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Author Topic: 3.4L V6 Teardown Part 4 - Valve Train/Lower Intake Manifold Removal  (Read 23127 times)
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« on: January 04, 2011, 11:09:08 PM »

I'm on a roll, and now we're gettin' into the thick of things:

Up to this point, I haven't bothered draining any fluids out because it's been mostly external stuff we've been taking off.  Now, however, we're going to have to drain the coolant because unlike the oil which drains back into the oil pan when the engine is off, the coolant remains all through the engine under pressure.

Every bucket/pan/pail I had wouldn't fit under the front end (hell, I  don't fit under the front end, lol), so I got one of these things from Farm and Fleet for all of $9.00:

Holds 12.5 quarts or 3.5 gallons of whatever - funnel snaps on the top, screws into the yellow cap near it on top...other yellow cap is for pouring liquid back out, and it will stand up so it's nice and skinny and portable:

Best of all, it fits under the Tek front end perfectly!

So, now we have something to catch the coolant in to either re-use it or dispose of it, now we need to get it draining.

The draincock is all the way at the bottom right side of the radiator (driver's side).  It's not easy to get to from the top or the bottom, so I started to get some stuff out of the way so I could see what I was aiming for.

First, I undid the latches for the air filter housing:

Underside of housing:

Filter in housing:

Filter taken out of housing.  If you didn't know, your Powertrain Control Module (PCM) computer is mounted right on top of that box, right in the path of air flow to keep it cool.  You can see the thick wire harness going into it just behind the black engine brace and right under the coolant recovery tank:

It ended up out of focus, but that white thing in the yellow circle - that's the draincock:

So, either from the top or lay down on your back and reach underneath, but have that pan under there and open that draincock and let the coolant come out until it stops.  Then maybe even squeeze the upper and lower radiator hoses to see if anymore will come out.  Then go ahead and close the draincock so you don't forget to do it later!

Next, you can use a screwdriver or a ratchet to loosen the clamp on the upper radiator hose at the thermostat housing, and pull the hose off and out of your way:

Next we need to get the black metal heater inlet hose that comes out of the back of the thermostat housing off.  This pipe just slides into a hole in the back of the housing, and has a tab welded to it a few inches back.  That tab has a 90 degree bend in it and a slot cut in it.  That slot fits over a stud that sticks out of the cylinder head, and has a 13mm nut on top holding the pipe in place.  It's not that easy to get to, and you can't really see what you're doing:

With the nut off, you can now slide the pipe back and out to clear the stud:

Now, we can finally get that manifold off!

There are 8 10mm bolts holding the manifold on.  4 are right on top, circled in yellow - you can see two of them, the other two are hiding in the shadows directly across from those:

The other 4 are on the sides - 2 on each.  3 of those aren't so bad to reach.  The 4th one sucks.  Bad...

The front left one is the one that sucks.  The engine front cover where the power steering pump was mounted is right in your way from any serious swing motion with a ratchet or a wrench.
Add to that, my standard 10mm socket's walls were thick enough that I couldn't get it to even get ON the nut, and even if I could, but the time you add a 3/8" drive ratchet on top, you had no vertical clearance to begin untightening the bolt.  I don't even think there's room for one thread to be backed out before you'd hit the overhanging manifold lip.
The only thing I found that worked, was a little 1/4" drive ratchet with a 10mm socket from one of those bit/driver sets.  The only reason that socket worked was because it was a very thin, straight walled socket and it fit right on.  However, even with that, it was still literally one click at a time was all the swing I could get.  Fortunately, these bolts are not on tight (or they're not SUPPOSED to be on tight), so you shouldn't have to struggle with them, it just takes a lot of time.

After I got as high as I could go with the ratchet, I switched to a 10mm wrench and even then at a weird angle to loosen it more.  At this point, I wasn't having to use pressure any more, I was just using the wrench to back the bolt out, so I wasn't too concerned about the angle I was at.

After you make sure all the bolts are loose enough that they're just sitting in their holes not threaded at all, you can take the manifold off.  I can't remember if it's these bolts that need to go back in their same spots or not, so just to be safe, I left them in the manifold so they'd go back where they came out of.  I know there's a specific torque sequence when tightening the bolts, but just don't remember if it matters which bolts go where -they're all the same size.

In the valley of the manifold on the sides, more than likely there should be a bead of gasket sealant or Form A Gasket going from one head to the other on both sides.  It may take some GENTLE prying with a prybar or long handled screwdriver to break that seal so you can get the manifold off.

Once you break it free and it's sitting on your bench, it'll look like this:

Left end showing the 'fun' bolts:

Right end showing thermostat housing:

If you want to get yours out, just take those two bolts off where the pipe meets the manifold and the thermostat is right there.  I put a new one in last time this was put together, but I'll probably check on it when I get to re-assembling things to see how it's doing.

Underside of manifold - you can see we got a good seal on the right side, but not so great a one on the left side:

And now we're REALLY getting into it here!  Now, you can see the rocker arms, push rods, valve springs and the the black things going across the port openings with the orange rectangles?  That's the infamous Lower Intake Manifold gaskets that go bad on these engines.  These are actually brand new as they were put on at the last tear down just a few months ago, so this is what new ones look like.  The silver curved thing on the right side of the picture is the heat shield covering the crossover exhaust pipe.  You couldn't even see any part of this before with all that other crap piled on top of it.

The two skinnier ports to the outside of each head are coolant passageways, while the 3 big ones in the middle are the combustion or intake ports.  If you look inside those ports, you'll see the back (bell) sides of the valves.

A shot down into the valley in the center.  The brown plastic (!?) rectangles that the push rods disappear into are the lifter keepers.  Note how the gasket winds its way sometimes in front of and other times behind the push rods:


« Last Edit: January 05, 2011, 08:37:17 AM by Aztek-Knight » Logged
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« Reply #1 on: January 05, 2011, 12:38:28 PM »

Close up of the ports and parts for Cylinder 1, source of my woes...Note the sideways 2nd rocker arm up top:

Closer inspection revealed gasoline up to about my middle pinky finger in that first port:

This of course, should not be there....it meant that because of that twisted rocker arm, this valve was not opening to let the fuel get ignited, but the injector kept spraying fuel in there anyway and it built up.

The twisted rocker arm.  The bolt is actually still tight.  I'm guessing that I  didn't get the helicoil drilled deep enough to get the arm seated all the way down.

The arm is so floppy that it can't even hold its push rod in place:

They should look like this:

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« Reply #2 on: January 05, 2011, 01:23:26 PM »

The next step is to get the rocker arms and push rods out of the way so you can get to the head bolts and get the heads off. 
IMPORTANT NOTE:  If you are re-using all the valve train parts, you absolutely MUST organize them when you remove them so they go back in the exact place they came out of.  If you put them into different cylinders, you can cause premature wear on the lifters, push rods, and the cam shaft.  The first time I did this, I used a heavy cardboard box and drilled holes in the top of it to make my own tray - the holes were drilled the same way the parts are in the engine and I used a marker to write on the cardboard the cylinder number, front or back head and and arrow indicating the front of the car so I knew exactly where everything went.  You can buy valvetrain parts organizer trays from auto parts places if you wish.  If you are, say, replacing all the lifters or something like that, then it doesn't matter so much.  But, each cam lobe gets 'used' to the wear from each lifter and if you switch them around, you may cause a lobe to start wearing faster than it should.

So, begin by using a 10mm deep well to remove the rocker arm bolts:

The bolts and the arm are an assembly and come out together:

Back head rocker arms all snug in their bed:

Next, just pull the push rods out.  IMPORTANT NOTE:  If you're doing what you should and organizing them as they come out this shouldn't be a big deal, but it's important to note that this engine uses two different size push rods - short and long.  PAY ATTENTION TO THIS!!!  If you screw up and put a long rod in where a short one goes, you're going to be doing this all over again and buying some more parts!

Single push rod:

Back head push rods...I just wrapped some masking tape around one end of the rod and labeled them 1-6...in this case, that's not cylinder number, but just 1-6, left to right in the head.

Next you can just lift the LIM gasket off:

The evil Lower Intake Manifold gasket:

Side view of the back head with the gasket gone:

Top view of engine with all rocker arms, push rods and gaskets removed:

Now, remove the 4 10mm bolts (2 on each one) holding the plastic (!?) lifter keeper in place:

It's odd seeing this made out of plastic being where it is smack dab in the middle of all the heat and metal around it, but they are definitely plastic.

You can now take the lifters out of their holes.  They make a tool for this but it's just a small piece of stiff wire with a small hook at the end to catch the inside lip of the lifter and pull it out.  I used my handy telescoping magnetized part grabber thing to pull them each out:

Top of lifter.  There is a small metal wire keeper that sits in a groove at the top.  You pry that out, and the contents of the lifter should fall out if you wanted to really clean them good.  There will be the keeper, the metal disc with the oil hole you see on top, a tiny flat disc behind that, the piston and a spring inside.  If you get the coolant mixed with oil sludge like I did the first time, that gets pumped into the lifters and gums them up and even makes them lock up so they don't move.  This 'stuck lifter' is what causes the bad ticking you can hear sometimes.  The roller bearing on the bottom of the lifter rides on and follows the shape of the cam shaft lobe.  As it does, it rises and falls with the shape of the lobe.  The parts inside the lifter are under hydraulic pressure from oil being pumped through them.  This keeps them stiff.  The push rod sits on top of the lifter, and the other end of it rests under one side of a rocker arm.  When the cam lobe is highest, the lifter goes up, push rod goes up and lifts the rocker arm which pivots and depresses the valve spring on the opposite side.  This causes that valve to go down or open admitting fuel and air, or letting exhaust out.  When the cam lobe goes to its lower side, the pressure from the spring and now lack of pressure on the push rod side lets the valve close, the rocker tilts down on the push rod, pushing the lifter back down.  This process repeats thousands of times a minute for each valve the whole time the engine is running.  The lifter acts as a cushion or buffer of sorts between the cam and rocker arm.  There shouldn't be any slack between the cam, lifter, push rod, and rocker arm.  If the lifter got compressed and then got gummed up and stuck so it didn't spring back up, you'd now have slack between the top of the lifter and the push rod, or between that push rod and its rocker arm.  The result is that tapping or ticking noise you may hear as the metal parts knock together when the whole thing moves.  You may get lucky and be able to take the lifters apart and clean all that gunk out of there and re-use them.  Mine were too far gone, so I just put new ones in.

Roller bearing or bottom end of lifter.  This roller should move smooth as silk with no binding or resistance at all.  If they bind or are stiff, clean them and see if that helps...if not, chuck 'em in the trash and replace it or the whole set:

Here you can see some lifters up and some down.  You can see that a push rod sitting on those would be up or down and pushing against its rocker arm in relation:

Pulling a lifter out with the magnet:

Damn that thing is handy!  Wish the light on the end hadn't quit working...

If you set the keeper shields up to the same orientation as the engine, they make the perfect place to keep the lifters in the right order, just upside down.

Lifters and all valve train parts removed:

Close up of lifter valley.  Picture doesn't show it very clearly, but when you look in each lifter hole, you can see the camshaft lobes.

It's a good idea to place rags or maybe even a piece of cardboard over this valley once the lifters are out so dirt, liquids or even tools or screws don't fall down into the block.

Backing away with the camera, the whole engine now looks like this:

Next, we go after the heads, finally!!!

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« Reply #3 on: October 17, 2011, 07:23:09 PM »

Is there a torqe spec for the rocker arms? how about the lower intake bolts,how tight? I started the LIM repair this evening and got to taking the alt off and decided to call it a day. Tomorrow should be able to finish teardown and prep all surfaces.  This Post is GREAT, i would have never tried to do this myself in the yard without these great instructions. Thanks for all the hard work.

If you have any usefull info on the torqe specs and putting back together i would greatly appreciate it

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« Reply #4 on: October 17, 2011, 07:47:10 PM »

Hi Ricky - thanks for the kind words and glad it's helping you out. 

Rocker arm bolt torque is 11 ft. lbs then 30 degrees.

For all those specs, here's a chunk of gold for you.  Go to www.gpona.com (Grand Prix Owners of North America website).  It's a forum site just like this one for Grand Prix owners.  Register there (it's free - just pick a username/pwd and wait for the confirmation email.)  Once you're logged in there, on the homepage menu at the top, 2nd from the end on the right you'll see 'GM Service Manuals'.  Click that, enter your username/pwd (for the gpona site), then save that as a bookmark or favorite.  This is the official GM Service Manuals - same 2 volume books you previously had to pay $100 or more for online - same info the shops use.

You don't need a VIN, just choose year/make/model from the drop downs and hit next.  The Service Manual section covers the whole car, while the Unit Repair zeroes in more on engine transmission repair...So, to get the engine out, you'd look at the service manual...To tear it down, you'd go to the Unit Repair.  There's full fastener torque spec charts there for every fastener in the car.

If you need help finding something, or have more questions than I answered in the posts, drop me a line and I'll be glad to help out if I can!

Good Luck,

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« Reply #5 on: October 17, 2011, 07:50:38 PM »

One more piece of advice, though I'm sure I mentioned it in the write up - do NOT get the black plastic with orange port surrounds gaskets or you'll likely be doing this again.  Spend the extra $20 or so and get the FelPro "Problem Solver" gaskets.  These are metal with black port surrounds - you should not ever have to do this again if you use those.
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