puff of blue smoke - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bucket · 10-17-2004, 01:45 AM

noticed today that when i press in the clutch to shift from third to fourth (3,000 rpm), i will get a quick puff of blue smoke from the tailpipe when the clutch is released. 4,000 miles on 327 since complete stock rebuild. thoughts?

sdkid · 10-17-2004, 01:49 AM

Valve seals or guides. What was done to the heads for the rebuild?

bucket · 10-17-2004, 01:51 AM

machine shop rebuilt them. i'm thinking they were knurled which might be the problem?

sdkid · 10-17-2004, 01:55 AM

I hate knurling, just a band-aid. Could be your problem.

bucket · 10-18-2004, 10:33 AM

just got off the phone w/ a mechanic i know.............he thinks it might be a ring since it also is smoking a little on hot startup. i don't want to tear this thing apart already!

chickenwing · 10-18-2004, 10:47 AM

What is knurling?

curbyk · 10-18-2004, 02:40 PM

it is like what you get on some of the handles a ratchet or breaker bar has for grip, cross patterns, it pushes the metal up in some places to take up the play in the guide, usually only temporary.

chickenwing · 10-18-2004, 02:43 PM

Is this done on the head itself, inside or outside of the guide? Not on the valve!?
Rich

mocwon · 10-18-2004, 03:21 PM

Its done on the inside wall of the valve guide where the valve stems fits.

bucket · 10-20-2004, 06:39 PM

well i had a leak down test done today.............inconclusive on the oil burning. all cylinders are consistent w/in 10% and are all like 95% sealed. spark plugs were all consistent too. they looked pretty good. the mechanic told me to put some more miles on it till a suspect cylinder shows up (like a misfire). asked him about the knurling (although he's the one did them, but still is a straight shooter so i believe him) and he said that he didn't think that would be the issue. said that since they had not been knurled before, they had a quite a bit of material to work with and they wouldnt be leaking enough to exhibit these symptoms. he did acknowledge that both sides are burning to some extent.

10-17-2004, 01:45 AM	#1
bucket Registered User Join Date: Aug 2001 Location: Shawnee, KS Posts: 923	puff of blue smoke noticed today that when i press in the clutch to shift from third to fourth (3,000 rpm), i will get a quick puff of blue smoke from the tailpipe when the clutch is released. 4,000 miles on 327 since complete stock rebuild. thoughts?

10-18-2004, 10:47 AM	#6
chickenwing Lovin' Life in Miss.! Join Date: Mar 2004 Location: Puckett, Mississippi Posts: 1,937	What is knurling? __________________ The truck... you hear that? No really, you did hear that?!!!

10-18-2004, 02:40 PM	#7
curbyk 69 C-10 project Join Date: Sep 2004 Location: Eastern, NC Posts: 184	it is like what you get on some of the handles a ratchet or breaker bar has for grip, cross patterns, it pushes the metal up in some places to take up the play in the guide, usually only temporary. __________________ 69 C-10 Work is complete

10-18-2004, 02:43 PM	#8
chickenwing Lovin' Life in Miss.! Join Date: Mar 2004 Location: Puckett, Mississippi Posts: 1,937	Is this done on the head itself, inside or outside of the guide? Not on the valve!? Rich __________________ The truck... you hear that? No really, you did hear that?!!!

10-18-2004, 03:21 PM	#9
mocwon Keep On Truckin' Join Date: Mar 2003 Location: Buda, Texas Posts: 1,354	Its done on the inside wall of the valve guide where the valve stems fits. __________________ Just Passin' Thru Some projects are like herding cats; others are like putting out fires; this one was like herding cats on fire.....

10-17-2004, 01:49 AM	#2
sdkid Registered User Join Date: Sep 2004 Location: Pierre SD Posts: 1,533	Valve seals or guides. What was done to the heads for the rebuild?

10-17-2004, 01:51 AM	#3
bucket Registered User Join Date: Aug 2001 Location: Shawnee, KS Posts: 923	machine shop rebuilt them. i'm thinking they were knurled which might be the problem?

10-17-2004, 01:55 AM	#4
sdkid Registered User Join Date: Sep 2004 Location: Pierre SD Posts: 1,533	I hate knurling, just a band-aid. Could be your problem.

10-18-2004, 10:33 AM	#5
bucket Registered User Join Date: Aug 2001 Location: Shawnee, KS Posts: 923	just got off the phone w/ a mechanic i know.............he thinks it might be a ring since it also is smoking a little on hot startup. i don't want to tear this thing apart already!

10-20-2004, 06:39 PM	#10
bucket Registered User Join Date: Aug 2001 Location: Shawnee, KS Posts: 923	well i had a leak down test done today.............inconclusive on the oil burning. all cylinders are consistent w/in 10% and are all like 95% sealed. spark plugs were all consistent too. they looked pretty good. the mechanic told me to put some more miles on it till a suspect cylinder shows up (like a misfire). asked him about the knurling (although he's the one did them, but still is a straight shooter so i believe him) and he said that he didn't think that would be the issue. said that since they had not been knurled before, they had a quite a bit of material to work with and they wouldnt be leaking enough to exhibit these symptoms. he did acknowledge that both sides are burning to some extent.



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