Smokes only after running 5K

[dp88]

I know this thread sounds like I smoke after running a marathon but my stock 302 smokes after I run it to 49000- 5300rpms and shut it off. It just smokes on start up for 10 or 15 seconds and then is fine but it only happens when I've ran it at the rpms mentioned. The smoke isnt White white but its not black I guess blueish I just wonder if that is valve seals or piston rings?

 

[87WhiteStang1]

sounds like heads or rings

 

[dp88]

I hope its heads.a lot easier than a complete rebuild.

 

[Mr. Rustypwnz]

that sounds like the heads to me, the valve seals..

 

[riceslayer302]

if you rev any engine, let alone a 302 to 49,000 rpms bad stuff will prolly happen. haha typo i know

does it happen when you are accelerating or when you let off? both?

you prolly need new rings

 

[Foxfan88]

generally a ring issue causes smoking all the time.

my old stock motor a few years ago would puff a little blue smoke during a high rpm shift, pretty sure it was the valve seals. was a fairly high mileage motor.

a little oil burning never hurt anyone...

 

[dp88]

it doesnt smoke while im driving it only when i start it up after ive ran it to 4900 plus rpms.

 

[snakebite01]

it's going to be valve seals... my 01 cobra had a valve seating problem (like many of them did) and it only blue smoked when i was in high rpms... if it was the rings you would have blue smoke almost all of the time because your oil shooter will shoot the oil right by the rings causing it to combust and exit through the exhaust..

 

[dp88]

alright update...i am now getting a knocking sound from my passenger side head. it is deffinatley in the head and not the bottom end you can hear it when it idles its like klunkklunkklunk klunk klunkklunk i know that impression will be in someones signature before long. sorry its the best i could do.

 

[1987stangman]

alright update...i am now getting a knocking sound from my passenger side head. it is deffinatley in the head and not the bottom end you can hear it when it idles its like klunkklunkklunk klunk klunkklunk i know that impression will be in someones signature before long. sorry its the best i could do.

I can tell you that there is alot of reasons why your getting that smoke. 1.... It could be bad valve seals in the heads or... 2. it could be a clogged PCV system and that includes the vac line from the PCV to the intake manifold and 3.... worn piston oil rings. I would not be so quick to determine bad rings or valve seals without making 100% sure the PCV system is not clogged or working.

Your knocking sound could be a lifter

 

[dp88]

im going to take the valve cover off tonight and see if i notice anything obviously wrong i dont know what to really look for but the sound is getting worse.

 

[85_SS_302_Coupe]

My vote goes to blow by on the rings, not so much the heads. The reason i say that is that i have freshly rebuilt heads with new guides and seals, but my engine does the same thing. I know for sure it's not the heads, so the only other variable is worn rings which i know i have. Still, there's a chance it could be both.

 

[dp88]

Intermittent Rapping Noise. An intermittent rapping noise that appears and disappears every few seconds indicates leakage at check ball seat due to foreign particles, varnish, or defective surface of check ball or seat. Recondition, clean, and/or replace lifters as necessary.

This seems to nail it on the head (no pun intended) This was taken from a shop manual i had laying around. of course it still doesnt explain the smoke.

 

[snakebite01]

I can tell you that there is alot of reasons why your getting that smoke. 1.... It could be bad valve seals in the heads or... 2. it could be a clogged PCV system and that includes the vac line from the PCV to the intake manifold and 3.... worn piston oil rings. I would not be so quick to determine bad rings or valve seals without making 100% sure the PCV system is not clogged or working.

+1

Your knocking sound could be a lifter

My vote goes to blow by on the rings, not so much the heads. The reason i say that is that i have freshly rebuilt heads with new guides and seals, but my engine does the same thing. I know for sure it's not the heads, so the only other variable is worn rings which i know i have. Still, there's a chance it could be both.

+1 it would have to be a minimal wear.. other wise it would happen in most of the rpms..