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post #1 of (permalink) Old 07-18-2004, 09:30 AM Thread Starter
 
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Slow Cranking Engine

I just had a 350 dropped in my truck to replace the old 305. The problem is the 350 cranks REALLY slow, even with no spark plugs installed. This engine sat for a few years in a wrecked vehicle (without being ran) before I bought it. Could this thing be trashed? I hate to give up on the truck, but I'm NOT going through another engine swap. If anybody has any ideas on what to try, or look for, I'd love to get some input.

I put Marvel Mystery Oil in the cylinders before we even started the engine swap, and let it sit. Also, I replaced the starter with a known good one. It doesn't act any better. Thanks for any ideas that you can dish out!

Ron
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post #2 of (permalink) Old 07-18-2004, 06:52 PM
gregmgm
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Re: Slow Cranking Engine

My friend who builds engines tells me that without plugs, you should be able to turn the engine fairly easily with a socket and wrench on the crank pulley bolt. If you can, then something in the starting circuit may be at fault.(I know you changed the starter) How many miles are on the engine? Do you know the history of the engine? My guess is rust on the cylinder walls. Can you drop the oil pan and check inside? There may be rust in the lower section. I think a drill can be used to operate the oil pump, through the distributor hole. You may want to spin the pump for a while before you continue. Watch for oil pressure on the dash gauge while you do that.
post #3 of (permalink) Old 08-04-2004, 07:45 PM
greg_Z71
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Re: Slow Cranking Engine

is the battery charged ?
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post #4 of (permalink) Old 08-04-2004, 07:49 PM Thread Starter
 
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Re: Slow Cranking Engine

Yesterday I finally had a chance to spin the oil pump with a drill. It didn't seem to make any difference in how the engine cranked over. It's still REALLY slow.

If I need to be looking for a problem in my starting circuit, does anybody have any suggestions on where to begin? Any help is appreciated!

Ron
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post #5 of (permalink) Old 08-05-2004, 12:30 AM
gregmgm
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Re: Slow Cranking Engine

At least by doing that, you've got oil splashed around inside- a good thing. Next, I would try pulling all the plugs, then see if the engine can be turned by hand (socket wrench on crank pulley bolt) If it turns hard, then something inside the engine is at fault. Edit- when you crank the engine, does it spin at a constant speed (although slow)? Or is it slowing at a certain point, then speeding up a little? My thinking is maybe one cylinder/rod/bearing is bad or seized.
post #6 of (permalink) Old 08-08-2004, 03:50 PM
lwhbear
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Re: Slow Cranking Engine



If you have a multimeter check for voltage drops in your starting cicuit, if you don't look for corrosion
on the cables and also make sure the bottom of the block where the starter mounts is clean and free of paint and do the same on the starter, it's how the starter grounds so be sure it's clean. ALso check your secondary starting circuit= all the wires to and from the key for the starting circuit
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