intake manifold gasket - selected posts

i searched google groups prior to changing the intake manifold gasket on my truck (1999 Chevy K1500), and jotted a few posts from different people. just in case that somebody might find this helpful, i will copy here my text file that i ended up with of snippets from the posts that i saw. basically it lists recommendations and experiences from people that previously changed intake manifold gaskets. i saw somebody else do something like this in a digital tv newsgroup and i thought it was helpful. here it is....

====================================

Being used to wrenching on asian designs for many decades and still getting

used to the 'merican way of design and doing things, I have to say whatta

PITA! Who decided that the rear of the engine is a great place for the

distributor??? Once I pulled the manifold, I was amazed to find that the

coolant ports that were leaking from the head side had no peer port in the

manifold. WTF? Only the front ports in the heads flow into the manifold

and the rear are blocked (yet there is still a gasket with a hole in it and

a point of failure to leak like mine was doing). Astounding.

Gettin' it all bolted back up single-handedly was a joy in that you have to

angle the thing in just right to clear the sending unit at the back of the

block but not low enough to bugger the bead of RTV you have to lay on the

front and the back of the block between the gaskets. You have one shot to

position it and drop directly down into position or you need to pull it off

and redo the RTV bead. Flimsy. On the asian designs, there would be an

channel machined into the intake manifold where you'd lay a nice o-ring and

the whole works would bolt up without all the rigmarole associated with this

design.

OK, the damn thing is on, bolts smeared up with red loctite, torque up to 11

ft.-lb., the wiring harness and vacuum lines installed, coolant topped off,

oil changed and all the shrouds put back on and the thing fires up. She's

holdin' seal (so far). Now, we'll have to see how long that lasts since

when you mate dissimilar metal components, the differential in thermal

expansion/contraction induces a lot of shear on the gasket making them prone

to leak. Any bets?

I'll bet that if you used the Fel-Pro replacement gasket set it won't leak.

============================================================================

It's unfortunate that you dis-assembled this part of the intake as

there is no need to do this, unless you were also replacing the

upper plenum gasket. I would re-install the upper on the lower,

take those small fuel line sections that connect to the CSFI and

make sure they are re-installed on the upper "before" you install

the entire manifold assembly.

I don't know what else you can use. If you make sure both the block

and the intake is perfectly clean and dry, and you apply the proper amount,

and you are careful to basically levitate the manifold above the RTV until

you are exactly above the RTV in the correct position..and then lower

the manifold straight down on it....it will seal quite well. As an added

precaution...you could torque down the manifold and then let the RTV

setup for a few hours, or overnight.

You are probably missing a nut. There are three long bolts that run

through the bracket, one is down low...close to the harmonic balancer,

two are in plain sight at the top of bracket. There is also one stud with

a nut at the top of the bracket. Then.....there is a bracket with a nut

securing it down behind the ps pump on the drivers side head....and

there is one more bracket with a nut....way down low on the drivers

side of the block. The nut behind the ps pump can simply be loosened,

the bracket is slotted there....the other nut down low, must be removed.

4) get a powersteering pully puller to remove the pully to get at the

bolts and just slide it forward not all the way out. don't tear shit

off that does'nt need to come off. remove top half of shroud, alt and

slide bracket, fan off, bungee the a/c unit up with the wiring ( you

may need to prop hood due to weight. bend back brackets and get all

the shit out of the way of the manifold so you can set it straight

down.

5) use the RTV and nothing else. this silicone sealer will probably

last the longest. Kind of like doing the bath tub. Lacquer Thinner is

a great cleaning solvent. Clean,clean,clean no grease. use the whole

tube of RTV in the kit. You wiil get more for the next project. don't

be cheap; your saving $600 as it is.

6) reading the manual i quickly realized that i did not need to

disassemble the top manifold. no coolant up there and fuel system was

just fine. i would get the manifold together on the bench then fit

into the truck.

7) you only put sealant on the heads around the coolant passages and

on the ends of the block. install the gaskets (tabs push into the

block) then put a bead of sealant(RTV) 1/2 in up the gaskets on the

gasket at the block ends.

Remember to clean the threads of your intake bolts and apply some

Loctite medium strength threadlocker before you install them.

============================================================================

All messages from thread

Message 1 in thread

From: Tim ( snipped-for-privacy@hotmail.com)

Subject: Skill/Tools required to replace 5.7 Vortec intake manifold gasket

View this article only

Newsgroups: alt.trucks.chevy

Date: 2003-01-09 06:38:46 PST

Gentlemen,

I have apparently become a member of the "Chevy 5.7 Vortec w/ coolant leak"

club.

My '96 Yukon 2DR 4WD, has been (up until now) running great. - 61,000 mi.-

As I intend to keep the truck for at least 2 more years, I need to get it

fixed.

After calling several dealerships in the So. Florida area, I received quotes

ranging between $500 to $900 for replacing the gaskets.

Since I have an interest in both saving money and getting my hands under the

hood...

I have a few questions:

What are the Skills requires to replace the (what I am assuming is the Lower

Intake Manifold Gasket?

Do I need to replace the Upper Intake Manifold gasket?

I already have the Haynes Manual, Should I get the 96 GM C/K Truck Shop

Manual also?

Can this be done by an inexperienced DIY'er? (me)

My DIY service experience on the Yukon:

Oil Change

Alternator replacement

Heater Core Valve replacement

Lastly, please share any insight into this procedure that you might think

make the job go easier.

Tim I recently changed the intake gaskets on a 95 4.3l engine and the job

wasn't too difficult. Take your time and mark connectors, etc. Most will

only go back on specific connectors but makes the job so much easier if you

have everything marked. The 95 was a CPI engine and I changed the upper

gasket was well as the lower one (the one that actually was leaking). You

will probably have to remove the distributor to get the manifold off. Mark

the relationship of the rotor with the housing and the housing with the

engine. In my case and maybe yours, the distributor housing was fixed via a

pin so only one position was correct when it was slipped back in to place.

The bolt holding the distributor is awkard to get at. I bought a $4 wrench

at Autozone. Of course don't rotate the engine once the dist. is out. One

caution that added an hour to the job. When you remove the distributor the

drive gear is spiral cut and it will rotate as it's being removed. A cam

gear drives the distributor. The oil pump is driven off the distributo

shaft. When I removed the distributor the oil pump also rotated and when I

first started to reassemble it wouldn't engage the oil pump shaft. Through

trial and error I rotated the oil pump shaft slightly until the distributor

shaft would engage and slip into place. The hardest part of the job was

cleaning off the old gasket. I used felpro replacement gaskets. If the

dist. is at the rear of the engine it would be a good time to replace cap

and rotor and maybe plug wires too. Total cost of the job was less than

$40.

Although your 5.7 is a bit different than mine (mine's a '95), the

concept and procedure are still much the same.

Remember this: Be patient, and methodical. Mark everything so it

goes back together, etc., keep all bolts in order, as they might be

different lengths, etc. I used a scotch-brite pad on my air

die-grinder to clean all the surfaces. It's kinda tough getting it

clean using a gasket scraper, even if you use that spray-on gasket

remover. I used a tap to chase the threads clean in the heads, then

used a good anti-sieze on each bolt. I also sucked all the nooks and

cranny's clean with my shop vac; you'll get coolant, gasket chunks,

sealer, and everything else under the sun down in there. I then

drained the oil, and flushed out the block again with 4 quarts of

cheapie oil, then filled up with Mobil 1. Overkill maybe, but I

watched the crap come outta the oilpan, so better safe than sorry.

If you have a Haynes manual, etc., just follow all the steps, and you

should have no problems.

One more important note: Never, ever, ever, swear at your beloved

truck if you have the engine apart. It will never, ever, EVER start

once you get it back together!!!!!

=========================================================================

As it turns out, my Dad's '98 Chevy 3/4 ton pickup with the 350 Vortec has

just developed the intake manifold gasket leak at 120,000+ miles. Appears to

only be external on the side behind the alternator. The oil has never shown

any problems. I've seen people mention the Fel-Pro gasket set as the choice

replacement. Went to their website tonight, but couldn't locate a dealer

list. What is the approximate cost of the set and what types of dealers

carry them?

Also, is it a "liquid" type OEM gasket that was used on the engine? He

mentioned the same thing I noticed on my '95 Yukon with the TBI today while

replacing the water pump. It looks like oozed silicone under the intake

manifold. Just curious

Some of the Chevy's late model engines use silicone for the gasket

on the ends of the intake. That is the part that goes across from side

to side in the front of the intake, and also across the back area. It

should be a regular gasket down the sides where the actual intake ports

in the heads and water jackets are. Where I work FelPro intake gaskets

for the regular chevy blocks are around 8 bucks. I am not sure about

the Vortec sets as I suspect that they are a few dollars higher. Be

sure and "torque" the intake bolts to the appropriate torque and make

sure that they are all torqued evenly. That can help prevent the

problem from cropping up again down the road.

Sterling......

==========================================================================

At first I though, geez what a snap, give me 5 min and I'll tell you

everything you need to know. Then I wrote a small book. Then I decided

to add this at the top.

I don't know if I would attempt this unless I was familiar with

Distributor removal and installation and able to set the ignition timing

with a timing light.

Chevy intakes are notorious for leaking at the ends, usually a vacume

leak.

There are two places for water to escape. At the water passages in the

cylinder head or from a bolt which threads into a thru hole that has a

water

jacket at the bottom. There is nothing you can just apply to the outside

of manifold to stop a leak. The manifold needs to be removed, cleaned

and reinstalled.

I would first retorque the intake bolts to 40 ft/lb max, starting at the

center and working in a crisscross pattern from side to side ( pass vs.

driver side) moving towards the ends of the engine. If the leak is from

around a bolt ( does not sould like it in your post), you could remove

the one bolt, clean it and the surface of the intake where it mates.

Apply silicone (recommend permatex ultra blue)around the shank of the

bolt and reinstall bolt. If intake still leaks after a few days you will

need to replace intake gaskets.

Go to the library and find a GM shop manual specific to your year make

and model for no surprises on the specifice procedure.

This could be a reference book that you can not remove from the library,

so you will have to make copies. I would get the procedures for fuel

system depressurization, distributor removal/replacement, intake removal

and replacement and setting ingniting timing w/ a timing light. Read

these over several times before you decide to tackle this.

A generic intake removal is as follows:

WARNING...On ANY type of fuel injection the fuel line should always be

under pressure. You need to depressurize the fuel system and disconnect

the battery before removing any fuel lines. This usually requires

unhooking the electic fuel pump or relay and starting the engine untill

it dies from lack of fuel. I can NOT stress the imporntance of this or

the dangers involved with removing a pressurized fuel line. Go to the

library and copy the specific procedure for your vehicle.

Depressurize fuel system, Unhook battery, drain coolant, remove all

electrical connectors and vacume lines to carb and intake. Mark these

with masking tape so you can just plug them back up. You WILL NOT

remember where they go! Remove radiator hose and heater hoses from

intake. Remove fuel line from carb AFTER DEPRESSURIZING the fuel system.

Take off distributor cap and mark intake or firewall with a magic marker

in line with the distributor rotor so the distributor can be replaced

with the rotor in the same position that it was in before removal. Very

imporntant. You may want to copy this procedure from the gm manual just

in case. Do not turn the engine over with the dist. removed or your

timing will be lost requiring you to find Top dead center to syncronize

dist and valve timing. remove bolt and clamp at bottom of dist. Pull

dist straight up and out of engine, notice how rotor rotates as dist is

removed. At installation you will need to move rotor off the mark on

intake or firewall and as you set it down it will rotate into position.

If you are not familial with dist replacement this will be the tricky

part. Now that the technical garb is out of the way. Remove intake bolts

and any brackets that may be bolted to the intake. This may require the

removal of AC unit, alternator, throtle bracket which holds cable from

gas pedal. ect...You can leave the carb (fuel injected or not) bolted to

the manifold. The manifold will be stuck on requireing some very

carefull help to break loose. Take a rubber mallet and tap around on the

ends of the manifold to try to break it loose. Be very carefull not to

break or crack the intake. Note the position of any square metal water

block off pieces. Some engines run coolant through the intake and some

don't. The new gaskets will be generic to allow either way. Save old

gaskets and mark which side they came off of so you can intall the new

gaskets w/ plates in the correct position. Note original gaskets may not

have metal plates, but the new gaskets will. once manifold is removed,

the carb is full of gas so turn upside down to drain gas.clean off the

old gaskets from intake, cylinder heads and block. Put rags in lifter

valley so this crud does'nt get into engine. After you remove the rags

try to get every little piece of doodoo out that fell down in there.

Clean manifold gasket surfaces, If aluminum be careful to not create any

deep grooves or scratches.

Now is the time to check for a warped manifold which may not ever seal.

lay a straightedge along gaskets surface to check for any gaps,

especially on the ends. Some warpage is imminent but acceptable. Use a

feeler guage between manifold and straightedge to determine gap. This

warpage limit should be found in the gm manual, you can usually get away

with a little more warpage than the book says. Clean all gasket mating

surfaces ( not the gasket) with alcohol, they must be clean. I usually

install the 2 rubber gaskets on the ends to the block w/ a generous

amount of permatex, allow to dry before installing intake. Do not put

any permatex on the intake side of these gaskets at this time. Use

gasket cement ( red sticky goo in a can w/ a brush) to the intake and

install gaskets,(Only apply cement to one side of gasket at this time)

make sure the are aligned and allow to dry to the point they will not

move. . Now apply gasket cement to the gaskets on the cylinder head

side, apply a generous amount of permatex to the tops of the rubber

seals which are already glued into place. Install manifold very

carefully so the gaskets dont move. Put a bolt in each end of manifold

when installing so you can line up the bolts with the holes before

gasket sealer contacts cylinder head. Install bolts and torque to specs

in the crisscross pattern described in your library papers. Install the

remaing components. Now is the time to install a new 5 dollar thermostat

before installing radiator hose.

Intall distributor so the rotor lines up w/ the mark on intake or

firewall. Make sure dist goes all the way in, no gap between the dist

and intake, install clamp but do not tighten bolt tight so you can

adjust timing later.

Allow gasket sealer to dry for several hours before starting. Overnight

is best. Don't forget to add coolant and hook fuel pump back up. After

staring set timing w/ a timing light, something else to get from the

library if you are not familiar with. Good luck. Feel free to write w/

any questions. I'm only home on the weekends and no internet access

during the week. Jim.

The good news is you don't have to remove the exaust manifolds.

Do NOT torque the intake manifold bolts before consulting your gasket

manufacturer's specs. On my Ford 302, the manual says to torque to

23-25

ft-lbs, but Fel-Pro's printoseal gaskets call for 18 ft-lbs, anything

higher and it would crack (Fel-Pro Technician's statement, he even said

that there was a high failure rate due to torquing the bolts to manual

specs instead of Fel-Pro specs).

==========================================================================

The distributor must come out. Because it's not necessary on

this engine to "set the timing"...the best way to deal with the

distributor is to first mark the position of the cap in relation

to either the engine or the firewall. The cap has two long ridges

on the top of it that run front to back.....I use these to make

marks that correspond to them on the metal of the firewall.

Then remove the cap and see where the rotor is pointing.

Don't attempt to turn the engine over and get it lined up

with #1.....just mark it's relationship to the firewall/engine

in a way that will be easy for you to remember. Because

the distributor in this model of Vortec v-8 is really nothing

more then a cam sensor.....it's important to get everything

lined back up, but there is no need to "fine tune" the

position of the distributor unless you end up with service

engine light on. If you mark it carefully and reinstall it as

it came out...you wont have any problems.

You also need to remove one valve cover in order to

get the intake manifold out.

You also need to remove the bolts and nuts that hold

the drivers side (a/c and ps pump) bracket and slide

it forward on the long stud that is located on the drivers

side head. This is so that you can access one of the

intake bolts that is underneath that bracket.

Do not attempt to completely get the wiring harness

out of the way....just disconnect everything and then

I usually bungee cord the harness so that it is suspended

above the intake....you slide the intake out from underneath

it.

Do not attempt to remove the fuel lines where they go

into the upper plenum in the middle. Once you have

the distributor out, it's easier to disconnect the lines

right back at the firewall....leaving the fuel lines on the

manifold alone.

There is a bracket that holds the wiring harness at the

passenger side rear of the engine. Don't bother trying

to get it completely out of the way. Just unbolt it where

it is secured by the coil and then just move it up and out

of the way. There is no need to attempt to unbolt it where

it is secured to the rear of the head. You will note though

that the bracket has a small tab right where it intersects

the cylinder head/manifold area that sticks forward over

the intake. You need to bend this tab out of the way,

before you re-install the intake, otherwise it can interfere

with the manifold as you are moving it into position.

When you install the manifold you need to be able to

move it into position while keeping slightly above the

gaskets and the RTV at either end....before you lower

it. Otherwise you can wipe the RTV off the ends and

then you end up with a leak after it's all together.

Typical newbie type mistake.

Ian

Its common for the 5.7 to leak from the right rear of the intake, coolant

and oil. If you replace the intake gasket you will have to pull the

distributor, just mark the position of the rotor in relation to the

distributor itself before you remove it. Also when you get the intake off

your might want to remove the EGR valve and clear the egr passages as they

are probably full of carbon. When you have it al back together just set the

timing and you'll be all set.

Good Luck

Please don't confuse the original poster. There is

no timing to set on these engines.

Ian

Unfortunately, Mastermech doesn't know what he's talking about

when it comes to "timing" these engines. Please understand that

you simply need to be careful to install the distributor "exactly"

as it came out, ie: both the rotor and the body need to be in the

same relationship to each other and to the engine as when they

were removed.

If you do this, the timing will be right where it should be, if you

get a "check engine" light coming on after you finish (note, the

engine will still appear to run fine), then somehow you have

changed the "camshaft retard offset", which is a fancy way of

saying that the dist is not at base timing.

Please do not attempt to "power time" it.....this will not work

on these engines. It's also not complicated to return the dist

to it's original position if you just take some time to mark

the cap and it's position to the firewall, and then remove the

cap and mark the rotors position to something before you

remove the distributor body. I've done literally hundreds

of these and have only had the check engine light come on

a couple of times...and that was always due to carelessness

on my part

If you do happen to get the "check engine" light coming on,

(always realizing that it might be something as simple as

you left an electrical component disconnected) you may have

to have a scan tool hooked up so that you can adjust the

base timing (camshaft retard offset).

Ian

==================================================================

After the gasket replacement...but before the engine is started. If

you are doing the work, take it for a spin around the block, get it

warmed up, and then drop the oil and filter again. A little overkill,

but if you have the time and it's your own vehicle, I'd do it.

I know that people don't like the quick connects, but they can be

useful at times. It's very easy to fill and bleed the v-8 vortecs by

just popping that heater hose off, fill the rad until it starts to come

out at the fitting, push it back and and continue filling. You won't

have hardly any air to bleed by doing that. Of course, the problems

with them leaking coolant are frustrating.

I'd check the starter for traces of dried dexcool. Usually looks

like a white/tan powder. Often the gasket leaks

on right rear side (but I have seen them leak at all four corners)

and at the left front side.

If you have drips of dexcool, I have little doubt that you have

a manifold gasket leak. Probably best to just plan to do it

soon.

Ian

Just some things that I've observed. One, if the coolant has been

leaking internally, it often leaks so slowly that the water in the coolant

evaporates, and whatever is left over begins to settle on the surfaces

of the engine in what looks like a brown chocolately colored scum. An

extra oil change can only help to start to remove that residue that

has been left by the coolant in the oil.

Two, when you lift the intake manifold off of the vortec v-8's, because

of the way that the coolant passage is designed inside the manifold, it's

impossible to lift off the manifold and not dump some coolant into the

vally of the engine. So right there, you have a certain amount of coolant

in the oil. Then, as you clean the surfaces of the cylinder head, there

is often a lot of dirt and grit up along the top of the gasket surface.

It's

hard not to have some of it spill into the valley. The best thing is to lay

rags in the valley after the intake is off, in order to catch any crap that

you might send into the valley.

A lot of shops had a lot of engine failures right after doing intake

manifold gasket work. A large part of the problem was the fact

that tech's were not careful about coolant and/or dirt getting in the

engine....and the biggest problem was tech's using sanding discs

to clean up the head surfaces. The grit from the sanding discs

would tear the crank and bearings right out of an engine within

a day or two. Now, the oil change is standard procedure and

the sanding discs are prohibited. Common sense also dictates that

you do simple things, like putting rags in the valley so that you

can catch as much of the crap as possible.

Ian

=======================================================================

I'm getting ready to replace the intake manifold gaskets on a '91 K1500/350.

I have a couple of questions I would like to try to get answered.

First, do I need to take the TBI unit off of the intake?

Second, does the distributor use an 'O' ring or a gasket to seal it? What

size?

Any words of advice to make things go easy? I will have help, so that in

itself will make things a little easier.

Thanks in advance,

you don't have to remove the tbi unit from the intake, you just have

to disconnect the fuel lines and linkage from the tbi unit.

yes the distributor has a gasket......... fairly common GM

350 distributor gasket. You should get a new one in your intake

gasket set. You can get these from just about any parts store.

change the engine oil and filter before you start the engine for the

first time. Use good quality RTV sealant on the front and rear lip of

the lifter valley (the front and rear bottom area where the intake

mates to the engine block. I like fel-pro intake gaskets, GM even

makes some good ones too. Mark the position of the distributor rotor

button where you will be able to re-install the distributor back in

the correct position and in time. If you have to remove any spark

plug wires make sure and mark them and their position on the

distributor...(assuming you are new at this)..

Make sure you change the oil !