GM 3.1 Intake Manifold gasket??

[3Bar_Mopar]

How difficult are these to change? Is there a How-to online somewhere?

[turbovanman²]

What vehicle?

They can be a PITA, yes.

[3Bar_Mopar]

What vehicle?

They can be a PITA, yes.

Man, I was thinking when I typed this post that "Simon would sure know!", lmao!

The vehicle is a 1995 Olds Achieva S. Relatively speaking...would it be as big a pain or as involved as say....removing a head on a TD? Doing this job for a friend and kinda wanted to know what I'm getting myself into.

[turbovanman²]

Well on a scale of 1-10, 1 being easy, a TD head would be a 3-5, I feel depending on how rusted, seized stuff is. A GM intake would be a 7-8.

You have to follow a certain order otherwise you go in circles.

Its a long proceedure but if you take your time, you can do it.

In a nutshell-

Drain coolant, remove air box and snorkel, upper rad hose, unbolt front coil mount brackets and bend back or remove, upper intake, alt, leave fuel rail hooked up to the fuel lines and unbolt, put aside, unbolt ps pump and put aside, blow off top of intake, remove coil pack if not done earlier, valve covers, intake. Remove rocker arms, note pushrod location as there different sizes for intake and ex. Clean off, make sure to degrease end seals and remove all traces of RTV, blow out holes, yada. Install gaskets dry, then rocker arms/pushrods, then RTV block and under/over end of gasket where it meets the block, install intake, apply blue loctite to bolts and torque to 12 ft/lbs-NO TIGHTER. Put back together, change oil and filter BEFORE you start it. I would also change the thermostat with the intake off and use a gm one, I find the aftermarket ones run too hot.

[iTurbo]

I take it the lower intake manifold gasket blew, getting coolant in the oil? Or are you just changing the upper? Hope the engine bearings are still OK..

[supercrackerbox]

He ain't kidding on the over-torquing the intake bolts. Been there, done that, had to replace an intake.

[iTurbo]

Yep I'd probably use an inch pound wrench on them. My brother stripped one on his turbo Cutlass once..he got by by using an oversize tap and bolt but eventually replaced the lower. There is also a tightening sequence that should be followed.

[slasky]

At least you don't have to change one on a mini van where half the engine is under the dash. As long as yo follow the proper procedure, get new intake bolts, and take your time it is not too bad.

[turbovanman²]

At least you don't have to change one on a mini van where half the engine is under the dash. As long as yo follow the proper procedure, get new intake bolts, and take your time it is not too bad.

Thats why I asked what car, lol.

I think its almost easier to drop the engine, I do that for head gaskets, I can have it on the ground on my GM roller stand in about 1.5 hours,

[TurboSedan]

it's not too bad of a job. make sure you get the revised lower intake manifold gasket, preferably GM. the 3100/3400 engines are notorious for the lower intake manifold gasket failing resulting in coolant spewing into the engine.

i've never done a lower intake on the GEN-III 3100 but it's probably about the same as the older GEN-II 3.1

lots of good info at 60degreev6.com

-----------------------------------
Joshua Mitchell
'91 Dodge SPiRiT R/T
'98 Buick Regal GS

[Skeezix]

Also lots of info on v6z24.com many of these guys swap their Gen II motor for a 3400 Gen III motor.

[TurboSedan]

Also lots of info on v6z24.com many of these guys swap their Gen II motor for a 3400 Gen III motor.

yeah, the 3x00 is definately a better engine than the older 3.1 MPFI that's for sure. they can actually breathe above 5000 RPM, better oiling, roller cam etc. alot of those guys on v6z24.com are making killer power with a turbo as well.

-----------------------------
Joshua Mitchell
'91 Dodge SPiRiT R/T
'98 Buick Regal GS

[looneytuner]

I was at the garage last week and the owner was talking about a valve (don't know which) on the front of the block that gives you the whipped cream oil symptom. You may want to check that first.
I wasn't paying attention so I can't give you more details.

[turbovanman²]

I was at the garage last week and the owner was talking about a valve (don't know which) on the front of the block that gives you the whipped cream oil symptom. You may want to check that first.
I wasn't paying attention so I can't give you more details.

Never heard of that one?

[1FastCSX289]

Never heard of that one?

Hes probably talking about the 3.8 EGR valve port that pukes coolant into the intake manifold?

On this 3.1 note......there is a colleague at work who has a 92ish Lumina APV van with the 3.1 THROTTLE BODY motor (yea, I know?). Lots of coolant in the oil, running a bit rough.....I told him to do a compression and leakdown on it to eliminate HG's as the source. I know that the HG's are fairly common on the 3.1's with MPFI and aluminum heads.....this one has cast heads and TBI. Do the intakes go on these as well? Basicly, if you had to bet as to the problem, what would you wager on? HG's or intake?

[88_pacifica]

Hes probably talking about the 3.8 EGR valve port that pukes coolant into the intake manifold?

On this 3.1 note......there is a colleague at work who has a 92ish Lumina APV van with the 3.1 THROTTLE BODY motor (yea, I know?). Lots of coolant in the oil, running a bit rough.....I told him to do a compression and leakdown on it to eliminate HG's as the source. I know that the HG's are fairly common on the 3.1's with MPFI and aluminum heads.....this one has cast heads and TBI. Do the intakes go on these as well? Basicly, if you had to bet as to the problem, what would you wager on? HG's or intake?

cracked intake.... I've seen it before on these motors from overtightening the bolts. Try and look at the intake bolt heads and see if they are slightly rounded(previously worked on) as the flange tends to crack at the intake "ears."

[turbovanman²]

Hes probably talking about the 3.8 EGR valve port that pukes coolant into the intake manifold?

On this 3.1 note......there is a colleague at work who has a 92ish Lumina APV van with the 3.1 THROTTLE BODY motor (yea, I know?). Lots of coolant in the oil, running a bit rough.....I told him to do a compression and leakdown on it to eliminate HG's as the source. I know that the HG's are fairly common on the 3.1's with MPFI and aluminum heads.....this one has cast heads and TBI. Do the intakes go on these as well? Basicly, if you had to bet as to the problem, what would you wager on? HG's or intake?

Intake again is the most common. Head gaskets are fairly good on the old Cast Iron headed models.

[turbodaytona87]

Yeah its a pain, will probably take a few hours the first time, but after that it goes real smooth. My friend has changed his a few times(The first was because it was leaking, then I'm not sure why, I think his head gasket blew or something like that)

[TurboSedan]

while you are doing the lower intake manifold gasket you might as well add a few more parts



-----------------------------
Joshua Mitchell
'91 Dodge SPiRiT R/T
'98 Buick Regal GS