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Compression Test Error

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Likewise... I would think that to make the measurements "measurable", they had to apply some finite, expected limits to rpm varation. I think the message is simply urging us to ensure our correct test conditions are met.

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I told the tech to graph out cranking RPM (it's a no start) and he sheepishly replied it was between 95 and 125.

 

Problem solved.

 

Thanks guys.

 

 

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  • 1 month later...

I got one of these with the exact same screen. I thought for sure the starter was fried. I checked both batteries and they are 100%. I replaced the starter with a "Motorcraft". Same V-e-r-y slow crank speed. Funny thing is if I crank it long enough it will run like crap at the speed the starter spins, but will not run above that and stops as soon as disengaging the starter. While it is running everything in the diag sheet you moniter is good, it should run.

 

Yesterday I crawled under it and tried to turn it over by hand with my double box snap on wrench. I can't turn it!!!! This is the sam wrench I use to turn over others that run when I am removing torque conv nuts.

Now thru the grapevine I found out this thing was driven "normally" to its delivery stop and was shut off. When restarted it started and something in the eng compartment cracked. "That is when the slow crank started and it wouldn't run. "They" unhooked the batteries to clean the terminals. Thus why I had no codes, thanks. Right now I am thinking jumped timing???? Something broke in engine??? It is not hydralocked.

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I have had a few engines crank and not start like that after performing repairs and then clear up after finally getting them to start but this is a different situation. Did you remove the FEAD belt and try turning it over? Over the years I have run across 10 or 12 trucks where the A/C compressor had seized causing a slow crank condition preventing the engine from starting - Both 6.0L and 4.5L engines.

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