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| Compression Test Results; Worse shape than I thought? | |
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| Tweet Topic Started: Sep 16 2017, 01:32 PM (987 Views) | |
| ESVAGeo | Sep 16 2017, 01:32 PM Post #1 |
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Mechanic Wannabe
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So I finally got around to doing the compression test on my 90 XFI w/250,568 miles this morning after work. Test was done with a cheapo $20 eBay china tester that comes in the red plastic case. #1- 167 #2- 171 #3- 171 That was on the first measurement w/warmed up engine and WOT. I noticed while cranking the engine for the measurements(my wife was cranking while i watched and held the tester) on cylinders #2 & 3 that there was this loud chirping noise and little puffs of smoke coming from the spark plug holes apparently around the tester plug so I took that to mean maybe it was air squeeking by cuz I didnt have it screwed down tight enough? I did it just hand tight like the guides say but I figured id retest anyway. As i went to retest cyl#1 again making extra sure i had it as tight as i could get it by hand this time the tester needle would not hold its position when she let go of the key?! And I could feel a little air blowing out of the release vavle WITHOUT me pressing the button during the test. And the reading were all lower on all 3cyl on that test sequence from what I could see before she stopped cranking(didnt wanna kill the battery or tesr up anything cranking too long) than they were on the first test. So I think my cheapo tester broke on me after measuring 3 cylinders with it a grand total of once! Damn you China! LOL So I figured well I think my tester is busted/inaccurate but hell Im already here might as well try the wet test and see what happens... #1-200 #2-193 #3- 205 They all went up considerably. So this means that the piston rings are likely worn out and need replacing, correct? I have no way to know how accurate my readings are given how the tester is acting but even if the tester isnt totally true the fact that the numbers jumped up after adding oil means bad rings regardless of complete accuracy right? BTW the guage did hold its pressure intermittently while doing the wet test like the seal had righted itself inside there temporarily then on the next cyl went back to not holding. Are you supposed to wait until you take the tester all the way out of the plug hole before pressing the pressure release? I think I actually may have broken the tester myself now that I think about it because on the last cyl of doin the dry test i accidentally grabbed the guage wrong while unscrewing it and released some of the pressure while it was still attached to the engine. Did backpreasure on the seal tear it up? There were no instructions of any kind with the tester kit...anyway would like to know so I dont tear up the next one too. Besides the comp test situation the car has a miss you can hear when its running(caused by worn rings?) and the exhaust including the manifold itself has several holes and will need replacing to pass inspection. Can feel just a hint of exhaust leaking out around the ex manifold gasket which looks like it is the original. The cat pipe is newish but leaks around the also badly rusted/falling apart gasket so they must have reused the old man-cat pipe gasket. The radiator has a big hole in it bt the car doesnt overheat or leak coolant? On top of all that the engine is half covered in oil which also makes me nervous that she has more bad problems... So, what you guys think? I was thinking the car was a screaming good deal for what I gave for it but now it is turning into a big pain in the ass. I did plan on rebuilding her eventually but was really hoping to get a year or two of cheap transportation out of it first as my truck is killing me on gas. Seems like my first set of measurements should be fairly accurate as they were taken before the guage starting tripping/I broke it. Should I just clean everything up under the hood the best I can with degreaser/rag, change the oil/plugs, replace the exhaust and ride or just keep it parked til I can get all my parts together and do Rings/bearings/repl head job plus all the other stuff like radiator water pump timing belt etc etc? Guess basically can I do the minimum and drive it like it is with my dry numbers or keep her in the shed til (semi)rebuild? Main reason I got this car(my 1st Met) was just to quickly pick up a cheap good milage beater that I could immediately put on the road as we only have the 1 truck and 2 drivers in the house and now look...into a whole can of worms. Dude must have had an inspection sticker hookup cuz no way could I get one as she is now but the old one just ran out few months before I got it so I figured it was ok n didnt look at it too close. Didnt give much for it atleast. Well thats about all the questions/concerns/cryin ass bitchin out of me for now lol Thanks for reading and any comments guys/girls. PS- supposed to be making a call on this other Metro-a 94 base w/135k Tuesday but now without being able to do a comp test on it first because of waiting on replacement tester I'm unsure if I should fork over the cash without the test. Even tho that ones engine/eng comp is way cleaner and cant hear any missing or knocking.... ![]() Edited by ESVAGeo, Sep 16 2017, 01:36 PM.
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| ESVAGeo | Sep 16 2017, 01:40 PM Post #2 |
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Mechanic Wannabe
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| 1DCGUY | Sep 16 2017, 04:28 PM Post #3 |
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Don't be a "Richard"
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You may want to find a quality gauge and try the test again. I don't think your first numbers are all that bad if the test was done correctly. Let's verify: Car up to temp? All plugs out? Throttle wide open? Fuel injector fuse pulled? Turn the engine over until the needle stops moving? If you followed all of those, then the numbers are correct, and not that bad. If you plan to keep it and drive it, give it the normal tune up stuff like plugs, cap, rotor, plug wires. |
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| freegeo | Sep 16 2017, 05:27 PM Post #4 |
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Don't forget to disable the spark too. Best place is at the coil. Since you have help with cranking it over, Watch the gauge as the engine is cranked over. There is a evaluation portion of the test that can help give you a idea what condition your engine is in.
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| ESVAGeo | Sep 17 2017, 12:59 PM Post #5 |
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Mechanic Wannabe
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1DCGUY & freegeo- Yes to both. I did everything 1DC decribed as well as pulled the center wire off of the distributor to disable spark. I have emailed the Chinese seller through eBay to see if they will give me a refund/send replacement tester but I suppose I cant be too mad if they wont(no response yet but its the weekend) since I may have blown the seal myself by hitting the button while still attached to the engine. Found a Ford Escort ZX2 for sale nearby that I'm gonna check out tomorrow but if its not stick shift(We both hate automatics in my house) and a relatively good deal(owned by mechanic) I'll likely just buy the 94 Metro base off other dude Tuesday for $450. This is the one that needs the underbody brace/frame horns welded from my underbody brace thread. Possible exhaust leak too but overall that one actually needs less work to pass inspection/be legal than my 90 does. 90 also needs interior stuff done to pass like reinstalling cowl push button headlight switch, new steering wheel w/working horn pad(apparently the horn switch being in the dash is a nono in VA-must have factory setup working)etc. The 94s interior is perfect just needs brace, welded frame horns and possible exhaust leak fix to get on the road...hopefully. I guess with cars this old I should not expect to just buy it and put it on the road immediately without fixing stuff huh? Still, if I buy the 94 i will have under $1000 into purchasing 3 different Metros. 2 hatches and a vert so I guess I'm doing ok. Vert doesnt run tho. Guess Ill try doing a full tune up on the 90 and go from there AFTER I get the interior back straight and replace the entire exhaust system and the rusted out rear control arms I just discovered. I did look over the 94 all underneath and no rust except for the frame horns and under the drivers door on the body. Good clean engine compartment no knocks so i think engine wise that one is way better shape since it only has 136k or so compared to 250k. Guess what im sayin is even tho they will cost me some money and time in replacement parts the insane gas mileage and weird charm of these cars is worth it. 4 months ago I had never heard of a Geo Metro... Hope everyone is enjoying their NFL Sunday. Go Cowboys!! |
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| Metromightymouse | Sep 17 2017, 01:41 PM Post #6 |
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Powdercoat Wizard
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You can not damage a compression gauge by pushing the release button while it is still threaded into the engine. That valve is the same type of valve on a tire, it just opens and releases pressure, it doesn't care what is behind it. You might check that the valve is fully screwed into the body, if it's partially unscrewed it could be releasing pressure. You could also remove the valve and check the tiny oring for damage. |
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| ESVAGeo | Sep 17 2017, 01:44 PM Post #7 |
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Mechanic Wannabe
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Oh, and in all cases before and after the tester messed up I did notice that every time there was a big jump on the first compression stroke when turning the engine over. Like it would jump up to say 75-100psi on the first stroke then like 25-35psi each stroke after....thats good I think? |
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| ESVAGeo | Sep 17 2017, 03:29 PM Post #8 |
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Mechanic Wannabe
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Is it possible for a compression test procedure to blow other seals and cause an oil leak? I never noticed this car leaking any oil at all til I did the test and now there is oil on my concrete garage floor under the oil filter after doing the test.... |
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| Metromightymouse | Sep 17 2017, 08:56 PM Post #9 |
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Powdercoat Wizard
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No |
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| ESVAGeo | Sep 17 2017, 09:02 PM Post #10 |
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Mechanic Wannabe
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Everything appears to be tight on the tester, how do I go about checking out the O ring? The 2 Philips screws on the back of the guage? |
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| freegeo | Sep 17 2017, 09:47 PM Post #11 |
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There is a oring on the threaded end of the hose that screws into spark plug hole. Make sure it is good shape. |
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| Metromightymouse | Sep 17 2017, 09:56 PM Post #12 |
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Powdercoat Wizard
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Usually the little valve you press to release the pressure is the same type as in a tire valve. The center portion can come loose and cause it to loose pressure. There is also a tiny oring on it that seals it in its housing. You use a pair of very small needle nose pliers or a tire valve tool to remove and replace it. |
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| Dystopiate666 | Sep 18 2017, 06:58 PM Post #13 |
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Tree Banger
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"The sting of poor quality will outlast the joy of low prices..." A wise man once told me this. Get a good compression gauge. What was your initial problem that you felt the need to do a compression test? MPGs ok? Engine noise? Low power? Does it consume oil? Does it Smoke? With those compression numbers I wouldn't expect much in the way of driveability issues. As far as your oil covering the top of the engine....is there any oil on the underside of your air filter? If so it is a sign that oil is blowing through your PCV valve and can present as what appears to be an oil leak from the top of the engine....however I have only seen this on SERIOUS oil burners. Other common oil leaks are the distributor o-ring (gathers in a pool on top of the trans) and the cam and crank seals (presents at the bottom of timing cover and the flat tabs of the block that protrude from just below the head where the timing cover meets the block). I have had oil leaks also from a poorly seated filter, and from the oil pressure sensor just below the filter. A fairly tricky one to find was also the dipstick tube entry point into block. Your radiator.... the hole that you see is only missing fins. the coolant travels through the vertical parts from top to bottom. It is probably not helping your cooling system any as you have lost a fair amount of surface area to dissipate heat from, but as long as the needle is where it is supposed to be on the gauge, I wouldn't mess with it. |
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| ESVAGeo | Sep 19 2017, 07:57 AM Post #14 |
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Mechanic Wannabe
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Metromightymouse- Awesome. Good to know. Sorry for all the dumb questions, I'm sure Google could have told me that one but it's nice to hear it from someone on GMF who I believe. Dystopiate666- Well actually curiosity and everything I've learned on here is why I did the test. Everyone says compression test/leakdown test is the best(only?) way to find out the overall health of your engine, right? And since the car has 250k on it I figured it was definitely worth the cost of the tester to know. I'm a little bit OCD so I tend to jump way into something when I decide I like it lol. I have not driven the car much as it failed inspection cuz of the exhaust and non factory headlight/horn switches. Have only driven it around the block near my house a handful of times and to the inspection garage(30mi round trip) and back. Has not burned any oil noticable oil or even much gas since I got it, like the guage has not moved! Amazing. I don't really know as of now if it burns much or any oil since I haven't really driven it enough. Do know that it leaks a little oil around the oil filter or at least that's where I think it's coming from(could be dripping down from top of engine?). Hoping maybe that's cuz the filter isn't tightened down all the way like you said. Doesn't smoke at least not that I can tell and has no problems in the power department. Actually surprised and impressed me how quick she is. From what I remember from Saturdays test session yes there WAS oil on the underside of the air filter housing. I think the next step will be taking a can of engine degreaser and couple rolls of the blue shop towels from Walmart and clean up the entire engine and engine compartment as best I can then do the tune up/exhaust. Will be posting pics and threads as I go. Thanks for the heads up on the radiator too, I was hoping that was the case to just leave it alone for now long as she doesn't overheat anything, cool. I'll definitely be replacing the radiator eventually tho if for no other reason than to help make everything look all pretty under the hood again. Thinking aluminum one off eBay..Good news-the seller has agreed to send me a replacement tester so that's cool. They may even just tell me to toss the old one and if so I'll definitely try taking it apart and fixing it then boom....2 cheapo testers . Definitely do plan to get a better quality one before any rebuilds though. And a leakdown.Thanks for all the info everyone
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| cwatkin | Sep 20 2017, 09:56 PM Post #15 |
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Those numbers are not that bad. They are above factory minimum spec. Remember that compression testers are loaner tools at any parts store that does the loaner program. Remember that you can buy the tool and simply return it for a full refund with no penalty when you do the loaner tool program. Go to several different parts stores and do their loaner tool program. Or return one loaner tool at one parts store and ask for a different unit if they have multiples available. I understand these are subject to being damaged by rough handling and usually bias in the low direction. Conor |
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Thanks for the heads up on the radiator too, I was hoping that was the case to just leave it alone for now long as she doesn't overheat anything, cool. I'll definitely be replacing the radiator eventually tho if for no other reason than to help make everything look all pretty under the hood again. Thinking aluminum one off eBay..
. Definitely do plan to get a better quality one before any rebuilds though. And a leakdown.

3:49 AM Jul 11