2.5 running on 3 cylinders - S-10 Forum
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2.5 running on 3 cylinders

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Old 03-09-2008, 02:45 PM   #1
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2.5 running on 3 cylinders

i recently bought a 2wd 91 S-10 has the 2.5l in it with 68k original miles for 300$... the truck sat for 3 years and ran fine before that... i was told by that the person i bought it from...but anyways its running on 3 cylinders the #2 cylinder is not firing but its getting spark. i have yet to do a compression check on it but my guess is a burnt valve? im not exactly sure whats wrong with it...ive been told piston rings, piston head, burnt valve, valve guide seal....i dont know i just want to know how to get a postive answer without tearing the whole motor apart to find out im hoping its just in the head and not the piston.... but any suggestions would be great! i am going to check the compression on it later today but like i said any help would be great...thanks

Last edited by Drag2Death91; 03-09-2008 at 02:46 PM.
Old 03-09-2008, 03:05 PM   #2
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Re: 2.5 running on 3 cylinders

When you turned it over the first time, Did you use the starter or did you break it loose by hand???
Old 03-09-2008, 04:55 PM   #3
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Re: 2.5 running on 3 cylinders

you could have broken a piston ring if the pistons were rusted to the cylinder walls.
Old 03-09-2008, 06:41 PM   #4
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Re: 2.5 running on 3 cylinders

what have you done to know it's #2? pulled the plug wires 1 by 1 and that was the one that didn't change anything?

since you already checked for spark, that's ruled out. fuel is also ruled out since there's only 1 injector. that leaves aspiration. pretty much any of the possible problems are resolved by tearing the engine down so at least you know you have to go all the way with it.
Old 03-10-2008, 04:40 AM   #5
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Re: 2.5 running on 3 cylinders

yeah i pulled the plug wire to find out what cylinder was dead.... and no it turned over with the key when it fired up it ran really rought at first but then smoothed out... its weird cause if you start it and let it run for a couple minutes before you drive it it dont run that bad for 3 cylinders but runs even worse if you shut it off for a few minutes and start it again after its warmed up...but i dunno guess i will have to tear it apart and hope for the best... i really didnt wanna do that. i was just hoping to be able to take the head off and fix the problem and be done! but thanks guys... anymore input would be nice too! ill keep this thread updated
Old 03-10-2008, 06:21 AM   #6
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Re: 2.5 running on 3 cylinders

Quote: Originally Posted by Drag2Death91
yeah i pulled the plug wire to find out what cylinder was dead.... and no it turned over with the key when it fired up it ran really rought at first but then smoothed out... its weird cause if you start it and let it run for a couple minutes before you drive it it dont run that bad for 3 cylinders but runs even worse if you shut it off for a few minutes and start it again after its warmed up...but i dunno guess i will have to tear it apart and hope for the best... i really didnt wanna do that. i was just hoping to be able to take the head off and fix the problem and be done! but thanks guys... anymore input would be nice too! ill keep this thread updated
Did you pull the #2 plug? Could be fouled out and not firing, or the plug wire could have a short somewhere - more common in the later overhead cam style motors, but I would try that before pulling the head.
Old 03-10-2008, 10:58 AM   #7
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Re: 2.5 running on 3 cylinders

no i have already put new plugs n wires, rotor button, and distributer cap on it, and changed the oil.... made it run a lil better but still ran like crap! but that #2 plug does keep gettin pretty black and nasty.. lot of carbon build up on it sometimes even has some oil on it! ive checked it a few times... ill probably tear into it a lil this weekend, or later today. i drove it to work and back yesterday and it smoked a lil bit when i shut it off and smelled like some burnt up oil... never smoked before... i was gonna just sell it but i think i might keep it, fix it and make a daily out of it and give my car a break... i mean the truck over all is pretty much perfect no dents anywhere and 2 very minor rust spots above the wheel wells on the bed. the interior is perfect. i did rob a few parts off of it for my bagged dime though lol but yeah if i tear into it today ill post up what i figured out!
Old 03-10-2008, 08:05 PM   #8
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Re: 2.5 running on 3 cylinders

sounds like your piston rings are busted on that cylinder, do a compression check to find out if the rings are busted
Old 03-11-2008, 11:13 AM   #9
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Re: 2.5 running on 3 cylinders

here she is with the 20's off my bagged dime on it
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Old 03-11-2008, 01:12 PM   #10
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Re: 2.5 running on 3 cylinders

You got THAT for $300?! Man you suck, that is a sharp S-10
Old 03-11-2008, 05:56 PM   #11
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Re: 2.5 running on 3 cylinders

lol well it didnt have the 20's on it... it looks like shit when i bought it, ive done a few things to make it look better... buffing and waxing was the first step lol

Last edited by Drag2Death91; 03-11-2008 at 05:59 PM.
Old 03-17-2008, 04:38 PM   #12
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Re: 2.5 running on 3 cylinders

ok so what i think is gonna go down is im tearin the 2.5 out and puttin a 350 in it! i just dont feel like messin with the 4 banger! just an idea but i think i might go through with it!
Old 03-17-2008, 08:46 PM   #13
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Re: 2.5 running on 3 cylinders

the 2.5 gets ALOT better mpg. Im getting close to 30 in mine.
Old 03-18-2008, 04:47 AM   #14
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Re: 2.5 running on 3 cylinders

well my bagd truck has a 2.5 in it so its cool ill get 30mpg with it and 20 somethin with my car the v8 truck can just be a toy
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