Ok, well, if you still have codes then address them first but I do recommend a compression test and post the results.
P0304 P0443 white smoke misfire 07 Tahoe 5.3 4x4
- Thread starter Jps0039
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Jps0039
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Today is the day the old hoe sees a shop for the second time in her life. Hope to get to the bottom of this today once and for all. Stay tuned...
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avalonandl
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We are waiting.........
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Jps0039
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Compression test. Cylinder 2 150. Cylinder 4 0. Cylinder 6 150
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Ding ding ding ding ding! We have a winner with cylinder #4. "0" compression means a dead cylinder. If the rest of the cylinders are showing close to the same compression, then you are running on 7 cylinders. Now to find the compression problem. I would pull the valve cover and look at the rockers while someone turns the engine over. See if the rockers for cylinder #4 are moving the same as the others under there. You may have bent push rods or lifter problems or a piston problem. Before you do this, remove the compression test line from cylinder #4 and squirt some motor oil in there and run the compression test again. If the compression comes up then the problem is with the piston rings but if you have a hole in the piston the compression will not come up. If the problem is in the valve train the compression will stay the same as well. You may have a severe leak at the head gasket but I have never seen that with "0" compression.
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Jps0039
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Will know more once I get into the engine. Possible head gasket, bad cylinder, bad piston, bad lifter. Don’t have any money to put into it unfortunately and they are Suggesting a whole new engine so... hope this thread helps someone else out there. Once I get another good job a new truck will be on the agenda.
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Ok, so a shop did the compression test. Did you ask them to do a wet/oil test yet? If you go under the valve cover they are going to charge more of course.
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Jps0039
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Appreciate your response. I guess best case scenario here would be head gasket or lifter then. He told me they have someone that can rework it unless it’s the piston then may as well go with new engine.
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Jps0039
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Buddy and I just did it outside his shop. Didn’t do a wet compression test, though I did mention it. They were swamped and he was really just trying to help me quickly no charge. Would love to have spent a little more time on their high dollar reader running tests but he said it doesn’t do much in terms of compression readings.
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kbuskill
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Could be as simple as a broken valve spring... pull the valve cover and inspect it... it's free and if it is a spring wouldn't cost that much to fix... assuming nothing else was damaged.
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Jps0039
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Yeah have to wait till I have my dads help to pull the head. Once we are in we will know more. I’ll keep y’all posted for sure and appreciate all the advice. A rocker arm wouldn’t make it blow smoke would it?
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You don't need to pull the head, YET. Pull the valve cover and inspect as stated above.
avalonandl
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Pull valve cover and rotate the engine....
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Jps0039
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10-4, I’ll be looking for bad casket and collapsed lifter in this case correct? Anything else I should look for?
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Do you man gasket and not casket? Spell check. The valve cover gasket will not come in to play on this problem. You can look for the rockers movement to see if they all move the same amount. Look for a broken valve spring. Look for a rocker stud or rocker problem.
avalonandl
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Stuck/bent valve, broken rocker, etc....
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Jps0039
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Pulled valve cover. 4 the rocker arm is seized up we are about to pull it.
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Meant to say the #4 rocker arm is seized up. We are about to pull it to examine the push rod
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Pushrod is straight the rocker arm is tight. We are thinking probably a collapsed lifter. Going to try to use an additive to free it. If that doesn’t work we will replace lifter
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Perfect time to at least replace all lifters if not the cam as well. When you remove the lifter make sure you get as good a look as possible of the cam surface.
