the same time, which would explain why there was no resistance to begin with. In any case, when my car runs, I hear pretty much the same air puffing noise like a steamtrain would make and it's louder as the throttle opens and faster as the rpm's increase.
What is a truly reliable backyard test, if there is any?
So I airsealed the throttle body and started blowing into the yellow marked hose, and it happened without any resistance (aside from the hose thickness that causes the resistance). Now I don't know if the intake and exhaust port were both open at the same time, which would explain why there was no resistance to begin with. In any case, when my car runs, I hear pretty much the same air puffing noise like a steamtrain would make and it's louder as the throttle opens and faster as the rpm's increase.
What is a truly reliable backyard test, if there is any?
Video would help.
Last edited by Loki; 07-30-2017 at 06:05 PM.
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TomX8 (07-30-2017)
#21
On a stock Renesis there is no overlap of intake and exhaust ports. Not sure what yellow marked hose refers to, but if you hear puffing in time with rotor revolutions, you have compression escaping somewhere. Logically there are only 2 places this can happen: the oil injector and the spark plug holes. No other removable parts see compression. But even the oil injector doesn't really see compression, it's just after the intake port.
Video would help.
Video would help.
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gwilliams6 (07-31-2017)
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Shaozhou Zhang (12-12-2019)
#25
I haven't investigated it thoroughly yet, could be just from the last time I changed the oil filter.
Last edited by TomX8; 07-31-2017 at 12:01 PM.