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#1 |
Registered User
Join Date: Feb 2008
Location: Carson, CA
Posts: 581
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Troubleshooting
So my truck recently went from running fine to running like crap and sometimes throwing black smoke out of the drivers tailpipe. It also sounds like there's a miss or something going on when the truck is running. Any ideas what may be going on? Here is a picture that may have some breadcrumbs in it. Notice what appears to be oil coming from the tailpipe on the ground
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69 C10 SWB -- Left to me by a loving father. Finishing the build we never got the chance to do together |
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#2 |
Junior Member
Join Date: Dec 2006
Location: Southeast Missouri
Posts: 2,436
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Re: Troubleshooting
Pull the spark plugs and see what they look like. If any of them are oil fouled you will have a better idea what is going on. Also do a compression check.
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'67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E. |
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#3 |
Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,143
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Re: Troubleshooting
How old is the tune up, not just the look over and assume all's well but a real tune up? Plugs, wires, points if still there, carb rebuild, timing. I would do a compression test, then a leak down. Those tests would tell you what to do next, could be just a real tune up, maybe some valve seals, or if engine work is needed.
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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#4 |
Registered User
Join Date: Sep 2011
Location: Greencastle, IN
Posts: 132
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Re: Troubleshooting
Black smoke usually indicates carbon build up either in the cylinders or in the carb. This is usually caused by running rich. Blue smoke is burning oil usually from leaking valve guides. The leak down will indicate if you have either an issue with rings or with a valve not completely sealing.
Best bet are your plugs, cap and rotor. A complete tune up like Lee suggested will more than likely solve your problem. |
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#5 |
Registered User
Join Date: Feb 2008
Location: Carson, CA
Posts: 581
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Re: Troubleshooting
Thanks for the suggestions so far. Can you guys explain how to do a compression or leak down test? I just changed the plugs two nights ago. I attached a pic of one of the old ones, all of them looked like this.
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69 C10 SWB -- Left to me by a loving father. Finishing the build we never got the chance to do together |
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#6 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: Troubleshooting
do you have cheap chrome valve covers withPVC valve installed without baffels?
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71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY |
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#7 |
Registered User
Join Date: Feb 2008
Location: Carson, CA
Posts: 581
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Re: Troubleshooting
I can't say for sure. They don't look to be anything special, but there is a baffle at the oil filler cap. I'll pull them tonight to see.
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69 C10 SWB -- Left to me by a loving father. Finishing the build we never got the chance to do together |
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#8 |
Registered User
Join Date: Sep 2011
Location: Greencastle, IN
Posts: 132
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Re: Troubleshooting
Plugs look good. Cap, rotor, and wires would be the next items to check. Check the routing of your wires. Often they are too close to the exhaust to last very long. You might also replace your fuel filter. Your issue could be one of fuel delivery.
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#9 | |
Registered User
![]() Join Date: Jan 2011
Location: Chattanooga TN
Posts: 6,208
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Re: Troubleshooting
Quote:
Does it have headers on it? Check your plug wire boots. You might have one too close and when the plug fires, it arcs over to the header pipe instead of going to the spark plug, causing that cyl to drop out. = firing on 7. I had a 406 in an old Firebird a long time ago and it was bad to burn through plug boots. .. just some things to try. An easy way to check is to raise the hood at night. At times you can see the arcing as it happens. Looks like a rich condition, that cyl is not firing and burning the gas causing the black smokey stuff to blow out. .. just my .02. Chad
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Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 *Currently underway* 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet *Sold* 1985 Silverado Short Fleet *Sold* 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride) |
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