Stumped on a 6.4 no start, any help greatly appreciated!
- Thread starter Matt_P
- Start date
sideactiondiesel
Member
So obviously no sync correct?
Yeah it's still going in and out of sync when it attempts to fire as well as throwing those codes. Just in sync consistently during cranking.
What is the second goofy drop on the crank? Thecrankdrop should look like the first one, kinda z ish. I think the cam signal is the blip right befor the first crank drop. Does the crank do the second drop everytime?
When I watched the video again that's when it's chugging and attempting to start. That does look really odd though. Your right though that blip does look like the cam signal. I was able to get the video to upload as well so you can hear what it's doing as well when that crank signal drops like that. Hopefully that helps and I can get some more videos if need be! https://vimeo.com/170615220
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webb06
Active member
Did this truck drive into the shop before the rebuild?
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Yeah it did
I think that secondary crank drop is your issue. If you watch it is there the entire time. The frequency gets tighter together when it almost starts, but the second drop is yhere the whole time it looks like. I would be checking the tone wheel on the crank personally. Pull the sensor, and see if you can wiggle it with a screw driver or a pick. Also try bumping it, and make sure it aint bent or something.
Yeah your right it does have that drop and it does stay there the whole time. That has to be the issue because I can't find anything else wrong with it. I did have the crank sensor out and put my boroscope in there and watched the tone wheel while turning the engine over and the wheel didn't appear bent at all. I'll double check again though and get a pick in there as well. I also double checked again to make sure end play was in spec and I swapped another good engine wiring harness I had on the engine As well. I'll double check the tone wheel again and report back in the morning
78f100
Active member
I had a 6.0 drive me nuts for a while, the tone ring broke free from the crank. Occasionally it would start and run like a raped ape, most times no start. I finally pulled the crank sensor put the bore scope in and had someone spin it over, when they stopped cranking on it the ring kept spinning for a sec. At first glance it looked normal, as it would bind up and move with the crankshaft. I could rock it back and forth with a screwdriver.
I'm sure that had to be a big pain in the ass! I just pulled the crank sensor back out and put a screw driver and pried on the tone ring while watching with the borescope and it didn't really have any rocking besides a little flex in it. The flex was about the same as when I compared it to prying on one of the cranks I have laying around though. I did take a video too I'll post up though. This thing is driving me beyond nuts now. I'll see if I can get the video to load, it's not wanting to cooperate right now
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im getting my ass kicked no too after helping you. LOL Just put a crank in a fire truck for a groove in the snout causing an oil leak. Didnt pay attention cause i was in a hurry and it needed to be running today, and this was friday, but dropped the crank in buttoned it all up, idles fine. As soo. As ylu accelerate throws wrench light and goes into reduced power mode, has code for oil overful. After chasing my ass for a few hours, come to find it appears the tone wheel is bent. My oscilloscope readings have a major ckp voltage fluctuation. I would say based off your reading vs what i am seeing, that there may be an kssue witha tooth on your wheel.
Haha yeah this is kicking everyones ass! I scoped it again today to see if I could see any damaged teeth and I couldnt see any. I did hook a battery up and jumped the starter while I had the cab back up and cranked the engine over while scoping the cam and crank sensor holes as well and everything was moving the way it should. I guess the only way Ill know for sure if the teeth are good is to pull the pan and look at it with my own eyes.
Well I am just about completely out of ideas, I dont know what else there is to check. I even rechecked the tone ring again today with a mirror and every tooth looks fine. cleaned every ground and connection again, swapped the wiring harnesses and still the exact same thing. This thing has me at a loss.
webb06
Active member
I keep coming back to this thread hoping for a resolution to this problem...sadly let down. I keep racking my brain each time I go back and reread it all
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I hate to tell ya this, but the motor may have to come back out and torn down to figur it out. At least the oil pans off so you can get a better view of the tone ring overall than a half inch hole to look thru. ot my 6.4 out and oil pans off today, and sure as **** wheel is bent a ton...
Luke@MillerPerformance
Member
Have you scoped the crank sensor without the connector hooked up? It should generate an AC wave even without power from the pcm.
I know the feeling every time go through something I hope that I turn the key and it will fire up. I've never had a truck stump me like this!
I just honestly don't see what would be wrong in the engine assembly that I'd need to tear it down and go back through it though . The rotating assembly all went together as it should. Everything was in spec. Pistons sized to the bore by the machine shop. Crank and cam specd and polished, brand new heads. I know it's not the best view through that hole but I've had a boroscope in there a mirror with a clear view to the tone ring with the cab off, turned over by hand and with the starter with the cab off. All the teeth looked perfect, the wheel had no play or kept moving after the engine was turned over. Not that I don't have a problem pulling the pan. I just know that when I assembled the engine that tone ring was solid and I would have though my machinist would have caught something when the crank was on the lathe. Unfortunately this truck hAs just cost me more money now in extra labor that it's destroyed my profit on this job. But I don't have an issue pulling the pan again either cause I'll eliminate anything possible at this point
I haven't done that yet but I will tomorrow
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