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Discussion Starter #1
How can you tell if a valve cover gasket is bad? I just bought my truck and it feels sluggish and underpowered and idles like 1 cylinder is firing good.And when the truck is cold and i try to drive it it will bearly move (i mean bearly)until it gets some temp in the engine. I had the truck running and pulled the plugs on the passenger side and the idle changed a little, but when i pulled the one on the drivers side the idle got alot worse. I just want to know for sure before i do all the work pulling the valve cover off. I am taking it to someone tomorrow to run a diagnostic to see.... Thanks for the help guys.
 

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I know nothing...
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How can you tell if a valve cover gasket is bad? I just bought my truck and it feels sluggish and underpowered and idles like 1 cylinder is firing good.And when the truck is cold and i try to drive it it will bearly move (i mean bearly)until it gets some temp in the engine. I had the truck running and pulled the plugs on the passenger side and the idle changed a little, but when i pulled the one on the drivers side the idle got alot worse. I just want to know for sure before i do all the work pulling the valve cover off. I am taking it to someone tomorrow to run a diagnostic to see.... Thanks for the help guys.
Wait... You say you pulled the UVCH plugs and it made little diff? There's your answer! Advanced carries them for $45 a side including new GP and inj plugs.
 

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Discussion Starter #3
Thats what i assumed i just want clarification before i tackled that.
 

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Discussion Starter #4
If he gasket is bad will it set off a check engine light?? I took my truck to someone this moring to hook to a computer and the guy i took it to said a check engine light would come on if that was the problem... what is your expierence with this??
 

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Discussion Starter #5
Any body ever have this problem??
 

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Demon Dually
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Whoever you took it to doesn't know these trucks very well apparently. The light may or may not come on depending on whether or not the circuit shorts to ground in which case the IDM will shut down that bank in order to prevent damage. You can pull the valve cover and visibly check the harnesses for damage. If it were me I would go ahead and replace the glow plugs and UVC harnesses while I am in there if you haven't done them before since buying the truck as it is excellent preventative maintenance.
 

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Discussion Starter #7
so it won`t always cause a check engine light? I was thinking i had my problem figured out til he said that lol. I think i will go ahead and change and the it just to see if thats it, if that doesn`t fix it it must be an injector. Is there anyway to test it before i change it just to be sure?? He is going to trouble shoot it for me.... but i just want to know of any other way!! He told me the check engine light would come on b/c of high or low voltage going to the injectors or something like that, not sure exactly what he said.
 

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Demon Dually
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Yes there is a way to check things over without him if you have a multimeter and know how to use it. I will post a pin out test you can perform by pulling the connector and using a meter check these pins for problems. This is the best way I know of testing both the glow plugs and injector harnesses both external and internal in one shot. If you do fine an issue you will have to unplug the harnesses at the valve cover gaskets to farther diagnose the issue.
 

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Discussion Starter #9
Thanks alot speeddemon, i do have a multimeter and i will check into this. Again thanks for helping me with my problem.
 

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Demon Dually
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No problem bud. I know there are guys on this forum that have to be near you. Somebody give the new guy a hand will ya. If I had already moved I would offer to help but I am way too far away to drive to the lonestar state. Moving to Kentucky in another month or two. Then I won't be near as far from most of the guys.
 

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Discussion Starter #11
The mechanic hooked my truck to a computer and said my fuel looked good, oil pressures looked good, and it passed the buzz test but it had a high and low circuit on #6 and #8 injectors. This solidifies my belief that the valve cover harness is bad.... what do you guys think?? How long does it take to change these?? And what do i need to buy the whole valve cover or can i just buy the harness?? Thanks in advance for answers.
 

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Demon Dually
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Hate to tell you this but if he told you he read fuel pressure through the computer he lied to your face. Our system is mechanical and the only way to check it is with a fuel pressure gauge connected to the schrader valve on the FPR.
 

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Discussion Starter #13
Not sure if he is saying that he checked that with the computer or not, he may have checked that with a gauge. I know for sure the fuel pressure is goo i just changed the lift pump and checked the fuel pressure myself.
 

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Demon Dually
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Oh ok. That is a bit more clear. The valve cover harness you are referring to, is it the under valve cover harnesses(UVCH) you are looking to change or the harness plug that plugs into the valve cover gasket through connector? You could have a bad valve cover gasket through connector or the UVCH could be bad or the harness plug from the main harness could be bad. Since his computer indicated #6&8 I would suspect the UVCH is bad. Unfortunately they tend to take out the valve cover gasket if left in that condition too long. I would inspect the plug outside the valve cover first and the valve cover gasket connector at the same time. If you do not see physical signs of damage as in broken, chaffed, shorted, or melted connections I would pull the valve cover(easy job) and check the UVCH which in this case would be the one closest to the firewall.
 
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