Bluish smoke on re-start
05-03-2019, 01:42 AM
#1
Racer
Thread Starter
Bluish smoke on re-start
When I restart my 1979 L82 coupe after sitting for say 5 minutes, there is a quite noticeable puff of bluish smoke from the exhaust.
I recall from years past being told that this is caused by 'leaking valve guides', allowing oil to get down into the combustion chamber. My concern, is that this only occurs once in a while and not every time I restart after a short 5-15m shutdown.
Could it be something ELSE besides leaking valve guides that I should look at...or just not worry about it at all for the time being? I would think if it were leaking valve guides that they would leak ALL of the time and not sporadically like is presently happening.
I recall from years past being told that this is caused by 'leaking valve guides', allowing oil to get down into the combustion chamber. My concern, is that this only occurs once in a while and not every time I restart after a short 5-15m shutdown.
Could it be something ELSE besides leaking valve guides that I should look at...or just not worry about it at all for the time being? I would think if it were leaking valve guides that they would leak ALL of the time and not sporadically like is presently happening.
05-03-2019, 07:10 AM
#2
Race Director
3 choices. replace valve seals. spend upwards of 3k rebuilding the whole engine. leave it alone.
05-03-2019, 09:05 AM
#3
Le Mans Master
Member Since: Sep 2001
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If valve GUIDES are not too badly worn, seals will help for a while.
You can air-up cylinder thru sp hole to hold valve closed as you R&R springs & seals.
Find plenty instructions on web /Youtube. Plan half-day for careful novice.
These sets for sbc with OE 11/32" stem valves:
Fel-Pro pn SS 72526 - Set of 8 o-rings & 8 umbrellas - install both umbrellas & o-rings on INTAKE valves.
Fel-Pro pn SS 72877 - Set of 8 o-rings & 8 umbrellas - install both umbrellas & o-rings on EXHAUST valves.
You can air-up cylinder thru sp hole to hold valve closed as you R&R springs & seals.
Find plenty instructions on web /Youtube. Plan half-day for careful novice.
These sets for sbc with OE 11/32" stem valves:
Fel-Pro pn SS 72526 - Set of 8 o-rings & 8 umbrellas - install both umbrellas & o-rings on INTAKE valves.
Fel-Pro pn SS 72877 - Set of 8 o-rings & 8 umbrellas - install both umbrellas & o-rings on EXHAUST valves.
05-03-2019, 09:26 AM
#4
Race Director
One more thing. 40 year old valve springs. THROW THEM AWAY!! there are lots of good single spring sets in the correct pressure for under 100 bucks.
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05-03-2019, 01:52 PM
#5
Race Director
Auto or manual trans.
I had a chevy 1 ton that would do the same thing.
After spending a ton of money on head work the problem continued.
I found that the $3.00 vacuum module on the trans was going out and it was sucking transmission fluid into the intake on start up.
As the module continued to fail the blue smoke started getting worse and I noticed my transmission fluid was low.
Installed a new module and the problem went away.
I had a chevy 1 ton that would do the same thing.
After spending a ton of money on head work the problem continued.
I found that the $3.00 vacuum module on the trans was going out and it was sucking transmission fluid into the intake on start up.
As the module continued to fail the blue smoke started getting worse and I noticed my transmission fluid was low.
Installed a new module and the problem went away.
05-03-2019, 02:52 PM
#6
Le Mans Master
Member Since: Sep 2001
Location: Unreconstructed, South Carolina
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Auto or manual trans.
I had a chevy 1 ton that would do the same thing.
After spending a ton of money on head work the problem continued.
I found that the $3.00 vacuum module on the trans was going out and it was sucking transmission fluid into the intake on start up.
As the module continued to fail the blue smoke started getting worse and I noticed my transmission fluid was low.
Installed a new module and the problem went away.
I had a chevy 1 ton that would do the same thing.
After spending a ton of money on head work the problem continued.
I found that the $3.00 vacuum module on the trans was going out and it was sucking transmission fluid into the intake on start up.
As the module continued to fail the blue smoke started getting worse and I noticed my transmission fluid was low.
Installed a new module and the problem went away.
quite true. Had an el camino w/ powerglide ... caught that before headwork.
05-03-2019, 02:58 PM
#7
Team Owner
Member Since: Oct 2004
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St. Jude Donor '05
Or buy the cheapest ones they can.
OP cant help but wonder if you got some gas boiling over before your hot restarts and thats what youre seeing?
If its a little once in awhile leave it. Otherwise pull the heads and $$ dive down that rabbit hole. New guides mean new valve job..may need seats, valves etc. Those dont last forever either
Lotta guys in the C5-7 sec cant figure why their guides/springs wont go 150k. Lots of lift, rpm they are gonna wear period thats hot roddin.
Keep us posted on what you find
05-03-2019, 04:24 PM
#8
Race Director
525 hp Mercury marine 454 engines need full valve job every 300 hours. 365 hp 454's? Never.
05-03-2019, 04:37 PM
#9
Had a 1976 L-82, 4-sp
Member Since: Mar 2011
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Royal Canadian Navy
Maybe go out and buy new modern iron/aluminium heads and bring that old engine into the 21st century.
05-03-2019, 06:25 PM
#10
Racer
Thread Starter
Auto or manual trans.
I had a chevy 1 ton that would do the same thing.
After spending a ton of money on head work the problem continued.
I found that the $3.00 vacuum module on the trans was going out and it was sucking transmission fluid into the intake on start up.
As the module continued to fail the blue smoke started getting worse and I noticed my transmission fluid was low.
Installed a new module and the problem went away.
I had a chevy 1 ton that would do the same thing.
After spending a ton of money on head work the problem continued.
I found that the $3.00 vacuum module on the trans was going out and it was sucking transmission fluid into the intake on start up.
As the module continued to fail the blue smoke started getting worse and I noticed my transmission fluid was low.
Installed a new module and the problem went away.
Thanks again to all that replied.
Last edited by TuffShift; 05-03-2019 at 06:26 PM.
05-03-2019, 07:31 PM
#11
Le Mans Master
Member Since: Sep 2001
Location: Unreconstructed, South Carolina
Posts: 7,739
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THAT, I will have to look into....thanks for the tip (yes mine's an automatic). It's still odd that it only does it once in a while. I appreciate all the helpful suggestions. Am not all that sure, what 'old springs' would have to do with it though.....mebbie someone better mechanically versed than I am could explain that for me.
Thanks again to all that replied.
Thanks again to all that replied.
But, if you're are going to loosen old springs in order to R&R valve seals ... that's a good time to freshen springs.