Worn piston rings :(
07-22-2009, 11:26 AM
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Worn piston rings :(
Just got my car back from Nissan because Ive been losing oil pressure and they told me my rings are worn. They also said I need a new engine which I dont believe. How should I go about this and what am I looking at for cost?
07-22-2009, 11:30 AM
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2003 with 110,xxx
07-22-2009, 01:07 PM
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If you have the equiptment you could verify this yourself, if not you could hire a shop.
There are a couple fairly easy ways to determine the piston ring condition in your car. A compression test and a leak down test, a leak down test is more accurate but is a little more involved and a leak down tester is more expensive.
Most Hayne's and Chilton's manuals describe how to preform a compression test fairly well.
The short version is as follows
Preform a dry test for each cylinder and record the pressure values.
Preform a wet test for each cylinder and record the pressure values.
A wet compression test is one where you add a small amount of motor oil to the cylinder just prior to preforming the compression test.
Compare the dry test results looking for similar pressure values for each cylinder within 10psi, this will give you a basic idea of how evenly the cylinders and rings are wearing. Then compare the dry values to the wet values, the general rule of thumb is if you see a pressure increase of 10psi or more that there is a ring sealing issue. The reason for this pressure increase is the oil added (for a few compression cycles) acts as an additional seal in and around the piston rings thereby increasing the cranking cylinder pressure.
A leak down test is slightly more involved, but it measures the actual percentage of leakage from each cylinder, and based on where the leak or leaks occur when air pressure is applied to each cylinder one can determine where it is comming from and what is the most likely cause.
I hope this helps.
There are a couple fairly easy ways to determine the piston ring condition in your car. A compression test and a leak down test, a leak down test is more accurate but is a little more involved and a leak down tester is more expensive.
Most Hayne's and Chilton's manuals describe how to preform a compression test fairly well.
The short version is as follows
Preform a dry test for each cylinder and record the pressure values.
Preform a wet test for each cylinder and record the pressure values.
A wet compression test is one where you add a small amount of motor oil to the cylinder just prior to preforming the compression test.
Compare the dry test results looking for similar pressure values for each cylinder within 10psi, this will give you a basic idea of how evenly the cylinders and rings are wearing. Then compare the dry values to the wet values, the general rule of thumb is if you see a pressure increase of 10psi or more that there is a ring sealing issue. The reason for this pressure increase is the oil added (for a few compression cycles) acts as an additional seal in and around the piston rings thereby increasing the cranking cylinder pressure.
A leak down test is slightly more involved, but it measures the actual percentage of leakage from each cylinder, and based on where the leak or leaks occur when air pressure is applied to each cylinder one can determine where it is comming from and what is the most likely cause.
I hope this helps.
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07-22-2009, 02:10 PM
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Brought it to one of my dads good friends for a double check. I may just get rid of the car and get my SUV back.
07-22-2009, 05:13 PM
#9
The symtoms of worn rings is loss of compresion, a smokey motor & increased oil consumption
07-22-2009, 07:10 PM
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07-22-2009, 07:18 PM
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My sister was following me when I got it from Nissan bringing it to the other shop and she said I was blowing smoke hardcore and when I went from a stop I shot out a big cloud.
07-22-2009, 10:32 PM
#13
Increased oil consumption on its own does not lead to low oil pressure, but if this increased consumption was not replaced & oil levels fell to very low levels then indeed low or even no oil pressure could be en counted
07-23-2009, 05:25 AM
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07-23-2009, 06:38 AM
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Worn rings by themselves will not cause a drop in oil pressure. It will cause an increase in oil consumption, as mentioned above, and if this oil consumption goes on long enough without adding more oil back you will lose oil pressure.....about the time the rod bearings seize up from not having any oil. If you're losing oil pressure it's most likely from the oil pump itself being worn or from sludge / buildup in the oil passages.
Since it looks like you're going to need to rebuild / replace your engine anyway if you keep the car it wouldn't hurt to try a couple of "miracle" cures before doing so. Try flushing the engine with something like Heartland Extreme Clean flush, this will clean out the oil passages and then replace your oil with a slightly heavier weight. If you're running 5-30 now go to a 10-40, the added viscosity can sometimes help prevent blow-by and consumption. Although this is mostly just going to work when the engine is cold as most all oils are designed to maintain the same viscosity at operating temp.
Since it looks like you're going to need to rebuild / replace your engine anyway if you keep the car it wouldn't hurt to try a couple of "miracle" cures before doing so. Try flushing the engine with something like Heartland Extreme Clean flush, this will clean out the oil passages and then replace your oil with a slightly heavier weight. If you're running 5-30 now go to a 10-40, the added viscosity can sometimes help prevent blow-by and consumption. Although this is mostly just going to work when the engine is cold as most all oils are designed to maintain the same viscosity at operating temp.
07-23-2009, 07:14 AM
#17
Worn rings by themselves will not cause a drop in oil pressure. It will cause an increase in oil consumption, as mentioned above, and if this oil consumption goes on long enough without adding more oil back you will lose oil pressure.....about the time the rod bearings seize up from not having any oil. If you're losing oil pressure it's most likely from the oil pump itself being worn or from sludge / buildup in the oil passages.
Since it looks like you're going to need to rebuild / replace your engine anyway if you keep the car it wouldn't hurt to try a couple of "miracle" cures before doing so. Try flushing the engine with something like Heartland Extreme Clean flush, this will clean out the oil passages and then replace your oil with a slightly heavier weight. If you're running 5-30 now go to a 10-40, the added viscosity can sometimes help prevent blow-by and consumption. Although this is mostly just going to work when the engine is cold as most all oils are designed to maintain the same viscosity at operating temp.
Since it looks like you're going to need to rebuild / replace your engine anyway if you keep the car it wouldn't hurt to try a couple of "miracle" cures before doing so. Try flushing the engine with something like Heartland Extreme Clean flush, this will clean out the oil passages and then replace your oil with a slightly heavier weight. If you're running 5-30 now go to a 10-40, the added viscosity can sometimes help prevent blow-by and consumption. Although this is mostly just going to work when the engine is cold as most all oils are designed to maintain the same viscosity at operating temp.
07-23-2009, 05:29 PM
#18
There can be many causes for this but by far the most usual cause is wear & excessive clearance due to high mileage.
This wear cycle can be shortened by lack of maintenance & severe usage.
EG: Wrong spec oil, oil not replaced, oil pickup gauze slugged up, excessive high rev use, constant motor operating at bellow optimum temps (short trips). severe overheating of motor. ++++
To prevent this happening to you: Don't buy a high mileage car & avoid the above usage, but remember age catches up with everything. I know because I've just turned 66 YO, look after myself & eat the right things but I am starting to get aches & creaks that were never there before, but unlike the motor mentioned my (blood) pressures are starting to rise
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07-23-2009, 05:47 PM
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