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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Lit549 on July 10, 2013, 12:18:22 am
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Well,im still chasing my rough idle problem and in the process ive noticed im going through a quart every 300 mi and my fuel milage sux .The engine only has about 7k on it.No oil leaks,doesnt smoke,and pcv is working right with no oil sucking into carb(its dry in hose).Its 96 vortech with zz4 cam,600 eddy,and professional products intake..Could overtightening the rockers cauze this? How about intake gasket or maybe bad oil rings? The compression and leakdown test was good..Im stumped..Where is my oil going??Plugs are pretty clean,a few have oil on sprkplug threads (not from valve covers)..thanks in advance.
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Was the motor rebuilt? And the plugs don't have oil on them?
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if the oil is on the threads its cause it leaked down onto them from the valve covers. this is a 96 engine with obdII?
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Valve seals? mine has one cylinder valve seal that leaked from the get go... Check your plugs to see if they look like....(http://img.tapatalk.com/d/13/07/10/e4e8atyp.jpg)
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Posting as Carter (Change)
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Travis Carter · Driver at Permian Crude
Number 7 had some oil on it pretty bad , BUT its only that bad if I go out and put my foot in itreal good.Like its getting oil in there worst at high rpm? And its in a 85 c10so know computer..Little history on the engine--ibought it from a local gm mechanic, he said itwas a warranty pulled from a truck in 96, he didn't state the issueit had just that it was basically a "new" engine.He is a respected mechanic locally..So, i bought it, installed a zz4 cam and we used the ls6 beehive springs with comp lifter( so no maching required on vortech head).Ok, we installed engine, ran it for 5 k mi and rings would not seat! We pulled it, my good close friend is also a mechanic and he tore it down and said whoever honed the cylinder didn't do it right and that's why they wouldn't seal.We went back with iron rings this time , installed engine and its been about 7k miles this time..Ive done compression test, leak down test, compression was all around 190 except for 1 and 3 which were 170, leakdown on all were 7%…Again , the #7 cylinder had alot of oil on plug after a hard run, normal driving it just has a touch of signs of oil, all the rest had dark spots(like dried oil) on the porcelins forever, now they are clean..What's baffling me is why doesn't it smoke? There is no leaks what so ever, and truck runs ok but not like it should in my opinion..Ive said it runs like a 305 since we put it in, put it does have a 308 gear so go figure..Long story but that's how its gone down, and ive chased my tail every since.Im knowlegable on cars and can do alot but this ones getting to me..
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Mine doesn't smoke one but with the valve seal leak, but still have to put in oil.
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Hmm,maybe thats it? I may just pull it and build a new ,on my own this time!
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Our try changing the valve seal ... Hope you get it resolved
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How can i tell if its the valve seal??Replace them? ?Thanks man
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Oil drips on the plug and looks like mine in the photo. I change that plug everytime it starts to miss... Every 3 oil changes. I'm to lazy to do the valve seals in 100+ outside temps.:-)
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Also you get a puff of smoke when you start it up after sitting a while.
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lit the reason i asked about the computer you stated it was a 96 vortec. in 96 is when gm made all vehicles obdII. and since your had (im guessing) cpi or at least a tbi, it would need a computer to run it has nothing to do with what year your truck is.
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Ya Irish,its a 600 edelbrock..Icarburated it,so no computer needed..But youare right..
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lmao 600 eddy missed it, my bad ;)
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but like 74 said do you get a puff of smoke when you start up?
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on another note about leaking valve seals...i don't know how dirty your engine is but if you have a lot of crud on the head when you take off the valve cover then another thing you can try is to make sure and clean all the crud off and to make sure the oil return holes are free of anything....they do get crud and this will keep oil up around your valves on top of the head and this can cause your valve seal leak too..also look to see which valve seals you have.....the oring seal chevy used was not one of the best..the umbrella seal was a better one...i use the oring type along with the umbrella type over the oring....i never have any problems...hope this helps.
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well,i look everytime i start it and theres no smoke on startup.. My pipes run where i can see them and theres nothing..Thats why im baffled,that much oil consumption would have to be putting out smoke! crazy stuff..
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Yeah I thought the same thing but nope.
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The first is #7,and the other is how all other 7 look.Notice how one side of porcelin is darker? Like they are burning oil??Ive never seen plugs like this..
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Heres the second pic..
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also,ya notice the oil on the threads? Myvalve covers dont leak at all either...
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Yup they look like mine if I dint leave them in a while longer.
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What vortec intake gaskets did you use ?? More than a couple of times I've seen cheaper gaskets leak vacuum and pull oil out .
That last one I dealt with was a young friend that was having Idle troubles and oil disappearing . He used a set of Fel pro intake gaskets Part Number: MS98000T . Fully cured both problems . Not sure that's your problem but if I was betting .....
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if your plugs where tight then the oil would of had to compress the air in the threads for the oil to travel up the treads. and if oil was able to pass threw the threads of a plug then air can also. then if there was this much oil getting by the plug it would blow out. again this is just my opinion. but how do you explain the oil on the non fouled plug. it maybe just me also but i dont think your plugs where tight enough. if you noticed the pictures i posted the compression washers are crushed and yours still have the round shape at least thats how i see it. now from what i seen on oil soaked plugs it would be all gummed up black not a brown color which is from a miss fire. something else about your pictures. the fouled plug only the first thread has carbon on it while your non fouled plug has 3 threads with carbon this points to the fouled plug not getting hot enough. im not a spark plug annalist but this is some of the things i learned, could be bad plug or wire or connection that causes a plug not getting hot enough
normal
(http://www.procarcare.com/images/shar/encyclopedia/Tccs2135.jpg)
carbon build up
(http://www.procarcare.com/images/shar/encyclopedia/Tccs2136.jpg)
oil build up
(http://www.procarcare.com/images/shar/encyclopedia/Tccs2138.jpg)
also this picture i posted about spark plug temp this is from ngk
(http://ngksparkplugs.com/tech_support/spark_plugs/image/charttempfiringend.gif)
now with these pictures you dont know how the valve cover gasket was, or how many times they changed the plugs with leaky valve covers. but if you noticed your oil had a nice color to it, if it went threw the combustion chamber it would be burnt. something to try is a compression test, this would tell you what problem you can have.
but i understand you know your valve covers arnt leaking but read this
http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-analysis
i have been known to be wrong a time or two or three but. till someone tells me im wrong how will i know
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hey Irish,i looked and thought that also.But i tighten the snot out of em,the washer never gets crushed..Theyre the right plugs for this engine and head so idk?? Think im gonna try and change seals here soon,this engine did set for along time come to think of it..Maybe the rubber seals were dried out or maybe with this spring,lifter combo is letting them get crushed?I opted for the ls6 beehive springs-comp lifter set so i could run a higher lift cam with thse vortech heads without machining the spring pockets..Ive never set up the geometery on a head so i need to check on that too and see if he did them correctly..thanks for all the help!