Intake manifold question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Row · 02-15-2009, 11:34 AM

So I'm in the process of replacing my transmission. While under the hood, loosening bolts for the transmission, I noticed a bolt was missing from the rear of the intake manifold. So, me being new to engines/transmissions, I asked two different friends about this problem. One friend said all I have to do is replace the bolt and I'm done. The other friend said I have to remove my intake manifold and clean then replace the gasket. I've looked (maybe not hard enough) but I cant seem to find an answer. Here are some pics of my intake manifold.

PanelDeland · 02-15-2009, 11:43 AM

Since it doesn't appear to be leaking,I would replace the bolt.Try putting a small screwdriver in the hole.The bolt may be broken off but if it ain't broke don't fix it.(in other words replace the bolt if it's just missing,but don't worry about it if it's broken off as long as it isn't leaking).You can remove the broken one when it starts leaking or if you tear into it for some reason.

sjarrett71 · 02-15-2009, 11:46 AM

If the truck has been running fine with no vacuum leaks, I would just replace the bolt.

Row · 02-15-2009, 11:52 AM

So, a missing bolt wouldnt cause the gasket to go bad?

truckpoorpackrat · 02-15-2009, 12:05 PM

Looks like you have 1 bolt missing & the back 1 is loose. To replace just the bolt or the gaskets and the bolt depends on if it is leaking. I would suggest replacing the bolt & tighten the other one, clean off the area with brake clean and check for leaks in a few days. You might want to check your fluids (water & oil ) to make sure no leaks inside. I guess it is running OK . If no leaks you should be ok, if there is a leak then you will probably want to replace the intake manifold gaskets like your friend suggested.

cdowns · 02-15-2009, 12:53 PM

spray brakekleen in the hole //put thread sealer on new bolt and install //while your at it check to see if the other bolts are snug

Row · 02-15-2009, 12:57 PM

After I put in the new bolt, how can I tell if I have a leak?

truckpoorpackrat · 02-15-2009, 01:40 PM

After you have replaced the bolt & cleaned off the area, it should stay clean. From the look of the area behind the intake it may be leaking or may have just been seeping so tightening the bolt & replacing the other one may fix it. You will want to clean off the area behind the intake also.

Row · 02-15-2009, 10:29 PM

how can i tell if the gasket needs to be replaced?

**El Jay** · 02-15-2009, 10:55 PM

After you get the bolts tightened/replaced, fire up the engine.
After it will slow down to an idle, spray some carburetor cleaner around the mating surfaces between the manifold & the head, you may as well spray around the carburetor while you're at it. If the idle speed increases, you have a vacuum leak.
Pretty simple when you get right down to it.

Row · 02-15-2009, 10:56 PM

Thanx!

**El Jay** · 02-15-2009, 11:05 PM

I should have said, "If the idle speed increases, you have a vacuum leak in the area you are spraying."

Sport/Truck · 02-15-2009, 11:25 PM

Don't use a bolt thats longer than 1.25 in. there are a couple of areas for leaks; intake vacuum & water. If your oil is milky it's leaking inside, if it's leaking antifreeze on the out side you should be able to see it. The above methods are good for checking for vacuum leaks.
s/t

Row · 02-15-2009, 11:37 PM

Thanx for the tips! As soon as u get my new transmission I'm gonna get those bolts fixed

02-15-2009, 11:34 AM	#1
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Intake manifold question So I'm in the process of replacing my transmission. While under the hood, loosening bolts for the transmission, I noticed a bolt was missing from the rear of the intake manifold. So, me being new to engines/transmissions, I asked two different friends about this problem. One friend said all I have to do is replace the bolt and I'm done. The other friend said I have to remove my intake manifold and clean then replace the gasket. I've looked (maybe not hard enough) but I cant seem to find an answer. Here are some pics of my intake manifold.

02-15-2009, 11:43 AM	#2
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: Intake manifold question Since it doesn't appear to be leaking,I would replace the bolt.Try putting a small screwdriver in the hole.The bolt may be broken off but if it ain't broke don't fix it.(in other words replace the bolt if it's just missing,but don't worry about it if it's broken off as long as it isn't leaking).You can remove the broken one when it starts leaking or if you tear into it for some reason. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil" Last edited by PanelDeland; 02-15-2009 at 11:44 AM.

02-15-2009, 11:46 AM	#3
sjarrett71 Registered User Join Date: Dec 2006 Location: Rolla, MO Posts: 2,463	Re: Intake manifold question If the truck has been running fine with no vacuum leaks, I would just replace the bolt.

02-15-2009, 11:52 AM	#4
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Intake manifold question So, a missing bolt wouldnt cause the gasket to go bad?

02-15-2009, 12:05 PM	#5
truckpoorpackrat Registered User Join Date: Dec 2008 Location: joplin mo. Posts: 272	Re: Intake manifold question Looks like you have 1 bolt missing & the back 1 is loose. To replace just the bolt or the gaskets and the bolt depends on if it is leaking. I would suggest replacing the bolt & tighten the other one, clean off the area with brake clean and check for leaks in a few days. You might want to check your fluids (water & oil ) to make sure no leaks inside. I guess it is running OK . If no leaks you should be ok, if there is a leak then you will probably want to replace the intake manifold gaskets like your friend suggested.

02-15-2009, 12:53 PM	#6
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Intake manifold question spray brakekleen in the hole //put thread sealer on new bolt and install //while your at it check to see if the other bolts are snug __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

02-15-2009, 12:57 PM	#7
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Intake manifold question After I put in the new bolt, how can I tell if I have a leak?

02-15-2009, 01:40 PM	#8
truckpoorpackrat Registered User Join Date: Dec 2008 Location: joplin mo. Posts: 272	Re: Intake manifold question After you have replaced the bolt & cleaned off the area, it should stay clean. From the look of the area behind the intake it may be leaking or may have just been seeping so tightening the bolt & replacing the other one may fix it. You will want to clean off the area behind the intake also.

02-15-2009, 10:29 PM	#9
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Intake manifold question how can i tell if the gasket needs to be replaced?

02-15-2009, 10:55 PM	#10
El Jay Gone to greener pastures Join Date: May 2007 Location: Gateway to the Delta Posts: 7,354	Re: Intake manifold question After you get the bolts tightened/replaced, fire up the engine. After it will slow down to an idle, spray some carburetor cleaner around the mating surfaces between the manifold & the head, you may as well spray around the carburetor while you're at it. If the idle speed increases, you have a vacuum leak. Pretty simple when you get right down to it. __________________ '69 Chevy 1/2 T LWB Stepper: Daily Beater '72 GMC 3/4 T Fleet: Another Daily Beater '72 Plymouth Gran Coupe: ? "Ah women. They make the highs higher and the lows more frequent." Friedrich Nietzsche "Never kick a fresh turd on a hot day." Harry S. Truman GUN CONTROL: Never having to say, "I missed you." Always fire two warning shots into your attacker's chest area before putting a bullet between his eyes. Paraphrased from Louis Awerbuck Last edited by El Jay; 02-15-2009 at 10:56 PM.

02-15-2009, 10:56 PM	#11
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Intake manifold question Thanx!

02-15-2009, 11:05 PM	#12
El Jay Gone to greener pastures Join Date: May 2007 Location: Gateway to the Delta Posts: 7,354	Re: Intake manifold question I should have said, "If the idle speed increases, you have a vacuum leak in the area you are spraying." __________________ '69 Chevy 1/2 T LWB Stepper: Daily Beater '72 GMC 3/4 T Fleet: Another Daily Beater '72 Plymouth Gran Coupe: ? "Ah women. They make the highs higher and the lows more frequent." Friedrich Nietzsche "Never kick a fresh turd on a hot day." Harry S. Truman GUN CONTROL: Never having to say, "I missed you." Always fire two warning shots into your attacker's chest area before putting a bullet between his eyes. Paraphrased from Louis Awerbuck

02-15-2009, 11:25 PM	#13
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Intake manifold question Don't use a bolt thats longer than 1.25 in. there are a couple of areas for leaks; intake vacuum & water. If your oil is milky it's leaking inside, if it's leaking antifreeze on the out side you should be able to see it. The above methods are good for checking for vacuum leaks. s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.

02-15-2009, 11:37 PM	#14
Row Registered User Join Date: Feb 2009 Location: )(&)(&&&^%$ Posts: 51	Re: Intake manifold question Thanx for the tips! As soon as u get my new transmission I'm gonna get those bolts fixed

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