Test for Engine Oil Burning
Postmaster
Joined: Mar 2001
Posts: 4,968
Likes: 3
From: So Cal
Losing almost a quart in a couple days is too much. Unless the plugs you have are a higher heat range and are burning off the oil, which is a common bandaid, the oil should show up on the plugs if it is getting past the rings or valve seals. So I am starting to lean more towards an external leak or getting blown into the air filter box.
If you can, crawl around under the truck with a good strong light and look for oil streaks. Sometimes it is hard to see these, so look for dirt sticking to things, usually has a fuzzy brown appearance. Trace it back towards the engine. Also feel your bumper or where ever the exhaust pipe comes out for greasy deposits.
This oil has to be going somewhere and I am starting to think not in the cylinder, unless it has hot plugs. Burned oil on plugs looks either very greasy or kind of velvety black thick soot. Hot plugs can burn it off and I forget what color that looks like but I think more towards dry black or brown deposits. Somewhere on the web there has got to be one of those pictures of what spark plugs look like. OH, here yah go...
http://www.verrill.com/moto/sellingg...colorchart.htm
See ash fouled and oil fouled.
Good Luck,
Jim Henderson
If you can, crawl around under the truck with a good strong light and look for oil streaks. Sometimes it is hard to see these, so look for dirt sticking to things, usually has a fuzzy brown appearance. Trace it back towards the engine. Also feel your bumper or where ever the exhaust pipe comes out for greasy deposits.
This oil has to be going somewhere and I am starting to think not in the cylinder, unless it has hot plugs. Burned oil on plugs looks either very greasy or kind of velvety black thick soot. Hot plugs can burn it off and I forget what color that looks like but I think more towards dry black or brown deposits. Somewhere on the web there has got to be one of those pictures of what spark plugs look like. OH, here yah go...
http://www.verrill.com/moto/sellingg...colorchart.htm
See ash fouled and oil fouled.
Good Luck,
Jim Henderson
Thread Starter
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New User
Joined: May 2003
Posts: 20
Likes: 0
I've checked the air filter and it looks fine.
I got the actual write-up from the mechanic and he showed 140 psi dry and 165 psi wet, or a difference of 18%. This seems to indicate piston wear to me, based on what I've seen on the net. e.g. http://autotechrepair.suite101.com/article.cfm/032106
After the mechanic noted the shape of the plugs, the dealer helpfully went and replaced them, so I don't know if I can do any new analysis. Regardless, it would seem, based on the difference in the readings, that piston wear is indicated. So it would seem that I am done with it, and I am going to return it to the guy for good tomorrow, unless you disagree and think the test does not indicate worn rings. Please let me know.
Thanks again.
I got the actual write-up from the mechanic and he showed 140 psi dry and 165 psi wet, or a difference of 18%. This seems to indicate piston wear to me, based on what I've seen on the net. e.g. http://autotechrepair.suite101.com/article.cfm/032106
After the mechanic noted the shape of the plugs, the dealer helpfully went and replaced them, so I don't know if I can do any new analysis. Regardless, it would seem, based on the difference in the readings, that piston wear is indicated. So it would seem that I am done with it, and I am going to return it to the guy for good tomorrow, unless you disagree and think the test does not indicate worn rings. Please let me know.
Thanks again.
Postmaster
Joined: Mar 2001
Posts: 4,968
Likes: 3
From: So Cal
There is some ring wear indicated but maybe not as bad as you think.
Usually when I look at compression tests, I am looking for changes for example from say from 120 to 165 or so. Also if you know what the spec for a new engine is for comparison that is a good indicator too.
140 isn't too bad in general and moving to 165 with oil shows some leakage but not terrible. I don't think this much leakage explains the huge amount of oil you are burning. I have seen engines that went from 150 new down to about 110 and only burned a quart every thousand miles or so.
BUT, I do not know your engine so those figures might actually be terrible for your engine.
I don't think the rings are bad enough to eat all the oil you are eating. So where is the oil going? An interesting problem.
Good Luck,
Jim Henderson
Usually when I look at compression tests, I am looking for changes for example from say from 120 to 165 or so. Also if you know what the spec for a new engine is for comparison that is a good indicator too.
140 isn't too bad in general and moving to 165 with oil shows some leakage but not terrible. I don't think this much leakage explains the huge amount of oil you are burning. I have seen engines that went from 150 new down to about 110 and only burned a quart every thousand miles or so.
BUT, I do not know your engine so those figures might actually be terrible for your engine.
I don't think the rings are bad enough to eat all the oil you are eating. So where is the oil going? An interesting problem.
Good Luck,
Jim Henderson
