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| Geo Metro Rebuild fail perhaps? | |
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| Tweet Topic Started: Jul 20 2012, 10:17 AM (2,143 Views) | |
| rtp129495 | Jul 20 2012, 10:17 AM Post #1 |
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Advanced Member
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Hello everyone, I had a post earlier with my Compression testing results. At the time it wasnt too bad, But lately it seems to miss at idle to about 2500-3000 RPM. On the freeway it seems better. Yesterday i was curious and remove the #3 spark plug wire while running at idle. The engine DID NOT CHANGE at idle. This is how I determined which cylinder. Took out spark plugs( since i had to anyway) i did a compression test again. This time i got 205 #1 205 #2 and 160ish #3, i would assume the compression difference would cause a miss? the lower compression one is the one that is missing. I know it not the spark plug or spark plug wire because I used different one including a brand new MSD 8.5MM wire. I also traded spark plug with #2 and #3 cylinder and still #3 missed. Also when I held the spark plug boot near metal you heard the TICK TICK TICK of the spark. So spark is travelling to the cylinder. The sadest part of all this is that this engine has 8000 miles on a rebuilt motor(not by me) by an engine shop. I installed the motor and such and did that labor. But the engine itself was done at engine shop. Also california has a very strict smog check and i doubt it can pass with a miss like that. How can this happen at 8000 miles? ive worked on cars for years and never seen this? it was bad originally due to burnt valves. how can it go 220,000 burn valves and then do it on another engine with only 8000? Anyway i removed my $400 catalytic converter and drove it around to listen and I could hear this missing in the RPM ranges. This is how i know. I could compare this becuase when i first ran it when i put it together it sounded smooth and no missing or poping. Now you hear the miss while driving with poping without the converter on. Lastly, this is a 1992 geo metro LSI 3 Cyl. It is wonderful car(when the valves work and engines last). |
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| Bad Bent | Jul 20 2012, 03:15 PM Post #2 |
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Facetious Educated Donkey
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Well, how about the distributor? Is it cracked? Posts clean? And mwebb gave us NEW = Never Ever Worked. You can also test for errant spark with Windex... |
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| Alpine | Jul 20 2012, 03:21 PM Post #3 |
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1020cc G10 GOML
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sorry about your problems, where in San Diego are you located? |
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| 91 ragtop | Jul 20 2012, 03:25 PM Post #4 |
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That cylinder should fire fine at 160 pounds of compression. Ken.... |
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| JellyBeanDriver | Jul 20 2012, 10:21 PM Post #5 |
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That's as much compression I have on my engine with 418,000 miles on it. Runs fine. |
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| rtp129495 | Jul 23 2012, 08:22 AM Post #6 |
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Advanced Member
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This is the most bizzare problem i've ever experienced in cars in general. I determined that the compression tester I have is unreliable. I have to go buy another one. So i am not sure those compression numbers are correct. More will follow on that topic. Alpine: I am located in north park which is basically in mission valley just off 805. no more details there for now since this is a public forum! Bad Bent: I cleaned the posts on the distributor cap and rotor and also changed to a different spark plug wire on cyl #3. no change still misses the same and it doesn't happen on the other cylinders just that one. Also I changed the spark plugs around to different cylinders and it still missed on same cylinder. Once I determine for sure what the compression is. I will be able to go further I guess. Another question for the engine rebuilders, is it normal for lifters to slightly push open a valve when the head is rebuilt and lifters are empty when the lobes aren't pushing them down? I ask because the #3 cylinder would blow just a small amount of air out the valves when I was turning the motor outside the car before i put it in. I had asked around about this and i was told "lifters do this just run it and it should work it out". Since I hadn't done a rebuild ever and had a shop do that i dont know how it "should have been". I'm begining to wish I had done it myself and learned more. Anyway, im trying to learn now. I will follow up with more info! Edited by rtp129495, Jul 23 2012, 08:23 AM.
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| snowfish | Jul 23 2012, 08:39 AM Post #7 |
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Basic GearHead
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Absolutely not. The valves have to close all the way. Either the lifter is not/was not bled down, or the new valve is too long. Every head, that I've received from 3Tech, All valves are closed, regardless of cam lobe position. ![]() And he does 100's of G10 heads per season. This one has a 222/365 cam with 5mm over sized valves. Cam is installed. The lifters, or more correctly, lash adjusters, need to pump themselves up to adjust valve lash.
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| snowfish | Jul 23 2012, 08:39 AM Post #8 |
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Basic GearHead
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ooops! double post.
Edited by snowfish, Jul 23 2012, 08:40 AM.
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| clarkdw | Jul 23 2012, 09:24 AM Post #9 |
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Could the lifter be assembled incorrectly? The valves must be closed unless it is on the lobe of the cam. If they filled the plunger with oil before assembling the lifters it could hold the valve open as well. In either case you need to take the cam out and see what is up with the lifter. Not a hard job but a PITA when it is not your fault. @snowfish. You are gonna LOVE that cam. My vert is a new beast with it. |
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| rtp129495 | Jul 23 2012, 09:48 AM Post #10 |
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Advanced Member
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Well, im glad I have some reliable info. So, so far from my experience and what you guys have said. since I have assembled it and driven 8000 miles and now have cylinder #3 missing. If I check the lifter and/or valve if its too long, do I assume becuase of this fact that the valve is burned also and will need to be replaced? it barely passed smog with a new cat when i first had it running, Maybe this is why? yes PITA!!! I was needing this car to save money, and they have grown on me. I want to enjoy this car and save $$$. I like it done right first time. P.S. that head looks nice with those stainless valves!!! |
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| rtp129495 | Aug 6 2012, 09:44 AM Post #11 |
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Advanced Member
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Ok everyone, i finally got an accurate Compression tester, Here are the results: Dry: #1 - 180 #2 - 180 #3 - 155 Wet: 210-215 all the way across!!! For those that wonder these are with WOT and warmed up engine. It would appear that rings are weak? how is this possible with a rebuild? did the rings fail? I am amazed that its showing ring troubles. 8000 miles and rings!!! wow!!! perhaps this im balance makes it miss at idle and not at higher RPM? is there any Workaround to make the cylinder fire at idle? Does anyone have any idea how rings do this at 8000 miles?
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| lwgm | Aug 6 2012, 10:23 AM Post #12 |
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New Member
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you need to do a leak down test. You could check the valves with an air compressor. Put number three cylinder at tdc and hook the compressor up through the spark plug hole at about seventy pounds. Its probably an exhaust valve and you would here air coming out the exhaust. My guess is that the lifters were not rebuilt (cleaned) and a valve is sticking open very slightly. You could pull the cam and clean the lifters to confirm as well. I'm putting a new cam in mine this morning, doesn't take long and the lifters can be done in about an hour. I'm in National city by the way.
Edited by lwgm, Aug 6 2012, 10:28 AM.
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| Norby | Aug 6 2012, 10:41 AM Post #13 |
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I don't know, those wet numbers shoud not come up with a bad exhaust valve. |
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| starscream5000 | Aug 6 2012, 11:14 AM Post #14 |
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Got 70 MPG?
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Did the engine rebuilders even replace the rings when they did the motor? How did you go about breaking in the engine? |
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| rtp129495 | Aug 6 2012, 12:08 PM Post #15 |
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Advanced Member
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Unfortunately, it is not possible to contact the place that rebuilt it as it was a year ago, it took me sometime to get it back together and running again. So I doubt they would remeber. Anyway, if the leakdown test reveals bad lifters, would i also assume that the valves are burned from this lifter issue? if thats what it actually is? Would the compression improve after being driven this way and then fixing the lifters?? |
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The valves have to close all the way.

9:34 AM Jul 11