I have a 290HP SBC crate motor in my 40 coupe. Upon start-up, usually cold, anyone behind me says they notice a small "puff" of blue smoke from the tailpipes that stops almost Immediately. It's also seen at times under hard acceleration by those cruising behind me. I use Royal Purple synthetic 10/30 and watching it I used 1/2 quart of oil in 2400 miles at one point last season. I was able to discover that GM knew of a problem and at one time offered a valve seal & spring replacement kit. After checking the build date on my engine it doe not fall into the range of dates this was the recommended repair. I've already used the GM upper engine cleaning fluid procedure. Has anyone else here had the same problem? Any suggestions on how to approach this without just throwing parts at it? Btw it is no longer under warranty and has about 20K miles. Posted using the Full Custom H.A.M.B. App
Sure sounds like bad valve guide seals, or worn valve guides. Usually this happens on older high milage SBC engines though.
It was the valve spring retainer. GMPP actually admited that they installed the wrong valve spring retainers on a run of 350/290 motors. Mine was one of them. I had the motor ina 56 Chevy I owned. The retaineres used were too thick and crushed the valve seals. GMPP told me to drop dead on a warranty claim because my motor was over one year old. I had purchased the motor and by the time I actually finished my build it was past the 12 month warranty. A new employee on the line pulled from the wrong parts barrel and I get stuck for it. GM ****s! I replaced the wrong GM retainers with the correct GM retainers (Visually noticable difference in the thickness of the retainer) and Fel-Pro valve seals. I then took the car on a 1400 mile trip and it no longer burns oil. I know yours wasn't within the date range and with 20k miles on the motor it doesn't fit the symptoms bill. Mine and everyone elses at the time occurred under 3k miles. However, it is worth looking at your seals to see if one or two has gone bad. Of course it could also be something simple like your pcv valve. I've seen that happen a lot over the years. Check that and other easy things first.
I would just keep driving it....that's not bad at all for an early design Chevy engine. although I also wouldn't be spending extra $$$ for fancy oil.
The valve guide seals can be replaced in car without removing heads, not that big of a project, check with a few GOOD mechanics. John
i would just drive it till it got real bad. keeps the guides lubed anyway. if need be. remove rockers, pump air in the cylinder, remove springs, replace seals. no biggy.
Thanks guys, all of your comments helpful and appreciated. The bulletin I was able to acquire states any engine built after 4/1/07 should NOT replace valve seals,state to do a comprehension check with 4 " puffs " enter data and notify GMPP, dead end after that. I guess I will watch it a while longer and then decide on using the GM kit or the Fel-Pro seals,as I have checked PCV valve and I do have a breather. Posted using the Full Custom H.A.M.B. App
Did the intake come on the engine or did you install it? I was woundering if there was a chance that the intake gaskets were ****ing oil from the lifter valley.
The standard answer in the Chevy garage was "they all do that". 2400miles/ half quart is well within the acceptable standards of oil useage. At one point in the late 70's GM policy was it was good at a quart/ 700 miles.
2700 miles to a quart of oil sounds pretty reasonable to me but like Jim I don't run that spendy oil either. If it bugs the **** out of you though, valve seals aren't all that expensive or hard to change, especially if you have a good compressor to push plenty of air pressure to the cylinder when you pop the valve springs off.
late 80s Ford policy was 500 miles/qt, iirc Having had big block chevys for decades, I usually check the oil level when I get gas
Intake was installed,it's an Edelbrock EPS, are you thinking the gasket may be mismatched or damaged? Wouldn't That cause a vacuum leak? Engine idles and runs smooth thru the entire rpm range but it's something else to consider. Posted using the Full Custom H.A.M.B. App
I've been convinced to worry about something else for awhile, sometimes hard when you're **** Again thanks to all for responding, Posted using the Full Custom H.A.M.B. App
1/2 quart in 24-hundred miles. That is really a pretty tight engine. That's Albuquerque to N.Y. on a half a quart. I don't see any problem............
Alot of time when I pull intakes you can see that the gaskets have been seeping oil into the intake runners and not have an apparent problem with idle problems.
My dad was a Chevy fan and checking the oil, when he got gas was a reflex action. I do it every 3 days of driving.
I love your '40. My first car 40 years ago had a 396. As squirrel said, I had to check oil every fill-up. A puff of blue, valve-guide-seal-related smoke on a mouse motor is pretty typical. My Nomad does the same. Just keepin' those valve guides lubricated!
I had a Goodwrench 350 in an OT car some years ago. It started doing the blue smoke thing around 20K. Just one of those things I guess...
a small block that doesn't puff at start up means your out of oil ... chevy doesn't use a true valve guide so a little wear in the cast iron is expected . now when it smokes when you let your foot off the gas time to get the guides done ... my BBC vortec is 1 quart every 4 fill ups ( 1200 Mi ) and after taking care of several fleets of vehicles with these its about average , the new O/t Ls series drink oil like a little kid with a can of soda on a hot day .
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