10 % leak down
12-13-2010, 09:25 PM
#1
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Join Date: Dec 2010
Location: Winnipeg
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10 % leak down
Hey just bought an a4 had tbelt done r bank was out had head removed found 3 valves intake bent got scared towed to Audi they did leak down on other head said 10% leak and want to pull other head will cost alot love my Audi but can't afford does this sound right?
12-17-2010, 12:12 PM
#2
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Location: Calgary AB
Posts: 84
Re: 10 % leak down
As a licenced mechanic, I would be doing both heads, no question! You are almost certain to have to do it as soon as you get the engine back together and then you need to remove the same parts to do that side. Post us as to how it turns out.
12-17-2010, 10:33 PM
#3
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Re: 10 % leak down
as a licenced mechanic if one cam is off and the other three are in time it whould only make sence that the cam that is out (intake) on right head would only have damage. on a car with 120000 km leak down would be present as an audi guy carbon build up is very relevent on these cars dont you think? i think the dealer is trying to rip me off. engnering of an engine in my experince there is no motor with 0% leak down 5 to 10 percent is a good running motor especialy when i have 120000 k whats your thought?
12-18-2010, 02:07 PM
#4
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Location: Calgary AB
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Re: 10 % leak down
Hello Jonny7798.
As a mechanic, I type too damn slow to get a response typed up before this forum thinks I went to sleep.
I haven’t had much leakdown experience, we mostly use compression testing as our gauge. As an engine wears in and carbons up, leakdown should decrease because the engine rings and valve seats fit each other perfectly then. Cold leakdown or compression tests are almost useless as the oil seal is either lost or not representative of operating condition. If the leakdown is uniform across the remaining cylinders, I would say that the seal is still good. If one cylinder came up poor, the decision would be obvious. That doesn’t say that valves have not been compromised by contact, only that they are now sealing.
If you were the service manager at that business, you would have to come to the same recommendation. It sounds to me like there have been several individuals/companies involved in this repair/diagnosis. If you are the one that removed the cover and found that only one cam was out of time, then you are the one to decide that you are comfortable enough to make that decision to re-assemble and carry on. Since you have defaulted that decision to the dealer, I presume that you are not that comfortable about what went on before you got involved, so now, you can imagine how uncomfortable the dealer would be about his having to make a call for you. I, as a mechanic, would not be uncomfortable about making a decision if I took it apart and was certain that only one cam was out of time and all evidence supported that.
I would say that the worst that could happen is that if you put it back together and a valve fails, you will have to replace the other head and the related gaskets and seals. Also if the valve head falls off of the valve you may need to do a piston. The best is that it runs like a top and the problem is resolved. There should have been very little wear to the cylinder walls in that time so if everything else looks good, the ball is in your court. Serve it however you are comfortable.
Keep us posted on how it turns out. Good luck with your decision. Sincerely,
As a mechanic, I type too damn slow to get a response typed up before this forum thinks I went to sleep.
I haven’t had much leakdown experience, we mostly use compression testing as our gauge. As an engine wears in and carbons up, leakdown should decrease because the engine rings and valve seats fit each other perfectly then. Cold leakdown or compression tests are almost useless as the oil seal is either lost or not representative of operating condition. If the leakdown is uniform across the remaining cylinders, I would say that the seal is still good. If one cylinder came up poor, the decision would be obvious. That doesn’t say that valves have not been compromised by contact, only that they are now sealing.
If you were the service manager at that business, you would have to come to the same recommendation. It sounds to me like there have been several individuals/companies involved in this repair/diagnosis. If you are the one that removed the cover and found that only one cam was out of time, then you are the one to decide that you are comfortable enough to make that decision to re-assemble and carry on. Since you have defaulted that decision to the dealer, I presume that you are not that comfortable about what went on before you got involved, so now, you can imagine how uncomfortable the dealer would be about his having to make a call for you. I, as a mechanic, would not be uncomfortable about making a decision if I took it apart and was certain that only one cam was out of time and all evidence supported that.
I would say that the worst that could happen is that if you put it back together and a valve fails, you will have to replace the other head and the related gaskets and seals. Also if the valve head falls off of the valve you may need to do a piston. The best is that it runs like a top and the problem is resolved. There should have been very little wear to the cylinder walls in that time so if everything else looks good, the ball is in your court. Serve it however you are comfortable.
Keep us posted on how it turns out. Good luck with your decision. Sincerely,
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