Replacing Head Gaskets - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69C10@16 · 02-22-2008, 12:49 AM

Ok, my engine has been running more than extremely crappy lately. Could NOT figure out why. It had a "puff rattle" when the engine was under load and when it got to about 1800 RPM it "suddenly" gained some power. Tried a timing light out and Number 1 wasn't firing at normal intervals. It was sperratic. Walked the timing light around the engine and pistons 4 and 8 did the same. Firing order: 18436572. 1, 8, and 4. Huh, replace dist. cap. Same crap. Started inspecting the "puff rattle" with some compression testing. 4 and 6 have ZERO compression. Put a plug back in 6 and compression tested 4 and got a little compression. So i'm guessing the head gasket is blown between 4 and 6. Valve springs are good. And if it was the valves then putting a plug back in 6 wouldnt have given me compression on number 4. The puff is clearly coming through the carb so when 4 is on its exhaust stroke the intake valve for 6 must be open causing the noise. I figure I'll replace the head gaskets to get my compression back and then inspect my ignition issues. Just wanted to make sure I was on the right track.

Heres the list of stuff I know I need, add to it if I've missed anything please.

Torque Wrench (65 ft. lbs on head bolts)
Head Gaskets
Intake Gaskets
Exhaust Gaskets
Someone that knows more than me

**truckdude239** · 02-22-2008, 02:13 AM

sounds about right remenebr to torque your head bolts in 3 steps like 15 35 65 have the heads checked at a machine shop and get new head bolts

89 crew · 02-22-2008, 02:27 AM

Don't forget to take a thread chaser to the head bolt holes then antiseize

69C10@16 · 02-22-2008, 05:31 AM

Do I have to replace the head bolts? I JUST got a job at O'reilly's and I don't get payed for two weeks but this has GOT to be done, well, NOW. I think I'm gonna be able to con my uncle into helping me. He's been working on these engines for 40 years so he oughta know what the heck he's doin.

Old Chevy Mech · 02-22-2008, 06:04 AM

If you are running an aluminum intake make sure you run the torque sequence about 6 times to get a proper torque on all bolts. Just my experience but not doing that caused me much grief and poor performance over the past few years. Engine runs great now!

Frank

89 crew · 02-22-2008, 07:40 AM

as long as the threads are not beat up you can get away without replacing them. I would run a thread chaser over them before use just to make sure they are right.

stllookn · 02-22-2008, 08:20 AM

Don't forget to replace those heads with some Vortecs and put in a new cam/lifter kit while you are in there.

joedoozer · 02-22-2008, 08:32 AM

Quote:

Originally Posted by stllookn

Don't forget to replace those heads with some Vortecs and put in a new cam/lifter kit while you are in there.

Haha......nice logic

but thats not your wife you are talking to hahaha. Thats the guys version of "it was on sale", that they use on us all the time haha.

72BLUZ · 02-22-2008, 08:37 AM

dont forget to seal those head bolts. some of them go into the water jackets. without sealant on the bolts you could leak coolant. make sure you torque in the correct sequence. i always start in the center and work outward in a circle pattern. then repeat to reassure myself.

**truckdude239** · 02-22-2008, 09:52 AM

you dont have to replace them but at 15 buxs a set its easy reassurace i'd hate top do a job that big and have to go back and replace just because one was stresated from many years of oh heating up and cooling down they do get longer over time

tim21391 · 02-22-2008, 12:17 PM

i am missing on 1 and 4 cylinders and my mechanic said my valves need to be readjusted...he said to torque them to 0 + 1/2

**truckdude239** · 02-22-2008, 07:12 PM

misadjusted valves wont cause a miss just alot of noise

69C10@16 · 02-23-2008, 12:39 AM

I didn't realize the bolts were that cheap. I'll just replace them. I'd absolutely love to put in a Lunati Voodoo cam with some Lunati roller lifters and rockers. I don't think I'm gonne sneak that one by my dad though.

I've got the bolt sequence in a Haynes Repair Manual so that's all taken care of. I think my uncle is gonna be able to help me out after all so he'll have more input too i'm sure. The best thing is he won't just do it. He'll expect me to do all of it while he watches and makes sure I don't mess up. That means I get to learn what I'm doing as I do it. I love it when that happens!

**truckdude239** · 02-23-2008, 09:11 AM

yeah but it does take 2 sets

tim21391 · 02-26-2008, 10:13 PM

ok sorry truck dude

02-22-2008, 12:49 AM	#1
69C10@16 Registered User Join Date: Aug 2007 Location: Greenfield, MO Posts: 215	Replacing Head Gaskets Ok, my engine has been running more than extremely crappy lately. Could NOT figure out why. It had a "puff rattle" when the engine was under load and when it got to about 1800 RPM it "suddenly" gained some power. Tried a timing light out and Number 1 wasn't firing at normal intervals. It was sperratic. Walked the timing light around the engine and pistons 4 and 8 did the same. Firing order: 18436572. 1, 8, and 4. Huh, replace dist. cap. Same crap. Started inspecting the "puff rattle" with some compression testing. 4 and 6 have ZERO compression. Put a plug back in 6 and compression tested 4 and got a little compression. So i'm guessing the head gasket is blown between 4 and 6. Valve springs are good. And if it was the valves then putting a plug back in 6 wouldnt have given me compression on number 4. The puff is clearly coming through the carb so when 4 is on its exhaust stroke the intake valve for 6 must be open causing the noise. I figure I'll replace the head gaskets to get my compression back and then inspect my ignition issues. Just wanted to make sure I was on the right track. Heres the list of stuff I know I need, add to it if I've missed anything please. Torque Wrench (65 ft. lbs on head bolts) Head Gaskets Intake Gaskets Exhaust Gaskets Someone that knows more than me

02-22-2008, 02:13 AM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,230	Re: Replacing Head Gaskets sounds about right remenebr to torque your head bolts in 3 steps like 15 35 65 have the heads checked at a machine shop and get new head bolts __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

02-22-2008, 02:27 AM	#3
89 crew Registered User Join Date: Mar 2006 Location: Kansas Posts: 865	Re: Replacing Head Gaskets Don't forget to take a thread chaser to the head bolt holes then antiseize

02-22-2008, 05:31 AM	#4
69C10@16 Registered User Join Date: Aug 2007 Location: Greenfield, MO Posts: 215	Re: Replacing Head Gaskets Do I have to replace the head bolts? I JUST got a job at O'reilly's and I don't get payed for two weeks but this has GOT to be done, well, NOW. I think I'm gonna be able to con my uncle into helping me. He's been working on these engines for 40 years so he oughta know what the heck he's doin.

02-22-2008, 06:04 AM	#5
Old Chevy Mech Keepin it runnin! Join Date: Oct 2007 Location: Deep River, CT Posts: 1,036	Re: Replacing Head Gaskets If you are running an aluminum intake make sure you run the torque sequence about 6 times to get a proper torque on all bolts. Just my experience but not doing that caused me much grief and poor performance over the past few years. Engine runs great now! Frank __________________ 1970 K-5 4X4 Blazer 1970 K-20 4X4 Long Bed "Liberty Means Responsibility, that is why most men dread it"

02-22-2008, 07:40 AM	#6
89 crew Registered User Join Date: Mar 2006 Location: Kansas Posts: 865	Re: Replacing Head Gaskets as long as the threads are not beat up you can get away without replacing them. I would run a thread chaser over them before use just to make sure they are right.

02-22-2008, 08:20 AM	#7
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	Re: Replacing Head Gaskets Don't forget to replace those heads with some Vortecs and put in a new cam/lifter kit while you are in there. __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary)

02-22-2008, 08:37 AM	#9
72BLUZ Registered User Join Date: Nov 2006 Location: lafayette, ga. Posts: 832	Re: Replacing Head Gaskets dont forget to seal those head bolts. some of them go into the water jackets. without sealant on the bolts you could leak coolant. make sure you torque in the correct sequence. i always start in the center and work outward in a circle pattern. then repeat to reassure myself. __________________ Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same.... Ronald Reagan

02-22-2008, 09:52 AM	#10
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,230	Re: Replacing Head Gaskets you dont have to replace them but at 15 buxs a set its easy reassurace i'd hate top do a job that big and have to go back and replace just because one was stresated from many years of oh heating up and cooling down they do get longer over time __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

02-22-2008, 12:17 PM	#11
tim21391 Registered User Join Date: Jul 2007 Location: Salina, Kansas Posts: 1,998	Re: Replacing Head Gaskets i am missing on 1 and 4 cylinders and my mechanic said my valves need to be readjusted...he said to torque them to 0 + 1/2

02-22-2008, 07:12 PM	#12
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,230	Re: Replacing Head Gaskets misadjusted valves wont cause a miss just alot of noise __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

02-23-2008, 12:39 AM	#13
69C10@16 Registered User Join Date: Aug 2007 Location: Greenfield, MO Posts: 215	Re: Replacing Head Gaskets I didn't realize the bolts were that cheap. I'll just replace them. I'd absolutely love to put in a Lunati Voodoo cam with some Lunati roller lifters and rockers. I don't think I'm gonne sneak that one by my dad though. I've got the bolt sequence in a Haynes Repair Manual so that's all taken care of. I think my uncle is gonna be able to help me out after all so he'll have more input too i'm sure. The best thing is he won't just do it. He'll expect me to do all of it while he watches and makes sure I don't mess up. That means I get to learn what I'm doing as I do it. I love it when that happens!

02-23-2008, 09:11 AM	#14
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,230	Re: Replacing Head Gaskets yeah but it does take 2 sets __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

02-26-2008, 10:13 PM	#15
tim21391 Registered User Join Date: Jul 2007 Location: Salina, Kansas Posts: 1,998	Re: Replacing Head Gaskets ok sorry truck dude



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