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| timing belt - bad compression ? | |
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| Tweet Topic Started: Nov 26 2016, 07:43 PM (980 Views) | |
| cwatkin | Nov 27 2016, 11:04 AM Post #16 |
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As stated, these engines ARE NOT interference. They are also very easy to work on and the timing belt is not hard. I was driving a friend's Metro down the highway at 55 mph when it lost all power and rolled to a stop. The belt had broken. We paid someone who stopped $20 to drive me home where I knew I had a used belt on hand. I drove another car back to the location and installed the replacement belt in an hour. The car started and ran fine but was driven home and parked until I had a new timing set on hand. It is also very easy to be a tooth or so off. You can line of the timing marks and when the belt rotates and the slack evens out, you will be off. The car will run but run POORLY. Again, is the compression low on ALL cylinders or just one? These engines are notorious for burning valves and this will cause one dead cylinder. That being said they seem to somehow run OK if you keep the RPM up even with a dead cylinder. Definitely take this to a competent mechanic or figure it out yourself. All the SOHC engines in these cars are non-interference so the valve isn't bent. Only the DOHC 1.3 is interference. This only came in Swifts from the factory although I know of at least one Metro with one transplanted in. If the valve burned, it is a coincidence and not the fault of the mechanic. Conor |
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| 92 blues | Nov 27 2016, 03:10 PM Post #17 |
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New Member
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hi all, just getting back in the saddle again here... - thanks for your great feedback on this issue ! - according to mech. #2, the 2nd cylinder was down to 40 , and actually looking back at his receipt, #3 is at 140 , while #1 is at 180.... i'll go back to my regular mech. and see what results he gets, etc., - both of them are regarded as quite competent around here... - so the last 3 guys posting seem to agree that it's just a coincidence , that a valve blew, but NOT due to the timing being off.... - my question to this is , is it not likely that things began to get compromised as i have been driving it for about a 1000 miles or so after that, over the past couple months, noticing things like power and mpg gradually deteriorating... - an incorrectly installed timing belt couldn't cause such gradual deterioration ? - i'm just asking that in case y'all might have thought that this all happened recently right after the mechanic's work on this, as opposed to the actual more gradual time frame.... also, many of you are mentioning the likelihood that it is probably a burnt valve that these metros are known for, so that begs the question for a novice like me, is the repair on such an issue as drastic as repairing head gaskets, like a total engine rebuild ? - and i thought you'd like to know , related to this, is last night i noticed something i'm sadly familiar with from my old vw vanagon lemon that it was, is the all too familiar symptom of the overflow coolant reservoir bubbling up what must be those compression gases and stinking up that tank ! - unfortunately i'm all too familiar with that nasty issue... - would this be a likely indicating symptom of what many of you are surmising is a likely burnt valve ? - thanks again for your awesome feedback ! |
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| MR1 Kingsbury | Nov 27 2016, 03:32 PM Post #18 |
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Exp. builder/rebuilder
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Incorrect Timing belt timing will have a compression reduction across the board, and with one cyl. already low due to burnt valve, It will certainly reduce the ability to run or even start in some cases. A head gasket is just as easy as a timing belt, but maybe a bit longer... Should really get some tools for yourself... Paid repairs can quickly bury a poor metro Edited by MR1 Kingsbury, Nov 27 2016, 03:41 PM.
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| freegeo | Nov 27 2016, 03:44 PM Post #19 |
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If you are seeing bubbles in the coolant reservoir, that is a classic sign of a blown head gasket. Has the engine overheated any that you can remember? Does the coolant gauge read hot? |
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| suzukitom | Nov 27 2016, 03:44 PM Post #20 |
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Tom
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If it is a burnt valve in #2 cylinder it is likely the exhaust valve that is no longer providing a good seal. So as the spark plug fires in that cylinder, the hot gases will escape from the edge of the burned valve, eroding it more and more if you keep driving it.. You can also try holding a piece of paper over the exhaust tail pipe while the engine is running. If the paper is sucked inward whenever that #2 cylinder spaek plug fires.. it can verify that an exhaust valve is burned. As for what can cause an exhaust valve to burn.. many things, including overheating the engine.. which can contribute to an exhaust valve burning event and progression . Edited by suzukitom, Nov 27 2016, 03:47 PM.
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| 92 blues | Nov 27 2016, 04:03 PM Post #21 |
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New Member
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thanks for the feedback again guys ! - i was just regretting that i didn't add that key factor about it NOT ever overheating , which seems strange cuz as stated i'm all too familiar with that nightmare from my ol' lemon vw vanagon ! - though as MR1 Kingsbury mentioned, it certainly is getting very rough to start, especially with winter setting in up here in Maine... - but so far it runs nice once warmed up... - and the temp gage always stays right in the middle.... - but now with those bubbles, i won't be surprised to see that all morph into how my ol' van sadly behaved... - i thought i was all done w/ that lemon head gasket crappy design of that vw , seems to be a never ending curse instead.... so i suppose that any re-adjustments on the ol' timing belt is not gonna reverse this problem at this point ? - and if that is to be the case, any thoughts on what's one "in for" w/ a burnt valve on these ol' cars - is it a total rebuild, or is the valve issue not that bad to get into for a competent mechanic ? - thanks again y'all .... |
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| MR1 Kingsbury | Nov 27 2016, 05:15 PM Post #22 |
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Exp. builder/rebuilder
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If your mechanic has a computer (or a good phone) refer him to this site... There are plenty of threads and pics all about a head gasket job. pretty simple work and will save him time and you $$$. Head work at the machine shop should cost from $60-120 to mill, check, and re seat/ replace valves and seals. gasket set, and some fluids and youll be set. bout 4 hours labor done right. Ever Important Checkvalve between head and block. Must make note that it gets cleaned up and put back. |
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| myredvert | Nov 27 2016, 08:45 PM Post #23 |
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myredvert
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Corrected that incorrect correction for you. ![]() First, the fact that the G10 is not an interference design has been well covered. As far as how much incorrect timing belt position affects timing depends on how many teeth it is off and in which direction. Statistically, if your timing belt is installed incorrectly, you have 50/50 odds of your actual compression being lower or higher than indicated during the test. When the compression test is performed correctly, advancing the cam timing by one tooth results in an approximate 8% increase in compression. 2 teeth = roughly 10%. Retarded 1 tooth will reduce compression by roughly 12%, 2 teeth retarded roughly 27%. Worst case, if your timing belt resulted in your cam timing being retarded by two teeh and the throttle was not held wide open during the test as specified, your compression will only be roughly 60% of what it would be had the timing belt been installed correctly and the test performed properly. Which means if a cylinder would have compression at the minimum specified 156 psi with those two mistakes in play simultaneously your compression should still test at roughly 94 psi, give or take for variations in density altitude from standard sea level conditions. If your mechanic has access to a computer, let him sign in under your user name and give him a link to the 1994 Factory Service Manual in the forum library - it has all the correct instructions for checking compression and installing the timing belt. |
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| 92 blues | Nov 27 2016, 09:41 PM Post #24 |
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New Member
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thanks there, MR1 Kingsbury, and myredvert, and all others.... - yet i can't still help wonder whether the timing belt being incorectly installled led to a gradual deterioration, compromising the health of this wonderful engine that was running just fine for years before this timing belt/ water pump "job"....... |
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| cwatkin | Nov 27 2016, 10:03 PM Post #25 |
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If the car was running fine after the work, odds are it wasn't the work that caused the valve to burn. It just happens after a lot of miles, especially if the engine is using some oil. There is no reversing this without having a new valve put in. I would do all of them at the same time as they are all probably about the same age. Replacing the valve is like replacing the head gasket. In fact the head has to come off so a new head gasket will need to be installed. You do not fix the valves. They must be replaced and the head must come off. Conor |
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| 92 blues | Nov 28 2016, 01:16 AM Post #26 |
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thanks there, cwatkin - yup , spose it was bound to happen, since nearing that 300,000 mark, and as you pointed out w/ burning some oil to boot.... - so this begs the question then, as i do recall another inquiring a while back when i was reading some posts, that there is a list of geo mechanic buffs across our great nation that might be able to tackle such an endevour.... i happen to be up here in Maine , so it'd be nice to find out if any reside nearby these parts... - thanks again, all........ |
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| Woodie | Nov 28 2016, 06:32 AM Post #27 |
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If you have 180 psi in one cylinder, then your timing belt is most like installed correctly. Most G10's burn a valve somewhere around the 150K mile mark, if you're nearing 300K, then you've been on majik time for quite a while. |
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| Mrbreeze | Nov 28 2016, 12:26 PM Post #28 |
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Don't fear the G10, it's like working on a motorcycle or a jet-ski/sea-doo, don't let it intimate you, easy peasey, you're just over thinking it.. |
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| 92 blues | Nov 28 2016, 08:23 PM Post #29 |
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New Member
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thanks for the optomistic look on things there , mrbreeze.... - just happens to be a bit rough this time o' year up here in Maine w/ out a garage to "dive" into such unchartered territory .... - thus i was wondering about a list i saw somewhere in this forum where others were talking about a list of various geo mechanics in each state that might be able to tackle such a project as i'm now facing...
Edited by 92 blues, Nov 28 2016, 08:24 PM.
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