Compression & Leakdown Question
04-20-2009, 10:11 AM
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Compression & Leakdown Question
I was just curious about this. When I bought my car a little over a couple months ago, I called the Honda dealer to see if they could do a compression and leakdown test on the car. The service advisor said that if there were any leaks in the engine, including compression, that a CEL would automatically be present and that the car was extremely sensitive to these changes. He said I would be better off saving my money. Is all this true? Or does it have to be a really bad case of either for the CEL to turn on?
04-20-2009, 02:14 PM
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not true.
from my personal experience-
i purchased a used s2k from a local honda dealership, they said it was honda certified. so with the guarentee i decided to pick it up. it felt a little sluggish and i admit i was overly excited to own my dream car so i brushed it off. anyways to make a long story short i noticed a bunch of problems with the vhicle over a span of 2 days-missing transmission bolts, no heatshields under the vehicle etc. i decided to get a leak down and compression check just to make sure the health of the engine was ok.
brought it to another dealership and they performed the test and the car failed both the leakdown and comp. no check engine light was present on the vehicle. if i can remember, cylin1 185, cylin2 130, cylin3 120, cylin4 190. and the car failed leakdown. i think it was like leaking about 20-30% in one of the cylinders.
and the whole time no cel.
there is no sensor in the combustion chamber that monitors the compression. nor is there and type of sensor that measures the leaking of exhaust gasses past the piston rings.
but one thing to note is that there are varying degrees of having bent valves or no good piston rings. if they arent bent that bad but still leak your car may feel slow. if they are totally powned then the engine could fail to run.
hope this helps.
from my personal experience-
i purchased a used s2k from a local honda dealership, they said it was honda certified. so with the guarentee i decided to pick it up. it felt a little sluggish and i admit i was overly excited to own my dream car so i brushed it off. anyways to make a long story short i noticed a bunch of problems with the vhicle over a span of 2 days-missing transmission bolts, no heatshields under the vehicle etc. i decided to get a leak down and compression check just to make sure the health of the engine was ok.
brought it to another dealership and they performed the test and the car failed both the leakdown and comp. no check engine light was present on the vehicle. if i can remember, cylin1 185, cylin2 130, cylin3 120, cylin4 190. and the car failed leakdown. i think it was like leaking about 20-30% in one of the cylinders.
and the whole time no cel.
there is no sensor in the combustion chamber that monitors the compression. nor is there and type of sensor that measures the leaking of exhaust gasses past the piston rings.
but one thing to note is that there are varying degrees of having bent valves or no good piston rings. if they arent bent that bad but still leak your car may feel slow. if they are totally powned then the engine could fail to run.
hope this helps.
04-20-2009, 02:20 PM
#3
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Originally Posted by RedSex2k,Apr 20 2009, 11:11 AM
When I bought my car a little over a couple months ago, I called the Honda dealer to see if they could do a compression and leakdown test on the car. The service advisor said that if there were any leaks in the engine, including compression, that a CEL would automatically be present and that the car was extremely sensitive to these changes.
But I don't know if the typical dealer is even set up to do leakdown tests. If you have an air compressor, this is something you can do at home without too much trouble. Otherwise, if you find the right shop you can get it done reasonably quickly.
But do you suspect anything is wrong with the engine? It's not something I would do routinely on any used car I purchased.
04-20-2009, 03:29 PM
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Originally Posted by mikegarrison,Apr 20 2009, 02:20 PM
Not true.
But I don't know if the typical dealer is even set up to do leakdown tests. If you have an air compressor, this is something you can do at home without too much trouble. Otherwise, if you find the right shop you can get it done reasonably quickly.
But do you suspect anything is wrong with the engine? It's not something I would do routinely on any used car I purchased.
But I don't know if the typical dealer is even set up to do leakdown tests. If you have an air compressor, this is something you can do at home without too much trouble. Otherwise, if you find the right shop you can get it done reasonably quickly.
But do you suspect anything is wrong with the engine? It's not something I would do routinely on any used car I purchased.
04-20-2009, 05:34 PM
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On the other hand, you never want to fix what isn't broken. If there is no reason to think there is anything wrong with the engine, why screw around with it?
Yeah, you could go in and get the tests, visually inspect the head, check the valve gaps, check the plugs, etc. But every time you pull that valve cover off there is some chance you will screw something up. A small chance, maybe. But why do it if you have indication of any problem?
Yeah, you could go in and get the tests, visually inspect the head, check the valve gaps, check the plugs, etc. But every time you pull that valve cover off there is some chance you will screw something up. A small chance, maybe. But why do it if you have indication of any problem?
04-20-2009, 09:39 PM
#7
Originally Posted by mikegarrison,Apr 20 2009, 07:34 PM
On the other hand, you never want to fix what isn't broken. If there is no reason to think there is anything wrong with the engine, why screw around with it?
Yeah, you could go in and get the tests, visually inspect the head, check the valve gaps, check the plugs, etc. But every time you pull that valve cover off there is some chance you will screw something up. A small chance, maybe. But why do it if you have indication of any problem?
Yeah, you could go in and get the tests, visually inspect the head, check the valve gaps, check the plugs, etc. But every time you pull that valve cover off there is some chance you will screw something up. A small chance, maybe. But why do it if you have indication of any problem?
A leak-down test is non-invasive and easy to do - it doesn't require you pull anything but the spark plugs. You don't need to pull the valve cover for a leak-down test
And on that note... I've pulled my valve cover countless times (valve adjustments, retainer inspections, retainer replacement, pulled cams prior to 3 years of storage...) without a single issue. Careful attention to detail is all that's required - no reason to be paranoid.
A quality MAC or Snap On cylinder leak-down gauge runs less than $200 (a little more than what you may get charged to have one test run) - and the peace of mind in knowing how well your engine is sealing is worth it. I run a leak-down test every 10,000 miles and have done 3 leak down tests to date (my car has 60,000 miles on it currently). It's more comprehensive than a compression test.
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04-20-2009, 10:11 PM
#8
If you really want a good inspection with this, let Supertech take a look, he is freaggin awesome with all he does on our cars, hes the first dude Id trust to do anything on my car.
Then second is Autowave, also a very good shop to deal with.
Then second is Autowave, also a very good shop to deal with.
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