Home page

Topic: Blue smoke/blow by when driving up steep driveway

in Forum: C3 Engines


Already a Member?
Login
Not yet a Member?
Register for Free!

Blue smoke/blow by when driving up steep driveway (1/6)
 3/22/22 11:36am
CKOsC3
Standard Member
Send Private Message

ALPHARETTA, GA - USA

Vette(s):
1977 Black Beauty


Joined: 1/12/2022
Posts: 4

Got an odd issue in my 1977 Corvette with now only 43,984 miles (no modifications done to motor except headers). I have a pretty steep driveway and every time I drive up it in first gear (at low speed, not driving it hard), I get a significant amount of blow by coming from exhaust. if I go back out later, no smoke/blow by whatsoever upon startup. 

It will also occur very randomly at a stoplight after I have been driving it for about 30 minutes. The most consistent time it occurs is going up the steep driveway.  Any ideas of what this could be and why it is so random?  The intake gasket was replaced by previous owner a couple of years ago--maybe its not sealed all the way at some point? 

 

Our Sponsors help support C3VR
Re: Blue smoke/blow by when driving up steep driveway (2/6)
 3/22/22 5:01pm
F4Gary
Standard Member
Send Private Message

Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 1237

Worn valve stem seal on one of the back cylinders maybe? Oil flows back there on a steep incline?



______________

Re: Blue smoke/blow by when driving up steep driveway (3/6)
 3/23/22 10:20am
CKOsC3
Standard Member
Send Private Message

ALPHARETTA, GA - USA

Vette(s):
1977 Black Beauty


Joined: 1/12/2022
Posts: 4

Thank you--couple of others have said that as well from a recent car show, so good to hear confirmation. That's the first place I will look then. Thanks again/will report back once I get to it. 

Re: Blue smoke/blow by when driving up steep driveway (4/6)
 3/23/22 4:39pm
73shark
Limited Member
Send Private Message

Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
Posts: 794

I agree with the diagnosis of valve stem seals. In order to do it on the vehicle you will need an air compressor and adapter to fit in the spark plug hole to keep the valve from dropping into the cylinder. You'll also need a valve spring compressor to compress the valve spring in order to remove the keepers.



______________

1973 L-82 4 spd

Re: Blue smoke/blow by when driving up steep driveway (5/6)
 3/23/22 10:23pm
F4Gary
Standard Member
Send Private Message

Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.


Joined: 8/26/2006
Posts: 1237

You can also use a piece of rope.  Shove it in the spark plug hole, rotate the engine to jam it up against the valve, change out the seal, back up the engine slightly and pull out the rope.  Works great if you don't have the tools for the air compressor procedure.



______________

Re: Blue smoke/blow by when driving up steep driveway (6/6)
 4/5/22 10:21am
bob jens vette
Former Member

Send Private Message

osprey, FL - USA

Vette(s):
1973 350-l-82 coupe 4 speed


Joined: 11/26/2021
Posts: 1

P.S. take alook at the p.c.v. valve and the p c v hose . Bob.

Our Sponsors help support C3VR