Compression test
01-16-2016, 01:05 PM
#11
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Thanks for responding guys, the crickets were getting really loud.
#41 is the ECM fuse, I would guess that the ECM controls VVT, but I don't know if VVT is active during cranking anyway.
The hose has an O-ring where it screws into the spark plug hole, and there is a Schraeder valve there too. The gauge attaches to the hose with a quick connect like on an air compressor. The pressure doesn't leak down after cranking which tells me the quick connect and schraeder are good. It could potentially be leaking at the O-ring, though, giving a false low.
The hose from the second tester wouldn't thread in the hole, so I had to use the same hose with both gauges. If the O-ring is faulty, that explains why I got the same low results with the second tester. I'll try swapping the O-rings from one hose to the other and see what happens. Then I'll call the shop on Monday for a leak down.
#41 is the ECM fuse, I would guess that the ECM controls VVT, but I don't know if VVT is active during cranking anyway.
The hose has an O-ring where it screws into the spark plug hole, and there is a Schraeder valve there too. The gauge attaches to the hose with a quick connect like on an air compressor. The pressure doesn't leak down after cranking which tells me the quick connect and schraeder are good. It could potentially be leaking at the O-ring, though, giving a false low.
The hose from the second tester wouldn't thread in the hole, so I had to use the same hose with both gauges. If the O-ring is faulty, that explains why I got the same low results with the second tester. I'll try swapping the O-rings from one hose to the other and see what happens. Then I'll call the shop on Monday for a leak down.
01-23-2016, 07:41 PM
#12
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Alright got the SS back from the shop.
Cylinder #1, #2, #3 are at 150 PSI
Cylinder #4 is at 120 PSI
Cylinder leakage test on #4 shows 25%, loudest sound heard coming from crankcase. My mechanic is skeptical and advises me to walnut blast the intake valves first and see if that fixes it.
Recall that on my initial test, #4 was at 140, and a wet test only brought it up to 150. Besides the rings, is there another path to the crankcase? If the PCV valve were stuck open, could the air leak past the intake valves and thru the PCV valve into the crankcase? This thought occurred to me, but seems extremely unlikely.
Maybe a broken ringland would allow leakage, and a wet test would not show improvement?
Cylinder #1, #2, #3 are at 150 PSI
Cylinder #4 is at 120 PSI
Cylinder leakage test on #4 shows 25%, loudest sound heard coming from crankcase. My mechanic is skeptical and advises me to walnut blast the intake valves first and see if that fixes it.
Recall that on my initial test, #4 was at 140, and a wet test only brought it up to 150. Besides the rings, is there another path to the crankcase? If the PCV valve were stuck open, could the air leak past the intake valves and thru the PCV valve into the crankcase? This thought occurred to me, but seems extremely unlikely.
Maybe a broken ringland would allow leakage, and a wet test would not show improvement?
01-24-2016, 08:18 AM
#13
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There is no there is no other path to the crankcase other than past the rings. Can you tell for sure that the air sound is coming from the crankcase? Also, if your mechanic thinks the air is coming from the crankcase why does he suggest you walnut blast the intake valves? That isn't going to fix a crushed/broken ring land.
Do you have a means to do a leak-down test? HarborFreight has a cheap gauge set, Cylinder Leak-Down Tester. When connected and pressurizing cyl #4 you will be able to tell for sure if the air is passing toward the intake of the crankcase.
Also, for other not familiar with a leak-down test, here is some information. https://mobiloil.com/en/article/car-...-leakdown-test
Do you have a means to do a leak-down test? HarborFreight has a cheap gauge set, Cylinder Leak-Down Tester. When connected and pressurizing cyl #4 you will be able to tell for sure if the air is passing toward the intake of the crankcase.
Also, for other not familiar with a leak-down test, here is some information. https://mobiloil.com/en/article/car-...-leakdown-test
Last edited by DrLoch; 01-24-2016 at 08:22 AM. Reason: Added information
01-27-2016, 02:13 PM
#18
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Went to Harbor Freight on Monday, 100 mile round trip, couldn't find a reasonable priced leak down tester locally, so it was worth the trip. Got an inspection camera and some other goodies, too.
Thanks DrLoch for the instruction link, allowed me to see how the instructions included with the tool are wrong! Then I had to modify the tool to get accurate results, I'll post this in the sticky thread.
OK, got results finally!
Cylinder #1 4% leakage
Cylinder #2 2% leakage
Cylinder #3 4% leakage
Cylinder #4 23% with noise at crankcase and intake, a little louder at crankcase. Car has been torn down since Monday afternoon, would that make crankcase leakage seem worse than it really is(very slightly)? I would think not, since the other cylinders test with such little leakage.
I tested #4 at both TDC positions, with same result. I couldn't hear anything at the tailpipe at either TDC position, is that expected? No bubbles in coolant.
I removed the airbox (for access). I removed oil fill cap and brake booster fitting in the intake manifold for listening, with a long funnel as a listening aid. Testing performed with air pressure regulated at 100 PSI.
Thanks DrLoch for the instruction link, allowed me to see how the instructions included with the tool are wrong! Then I had to modify the tool to get accurate results, I'll post this in the sticky thread.
OK, got results finally!
Cylinder #1 4% leakage
Cylinder #2 2% leakage
Cylinder #3 4% leakage
Cylinder #4 23% with noise at crankcase and intake, a little louder at crankcase. Car has been torn down since Monday afternoon, would that make crankcase leakage seem worse than it really is(very slightly)? I would think not, since the other cylinders test with such little leakage.
I tested #4 at both TDC positions, with same result. I couldn't hear anything at the tailpipe at either TDC position, is that expected? No bubbles in coolant.
I removed the airbox (for access). I removed oil fill cap and brake booster fitting in the intake manifold for listening, with a long funnel as a listening aid. Testing performed with air pressure regulated at 100 PSI.
01-27-2016, 02:37 PM
#19
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1 - 3 are good to go, you obviously have a problem with #4. You could try cleaning #4 intake valves and then re-test. Although the fact you are hearing the noise in the crankcase says you have an issue with ring seal, be it broken/crushed ring land or broken rings.
01-27-2016, 03:23 PM
#20
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Or a bad cylinder sleeve? So drop the pan, pull the head, replace the rings and maybe the piston or sleeve? Can the sleeve be replaced with the engine still in the car?
I'm really happy with the numbers on 1-3, may not be much coking at all. I tried to look in at the intake and valves, but I couldn't get that dang inspection camera to go where I wanted it to. Gonna take more practice, I guess.
I'm really happy with the numbers on 1-3, may not be much coking at all. I tried to look in at the intake and valves, but I couldn't get that dang inspection camera to go where I wanted it to. Gonna take more practice, I guess.