Help understanding Leakdown--compression numbers
#1
Help understanding Leakdown--compression numbers
I don't want to assume, I don't think my knowledge level is quite there. Thanks for the feedback.
Compression--dry/wet
180/180
100/100
120/125
185/190
Leakdown--all cylinders air out the valve cover
12%
86%
81%
39%
Background on motor 1.6- picked it up off a guy who did basically a complete rebuild minus pistons. It was stupid cheap and already had a 1.6 setup. ripped it apart to double check everything, he never started it up. Everything checked out from our end and what the guy said he did, he did, so we put it all back together. After break in 500-600 miles started pushing smoke, then got worse, till it started pressurizing crankcase and pushing oil out everywhere (around 1200-1500 miles), I thought it was a head gasket, pulled it off, put new on, same problem. . . I know, still learning, . . . don't want to pull anything apart before I have a solid direction. . . When I pulled the head off, the cylinders all looked really good, no scaring. . at this point I have no idea if that means anything.
Just wanted to confirm what I already think, but I'm racking my brain before I rip the motor apart again. Just don't want to put money into a 1.6. My time is not a big deal, but if I rebuild, I'll just go 1.8 and sell the internals to the 1.6. . . . I'm not looking for crazy big numbers, was just looking for a fun daily, so 200-250 was the goals. I was pushing around 200, didn't even get a chance to turn the boost up. If I'm leaving any info out, let me know, I'll try to answer best I can.
Thanks for any help guys.
Compression--dry/wet
180/180
100/100
120/125
185/190
Leakdown--all cylinders air out the valve cover
12%
86%
81%
39%
Background on motor 1.6- picked it up off a guy who did basically a complete rebuild minus pistons. It was stupid cheap and already had a 1.6 setup. ripped it apart to double check everything, he never started it up. Everything checked out from our end and what the guy said he did, he did, so we put it all back together. After break in 500-600 miles started pushing smoke, then got worse, till it started pressurizing crankcase and pushing oil out everywhere (around 1200-1500 miles), I thought it was a head gasket, pulled it off, put new on, same problem. . . I know, still learning, . . . don't want to pull anything apart before I have a solid direction. . . When I pulled the head off, the cylinders all looked really good, no scaring. . at this point I have no idea if that means anything.
Just wanted to confirm what I already think, but I'm racking my brain before I rip the motor apart again. Just don't want to put money into a 1.6. My time is not a big deal, but if I rebuild, I'll just go 1.8 and sell the internals to the 1.6. . . . I'm not looking for crazy big numbers, was just looking for a fun daily, so 200-250 was the goals. I was pushing around 200, didn't even get a chance to turn the boost up. If I'm leaving any info out, let me know, I'll try to answer best I can.
Thanks for any help guys.
#2
since oil didn't raise the number, I'll go with valve(s). Or rings, and they're bad enough for the oil not to even affect it (which would be pretty terrible)
Either way not only is it a pathetic 1.6, but a crappy pathetic 1.6, and there is literally no reason whatsoever now to keep polishing the turd, but yank it for a 1.8
Either way not only is it a pathetic 1.6, but a crappy pathetic 1.6, and there is literally no reason whatsoever now to keep polishing the turd, but yank it for a 1.8
#5
The comp vs leak down appears transposed. Are you reporting the amount of leakage or the amount that shows on the second gauge? IE the cylinder with 12% the gauge showed 88%?
If #2 and 3 are the amount of leakage and not what is showing on the gauge (IE 86% was actually showing on gauge as 14%) then those are the worst leakages I have seen on a running motor...
I would expect cylinder wall damage on the two middle cylinders: easily seen damage. Or possibly broken ring lands which is the first thing that lets go on a factory piston. Normally when the lands are broken the motor no longer runs and the cylinder walls get trashed.
If you are reporting what was actually showing on the leak down tester then the leak test was done wrong. It has to be TDC compression stroke and if it's done at TDC exhaust stroke it will produce results like you have posted BUT it will be pumping air from intake and exhaust.
I'm down in Granbury, I can help...
1.8 is the SMART way to go if you have a popped 1.6 and it sounds like you do.
There is no replacement for displacement besides cubic money. Even 200 cc is worth the engine swap.
Hope this helps.
Rick
If #2 and 3 are the amount of leakage and not what is showing on the gauge (IE 86% was actually showing on gauge as 14%) then those are the worst leakages I have seen on a running motor...
I would expect cylinder wall damage on the two middle cylinders: easily seen damage. Or possibly broken ring lands which is the first thing that lets go on a factory piston. Normally when the lands are broken the motor no longer runs and the cylinder walls get trashed.
If you are reporting what was actually showing on the leak down tester then the leak test was done wrong. It has to be TDC compression stroke and if it's done at TDC exhaust stroke it will produce results like you have posted BUT it will be pumping air from intake and exhaust.
I'm down in Granbury, I can help...
1.8 is the SMART way to go if you have a popped 1.6 and it sounds like you do.
There is no replacement for displacement besides cubic money. Even 200 cc is worth the engine swap.
Hope this helps.
Rick
#6
SADFab Destructive Testing Engineer
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Either way the motor is trash.
Cylinder 1 12%. This either mean the second gauge was at 12% (and the motor is trash), or 12% and that cylinder is decent
Cylinder 2 86%. Either the second gauge was 86% and thats pretty good, or its really 86% leakdown and your pistons are swiss cheese.
Cylinder 1 12%. This either mean the second gauge was at 12% (and the motor is trash), or 12% and that cylinder is decent
Cylinder 2 86%. Either the second gauge was 86% and thats pretty good, or its really 86% leakdown and your pistons are swiss cheese.
#8
It's def possible my leakdown tests are done wrong. I thought the second gauge showed the % of leak. Didn't pay to much attention to the first gauge. I hooked it up to 100 psi, it was on compression stroke. I'm prob doing something wrong. I'll research more and get back.
I thought with the numbers I saw either I would see damage on the cylinder walls or holes in pistons. I didn't even see signs of detonation. I'm also still learning, so this has been a very reasonable learning experience for me. I'm in agreement with the 1.8, the numbers worked out ridiculously good for this motor, so even if this is just for my knowledge it was worth it, don't really want to have to discuss 1.6/1.8 arguments, I know most of you guys do. I'd like to learn, and if I can make this work I'd like that.
I thought with the numbers I saw either I would see damage on the cylinder walls or holes in pistons. I didn't even see signs of detonation. I'm also still learning, so this has been a very reasonable learning experience for me. I'm in agreement with the 1.8, the numbers worked out ridiculously good for this motor, so even if this is just for my knowledge it was worth it, don't really want to have to discuss 1.6/1.8 arguments, I know most of you guys do. I'd like to learn, and if I can make this work I'd like that.
#9
I tried my hand at a leakdown again. Not the greatest equipment but I have what I have. Pretty sure I landed solid numbers this time. Leaks out the oil cap still on all.
Couple questions before I start the tear down. Is there any possibility it could be head related? Is it also possible for the cylinder walls to be in good shape and have ring failure?
Again in thanks for the feedback.
#15
I'll know when I take the bottom end apart again. There are few things we chose not to address when we took it apart the first time to see what this guy did. If I can get a set of pistons cheap, the rest will cost minimal for me. Don't get all upset yet, this is a learning curve for me as well. One, I didn't build this car for the greatest hp, just a fun daily. 2, the way I see it this experience will cost much less than trying to go broke on building what I would like to do next, after I learn more. I'll follow the money curve, and yes I do agree with everyone on the 1.8 before I get flamed. I haven't hit the $800 dollar mark yet on this motor(sad for the guy before me,he spent what I didn't) so I'm fine with toying around and learning for the next one. I have spent time on it, but that I have(not in a hurry, spare car) money is better spent on the fam right now.