Replacing intake manifold gaskets on a 98 Silverado - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CRF230Rider · 02-27-2004, 12:27 AM

Has anyone here replaced the intake maifold gaskets on a 98 or similar model Chevy/GMC truck? Mine has a 5.0 or 305 motor that is leaking coolant badly at the back of the cylinder head at the intake manifold. Everything I've read says to change the manifold gaskets so I guess that's what I'm in for. How long will the job take for average shade tree mechanic, 8 hours?

99-2door · 02-27-2004, 03:38 AM

8 hours, I would hope not, geez. It took me about 2.5 hours and I wasn't really in a big hurry. I do work with these trucks a lot though.

bpmcgee · 02-27-2004, 10:53 AM

If you've never done it before, leaving yourself a full day (8 hours) isn't a bad idea. Especially on the newer vehicles, there are a LOT of wires up top.

Take your time as you disconnect things. Either take digital pics as you go or use tape and a sharpie to mark wires and hoses as you disconnect. TRUST ME, every minute spent documenting will save you an hour of puzzling over wires and hoses as you put it together.

Although leaving yourself a full day is a good idea, I'd guess if you're careful and good with wrenches, you'll be done in time for an early Beer O' Victory!

Brian

kaycee · 02-27-2004, 03:53 PM

Looks like I'm going in that direction too seen a small spot of coolant on the garage floor yesterday.

kxmotox247 · 03-03-2004, 02:16 PM

There must have been something defective about these gaskets from day one.
My intake manifold gasket went out when the truck had less than 50K on it. Right in the back on the left bank head.
It took my buddy about 3 hours and he was a licensed GM mechanic at one point. He said he had never seen a gasket do what mine did and he felt it was probably defective to begin with.

graywolf · 03-04-2004, 02:31 PM

i have alot of friends who are mechanics, and it seems intake manifold gasket failure is very common, in all vehicles, soom think its something with the newer long life coolant, anyone else hear that?

kxmotox247 · 03-04-2004, 02:46 PM

Yep...i forgot to add that to my last post. I've been told that the dex cool crap is damaging the gaskets as well as slowly eating away at the freeze plugs.

graywolf · 03-04-2004, 05:48 PM

couple shops that i know of are flushing cooling system and installing the green antifreeze after replacing intake manifold gaskets, oh yea and don't ever mix the two together, it'll turn brown, and i heard the two mixed break each other down so that the lubricating value for water pump won't be there

graywolf · 03-04-2004, 05:56 PM

gm and ford also say do not use the 3m roloc fiber pads on a angle die grinder to remove gasket material on aluminum surface, ford says use plastic gasket scraper, gm says you can use die grinder with white roloc bristle disc,120 grit

99-2door · 03-04-2004, 08:47 PM

I've never had a problem with the intake gaskets on one of these trucks. I had to change the intake cause of one of those stinking water fittings.

97Silverado · 03-15-2004, 10:32 AM

This problem is due to the fact that these gaskets are overtorqued from the factory. To date I have done about 8 of these.

jsledder · 03-15-2004, 11:43 AM

Watch out for the water fitting on the intake, you will probably end up breaking the nice little plastic piece that holds it in there, you just as well go down and buy a new fitting at NAPA before you get started (8-9.00). The wires and everything look intimidating, there is really nothing to it, the wires will only plug into one fitting so you can't screw it up that way. Make sure you get the distributor marked and back in right. I used carb cleaner to clean the intake off inside and out and it cleaned up like new with no scrubbing, took about 10 cans though.

Good Luck, I tied up most of a weekend but I took my sweet time and cleaned everything up real good.

STEVE A WILBURN · 03-15-2004, 02:46 PM

YOU KNOW CHEVY IS GOING DOWN HILL IT LIKE MY PAINT ONE DAY JUST STARTED TO FALL OFF, I THINK GM SHOULD BE MADE FIX BAD PARTS AND PAINT, I KNOW I WONT BUY ANOTHER CHEVY

jsledder · 03-15-2004, 09:31 PM

And no other brand ever has a parts problem???

kxmotox247 · 03-16-2004, 10:25 AM

Quote:

Originally posted by jsledder
And no other brand ever has a parts problem???

No kidding! My neighbor's Fords are constantly giving him problems. One thing after the other.

**bwood** · 03-16-2004, 10:34 PM

The intake gaskets on mine were plastic and had an o-ring embedded in them for the seal. The mechanic was suprised to see that they made it that long (70000). The new ones are the same and he blamed it on the gaskets themselves, the plastic gets harder and ridgid from the constant warm up and cool down and eventually breaks (he said 99% of them in the same spot on the back passenger side). Usually it shows up in the winter around here. Good luck they had mine for a day.

MarkMagwire · 03-20-2004, 03:46 PM

Quote:

Originally posted by bwood
The intake gaskets on mine were plastic and had an o-ring embedded in them for the seal. The mechanic was suprised to see that they made it that long (70000). The new ones are the same and he blamed it on the gaskets themselves, the plastic gets harder and ridgid from the constant warm up and cool down and eventually breaks (he said 99% of them in the same spot on the back passenger side). Usually it shows up in the winter around here. Good luck they had mine for a day.

Just out of curiosity, did you have a dealer work on it? If you don't mind me asking what did they charge?

**bwood** · 03-20-2004, 07:04 PM

I had the dealer work on it, it has an extended warranty through GM so it only cost me $50. I did ask though, they said between $600-$700. After I woke back up (from the shock) they told me it was an all day job. A local mech told me he normally does this for around $350 - $450 including replacing the nipple in the intake.

*1FaastC10* · 03-21-2004, 11:25 PM

DO NOT USE PARTS STORE GASKETS! use genuine GM gaskets, they're thicker and will seal better than anything out there.

97silv5.7 · 03-22-2004, 02:33 AM

Wondering how long do those gaskets last? my 97 has 51k on it and its still nice and clean. Just wonderin so ill be prepared. Thanks

MarkMagwire · 03-23-2004, 11:50 PM

Good question '97. My '96 just turned over 100k and it sounds like I'm one of the fortunate ones. Good luck with yours.

02-27-2004, 12:27 AM	#1
CRF230Rider Registered User Join Date: Feb 2004 Posts: 1	Replacing intake manifold gaskets on a 98 Silverado Has anyone here replaced the intake maifold gaskets on a 98 or similar model Chevy/GMC truck? Mine has a 5.0 or 305 motor that is leaking coolant badly at the back of the cylinder head at the intake manifold. Everything I've read says to change the manifold gaskets so I guess that's what I'm in for. How long will the job take for average shade tree mechanic, 8 hours?

02-27-2004, 03:38 AM	#2
99-2door Registered User Join Date: Oct 2003 Location: Broken Bow, OK Posts: 1,385	8 hours, I would hope not, geez. It took me about 2.5 hours and I wasn't really in a big hurry. I do work with these trucks a lot though. __________________ 95 K3500 SRW 5.7L Vortec 4L80e 4.10 G80 2001 GMC C3 6.0 AWD, Volant, 3/5 drop TBSS intake, HP tuners, pullies, 05 efans, 05 front brakes, etc. 2003 Tahoe Z71 Silverado front clip

02-27-2004, 03:53 PM	#4
kaycee Registered User Join Date: Jan 2000 Location: Wyoming USA Posts: 2,445	Me To Looks like I'm going in that direction too seen a small spot of coolant on the garage floor yesterday. __________________ 2001 Silverado K-1500 2005 FXDWG stage3 69 CHEVY Short/Step 327/4L60 373 posi 63 IMPALA 327

03-03-2004, 02:16 PM	#5
kxmotox247 Senior Member Join Date: Jul 2002 Location: Champaign, IL Posts: 1,396	There must have been something defective about these gaskets from day one. My intake manifold gasket went out when the truck had less than 50K on it. Right in the back on the left bank head. It took my buddy about 3 hours and he was a licensed GM mechanic at one point. He said he had never seen a gasket do what mine did and he felt it was probably defective to begin with. __________________ Baby Blue's Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=652776 Project 68's Build Thread: http://67-72chevytrucks.com/vboard/s...17#post8442117 www.stonecolumnclassics.com Email: Josh@stonecolumnclassics.com

03-04-2004, 02:46 PM	#7
kxmotox247 Senior Member Join Date: Jul 2002 Location: Champaign, IL Posts: 1,396	Yep...i forgot to add that to my last post. I've been told that the dex cool crap is damaging the gaskets as well as slowly eating away at the freeze plugs. __________________ Baby Blue's Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=652776 Project 68's Build Thread: http://67-72chevytrucks.com/vboard/s...17#post8442117 www.stonecolumnclassics.com Email: Josh@stonecolumnclassics.com

02-27-2004, 10:53 AM	#3
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	If you've never done it before, leaving yourself a full day (8 hours) isn't a bad idea. Especially on the newer vehicles, there are a LOT of wires up top. Take your time as you disconnect things. Either take digital pics as you go or use tape and a sharpie to mark wires and hoses as you disconnect. TRUST ME, every minute spent documenting will save you an hour of puzzling over wires and hoses as you put it together. Although leaving yourself a full day is a good idea, I'd guess if you're careful and good with wrenches, you'll be done in time for an early Beer O' Victory! Brian

03-04-2004, 02:31 PM	#6
graywolf Registered User Join Date: Mar 2004 Posts: 15	i have alot of friends who are mechanics, and it seems intake manifold gasket failure is very common, in all vehicles, soom think its something with the newer long life coolant, anyone else hear that?

03-04-2004, 05:48 PM	#8
graywolf Registered User Join Date: Mar 2004 Posts: 15	couple shops that i know of are flushing cooling system and installing the green antifreeze after replacing intake manifold gaskets, oh yea and don't ever mix the two together, it'll turn brown, and i heard the two mixed break each other down so that the lubricating value for water pump won't be there

03-04-2004, 05:56 PM	#9
graywolf Registered User Join Date: Mar 2004 Posts: 15	gm and ford also say do not use the 3m roloc fiber pads on a angle die grinder to remove gasket material on aluminum surface, ford says use plastic gasket scraper, gm says you can use die grinder with white roloc bristle disc,120 grit

03-04-2004, 08:47 PM	#10
99-2door Registered User Join Date: Oct 2003 Location: Broken Bow, OK Posts: 1,385	I've never had a problem with the intake gaskets on one of these trucks. I had to change the intake cause of one of those stinking water fittings. __________________ 95 K3500 SRW 5.7L Vortec 4L80e 4.10 G80 2001 GMC C3 6.0 AWD, Volant, 3/5 drop TBSS intake, HP tuners, pullies, 05 efans, 05 front brakes, etc. 2003 Tahoe Z71 Silverado front clip

03-15-2004, 10:32 AM	#11
97Silverado Registered User Join Date: Mar 2004 Posts: 5	This problem is due to the fact that these gaskets are overtorqued from the factory. To date I have done about 8 of these.

03-15-2004, 11:43 AM	#12
jsledder Registered User Join Date: Aug 2002 Location: sd Posts: 97	Watch out for the water fitting on the intake, you will probably end up breaking the nice little plastic piece that holds it in there, you just as well go down and buy a new fitting at NAPA before you get started (8-9.00). The wires and everything look intimidating, there is really nothing to it, the wires will only plug into one fitting so you can't screw it up that way. Make sure you get the distributor marked and back in right. I used carb cleaner to clean the intake off inside and out and it cleaned up like new with no scrubbing, took about 10 cans though. Good Luck, I tied up most of a weekend but I took my sweet time and cleaned everything up real good. __________________ www.outdoorsupplyonline.com (snowmobile and atv parts) www.ipsindustrial.com (industrial tools)

03-15-2004, 02:46 PM	#13
STEVE A WILBURN Registered User Join Date: Feb 2004 Location: TONEY ALA Posts: 307	YOU KNOW CHEVY IS GOING DOWN HILL IT LIKE MY PAINT ONE DAY JUST STARTED TO FALL OFF, I THINK GM SHOULD BE MADE FIX BAD PARTS AND PAINT, I KNOW I WONT BUY ANOTHER CHEVY __________________ JUST HAPPY TO BE ALIVE.

03-15-2004, 09:31 PM	#14
jsledder Registered User Join Date: Aug 2002 Location: sd Posts: 97	And no other brand ever has a parts problem??? __________________ www.outdoorsupplyonline.com (snowmobile and atv parts) www.ipsindustrial.com (industrial tools)

03-16-2004, 10:34 PM	#16
bwood Registered User Join Date: Jan 2003 Location: Denison, Texas Posts: 1,919	The intake gaskets on mine were plastic and had an o-ring embedded in them for the seal. The mechanic was suprised to see that they made it that long (70000). The new ones are the same and he blamed it on the gaskets themselves, the plastic gets harder and ridgid from the constant warm up and cool down and eventually breaks (he said 99% of them in the same spot on the back passenger side). Usually it shows up in the winter around here. Good luck they had mine for a day. __________________ 1998 GMC Sierra SLE 1/2 ton 2WD 305 Vortec -Gibson Stainless Cat Back Swept Side -SS Wheels 2005 Honda CRF250R 2006 Honda CRF150F



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03-20-2004, 07:04 PM	#18
bwood Registered User Join Date: Jan 2003 Location: Denison, Texas Posts: 1,919	I had the dealer work on it, it has an extended warranty through GM so it only cost me $50. I did ask though, they said between $600-$700. After I woke back up (from the shock) they told me it was an all day job. A local mech told me he normally does this for around $350 - $450 including replacing the nipple in the intake. __________________ 1998 GMC Sierra SLE 1/2 ton 2WD 305 Vortec -Gibson Stainless Cat Back Swept Side -SS Wheels 2005 Honda CRF250R 2006 Honda CRF150F Last edited by bwood; 03-21-2004 at 01:31 AM.

03-21-2004, 11:25 PM	#19
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,400	DO NOT USE PARTS STORE GASKETS! use genuine GM gaskets, they're thicker and will seal better than anything out there.

03-22-2004, 02:33 AM	#20
97silv5.7 MooMoo Join Date: Feb 2004 Location: Shapleigh, Maine Posts: 2,424	Wondering how long do those gaskets last? my 97 has 51k on it and its still nice and clean. Just wonderin so ill be prepared. Thanks

03-23-2004, 11:50 PM	#21
MarkMagwire Registered User Join Date: Mar 2004 Posts: 11	Good question '97. My '96 just turned over 100k and it sounds like I'm one of the fortunate ones. Good luck with yours.

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