I had what sounded like a valve tap about a year ago. It wasn't loud so I put off adjustment. After a few months the tapping stopped on its own. That made me wonder. Valves that are out of adjustment don't adjust themselves. Outside of the possibility that somebody popped my hood and ran the rack while I was sleeping, as a nice present, I can't envision any way that the noise would stop without me getting wrenches.
Recently the noise started again, but louder, sounding more like a minor clatter. Also, I noticed an intermittent miss. Then the clatter stopped, the second time the noise disappeared on its own. ????? Valve noise doesn't go away by itself, does it? In all my years I've never heard of this happening.
That's when I started to suspect the injector. Also, I now have an intermittent smoke problem. When I put the pedal to the metal, there is a long plume of dark gray smoke coming from the stack. Then, the next time I get on it hard, no smoke! What gives?
This must be an injector problem, no? Could an injector be intermittently sticking or jamming up or something?
I'd like to know if somebody here has had a similar experience before I pull the truck off the road and dig out the wrenches.
3406b smoke and a minor clatter
Discussion in 'Trucks [ Eighteen Wheelers ]' started by stonefly4, Oct 6, 2018.
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Could be a sticking air fuel ratio control. I think its sticking on my 3406A. It smokes like a chimney when I romp on it the first time and then its pretty clean after that. Wouldn't explain the tapping though.
@wore outLast edited: Oct 6, 2018
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I will bet you have timing advance issues. The 7FB and early 4MG carriers were press fit and will slip. With it off the truck hold the back with one hand and see if you can turn it. If so that is your problem. Some weld them. I have but think buying the updated carrier is better.
Also check the E clip and race. The race looks like a flat washer the weights will wear grooves in it and cause it to "stick". Also check the weights where the pin goes through it. They will get a lot of slack there.
In the end of the fuel pump cam there is a plastic screen/orafice. It will come loose and cause it to run full advanced.
Or the end will blow out of it and it wont advance at allsnowman_w900, MACK E-6, Oxbow and 4 others Thank this. -
Thanks, wore out, for the reply.
Man, that sounds like a lot of work, pulling the injector pump off the truck. I'm keeping my fingers crossed that it's going to be an easier fix than that.
What about the tapping noise that comes and goes on its own? That sound is definitely coming from inside the front valve cover.Last edited: Oct 6, 2018
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Thanks, AModel, yeah that sounds like my engine, smoke when I first tromp on it but it cleans up.
No, this long plume of smoke trailing behind is something new, and it follows on the intermittent tapping and then clanging that comes from inside the front valve cover, and according the stethoscope, right at the number 3 position. -
The timing advance is an easy deal. The pump stays on the truck. You just pull the cone off the front to pull the advance. Naturally time the pump first. Grey smoke is why I say timing. AFRC valve is black smoke or none.
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Can a malfunctioning injector cause smoke? -
A way lose intake valve can do that also?
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