Hammering?
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Freshman User
Joined: Jan 2004
Posts: 37
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From: Colorado (Native)
Hammering?
When I pull my flatbed trailer loaded with hay, I occationaly hear a sound I will call hammering. It happens when I am going up a hill on the interstate. It sounds like a knocking/missing. I haul about 7 tons of hay on a 30 gooseneck flatbed. The flatbed weighs about 5,000 lbs. in addition to the hay. It doesn't happen all the time at every hill and sometimes not even on the longest and steepest hills. Also when I am hauling the truck doesn't seem to have much power. I can give it about 3/4 thottle starting up a grade but when I give it WOT it doesn't change anything. It won't pick up any more speed. I can then go back to 3/4 throttle and it will still maintain the same speed. If I get stopped at traffic signal or stop sign the truck doesn't have much power to take off and go. It is real slow getting going again. When I am running empty or without the trailer the truck seems to run fine.
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
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From: Southwest Georgia
It could possibly be one or more injectors not firing (dead cyclinders). I have seen these trucks run down the road on four cylinders, but when you put them under a load, they knock like crazy (free floating piston). Have a buzz test and a cylinder contribution test performed to determine if you have an injector issue. Or you can pull the valve cover connectors (one at a time) and see if it changes the running of the engine (if no change when a connector is pulled, this means that one or both of those injectors are not firing, bad injector or connector, gasket or under valve cover wiring.) You can also pull the valve covers and fire it up and see if the injectors sre pumping out oil (no oil being pumped out means that injector is not firing).
Maybe someone else will have another idea or has had the same problem.
(edit) Also check your motor and transmission mounts.
Maybe someone else will have another idea or has had the same problem.
(edit) Also check your motor and transmission mounts.
Last edited by plowhand; Oct 12, 2006 at 12:02 PM. Reason: more info
Posting Guru
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have to agree with plowhand, you could have also just a worn injector.....or a few of them, another thing to keep in mind, you are pulling 21000 pounds plus, if you got 3.55's it will be a biatch to pull.
Just to add, my truck is about the same, the last 1/4 of the pedal does'nt seem to do much other then kick down the transmission. Wait for someone else to poip in.
hope you have a tranny gauge
Just to add, my truck is about the same, the last 1/4 of the pedal does'nt seem to do much other then kick down the transmission. Wait for someone else to poip in.
hope you have a tranny gauge
Posting Guru
Joined: Oct 2003
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From: Quesnel, BC, Canada
+1 (another) on the throttle dealio. I think it could be a computer safety thing to keep it from accellerating to hard, getting too much fuel and running hot/rich worse for mileage.
Like the new mustangs have an electronic controlled throttle, and the computer has an anti-spin function controlled by the computer which doesnt give the full accelleration if the wheels are spinning. There are kits to give this the feel of a mechanical throttle (with cable)...ive read it makes a world of difference.
When I accellerate untill further depression of the pedal is useless, I can wait untill the accelleration has stopped so the vehicle is maintaining speed at said throttle postition. If I then depress the accell pedal untill it stops affecting accell, wait till the vehicle reaches the set speed again. The same thing will happen over and over untill I am full throttle. Which seems to me more of a function of the computer limiting ability to accellerate at WOT from say 1/2 throttle.
Like the new mustangs have an electronic controlled throttle, and the computer has an anti-spin function controlled by the computer which doesnt give the full accelleration if the wheels are spinning. There are kits to give this the feel of a mechanical throttle (with cable)...ive read it makes a world of difference.
When I accellerate untill further depression of the pedal is useless, I can wait untill the accelleration has stopped so the vehicle is maintaining speed at said throttle postition. If I then depress the accell pedal untill it stops affecting accell, wait till the vehicle reaches the set speed again. The same thing will happen over and over untill I am full throttle. Which seems to me more of a function of the computer limiting ability to accellerate at WOT from say 1/2 throttle.
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From: Colorado (Native)
Are the valve cover connectors the ones that go into the top side of the valve covers? If so then there are 2 on each side? Also would I have to take the truck to a mechanic to have a buzz test and cylinder contrubution test performed, or is this something I can do? I have never taken, or seen the diesel without the valve covers on. Will I see the oil shooting out of the injectors without removing them? Thanks for the help.
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
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From: Southwest Georgia
1. The valve cover gaskets have two electircal connectors on each of them that allow the current to pass through the gasket to the under valve cover wiring harness. The gaskets are reusable. Check the pins in the connectors of the gasket, (both outside and inside the valve cover) and the connectors on the external wiring harness and under valve cover wiring harness for burnt pins/connectors. Replace any that are burnt.
2. A Mechanic or someone with the proper scanner can run a buzz/contrib. test. The cheap way to check your injectors is to pull the valve covers off, leaving the wiring connected, start your truck and then check each injector.
If the injector is firing, then oil will be pumped out of the injector after it fires. If the injector is not firing, no oil will be pumped out. You do not have to remove anything but the valve covers and whatever breather assembley is in the way of removing the valve covers. The oil will coming from the top (center of engine) of the injector.
2. A Mechanic or someone with the proper scanner can run a buzz/contrib. test. The cheap way to check your injectors is to pull the valve covers off, leaving the wiring connected, start your truck and then check each injector.
If the injector is firing, then oil will be pumped out of the injector after it fires. If the injector is not firing, no oil will be pumped out. You do not have to remove anything but the valve covers and whatever breather assembley is in the way of removing the valve covers. The oil will coming from the top (center of engine) of the injector.
FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
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From: Cabot, Arkansas
Correct. Two harness plugs on each valvecover gasket. If you have a diagnostic tool that is capable of buzz and contribution tests you can do them at home, but most people do not.
The oil won't exactly "shoot" out of the injectors, but you will be able to see it. You don't need to pull them for that. It's not all that different then watching the oil splatter out of the tops of the pushrods.
The oil won't exactly "shoot" out of the injectors, but you will be able to see it. You don't need to pull them for that. It's not all that different then watching the oil splatter out of the tops of the pushrods.
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Freshman User
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From: Colorado (Native)
Thanks for the help. I will try to check this out at the end of the week or beginning of next. I won't be driving it till I do. Thanks again.
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