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2nd Gen S-Series 4.3L Leaky Intake Manifold Gasket Replacement


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Old 01-28-2007, 08:10 PM   #1
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This is not a simple job to do, but it can be done with the proper tools and about a day's worth of work. I did mine about 2 weeks ago and it took a full day. Tear down took me about 1.5 hours. This included cleaning and careful removal of components due to the leak and accumulation of crap around the intake manifold/ head mating area.

Both of my gaskets were bad and provided a slow leak when the engine was cold and never leaked when it was up to full operation temperature. Cleaning takes several hours to do as it is not an easy task to keep contaminants and dirt from falling into the valley between the heads. I used a vacuum and a scraper at the same time to evacuate all the debris from the mating areas and the clogged water ports.

Here are the steps broken down if I remember correctly.


STEP 1:
Raise vehicle high enough and drain coolant from entire system. Make sure you don't raise it too high that you cannot access the engine bay, but high enough for you to get under and access the large A/C and power steering bracket. Remove all cooling hoses attached to manifold. No need to remove water pump or EGR valve.



STEP 2:
Remove all upper intake related parts, hoses, egr bypass tube, and related electrical connections (even the ones that go to the alternator, A/C compressor, ignition modules, and distributor) attached to intake manifold. If you have a bungee cord handy, wrap it around the main wire loom that crosses over the intake manifold and hook it to the holes/cutouts under the hood's internal bracing. Doing this with the loom simplifies removal and reinstalling manifold if you're doing this by yourself without a helper holding up the crossover wire loom. Then remove the ignition coil/module assembly.



STEP 3:
Remove the distributor. Take off the distributor cap. Turn the engine over until the distributor is pointing at something easy to remember. I usually get the little arrow pointing at the passenger side headlight. It would be wise to line up the harmonic balancer line with the mark on the timing cover before the distributor is removed. Once this is done I remove the distributor

NOTE: Don't turn the engine after the distributor is removed.

STEP 4:
Remove the hard fuel lines (relieve the fuel pressure first) attached to fuel distribution block. You should remove the two rear fittings as well that run down to the incoming and return lines.



STEP 5:
Remove Air conditioning compressor without detaching lines and swing over to side while providing support underneath the compressor.

STEP 6:
After this remove the two long bolts and nut that hold the aluminum A/C bracket to the block.

STEP 7: Now go under the vehicle and remove the 3 nuts that hold the power steering pump and bracket to the block. No need to detach the pump from the large aluminum bracket. Then go back up to the top and swing the bracket out of the way in a forward direction. No need to remove, just move it far forward enough to expose the bolt that holds the intake manifold down on the left front corner (driver's side). At this point you should have what appears to be a basic engine with a modern ABS intake plenum sitting on top. No need to remove the upper plenum. I did remove the MAP sensor as it sits a little high. This was done so that I don't break it while flipping the manifold assembly afterwords for cleaning.



STEP 8:
Remove the intake manifold. Use a criss cross pattern to remove the manifold from the block. Start from the outer bolts, then work your way towards the center. On mine, all the bolts were actually loose and some were even finger tight.

There will be some coolant remaining if you didn't drain the radiator completely. Before you take the manifold off, do a thorough cleaning of the area around the intake manifold mating areas next to the heads and block. This ensures you don't have any surprise debris falling into the engine. The manifold will be stuck on due to the RTV that holds the ends down. Carefully pry off and wiggle it loose. At this point you can lift up and remove it. Remember the bungee recommendation? This is where you will appreciate the wire loom not hanging up on the manifold while removing on you own.

STEP 9:
Clean up all mating surfaces with a gasket scraper. Make sure RTV is removed from all gasket surfaces. Clean out all coolant passages.











On mine the coolant passages looked like clogged arteries ( passenger rearmost cooling port). Luckily it was just the block off at the intake manifold. I guess the leak with small amounts air introduced into the cooling system caused a catalytic reaction and formed hard deposits and buildup at the point of infiltration in the gasket. The driver's side rearmost coolant port even appeared to have coolant mixing with water as there was a small muddy/milky mess. Luckily, there was no oil in the cooling system though.

STEP 10:
After cleaning up all mating surfaces on the intake manifold, heads, and block, apply RTV to the front and rear surfaces of the block. Make sure you have enough to compress when the intake manifold is placed on top to form a good seal. I added about 3/16" tall and wide bead. Apply RTV to the topside and bottom-side of the new intake gaskets around the coolant passages. Do this sparingly as it does not need much. Just extra insurance incase it reoccurs in the future if the plastic gaskets fail again. Make sure you do not disturb the RTV and carefully place the intake manifold assembly straight down without twisting or rotating it. If you do happen to do this you can ruin the RTV seal and must reapply the RTV again.

STEP 11:
Once the manifold is situated, torque the eight bolts in the correct sequence, 5-6-2-4-3-1-7-8 three separate times. The first time torque each to 89 inch lbs. The second time torque each to 106 inch lbs. The third time torque each to 132 inch lbs.

Finishing Up:
The rest of reassembly is reverse of removal for the external, and electrical components.

EDIT: Make sure you get the distributor back in the way it came out. You will need to make sure that it seats fully.




You will want to flush out the cooling system thoroughly and refill with the proper coolant along with distilled water and make sure you bleed the system properly to avoid getting trapped air in cooling system.

Test drive vehicle and make sure you have no leaks and performance is ok.

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Old 01-21-2011, 09:55 PM   #2
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Excellent how to dude, however perhaps you should write it up again and add instructions on removing the distributor correctly so when you put it back together you will be close enough to start it and re-set the timing. Just a suggestion. No offense intended. You take great pics too. Keep up the good work it is appreciated.

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Old 01-27-2011, 11:19 AM   #3
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Excellent walkthrough. And perfect timing. A big help! Thanks!

Your pix look exactly like my '01 Blazer. I disconnected everything except the fuel-lines yesterday. Got the gasket this morning: Fel-Pro MS98002T with the three sealing beads around the coolant passages (see Closing The Gap on Intake Manifold Gaskets: Engine Builder).

I am attempting to avoid the #1-TDC method of distributor re-installation: First - I tried to turn the crank pulley to make sure it wasn't eager to turn. Check. Second - I removed the cap from the distributor (T-20 bit) and marked the orientation of the rotor with respect to the rim of the distributor. (Incidentally, there is a little arrow molded in to the inside rim of the distributor. I used that arrow as my rim reference.) Third - I looked at the orientation of the distributor stem and noticed that the corner of it's square base was pointing EXACTLY toward the distributor clamp bolt. I took pictures of every step. As long as the crank doesn't turn, I should be able to line things back up. If that fails, there's always #1-TDC.

By the way, when I pulled the distributor out through the manifold, I noticed that the rotor turned cc as it's gear pulled away. So I expect that I will have to orient the rotor somewhat cc of the position I want it to rest in. I expect it will take a few tries.

I can post the pictures of the distributor removal if wanted.

-- coiley

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Old 01-27-2011, 06:31 PM   #4
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If you have those I can add them to the post above. I did make an adjustment to the post for the dist removal. Hope that it is clear.

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Old 01-27-2011, 08:10 PM   #5
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Quote:
Originally Posted by The Master View Post
If you have those I can add them to the post above. I did make an adjustment to the post for the dist removal. Hope that it is clear.
There is this thread on dist removal/replacement

2nd Gen S-Series Distributor Replacement Removal Procedure

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Old 01-29-2011, 09:26 PM   #6
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Quote:
Originally Posted by 97s10vortec350 View Post
Excellent how to dude, however perhaps you should write it up again and add instructions on removing the distributor correctly so when you put it back together you will be close enough to start it and re-set the timing. Just a suggestion. No offense intended. You take great pics too. Keep up the good work it is appreciated.
I now understand why TubbD left out the distributor remove/install steps.

When I went to put the distributor back in, I realized that the distributor on the 2001 4.3L is not adjustable - and re-installation is almost foolproof.

The distributor clamp is a fork. The fork captures the flat sides of the distributor base. The fork bolt goes through a round hole - not a slotted hole. THERE IS NO ADJUSTMENT. (However, I suppose you could turn the entire distributor 180 in the fork. Oops.)

Then, the distributor gear is keyed on the bottom/end of the shaft. If you try to drop the shaft in on the wrong gear tooth, IT WON'T GO IN. The shaft key will only fall in on the right gear-tooth. (Although, I suppose, but I haven't tried it, you could turn the rotor 180 and key it in wrong.)

If you make a rotor mark in the right neighborhood you can hardly go wrong.

The rotor turns 42 degrees cw upon insertion. That is a 1.25" arc on the perimeter of the rotor. (The math proved to be exact for me.)

I surmise that, considering the lack of mechanical adjustment of this distributor, the timing is adjusted dynamically by crank-angle, TPS/MAF, then knock - via "the computer". And then there's that fuzzy performance matrix in the computer that whimsically tunes things further as you drive.

-- coiley
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Old 01-29-2011, 09:52 PM   #7
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Awesome Info!

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Old 01-29-2011, 09:54 PM   #8
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Please tell me what buttons to press to give TubbD some tangible or electronic credit for his exceptional post. TubbD owns this thread. The post was comprehensive. I hope I have not distracted or detracted.

-- coiley

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Old 01-29-2011, 11:31 PM   #9
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P.S. - How do I put pix inline like TubbD does?

-- coiley

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Old 01-30-2011, 06:13 PM   #10
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You can do it with [ img ] url of pics [ / img ]

The images will have to be hosted on the web somewhere....even by attaching them to the post. After making the post open the image you attach. Right click go to "copy image location" click that. Then Edit your post....you have to do this within a few minutes of posting. When you do that click on the screen where you want the image to appear. then click on the little icon that looks like a mountain in the box. Paste the url that you copied. click ok. Click submit Now the image is in your post where you wanted it to be.

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Old 01-31-2011, 10:45 PM   #11
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Success! Woohoo!!!

My (wife's) '01 Blazer lives to die another day!

I put a '95 radiator in the '01. Some things have changed since '95 :-). The '95 radiator metal-part cooling thickness is 50% thicker than the '01. I don't see how this (50% more cooling ability) could be a problem. The transmission cooling lines have changed in both tubing-size and radiator-fittings. I will not tell you my adaptation solution because I do not recommend the solution that I chose. Also, the large, black, plastic air-intake/air-filter box no longer "wants" to fit around the ('95) upper radiator hose and upper crankcase-oil cooling line. I imposed some force upon it. It has now chosen to fit - and no harm done.

Incidentally, I plan on attempting to repair the crack in the original '01 radiator. The crack is on the front, high, driver's-side, in the crimped-on plastic region. After some painstaking surface-preparation, I plan to use two-part plastic-weld (methyl methacrylate) to heal the breach. (I can confidently recommend that nothing labeled EPOXY should be used in this case. Methyl methacrylate IS plastic. It does not just BOND TO plastic, it BECOMES ONE with the plastic - chemically. Epoxy is awesome - but it does not chemically bond with plastic.) Even though I do not expect to succeed, I can not not try.

I am totally sold on the Fel-Pro intake-manifold gasket. It's composition is very unlike the original manifold gasket. The OEM gasket is a pitiful plastic carrier with an equally pitiful excuse for a single rubber-ish bead. The concept was bright. But the OEM implementation is grossly deficient. These OEM gaskets are renown for their early failure. On the other hand, the Fel-Pro is a metal carrier encased with a triple-bead next-gen composite fluoroelastomer (whatever that means) FKM rubber compound (See: Closing The Gap on Intake Manifold Gaskets: Engine Builder) Examining these newer gaskets inspires some intuitive confidence. Plus - I HAVE NO LEAKS! Please - this job is not trivial - do not disrespect your own valuable time by buying a cheap, fail-sure, OEM gasket.

-coiley

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Old 02-03-2011, 09:57 PM   #12
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The OEM plastic gasket carrier portion crumbled in my fingers. It's "special" OEM excuse-for-rubber sealing bead was flattened and non-resilient. My OEM gasket blew out around the left front coolant port.

The Fel-Pro PermaDryPlus gasket appears to mitigate my concerns. It is a metal carrier - completely molded with rubber gasket material - with triple beads.

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4.3l, 4.3l intake manifold gasket, 4.3l intake manifold gasket replacement, 4.3l s-series, 4.3l s10, intake manifold gasket replacement


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