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timing belt - bad compression ?
Topic Started: Nov 26 2016, 07:43 PM (981 Views)
92 blues
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hi all - thought i'd join and post this since i couldn't find any help from previous posts i was reading....

my 92 metro has been running consistently great 'til this mechanic admittedly "got over his head" when he didn't realize he had to take off the timing belt in order to replace the leaking water pump... - he seemed competent on any other work he's done, 'til this time when he seemed a bit pale when he told me of all this extra work he had to spend around "dealing" with the timing belt, when initially he quoted me as it being an easy fix, by just taking out the water pump...

so after this , the water pump issues seems solved , but shortly after, the car began running rough, and losing power up hills, then noticeable mpg, now down to under 35, when normally always avg 45/50... - so i went to another mechanic to get a 2nd opinion , and right off the bat he checked the compression and said #2 is way down to 40 ! - and he said that it's probably a "bent valve" and that this could've happened if the other mechanic didn't competently re-install that timing belt back on correctly....

does any one know if its possible to correct this problem by re-installing the belt correctly, or is it all now a total lost cause with a "bent valve" on that 2nd cylinder , and now its all escalated way beyond to an engine rebuild ? - thanks....
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1DCGUY
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Don't be a "Richard"

First off, WELCOME!! :thumb

If you have the 3 cylinder, your motor is a non-interference motor, so no you did not bend a valve.
The belt can be reinstalled to the correct position.
Is this something that you think that you can do yourself??

What part of the country do you reside?? :hmm
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Mrbreeze


Hey 92 blues, timing belt is super easy on these little guys, if your mechanic cannot tackle this task, I would be lirious of his capabilities, although it's also super easy to be a tooth off on the belt also, that's why it's a good idea to rotate the crack two revolutions and double check your work, I'd check the belt timing, that could be the issue.. Welcome to the party..
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92 blues
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hey thanks for the response , 1DCGUY ! - yes, it's a 3 cyl manual... - so, are you saying that because it's the "non-interference" type that things might be ok ? - that's what i was reading on other posts, but very confusing , cuz everyone had a dif. opinion on whether this basic model of metro was a "non" or not ! - even this other mechanic i went to said that it was an "interference" and thus all was a lost cause and had to be a re-build...

- I would like to attempt to re-adjust it myself , if this all wasn't occuring now, here in the brutal oncoming winter of Maine, w/out a garage.... - but i think my regular mechanic would be able to fix it all back up again - i just wanted to make sure it was a do-able thing since this other "expert" i went to for that 2nd opinion stated that it is not , since it is an "interference"....
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92 blues
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hey Mrbreeze, thanks for responding as well... - this is definitely a new kind of dilemma i've never encountered before.... - so it makes sense to you that by having the timing off , one's cylinder compression can start to fail ?
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1DCGUY
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Don't be a "Richard"

92 blues
Nov 26 2016, 08:07 PM
hey thanks for the response , 1DCGUY ! - yes, it's a 3 cyl manual... - so, are you saying that because it's the "non-interference" type that things might be ok ? - that's what i was reading on other posts, but very confusing , cuz everyone had a dif. opinion on whether this basic model of metro was a "non" or not ! - even this other mechanic i went to said that it was an "interference" and thus all was a lost cause and had to be a re-build...

- I would like to attempt to re-adjust it myself , if this all wasn't occuring now, here in the brutal oncoming winter of Maine, w/out a garage.... - but i think my regular mechanic would be able to fix it all back up again - i just wanted to make sure it was a do-able thing since this other "expert" i went to for that 2nd opinion stated that it is not , since it is an "interference"....
Your 3 cylinder is not an interference motor, and if your 2nd opinion mechanic still insists that it is, you need to stop going to him for advice. Take it back to your original mechanic and have him make sure the timing is correct. As breeze stated, it's really easy to get the timing off by a tooth if you are not familiar with doing it. If he is not sure, let us know, and we can walk you thru it on here.
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92 blues
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thanks again, 1DCGUY ! - i certainly will check back with my regular mechanic, and avoid that 2nd one... - just wanted to try to understand this diagnosis w/ the timing being off... - how does it cause all of those symptoms like that compression failing ?
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1DCGUY
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Don't be a "Richard"

92 blues
Nov 26 2016, 08:38 PM
thanks again, 1DCGUY ! - i certainly will check back with my regular mechanic, and avoid that 2nd one... - just wanted to try to understand this diagnosis w/ the timing being off... - how does it cause all of those symptoms like that compression failing ?
If the timing is off, the valves are not opening and closing when they are supposed to, which in turn gives you a wrong compression reading, and the car will not run correctly.
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92 blues
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thanks for that... - i'll be visiting w/ that regular mechanic soon enuf... - maybe he'll be referring me to someone else that can get it done right this time !
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JellyBeanDriver


1DCGUY
Nov 26 2016, 08:41 PM
92 blues
Nov 26 2016, 08:38 PM
thanks again, 1DCGUY ! - i certainly will check back with my regular mechanic, and avoid that 2nd one... - just wanted to try to understand this diagnosis w/ the timing being off... - how does it cause all of those symptoms like that compression failing ?
If the timing is off, the valves are not opening and closing when they are supposed to, which in turn gives you a wrong compression reading, and the car will not run correctly.
I agree having the timing belt off in timing can reduce compression but it should still be even across cylinders.
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92 blues
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hey there , JellyBeanDriver , thanks for chiming in.... - i joined up after reading about so many dif. opinions about all of this, like whether or not this is even a "non-interference" engine or not, etc. ,
- and now , even if it is a "non", like you're hinting at, maybe things are a bit worse than others have opined a bit earlier.... - cuz one of the cylinders is getting that bad reading, as opposed to across the board , evenly , as you suggest...
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suzukitom
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Tom

Perhaps when your water pump was leaking the engine concurrently developed a head gasket leak. Usually 2 cylinders are involved though.. are you confident that mechanic 2 reported the low reading for only #2 cylinder correctly? Might not hurt to do another compression check to be sure.
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freegeo
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92 blues
Nov 26 2016, 08:26 PM
hey Mrbreeze, thanks for responding as well... - this is definitely a new kind of dilemma i've never encountered before.... - so it makes sense to you that by having the timing off , one's cylinder compression can start to fail ?

Sounds like the alignment of the crank and cam gear needs to be verified.


Do you feel comfortable doing a compression test yourself? Maybe you have a friend that is mechanically inclined that can help you?


Like jellybeandriver said the timing being off shouldn't effect only one cylinder.
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Woodie
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One of the major belt manufacturers misidentified our engines as interference long ago, and the misinformation became widely spread, so it's not an indication of incompetence for anyone to get this wrong. They're not interference, so the first mechanic did not bend or break a valve.

That being said, the engine is well known for burning valves, it could be that you've simply got a burned valve and first mechanic is a victim of co-incidence. It's also possible that the valve or headgasket was damaged due to the bad water pump. That usually means a leak and an overheat, which could easily lead to what you have now.
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davegran
Old Fart w/Wrenches

There is also the possibility that this "mechanic" doesn't know how to do a compression check either.... :shake :shit
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