I just took possesion of a 94 F250 7.3 turbo diesel (not powerstroke) with 5speed. The truck is hard to crank when cold but figure that is the glowplug timer/relay or the glow plugs. After I get the truck running it runs fairly good but after about 5-10 minutes when the temp gets to operating range it starts knocking. Not sure if its a diesel knock/injector or a lifter or a rod. My friend says it sounds like a lifter cause it sounds like its from the top end of the motor. I have been reading that a injector will make one sound like a rod is knocking. If it were a rod wouldn't it knock all the time?? Any input would be helpful.
Thanks,
Brian

94 F250 4x4 7.3 diezel

 

sound like you have a bad injector had the same thing happen to me i thought i had some major internal damage but it turned out to be an injector. If you wonna check the injectors take a 1 inch wrench and creack each injector open( 1 at a time) and if the engine starts to run real ruff that injector is fine but if the engine stays the same you may have found the problem. hope this gives you a starting point.

 

Yeah I've heard of this technique. I wonder if a mechanic stethescope would work to find the knocking cylinder?
I just got the truck today so I will be testing it in the next couple days. You think a rod would knock all of the time?

Brian

 

Also would a bad injector make the motor miss?

Brian

 

"""If you wonna check the injectors take a 1 inch wrench and creack each injector open( 1 at a time) and if the engine starts to run real ruff that injector is fine but if the engine stays the same you may have found the problem. hope this gives you a starting point."""

I don't think so.!!!!!!!!.........use a 5/8" wrench on the injection line nut at the top of the injectors. Unscrew the line nut one at a time about 1/2 turn or until the engine misses. If the knock goes away then that injector may be the culprit. Retighten the line nut to .........Torque on line nuts is 22ftlbs..

You could change the location of the suspect injector and see if the knock follows it, but you will need new copper seals(s) on injectors removed/installed.

 

sorry plc7.3 your are correct i have no clue why i said injector what i ment to say was the line thanks for the correction.

 

I cranked it up and let it run for around 35 minutes and thats when the knock starts. The last 5 minutes was run at 1500rpm. I took a mechanic stethescope to the oil pan and could not here the knock there. Sounds like top end, lifter or injector. It sounds like its coming from the 2nd or 3rd injector area. I cracked open 2nd injector line and it did not stop. I am going to try the other lines when I get a crowfoot wrench. Those lines and the glowplugs look like a dog to get out especially the glowplugs with the turbo and relay in the way.

Brian