97 Honda civic, 165,000 miles.
Symptoms: The car burns A LOT of oil, like more than 1 quart every 3k, for no good reason. No change after replacing valve stem seals. I doubt it's the rings because I have felt a pressure loss going up-hill once before, and the engine seems to perform poorly in hot weather. The engine also hiccups during a cold start. The cooling system seems to be getting bubbles in it, throwing off the IAC valve. (it was throwing a code recently) There is very little coolant loss, but there is some.
I bought this car at 90k miles in L.A., and the owner did not take care of the car. The cooling system was rusting because of running only water, but I managed to restore it. I suspect the engine was overheating a bit and it could have a slightly warped head. At 90k, it wasn't burning much oil, but it has gradually increased.
Minor headgasket leak?
- Thread starter Cleft_Asunder
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A leakdown test might be an indicator if your certain the rings and stem seals are good, but a coolant sniffer with th e blue fluid would be a better bet if theres coolant loss. Could it be sucking oil through the pcv?
You're right, I'm going to get a compression test done and then a leakdown. My PCV system is in good shape, and the valve is fairly new.
compression test + wet dry test (leakdown) should reveal the condition of your rings and more.
Q.
1qt/3K, not a lot.
Originally Posted By: Quest
compression test + wet dry test (leakdown) should reveal the condition of your rings and more.
Q.
Okay, so I did a dry compression test and it did very well so I didn't do a wet one. But on the leak-down test I'm experiencing lots of air loss through the intake valves.
Compression
1: 160
2: 160
3: 155
4: 155
Maybe I did the leak-down test wrong, I don't know. I hooked up an air compressor to each cylinder when it was at TDC through the hose that came with the compression tester. I did not use a standard leak-down gauge.
TDC means the piston is at it's highest point, right? So all 4 cylinders are leaking air past the intake valves into the intake manifold. They were quite loud and I could hear it and feel the air. When I put my ear next to the muffler, it was very faint on each cylinder, so no problem on exhaust.
What do you guys think? The oil burn is not caused by the rings, for sure. Could still be the head gasket.
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TDC on the compression stroke?
I would say the headgasket is good based on compression readings. It is still possible to get a tiny leak into the cooling system, but you will see continuous bubbles in the overflow jug with the engine running.
1 quart oil per 3000 miles is pretty good on an older car, even with no external drips. I'd say your engine is in good shape. Most people would be OK with what you have.
It doesn't sound like the leakdown test was done right, but if it was,you should be experiencing loss of power. Usually this type of leakage on all cylinders through only the intake valves would be caused by a cam timing problem (i.e. a slipped timing belt or chain), accompanied by poor power from the engine.
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Originally Posted By: hoosierrun
It doesn't sound like the leakdown test was done right, but if it was,you should be experiencing loss of power. Usually this type of leakage on all cylinders through only the intake valves would be caused by a cam timing problem (i.e. a slipped timing belt or chain), accompanied by poor power from the engine.
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Yeah so I did it right this time. Cylinders 2/4 were leaking the most past the intake valves, while 1/3 not so much. I did a valve adjustment recently to minimum spec, but it was based on valves that had carbon deposits on them. After inspecting the clearance today, a few of the intake valves had no clearance, causing the valves to be open.
So I adjusted the clearance to maximum allowable so that I can clean the valves through hard driving, allowing them an opportunity to seat in. (.009/.011) The car is already idling properly, which it wasn't before. After about 2 weeks of hard driving, I will do another valve job and put them back to minumum spec. (007/.009)
Thanks for your help btw.
A leak-down and/or a compression test won't do much to diagnose a bad headgasket. Neither will reveal anything about valve seals. A headgasket usually won't cause oil consumption.
You "doubt it's the rings because I have felt a pressure loss going up-hill once before, and the engine seems to perform poorly in hot weather." I'm not sure what this means. What kind of pressure loss rules out rings?
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