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post #1 of (permalink) Old 02-09-2002, 07:04 PM Thread Starter
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what\'s wrong with my engine?

Hey guys, I usually post on the Toyota side, but I've got a problem with my 92 GMC 1500 w/350 and five speed. It's got 160,000 on it and I don't know what happened to it. I go through a couple quarts of oil between changes and I am planning on putting a crate motor with vortec heads on it this summer. A couple days ago it developed a vibration in it. It occurs between 1500 and 2500 rpms mostly. It is not speed sensative, but does vibrate more under load than free revving. My idle is fine and it fires up with no problem. I haven't noticed any leakage anywhere. I can feel the vibration in the steering wheel and shift lever as well as the body. It seems sluggish upon acceleration as well. Anyone have any clues? I am planning a 600 mile round trip in it in the next two weeks so I am concerned. I don't have all the funds for the motor swap yet either. While we are on the swap subject, whose motors are best for the buck? Should I get a GM crate or a slightly built rebuild?

Thanks for your help guys (and gals!). I appreciate it!



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post #2 of (permalink) Old 02-09-2002, 08:13 PM
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Re: what\'s wrong with my engine?

Are you sure this is an engine problem, it sounds like it could be a driveline vibration.

For rebuilds, try finding a 350 with a 4 bolt main. Vortech heads are a good choice. You might be able to rebuild yours, but you'll have to find out what condition the block is in, and go from there.


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post #3 of (permalink) Old 02-09-2002, 09:04 PM Thread Starter
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Re: what\'s wrong with my engine?

AJM,

I'm just guessing that it's engine related because it is rpm specific, not speed specific. It also does it when in neutral whether moving or sitting still. When it is in neutral it is not nearly as noticeable, but it is there. And as I said earlier, it seems like the engine is lacking power, almost bogging down under load, especially up steep grades. I just checked it out again in the garage, no noticeable leaks, smoke or other signs. I'm stumped.

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post #4 of (permalink) Old 02-10-2002, 02:10 PM
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Re: what\'s wrong with my engine?

That is kinda strange. Is the vibe bad, or could it have been there all along and you just noticed it. Howz the clutch and pressure plate doin? Any chance a piece of it broke off and is throwing your balance off? How 'bout mud stuck in the main pulley, or something else in the belt system broke/bent. I can't think of anything internal that could throw a balance without serious side effects.

How about a miss fire? Any chance of a bad wire/plug. How about a burnt valve? Those things feel kinda like a vibe and obviously a power loss.

I'd go re-build, but if you got buckz to burn go for the new one. But best for the buck is a re-build, but I say that because machine work is so cheap around here (SD,CA). Some guys post that they have to pay outragous shop prices.

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post #5 of (permalink) Old 02-10-2002, 03:07 PM
 
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Re: what\'s wrong with my engine?

Yeah, I can have a block decked, bored, align bored, drilled for splayed 4 bolt mains, and all the other block prep stuff for 350 bucks here[img]/wwwthreads_images/icons/cool.gif[/img].

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post #6 of (permalink) Old 02-12-2002, 02:28 PM Thread Starter
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Re: what\'s wrong with my engine?

Chevota,

I can't find anything out of the ordinary on the exterior, belts are good, everything looks clean. It didn't have this vibration last week, it appeared in one day. I'm going to check the plugs and wires today if I get a chance. It is stumping me because the vibration is almost non-existant below 1500 and above 3500 rpm. Below 1500 it is definitely bogging down though. Any one else have suggestions?

Thanks

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post #7 of (permalink) Old 02-12-2002, 03:08 PM
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Re: what\'s wrong with my engine?

where i'm from (not where i'm at, there is no machine shop within two hours where i'm at) it cost pretty much $80 to do anything (rework heads, grind crank, line bore, cylinder bore, decking, et cetera). if they do a lot of stuff they cut you a good deal. i think it's $40 to dip the block though. the best part is that they're more meticulous than i am, and i'm pretty anal about things.

now if i could only find a damn SBC 400 for a reasonable price..

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post #8 of (permalink) Old 02-12-2002, 03:13 PM
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Re: what\'s wrong with my engine?

sounds like it might be an ignition problem.. i'd have a look-see at the plugs.

my 305 is about to die, it burns a couple quarts every 500 miles on the expressway. the rings appear to be stuck in cylinders 1 and 2, you can smell earl in the exhaust and the spark plugs show that earl has been getting to them. it's kind of funny because the truck still holds 44 pounds of pressure at idle.

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post #9 of (permalink) Old 02-13-2002, 10:52 AM
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Re: what\'s wrong with my engine?

Agree with the other poster. Plugs and wires first, probably needs them anyways. I found that in my 96vortec, it ran MUCH smoother after I ran a can of BG44K fuel cleaner in a 1/3 of a tank. I plan on doing another can and then changing out the fuel filter.

post #10 of (permalink) Old 02-13-2002, 10:57 AM
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Re: what\'s wrong with my engine?

The bogging down could be a cause of a plugged fuel filter and/or bad O2 sensor. The vibration could be a bad motor mount or two. I know that one would think the problems you are seeing are one and the same, but consider that they are two different problems. I know about KISS but sometimes I can troubleshoot for hours and replace multiple parts and then relize it was two different problems.

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