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i have an oil leak and i cant figure ouit where its coming from so my friends dad said i need to do a compression test because the rings could be bad. its a 1995 ford thunderbird with a v8 and it still has pretty good power. i heard that bad rings will burn oil but i didnt know that they could leak oil. can bad piston rings be the cause of my leak???
i have an oil leak and i cant figure ouit where its coming from so my friends dad said i need to do a compression test because the rings could be bad. its a 1995 ford thunderbird with a v8 and it still has pretty good power. i heard that bad rings will burn oil but i didnt know that they could leak oil. can bad piston rings be the cause of my leak???
Well, I have seen really bad blow by spew oil out the exhaust which backs up onto the back of a car... but a normal leak usually isn't blow by the rings. Blow by would also be noticable if it gives off blue smoke from the exhaust.
On a really old car, a compression test will indicate if all the cylinders still have good compression or not. However, if you have a leak that is dripping oil in the driveway, chances are it is coming from one of any number of seals. Oil pan seal, rear main seal, valve cover seals, head gasket seals, etc.
Take it somewhere and get a second opinion on the leak if it bothers you. If it isn't a bad leak, just keep an eye on your oil level and add some oil when needed.
i have an oil leak and i cant figure ouit where its coming from so my friends dad said i need to do a compression test because the rings could be bad. its a 1995 ford thunderbird with a v8 and it still has pretty good power. i heard that bad rings will burn oil but i didnt know that they could leak oil. can bad piston rings be the cause of my leak???
Are you leaking oil, where you find the oil wetting the underside of the car and dripping on your driveway, or are you just *using* oil, probably burning it, no drips or mess, the oil level just goes down?
If it's burning/using oil, sometimes going to a little thicker grade of oil will reduce this. I have seen engines that burnt some oil burn less with a synthetic. But keep in mind that synthetics generally leak worse than conventional oils.
If the car is not smoking badly enough to not pass smog, for the near term, I would just keep an eye on the oil level and keep driving it.
If you really have worn rings, to do anything about that, you would be rebuilding the engine or swapping it out for a rebuilt or junkyard engine, I don't think you want to go there.
Are you leaking oil, where you find the oil wetting the underside of the car and dripping on your driveway, or are you just *using* oil, probably burning it, no drips or mess, the oil level just goes down?
If it's burning/using oil, sometimes going to a little thicker grade of oil will reduce this. I have seen engines that burnt some oil burn less with a synthetic. But keep in mind that synthetics generally leak worse than conventional oils.
If the car is not smoking badly enough to not pass smog, for the near term, I would just keep an eye on the oil level and keep driving it.
If you really have worn rings, to do anything about that, you would be rebuilding the engine or swapping it out for a rebuilt or junkyard engine, I don't think you want to go there.
no its leakin like its getting oil on the underside of the oil pan and the tranny bellhousing so im pretty sure its coming from the top part somewhere? and i have not noticed my car smoking at all.
How many miles do you drive before you need to add a quart of oil?
Depending on how much of a mess this is making, it may or may not be worth trying to fix. Depending on how nice you want to try to make this car.
If you can run it up on ramps, and wash particularly the bottom side of the engine, do this with the engine cold and use a good degreaser, and rinse very thoroughly, this may help you figure out where the leak is.
You can just take a good strong light and look carefully all over the engine, and figure out where the oil is coming from.
Sometimes when an oil pressure warning light switch starts to leak, it will make a real mess. This happened to me with the Scirocco, the switch was only leaking when the RPM was up to 2-3000, full oil pressure, looked like the oil filter was leaking. It didn't leak when idling.
Anyway to answer your original question I don't think a compression test would tell you anything about your oil leak.
One final thought is to make sure the PCV system is not plugged and is working, if you lose crankcase ventilation that will definitely cause all sorts of small oil leaks.
I think I posted this before but Castrol High-Mileage oil sometimes will cause seals/gasketes to swell a little and reduce oil leakage. The stuff in the green bottles.
If you are convinced that it is an internal engine problem a compression test will tell you somethnig, but not everything. If you get uneven results it could be bad rings, or it could be a burnt valve or even a head gasket. Maybe toehr things too. I am no expert.
You also need to make sure that the compression test is done properly. I would have to look it up or ask someone here, but you need to remove some or all of the spark plugs to get an accurate reading. I do nto remember why, but some mechanics are either lazy or do not know and will rmeove only the plug for the cylinder that they are testing. For some reason this messes up the test if I remember correctly.
If you get a cylinder with low reading, then pour a little heavy oil in the spark plug hole and test again. If it goes up a lot, then it most likely is worn rings. If you pour some heavy oil in and the compression reamins the same, then the problem is most likely valves or a head gasket. Since you normally replace the valves and head gasket together as long as you have the head off, it really does not matter which one it is.
I had not done a compression test in a long long time. Last year (or so) I did a test on a car I keep around as a hobby and the compression was 85,85,85, 15 so it was obvious where the problem was. (I think that the 85s are supposed to be 120 or 150, but I was told that it is probably just a bad reading as long as they are all the same). I somehow confirmed that this car has a burnt valve, I do not remember how. THe funny thing is that it runs, it just lacks power and backfires a lot. Maybe the backfiring confirms the burnt valve. I do not remember. I rely on advice from others and on books a lot for working on cars. I have an uncle who is a retired mechanic and occaisionally we can call him, describe the problem, hold the phone up to the engine and he will tell us what the problem is. When he can tell us, he is correct every time. Sometimes he cannot tell by listening through the phone.
Then the question becomes should you go ahead and replace the rings while you have it partially apart? I have a car with a burnt valve. If I just do the head, I am concerned that the rings may blow out under the increased compression if they are badly worn. However on this particular car, refurbishing the head and replacing the rings involves a vastly different amount of work. I may gamble on the rings, but it is not always a good idea.
Good Luck. Hopefully your problem is one of the more minor issues suggested by the people here. Some of these people are pretty knowlegable and have helped me out a lot. Be careful, some posters have no idea what they are talking about.
Simple test...a leak down test will tell a person if it is a intake valve...exhaust valve...rings.
As to a compression test...the engine is turned over (via) starter so that there is a cycle of the piston going down on the intake stroke and returning up on the compression stroke...vola a compression reading.
Some people will crank the engine over a few times building up the reading by 5 pts each time which in essence is a waste of time and a false reading. One down and up is all thats needed.
Piston goes down...intake valve is opening for fuel/air mixture
Piston goes up...valves are closed... compression is made
Piston goes down...fuel/air is ignited for power
Piston goes up...exhaust valve opens to expell exhaust.
The cycle is repeated.
If there is oil on the exterior of the engine (oil pan, etc) it is 99 percent chance NOT an internal problem.
If it is definitely engine oil, it is likely to be the front or rear main seals, valve cover gasket(s), spills from filling the oil or oil filter, oil pan gasket, PCV gromet/line, or any other external oil seal/line. Keep in mind the leak is usually in front of where the oil is found due to wind.
It could also easily be ATF from a cooler line or P/S fluid from a leaking line or rack.
The only way it could be caused from an internal problem is if there is such excessive blow by that it is being pressurized out a crankcase breather or vent line. Since most OEM cars vent into the intake system, you are very unlikely to see this happen, and when it does, it sprays a fine mist everywhere.
If there is oil on the exterior of the engine (oil pan, etc) it is 99 percent chance NOT an internal problem.
If it is definitely engine oil, it is likely to be the front or rear main seals, valve cover gasket(s), spills from filling the oil or oil filter, PCV gromet/line, or any other external oil seal/line. Keep in mind the leak is usually in front of wear the oil is found due to wind.
It could also easily be ATF from a cooler line or P/S fluid from a leaking line or rack.
The only way it could be caused from an internal problem is if there is such excessive blow by that it is being pressurized out a crankcase breather or vent line. Since most OEM cars vent into the intake system, you are very unlikely to see this happen, and when it does, it sprays a fine mist everywhere.
ha thank you ythats wat i wanted to hear i was hoping it wouldnt be internal
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