what is causing smoke on start ups?
09-17-2018, 11:04 AM
#1
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what is causing smoke on start ups? i built an L33, had it bored and 799 heads worked and installed new seals and dual springs, block is bored .020 over with new pistons, turned crank .010, all new bearings including cam bearings with 228 cam, ls7 lifters and 7.4 pushrods. everything new but rockers and connecting rods... started smoking during break in proccess only on start up. been told i could have broken ring or blown valve seal. is burning a half a quart every 3 to 4 days. did a compression test and all cylinders came out to 180 give or take a few, #6 hit around 120 on first stroke but resumed normal after.
09-17-2018, 02:47 PM
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im using tsp with the dual springs, had a guy tell me that with these 5.3s they are having issues with a pvc valve on the passenger side or something in the oil pan, might you know anything about that?
09-17-2018, 03:50 PM
#4
PCV or valve seals would be the first things to eliminate as these are easy to fix in an assembled engine. You could install a temporary breather filter on the oil fill. See if the problem goes away with the crankcase vented. If the oil burning goes away, then fix the pcv and cap the oil fill back to normal.
If that doesnt fix it, then take the valve covers off and inspect the seals. Did you install the seals or were they installed by a shop? And HOW were they installed. If they were hammered on, it’s possible 1 or more may have been damaged.
If that doesnt fix it, then take the valve covers off and inspect the seals. Did you install the seals or were they installed by a shop? And HOW were they installed. If they were hammered on, it’s possible 1 or more may have been damaged.
09-17-2018, 05:48 PM
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ok awesome feedback, thank you! how bout this, after the compression test yesterday i changed the oil and also went to 20w 50 oil, it hasnt smoked the last four starts. oil pressure still is weaker than normal and with that said could clogged pcv cause the lowered oil pressure? forgive for 20 questions but im learning. (after very first start up after engine swap oil pressure idled at 40, a couple months later, now, its idles at 20) melling high volume pump
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09-17-2018, 06:09 PM
#8
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Clogged PCV will not affect oil pressure. Learn how these systems work and you will see why. In this respect LS's aren't any different than any other engine, function wise.
09-17-2018, 06:24 PM
#10
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If it's oil smoke, as said above, rings and/or valve seals. You did not mention before about oil pressure dropping. When did that happen?
09-17-2018, 07:52 PM
#11
Sometimes the pressure drops due to all the sludgy assembly lube. do not use 20/50 in a new build at all. 10/30 is likely what its set up for.
Also idk why people keep using the melling high volume pumps but its very unnecessary and can be agitating your oil burning issue. high pressure only.
Also idk why people keep using the melling high volume pumps but its very unnecessary and can be agitating your oil burning issue. high pressure only.
09-17-2018, 09:01 PM
#12
change the filter asap after a first fire after a fresh assembly. you could probably leave the oil in it, but I change it. Moly lube from under the bolt heads and the sticky red stuff I use on bearing surfaces...it clogs filters QUICK. Like inside 10 mins of run time.
09-17-2018, 09:55 PM
#14
ok awesome feedback, thank you! how bout this, after the compression test yesterday i changed the oil and also went to 20w 50 oil, it hasnt smoked the last four starts. oil pressure still is weaker than normal and with that said could clogged pcv cause the lowered oil pressure? forgive for 20 questions but im learning. (after very first start up after engine swap oil pressure idled at 40, a couple months later, now, its idles at 20) melling high volume pump
As as for the heavier oil, well thats a whole other story. I would be concerned leaving it in the engine long term. Sure it can be debated as to what’s best, but 20w50 sounds wrong. Bearing clearance will dictate what oil to use, so you’ll want to check this with your machinist too. Avoid any spirited driving before the oil is up to temp, or bettter yet just put the right stuff back in. Burning oil is better than burning bearings.
09-18-2018, 09:03 AM
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09-18-2018, 09:04 AM
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i did that after first start up and after 50 miles, i did complete oil change everytime
09-18-2018, 09:08 AM
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Ok interesting test with the oil weights. To me this seems to rule out PCV and valve seals as the issue.. Based on your findings, I would suspect blow by in your cylinder(s). You didn’t mention what weight oil you had in it before but it sounds like your rings are able to keep the heavier weight oil out of the combustion chambers. I would def talk with your machine shop on what they think.
As as for the heavier oil, well thats a whole other story. I would be concerned leaving it in the engine long term. Sure it can be debated as to what’s best, but 20w50 sounds wrong. Bearing clearance will dictate what oil to use, so you’ll want to check this with your machinist too. Avoid any spirited driving before the oil is up to temp, or bettter yet just put the right stuff back in. Burning oil is better than burning bearings.
09-18-2018, 09:09 AM
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