A compression and leakdown won't tell you anything about an oil consumption problem.
excessive oil consumption
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Originally Posted By: Scott_Tucker
A compression and leakdown won't tell you anything about an oil consumption problem.
I don't see how that's possible. If the compression is off or there is a leak, that could point directly to a possible cause of oil consumption. If the compression is fine and there are no leaks, that rules out a few things. Either way, there is information gained.
A compression and leakdown won't tell you anything about an oil consumption problem.
I don't see how that's possible. If the compression is off or there is a leak, that could point directly to a possible cause of oil consumption. If the compression is fine and there are no leaks, that rules out a few things. Either way, there is information gained.
Originally Posted By: d00df00d
Originally Posted By: Scott_Tucker
A compression and leakdown won't tell you anything about an oil consumption problem.
I don't see how that's possible. If the compression is off or there is a leak, that could point directly to a possible cause of oil consumption. If the compression is fine and there are no leaks, that rules out a few things. Either way, there is information gained.
So if a compression test comes back as all cylinder low, so what, you haven't pin pointed anything. If one is low, then there's a problem in that cylinder, so is the OP ready to tear down the engine ? Or keep adding oil?
A leak down test tells you how well the cylinder is sealing. If the valve seals are the culprit, then this test is irrelevant.
Originally Posted By: Scott_Tucker
A compression and leakdown won't tell you anything about an oil consumption problem.
I don't see how that's possible. If the compression is off or there is a leak, that could point directly to a possible cause of oil consumption. If the compression is fine and there are no leaks, that rules out a few things. Either way, there is information gained.
So if a compression test comes back as all cylinder low, so what, you haven't pin pointed anything. If one is low, then there's a problem in that cylinder, so is the OP ready to tear down the engine ? Or keep adding oil?
A leak down test tells you how well the cylinder is sealing. If the valve seals are the culprit, then this test is irrelevant.
Another vote for a compression test, dry and wet. Save the money on the UOA report. It would be a waste of money IMO.
Originally Posted By: MarkM66
So if a compression test comes back as all cylinder low, so what, you haven't pin pointed anything.
Never said it would pinpoint anything, did I?
In your example, the results would indicate a possible cause. Again, I fail to see how that's a useless piece of information.
Originally Posted By: MarkM66
A leak down test tells you how well the cylinder is sealing. If the valve seals are the culprit, then this test is irrelevant.
But there's no way to know valve seals are the culprit without ruling out everything else, is there?
Well, no way aside from a teardown anyway. But I'm assuming the OP isn't inclined to tear his engine down, so...
So if a compression test comes back as all cylinder low, so what, you haven't pin pointed anything.
Never said it would pinpoint anything, did I?
In your example, the results would indicate a possible cause. Again, I fail to see how that's a useless piece of information.
Originally Posted By: MarkM66
A leak down test tells you how well the cylinder is sealing. If the valve seals are the culprit, then this test is irrelevant.
But there's no way to know valve seals are the culprit without ruling out everything else, is there?
Well, no way aside from a teardown anyway. But I'm assuming the OP isn't inclined to tear his engine down, so...
Originally Posted By: widman
PCV...... a defective PCV mis 80% of the problems of high consumption when it goes up quickly or has good compression. If not the pcv, do a compression check.
Analysis isn't going to tell you anything.
+1, +2, I've seen it happen, and it's quick and inexpensive to check.
PCV...... a defective PCV mis 80% of the problems of high consumption when it goes up quickly or has good compression. If not the pcv, do a compression check.
Analysis isn't going to tell you anything.
+1, +2, I've seen it happen, and it's quick and inexpensive to check.
There are several reasons a leakdown and compression test won't tell you anything about an oil consumption problem. First of all, valve stem seals don't seal compression at all and the valves are closed during a leakdown test so you could remove them and they wouldn't even show up on either test. Second, it is the oil control rings that scrape the oil off the cylinder walls, not the compression rings. You could take the oil control rings out and compression would be higher than normal because of the extra oil sealing the compression rings. Of course, it would burn hideous amounts of oil. You could have low compression due to broken/stuck compression rings if you had properly working oil control rings and not burn any oil (that's not likely though). So if the engine had low compression the original complaint should have been "engine runs poorly", the oil consumption would have been secondary. But it sounds like to OP thinks the engine runs well.
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