is there anything , other than a harmonic balancer that is shot and about to come apart, that would cause a timing mark to jump around and not be able to get an accurate timing reading off it?
Thanks-----Robert
Thanks-----Robert
Follow the bouncing timing mark?
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icanfixall
Official GMM hand model
I think you may have a bad connection somewhere. Also make sure the magnetic pickup on the crank dampner is just about 1/32 from touching. I found that if my setup is placed far away from the pulley I get a bad signal. Hope this helps..
I'm not using the magnetic pickup bit ( I got rid of my snap on timing meter
, I have a Ferret, so I don't have to worry about all those silly things anymoreWhat's happening though is I'm getting a steady flash at the timing light, but the line on the balancer is not holding in a given spot when the strobe catches it like it normally does, instead the mark is dancing all over the place within about a 3- 4" range , which leads me to think that the balancer is coming apart. That;s the only thing I know of that will cause that to happen. I was just wondering if there was anything else that could cause that .
IIRC a dying injector pump can cause a similar problem. What happens is, as the pump's worn out, it can send pulses to the injectors unevenly, so that it isn't always firing at exactly the same time relative to TDC.
How old's your pump? If the pump's old, or if it's a fresh rebuild (that may be bad), I would tend to suspect the pump before the harmonic balancer. In fact, I don't recall ever having heard of a harmonic balancer failing on one of these engines before...
How old's your pump? If the pump's old, or if it's a fresh rebuild (that may be bad), I would tend to suspect the pump before the harmonic balancer. In fact, I don't recall ever having heard of a harmonic balancer failing on one of these engines before...
That was the other thing I was afraid of, but was REALLY hoping it wasn't. He'd just put a fresh rebuilt pump on the thing,by guess who..... good ol Pensacola diesel.
I'm kind of thinking that may not be it though, because before the pump switch we checked the timing and found that the gear was way off ( due to a PO screw up ) but I seem to recall it bouncing some at that check as well,and that was on an old pump, but then again it could be a case of two hammered pumps.
icanfixall
Official GMM hand model
Oh yes.... When the balancer fails the crank is not far behind it. There was a posting back a few months about a dampner failing and wrecking the injection pump. It broke the shaft. Then the motor let out a screaming sound later on. That proved to be a broken crank. Pics were awsume too... So maybe its the injection pump sending differant fuel signals to the motor. You will want that fixed fast too. Otherwise walking might be in store for you...
77f250diesel
Full Access Member
I've got the same thing happening with mine except mine only bounces every 4-5 seconds. The mark moves clockwise [retarding ?], other than that it runs great.
I was thinking dirty injector being it would change the pulse ?
Dennis
on edit I guess it would be smart if I put the sensor on another line, # 4 I believe ?
I was thinking dirty injector being it would change the pulse ?
Dennis
on edit I guess it would be smart if I put the sensor on another line, # 4 I believe ?
Last edited:
Yes, #4. We did that . Got a stronger signal on #4 indicating a possible fault in the injection system ralated to #1 but the fluctuation was consistant throughout.
punkmechanic
diesel tech
Mine jumps around like crazy and gets worse with higher rpms (as those at towcat's meet can attest to). I know its the pump. I would bet that anyone else having this symptom is likely the pump as well.
punk
punk
David94IDIT
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I have a Farret also. It is doing the exact thing your describing. I thought I had a bad connection
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