Leak Down result question
01-08-2005, 09:20 PM
#16
I'm no mechanical genious, but as far as I know leak down test is generally performed to determine where the problem with the engine lies. As Indicam already mentioned above, ideally you'd have the mechanic listen and make the appropriate remarks.
01-09-2005, 08:54 AM
#17
Rennlist Member
When I picked the car up after the service they did give me a verbal of where the leakage was happening - in none of the case was it the rings being the major component, with a mix of inlet or outlet valve leakage being the main culprit. I agree, ideally they should have noted this on the service report that than just the leakdown figures.
I don't think I'm going to be doing a valve job or full leakdown for the time being, as the car runs smooth and reliably with little oil usage. I suspect there may be some performance loss as a result of this, but I've found that since having the car little things such as changing old fuel filters, putting a bottle of fuel injector cleaner through it, cleaning the knock sensor connectors (which had been causing faults causing ignition retardation) and thrashing it to the redline have made a noticable difference to engine power!
Iain
I don't think I'm going to be doing a valve job or full leakdown for the time being, as the car runs smooth and reliably with little oil usage. I suspect there may be some performance loss as a result of this, but I've found that since having the car little things such as changing old fuel filters, putting a bottle of fuel injector cleaner through it, cleaning the knock sensor connectors (which had been causing faults causing ignition retardation) and thrashing it to the redline have made a noticable difference to engine power!
Iain
01-09-2005, 12:35 PM
#18
Burning Brakes
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Siberian, no it doesn't tell you anything like that, although it could be used to help you guess.
As Indycam has written, listening for air to come out of what one might think is a problem area, may very well be just that. But, only if you know (with out a shadow of a doubt) that the cylinder is on absolute TDC. The only way this is possible, is with a degree wheel. Checking with a probe, the finger over the sparkplug hole trick, or using a compression guage, to find TDC will not work properly (you are only guessing).
There is a right way, and a halfassed way of doing things. I would hope that the guy I hired to do the work on my car would be doing it the right way. Unfortunately, most people do not know these differences and subsiquently subject themselves to the mechanic that is suppose to know but probably doesn't either. That my freinds IS the sad but blatant truth. Using a screwdriver as a prybar, ??although it might work??, doesn't make it the appropriate choice.
On the other hand if the problem is significant (Like a burnt/broke/bent valve, etc...) then there really is no need for a leak down test at all. The engine will definately be runnig very porely and any mechanic (even one in the backyard) could tell that there is a major component gone south, after ruling out other factors.
So, once again I will re-iterate that a leakdown test is not neccessary for a diagnosis of internal engine damage or abrupt component failures. It is a test for determining performance and normal engine wear conditions.
But hey, use it however you wish.
Duncan
As Indycam has written, listening for air to come out of what one might think is a problem area, may very well be just that. But, only if you know (with out a shadow of a doubt) that the cylinder is on absolute TDC. The only way this is possible, is with a degree wheel. Checking with a probe, the finger over the sparkplug hole trick, or using a compression guage, to find TDC will not work properly (you are only guessing).
There is a right way, and a halfassed way of doing things. I would hope that the guy I hired to do the work on my car would be doing it the right way. Unfortunately, most people do not know these differences and subsiquently subject themselves to the mechanic that is suppose to know but probably doesn't either. That my freinds IS the sad but blatant truth. Using a screwdriver as a prybar, ??although it might work??, doesn't make it the appropriate choice.
On the other hand if the problem is significant (Like a burnt/broke/bent valve, etc...) then there really is no need for a leak down test at all. The engine will definately be runnig very porely and any mechanic (even one in the backyard) could tell that there is a major component gone south, after ruling out other factors.
So, once again I will re-iterate that a leakdown test is not neccessary for a diagnosis of internal engine damage or abrupt component failures. It is a test for determining performance and normal engine wear conditions.
But hey, use it however you wish.
Duncan
