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Old 12-30-2010, 12:24 PM   #1
mears
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Default Another GM 3.1 Intake Manifold Gasket Thread

I'm going to attempt a self-repair on my 2000 Malibu with a leaking intake manifold gasket (presumably lower). I had it replaced a few years back and the mechanic used a NAPA gasket that appears to have failed. I called around and it was going to run me $800-$1000 to fix it. Car isn't worth a whole lot more than that, and by doing it myself I can pick out my own parts. After much research, I settled on the Fel-Pro gasket in favor of the updated OEM gaskets.

To start, I'm trying to decide if I should use any form of sealer around the intake ports. I've found several how-to sites that recommend using Permatex Aviation Grade Sealant, so I picked some up. I figure if there is any pitting, this may help. The Fel-Pro gasket instructions do say not to use sealant, but I'm wondering if that is just to prevent people from using a silicone based sealant.

I'll be using Right-Stuff for the end seals.
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Old 12-30-2010, 12:48 PM   #2
wafrederick
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

Are they the upgraded metal gaskets?No sealant on the intake gaskets,put in dry and RTV silicone on the ends only.Another tip,make sure you have the push rods in the right spot or you will have bent valves.Yes,the push rods are two differant lengths (6 long and 6 short).I have done tons of these installing the gaskets dry.GM says not to reuse the intake bolts on the 3400s and this does not include the 3100s
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Old 12-30-2010, 12:58 PM   #3
kornjulio
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

I've done the LIM on the 3.4 - should be pretty much the same on the 3.1. Didn't use any sealant around the ports; just a healthy RTV bead at the ends. As mentioned, keep the pushrods in order & prep the surfaces well.
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Old 12-30-2010, 01:48 PM   #4
mears
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

Yeah, my new Fel-Pro gaskets are metal (PermaDry Plus).

Will it hurt to add sealant around the coolant ports? If it won't, I just may do so because I'm definitely not looking to redo it. Do you guys advise having a coolant pressure test done after I button everything back up?
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Old 12-30-2010, 02:22 PM   #5
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

I plan on doing this to my parents car this winter, so any guidance is appreciated.

You taking pictures or video!


Chris
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Old 12-30-2010, 02:27 PM   #6
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

Quote:
Originally Posted by mears View Post
Yeah, my new Fel-Pro gaskets are metal (PermaDry Plus).

Will it hurt to add sealant around the coolant ports? If it won't, I just may do so because I'm definitely not looking to redo it. Do you guys advise having a coolant pressure test done after I button everything back up?
You're just itching to put some extra goo somewhere, eh?

Have some faith in the parts you've purchased. Be more concerned about things like surface prep & bolt torque. I don't recommend a coolant pressure test when you're done. Just keep an eye on the level in the bottle & look for internal & external leaks - the little valley right below the throttle body is a good spot to shine the flashlight down into, looking for coolant.

I never did this job before I did my 3.4. With GM parts, lots of research on the 'net & an entire weekend of working slowly, it's been good for 3-4 years now?....
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Old 12-30-2010, 03:50 PM   #7
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

was the use of scotchbrite pads on small buffers the reason these engines started failing?...........i ask because i heard about the pads and figured that with all the manifold leaks gm had , techs were using these to speed up cleanup of the surfaces.......
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Old 12-30-2010, 04:44 PM   #8
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

DO NOT USE SEALANTS AROUND THE PORTS OF THE INTAKE!!!!!!!!

It is engineered to be dry sealed. And...the issue with this motor is that it leaks on the ends...not around the ports.
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Old 12-30-2010, 05:03 PM   #9
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

I've done many of these with no comebacks. My secrets
1. Use only the Felpro metal permafix gasket; do no use any sealants on the gasket sealing areas.
2. Clean all mating surfaces absolutely cleaan. Clean out bolt holes and clean up the bolts. I reuse bolts with no problems.
3. Use RTV black for end seals, nice thick bead, but don't get too sloppy.
4. Replace the rubber oil seal on gear pump shaft while you have the intake off.
5Replace the heater quick connector fitting while everthing is off.
6 Use a dial torque wrench (inch/lbs) when tighening bolts. Use 3 steps to achieve final torque. Use correct torque and pattern.
7. Lisles makes a tool to easily remove the pushrods.

Now that I have told you my trade secrets, I expect you to report back as to how the repair went.

Last edited by jay50; 12-30-2010 at 05:42 PM.
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Old 12-30-2010, 05:30 PM   #10
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

If the aluminum intake is badly pitted, I have one more trick.

Mix up some JB "quick" weld and apply it over the pits with a razor blade. If it does not come out smooth enough for you, wrap some scotch brite around a piece of wood (or anything flat) and smooth it out when it dries.
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Old 12-30-2010, 05:49 PM   #11
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

i can't tell you how many gasket kits and plenum replacement kits we sell for the 3.1's and 3.8's. just amazes me how bad of a design it was on those vehicles.

not to mention light bulbs for every SUV and truck from 2000 up on chevrolet gmc and cadillac. can't they just build a decent alternator with a good voltage regulator? there is no dought in my mind they are over volting lights for more brightness
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Old 12-30-2010, 10:30 PM   #12
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

Most engine builders will tell you not to use the scotchbrite pads for cleaning the gasket surfaces.The little pieces from the scotchbrite pads get inside the engine and that is not good.I use a wire cup brush on a diegrinder that will not do damage to aluminum wearing safety glasses.
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Old 12-30-2010, 10:39 PM   #13
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

Just started. Didn't get too far. I'm trying to use the Thexton Engine Tilting tool and can't locate the torque strut mount. Haynes manual doesn't have an image for it and it's not even mentioned in the service manual. Any ideas?

Based on my experience replacing plugs a wires a couple years back, I need to use this tilter
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Old 12-30-2010, 11:51 PM   #14
Andy Griffith
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

I did this job on my wife's 96 Old's earlier this year with much help from the people here on GJ.

2000 malibu is probably different but this is the engine tilter tool in use on the 96 (lower right in picture)



This is one thread from earlier this year.
http://www.garagejournal.com/forum/s...ad.php?t=60677

Last edited by Andy Griffith; 12-30-2010 at 11:57 PM. Reason: Add link to earlier thread
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Old 12-31-2010, 12:37 AM   #15
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

It's all nuts and bolts. If you're fairly handy, you can do this job yourself. I used to work in a GM dealer and did literally 100s of these intakes. They're not that hard at all.

As far as surface prep, I wouldn't use much more than a razor blade to scrape gunk and some brake clean to clean up the mess. It doesn't have to be spotless, just smooth.

I'd also use factory gaskets to do the repair. You can reuse bolts, but be sure to torque lower intake bolts properly. Also, only use RTV on the ends and make sure you put the pushrods back in the same place they came out of. The intake and exhaust pushrods are different lengths and will bend if they are not installed in the proper place.

Good luck.
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Old 12-31-2010, 12:54 AM   #16
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

pushrod lengths, how much difference?........visible by eye or side by side comparison?........never worked on one of these besdies plug change outs........
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Old 12-31-2010, 06:03 AM   #17
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

Quote:
.I use a wire cup brush on a diegrinder that will not do damage to aluminum wearing safety glasses.
the metal wires break off. Over time they wear out, those little wires are going to fatigue, wear, break off and go in to the motor.

I use safety razors or a gasket scraper.
And sometimes I use a shop vac to suck up small pieces and even small amounts of sludgy oil. Vacuum out the ports too.
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Old 12-31-2010, 06:09 AM   #18
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

That Olds looks pretty clean underhood for a '96...you do something special or are all cars in WA like that?
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Old 12-31-2010, 08:40 AM   #19
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

6 of the push rods are about 1/4" shorter.I never had any of the metal wires go inside the engine,they get on me stuck in my work shirt.One machine shop in my area advises not to use the scotchbrite pads when cleaning gasket surfaces unless rebuilding the engine.The complete Dorman kit for the 3400s come with new intake bolts since GM advises not to reuse the intake bolts.Will have to use a chrome 10mm universal socket in 1/4" drive on two of the intake bolts,the right front and rear left bolts.
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Old 12-31-2010, 12:32 PM   #20
mears
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Default Re: Another GM 3.1 Intake Manifold Gasket Thread

Quote:
Originally Posted by Andy Griffith View Post
I did this job on my wife's 96 Old's earlier this year with much help from the people here on GJ.

2000 malibu is probably different but this is the engine tilter tool in use on the 96 (lower right in picture)



This is one thread from earlier this year.
http://www.garagejournal.com/forum/s...ad.php?t=60677
Yeah, that's a bit different and I don't have a torque strut in that location.
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