1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

what should i look at when trying to buy a motor?

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Old Feb 27, 2010 | 07:56 PM
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ironworker's Avatar
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Default what should i look at when trying to buy a motor?

I found a 93 5.9 that is out of the truck and no way to start it. They said it was rebuilt by road builders 20,000 mi ago.
Here is what i was told about it.
stock injectors
injector pump is turned up
new rod,main,cam bearings

Any help with what should i look at and try and ask about this motor to make sure i don't buy Junk
 
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Old Feb 27, 2010 | 08:33 PM
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tltruckparts's Avatar
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get a hand written note guaranteeing it to run make sure theyll guarantee it. i dont know exactly what to look for i cant imagine looking at an engine and knowing itll run good or not just from strictly looking at it
 
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Old Feb 27, 2010 | 10:10 PM
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They can start them on a pallet if they're tied down. They don't really move around at all unless you're running it at high RPM (or until you shut if off...).


You could do a leak down test. Compression test, leak-down test and blow-by check are the best ways to determine an engine's health.
 
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Old Feb 27, 2010 | 10:23 PM
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also check the people that rebuilt it to see that it was done right when it was done
 
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Old Feb 28, 2010 | 02:19 AM
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ironworker's Avatar
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what is a leak down test? what kinda compression should it be running ? what should you see or not see in a blow-by check?
Sorry i m new to the Diesel and trying to learn
 
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Old Feb 28, 2010 | 08:18 AM
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leak down tests for valves that arent sealing.compression should be 400 ish with no or slight blowby when cold,by slight i mean enough to raise (not blow off)a piece of notebook paper when laid over the oil fill
 
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Old Feb 28, 2010 | 08:55 AM
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ironworker's Avatar
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how would i go about this leak down test?
 
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Old Feb 28, 2010 | 12:57 PM
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gotta pop the injectors out, you might be able to make your own adaptor. old school guys with gassers would pop the ceramic out of a spart plug and weld in an air fitting then screw the home made tool into the head. kind of the same idea. or you could find someone with a test kit, if its any decent type of compression tester it may have the stuff to do a cylinder leak down with it. basically roll the engine around to TDC per cylinder you test, gotta make sure its at TDC or else it'll just push the cylinder down and rotate the engine. listen for air comming from the crank case vent, exhaust housing, or intake. as stated before this'll give you an idea of how well the valves are sealing. if there's any substantial leak from the crank case do a wet cylinder leak down and get a little bit of oil and put in the cylinder, try and get it to the cylinder wall (probably best done with a bent piece of brake line at a 45* and you'll probably have to rotate the engine a bit to get some clearance to work with, cant just throw it in the cylinder, you'll just end up filling the bowl up and cause alot of smoke on start up) but purpose is to judge condition of the rings and the magnitude of the blow by leak. if the oil seals it up and the leak is now undetectable its livable, if it still pushin air out the crank case vent, its safe to say it needs a little more work than they put into it. actual leak down kits have a pressure gauge and then a pressure regulator, set it at X psi if the cylinder doesnt maintain that psi, or it varys with in a few psi that's how they gauge condition (manufacturer should actually have a spec) leak down tests arent usually done unless there are some major variations in the compression test. idk how else to explain it with out cutting details out; sorry about the length
 
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Old Feb 28, 2010 | 01:46 PM
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Originally Posted by Begle1
They can start them on a pallet if they're tied down. They don't really move around at all unless you're running it at high RPM (or until you shut if off...).


You could do a leak down test. Compression test, leak-down test and blow-by check are the best ways to determine an engine's health.
x2

Bring a jug of diesel, a battery or two, some wire and ends. Fire it up.
 
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Old Feb 28, 2010 | 07:43 PM
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ironworker's Avatar
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THANK YOU for the input and help
 
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