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Fresh 351 blowing smoke after 1500miles

1K views 17 replies 4 participants last post by  dragstang88 
#1 ·
the engine has ben running great, not burning any oil, and i cant really complain. it has about 1500 to 2000 miles on it, and just in the last 100 miles, it started blowing a little bit of bluish/whitish colored smoke. Now like i said, it burns very little oil, and also the oil pressure is 35-40 at idle, 60 at 6000. Ill admit i havent taken it easy on the engine and given it proper break in time, but i havent sprayed the car or anything yet. so i was wondering, what could be the MOST, and the LEAST of my worries?? If anyone can help, id greatly appreciate it, thanks, steve.
 
#3 ·
hey man, does it smoke all the time or just on start up? you said the motor was just rebuilt so i'm assuming that included your heads. if so, what valve stem seals did you go with? reason i'm asking is because the same thing happened to me. turns out i hung two seals. i ended up pulling them off and going with the much better viton seals, the nilon's are junk. pull off the valve covers and look between the springs this might be your problem. good luck, tommy
 
#4 ·
thanks...

the heads are new, and i think they are nylon seals. ill take off the valve covers tomorrow, but what exactly am i looking for? only 17, im not a genius, just tryin to learn.. hopefully i wont break anything, also, there seems to be oil seeping under the valve covers. thanks a lot, and ttt for anyone else that wnats to reply!
 
#6 ·
ok steve, here's what to look for. when you pull the covers, look between the springs to see if any seals have lifted. the seals fit over the top of the valve guides and keep the oil in the cover from sliding down the stem and into the combustion chamber. sometimes for different reasons the seal will come off the guide and ride up and down on the valve stem, when this happens you burn oil. if you do find a hung seal, you can pull that individual spring with a spring compressor that bolts to your rocker stud. you will also have to attach an air fitting to the spark plug hole to keep the valve from falling when you remove the spring. if you dont have access to an air compressor you can stuff a rope through the plug hole. this will keep you from having to pull the heads. summit and jegs both sell this tool for around 30 bucks if you can't borrow one. good luck tommy
 
#7 ·
thanks,

luckily my dad used to be a master technician and we have millions upon millions of tools. im tryin to do all the work myself on this car, with the exception of asking him for help, but i dont think he trusts me working on it:confused: . oh well, thanks again, ill look tomorrow, hopefully i wont freeze to death in the 25 degree weather
 
#8 ·
I think the first thing that needs to be cleared up is if its blue OR white smoke. White smoke is coolant, blue smoke is oil.

Smoke from coolant could either be a leaky intake gasket or blown headgasket, and oil smoke could be bad valve seals, guides, bad rings, and possibly sometimes a headgasket. With oil only though its ususally not the headgasket.
 
#9 ·
ok...

its blue smoke, a little at startup, than it clears up. than i get on it really hard, smoke comes out according to RPM, than i let off and it goes away. i dont know, shes been acting really weird lately. i hope its nothing bad, because like i said before, she really doesnt burn a lot of oil.
 
#10 ·
Does it usually do it when cold, or just on startup?

If it does it mostly on startup and is worse after sitting a good amount of time, then it might be valve seals. On my dad's old Honda when it sits overnight it smokes for quite a while until all the oil burns off the valve.
 
#11 ·
its hard to say...

i only really notice it at night, because i just dont think in the daytime, im like a bat, i sleep in the day. anyway, i dont know, i havent really noticed. how much money are we looking at for parts to fix this bad girl?? shes been actin weird and needs my attention immediatlely, hopefully i can fix her tomorrow. so viton seals?? oh yea, thanks for everyones help in this post and the other posts too.
 
#12 ·
First thing I'd do is run a compression check on all the cylinders to make sure everything is up to snuff. Then if you find any low cylinders check them out with a cylinder leakage tester, that will tell you where your air is escaping, and possibly oil leaking in.
 
#13 ·
already did the compression test...

way ahead of ya, 150 on all 8, even across the bored, well maybe like 149 and 151 on a couple, but i just rounded to 150. i thought that was kind of low, but i dunno??? why would it be that low anyway? i mean, it runs fine, does the engine compression being at only 9 to 1 have something to do with the low cylinder compression test?
 
#14 ·
Your compression ratio will affect the compression readings, the more it compresses the air mixture the higher the pressure is in the cylinder. If they're all about equal then you can rule out the headgaskets and rings. Its probably your valve guides or seals, but I think when the seals are bad then eat up a good amount of oil. If you have the heads dissassembled to put new seals in that would be a great time to check out the guides.
 
#15 ·
ok...

how long of a job is it to put the seals in and is it necessary to take off the heads? not sure if im ready to do a complicated job in the freezing weather. thanks. btw, ill just be "checking" them today, and i will not be fixing the problem.
 
#16 ·
steve, it is possible to change them the way i stated earlyer but it not as easy as if the heads were off. if you go with the viton seals you can use a deep socket to put them on since they are vulcanized to a metal collar. you will probably be better of using the rope trick though so that you can drop the valve down far enouph to get the socket on. if you do this make sure the piston is at tdc (top dead center). or mabe you could use the air method if you can find a piece of pipe with the right id, i don't know you just have to get creative. it's no fun pulling the head off so don't do it unless you have to. all that said, this might not even be your prob. :confused: tommy
 
#17 ·
haha

well, i took the valve cover off, took a look, and didnt know really what i was looking for. i took a bunch of digital pics but now i dont know where to host them from???? well thats all there is to that, i dont know what the problem is, today its not smoking as bad.
 
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