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Compression test diagnosis; From another post of mine
Topic Started: Jan 1 2017, 11:39 AM (1,461 Views)
Bannedfonz
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This is from another post I have about a starting issue. I'm curious to see what others think about the test results and thought it would get more traffic in a separate post.

A little back story. At this point, the car has been sitting and not ran for almost 2 weeks. It sat for a week or so before I tried to start it on Christmas day. It ran poorly, sounded like it was running on 2 cylinders. I shut it off and it sat for 2 more days. When I tried it again, it would just crank with no fire at all. I have fuel and I have spark. Cylinder #1 is flooding out (there is fuel sitting on top of the piston), #2 & #3 are damp but not flooded and all piston tops look to be in good shape. So, per advice, I did a compression test. The gauge from O'reilly's is questionable at this point, but Advance Auto's was out at the time. Here's the results...

Ok, compression check done... kind of... I have varying results with each cylinder. The first time I did the test (when I bought the car) everything was even and stable. This time I ran the dry test 3 times in a row per cylinder. Mainly because the tester I was using last night (an old tester that has to be held in the spark plug hole) was giving me numbers all over the board and I was trying to get consistent numbers.

So dry test:
#1 90, 60, 60 = TOAST! lol
#2 170, 175, 160 = GOOD!
#3 90, 125, 140 = I don't know what...

Wet test was a joke... My numbers (when I got them), were all over the place. I didn't even record them.

I used about 1/2 oz of oil. maybe that isn't enough to get pressure?

#3 results...



#1 and #2 were about the same.


At this point, I'm going to get the gauge from Advance and retest at some point this weekend or the first of the week. I'm looking for other input as well. Trying to make sure before I tear the head off my car! If it's not the gauge, then it's the valves?

Thanks to everyone that has helped me so far...
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1DCGUY
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Don't be a "Richard"

Can you confirm for us that you did the compression test correctly before we go any farther?
I'm not trying to be a smartass by asking the question, but on more than one occasion, the test was done wrong, and after doing it correctly, the numbers were pretty good.
Please confirm the below instructions were done:
Engine to full operating temp?
All plugs out?
Injector unplugged or fuse pulled?
Throttle help wide open?

Let us know,

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David95237


that gauge has a bad Schrader valve. it should not drop pressure.
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sphenicie


:gp

absolutely. retest before you go forward.

you should have 3 tests with almost identical results to put faith behind it.
Edited by sphenicie, Jan 1 2017, 01:14 PM.
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Bannedfonz
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That's good to hear from a few of you. I was going to re do the test anyway just to be safe, but it's good to know I'm on the right track with the re test.

1DCGUY, I know your just being safe and making sure things are done right before making an accurate assessment... Your not the only one! lol I like to make sure I'm doing things right, if I'm not, I always open to correction and better ways of doing things.

Test was performed (and will be again unless I'm otherwise instructed) as follows. Engine was NOT up to temp because it will not start. 15A Fuse under the hood for FI was pulled along with the ignition coil wire. All three plugs removed. Tested each cylinder 3 times (I know that's not necessary but I was trying to get a comparable reading), count of 5 for each test, with throttle wide open. After each test, the gauge was reset and repeated the test without removing the gauge from the plug hole. After 3 tests were completed on a cylinder, the same procedure was done on the next cylinder. Not that it matters, but I started with #3 and worked back to #1. The wet test was done with only one pass per cylinder using 1/2 oz of oil.

Hope that's more than enough information! lol

Thanks for the input guys, I'm getting ready to run to Advance Auto and see if they have the tester on hand yet. If they do, I will retest and report the findings. I'm looking forward to getting accurate results this time!
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ranger88den
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[ *  *  *  *  * ]
To add to 1DCGUY's compression test instructions, make sure the battery is fully charged, it does/will make a difference in compression readings. Once you have the battery fully charged, leave the charger on to ensure full voltage. In the end, do a leakdown test, that way you'll know the source of your problem. Good luck.
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freegeo
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Quote:
 
1DCGUY, I know your just being safe and making sure things are done right before making an accurate assessment... Your not the only one! lol I like to make sure I'm doing things right, if I'm not, I always open to correction and better ways of doing things.


That's the attitude to have if you want to learn. There's lots of us that have been where you are now.
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Bannedfonz
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It's not an easy attitude to have. I have a habit of jumping to conclusions when I get tired of messing with a problem. At some point, if you guys wouldn't be so awesome, I would just start throwing parts at it till I found the solution.
So Advance Auto doesn't carry a tester so I had to go to Auto Zone to get one... OEM brand. We will see how this one does...
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Bannedfonz
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Well, here it is... Second compression test done. Completed the same as the first, using a different tester. 3 consecutive tests per cylinder. 5 seconds per test. Wet test was taken twice, best result shown, try not to laugh! lol

I'm a little connfused because once again, each test resulted in a different number. The gauge did not leak down like the previous one, but the results overall weren't much different. All over the place.

Dry test:
#1 120, 175, 190
#2 90, 120, 150
#3 160, 185, 190 (I ran one test holding for 7 seconds and got 230)

Wet test:
#1 220 (same result both times!)
#2 35
#3 20 (first test)

The gauge acted the same way on cylinder #2 that the other gauge did in the video above. The needle bounced up and down, then about half way through the test, it started to make pressure. #3 and #1 were good this time though. They built pressure and I replicated the result on #1 with the same result both times. #3 was very week on both tests. The first test came in at 20 or so and the second was around 5...

I'm getting to the end of my sanity with this testing... Every time I run the test, I get different numbers. Not similar numbers either...
Edited by Bannedfonz, Jan 1 2017, 06:22 PM.
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freegeo
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I honestly have never seen test results like that. Certainly have never seen wet tests well below dry ones.

The only thing I can think is that when you did the tests and each time the numbers went up it was due to oil getting by the rings and sealing the rings more.

How many miles are on the engine?
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Hanuman
"The Almighty Grounds Cleaner"

freegeo
Jan 2 2017, 01:16 AM
I honestly have never seen test results like that. Certainly have never seen wet tests well below dry ones.

The only thing I can think is that when you did the tests and each time the numbers went up it was due to oil getting by the rings and sealing the rings more.

How many miles are on the engine?
Bingo! Freegeo.

Now go grab another compression tester and try again!.....when you see a test getting stupid results it's just a worn out tester that needs to be replaced......I've seen that before bunches of times.
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Bannedfonz
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Freegeo, I have 91,526 miles on my motor. No internal work has ever been done.

Hanuman, I'm glad you've seen that before. I've been racking my brain trying to figure out if I have bad rings or valves and which cylinder has which... Looks like I'm just going to go buy one. I only have one more place locally that does the loaner tools, and I don't know if they have them or not yet. I will look around and post back when I have a different tester and hopefully "correct" results.
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Bannedfonz
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So just to satisfy my curiosity, what happens if it's not the gauge? I know these readings are odd and it probably is the gauge (I trust Hanuman's advice) and I just got 2 bad gauges in a row. If I get a third gauge and a third reading that looks like this, is it possible that my compression can be all over the place?
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sphenicie


It is not uncommon for oil to foul the valve in a comp gauge......a standard tire valve will fit, but not function properly. could be someone put a standard valve in to a loaner tool. one of mine got too much oil inside and is just no longer functioning.



91K on the engine now, how many of these miles are yours? I am looking for history of this engine. it should not have issues at such a young age. How well has it been maintained along the way?

For the "average" of your comp readings, you should be able to get it running. I have run g10's for quit a time with comp readings at and below100psi.
Granted not running well, but able to start and push themselves down the road.
Edited by sphenicie, Jan 2 2017, 09:32 AM.
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Bannedfonz
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Sphenicie,

Lucky 7's on miles that are mine... 7,777 miles since I bought it in the end of May 2014. My grandparents owned the car before me, my aunt before that. In the family since '96... My grandfather was always really good at maintenance and always changed the oil and took care of his things the best he could. After he passed away, my grandmother tried to keep up with things but I noticed the oil was pretty dark when I bought it and changed the oil. I do know that the timing belt was replaced a year or two before I bought it. I did a tune up when I bought it as well, plugs wires cap and rotor. I switched to 0W40 Mobile Synthetic about 2 oil changes ago. I change it when it gets dark, not at the mileage, because I never hit the miles and I do mostly in town driving. Never used or leaked any oil. Antifreeze tests out at -25. As to my knowledge no work has been done to the motor, until I took the valve cover off the other day it has never been opened up. I did have a little issue with my idle being a tad high that I never fixed. Idles around 950 or so now. I also just recently replaced all 3 motor mounts.
You can check my other thread about a flooded #1 cylinder to get a background on this current problem.
I've also had a lifter tick when it's cold and only when it's cold. Once it warms up it goes away. It's a little better since I switched to synthetic, but it was still there...
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