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No start; 1992 Metro 3cyl/5spd
Topic Started: May 7 2011, 03:33 PM (816 Views)
Audacity
Sir TooManyHobbies
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What could possibly cause a 3cylinder to attempt to turn over but never get above 500 rpms or so?
I'm baffled and need this little booger to be at LEAST running in two weeks to get it rebuilt.

What should I check first?


Also, could this vacuum line have something to do with it? I reattached the hose but it didn't affect the starting issue.
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91 ragtop
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Check your compression. It sounds like you may be down to one cyl.

Ken.....
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Audacity
Sir TooManyHobbies
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That's what I'm worried about.
Pulled the plugs.
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GeoRating
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First plug looks a tiny bit scorched via oil, and as is common the third cylinder plug is burning oil from something. Middle plug looks like it's getting superheated, but that could be something else. Did you get that compression check done? I'm pretty sure your third cylinder is at least going to be a bit lower :(
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Audacity
Sir TooManyHobbies
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Compression check done. Though forgot to do WOT, I don't think it matters much given my readings...
0-60-50
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Car Nut
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Holy Cow, It's toast. Pretty weird to pull a zero tho. Usually it'll show something.
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mcmancuso
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Ouch man, thats pretty bad. Be sure its getting gas and spark, look into the TB while someone's cranking it for fuel spray, and pull all 3 plugs and hold them against the engine block while cranking to be sure you're getting blue sparks in each. If those 2 factors check out then its just bad compression :(
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GeoRating
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Yeah retest at WOT, those results should not even allow the engine to turn over, much less idle even up to 500 rpm...

Another thing since those numbers are very low across the board, put a battery charger on it in engine start mode when you do it, the battery may not be giving up enough power for the engine to do an appropriate compression check.

Pulling a zero on cylinder 1 is almost saying that the cylinder is not even turning on the shaft, but with numbers that low, a compression of 50-60 could be slipping through a horribly bad ring or a burnt valve.

Sorry to say it, very bad sign there though :( Let's hope we can raise those numbers by doing it with WOT, making sure the battery is giving the appropriate charge, and give us a wet test as well (Puit 1 teaspoon of oil in each cylinder and test with it in there, the oil can seal bad rings, but will not seal a burnt valve).

If you can manage it, do a MMO soak (put a 1/3-1/2 cup of Marvel Mystery Oil in each spark plug hole and let it sit over night, there may be some carbon really gunking up your rings and it may help you at least get a better compression test, but it's not going to do miracles and give you numbers over 150.

I am not putting forth anything about the spark of checking of your fuel spray because those things shouldn't be effecting your compression numbers, if the numbers were better, then I'd recommend checking those (with a full engine rebuild you'll be cleaning all these things anyway :P)
Edited by GeoRating, May 7 2011, 11:46 PM.
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Johnny Mullet
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Fear the Mullet

This would cause 0 compression.............

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GeoRating
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Wow I didn't realize such wear on the valves would cause ZERO :) Leave it to Johnny yo be the expert :D :thumb
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Audacity
Sir TooManyHobbies
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Thank you sir!
I'm betting thats what we find this weekend when we tear into it!

I'll definitely update the Project thread when it gets done.
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Memphis metro


Pay close attention to your lifters if you disassemble them and be sure to put them back the way you took them apart.
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