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Replacing '96 Tahoe Intake Manifold Gasket

FD611V

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Jan 26, 2012
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Gentlemen, It has been several months since I've been here. But, I do read many of the threads. Here's my reason on posting today.
I have a 1996 Chev. Tahoe with 5.7 litre V-8 Vortec with 127,312 miles. The past several months I've had to add anti freeze to the radiator. Just about pint or so each time. I don't drive the Tahoe much...maybe 15-20 miles a month....I'm retired and have a 2006 Buick Lacrosse wife and I use.

Here's the report on what I think the engine needs to fix the leakage. I change oil and filter and it has been driven about 150 miles since the oil/filter change, and I probably have added three pints or more anti-freeze since the oil/filter change. There's no anti-freeze to be found on the garage floor under the Tahoe. I can see where there is some coolant on the engine block to the left of the thermostat....not enough to make run down the engine on the floor. I've also check the oil and cannot see any suds/soapy type of residue of any kind, nor there's any soapy substance in the oil filler cap. So, my guess would be it is leaking some coolant around the water ports on the intake manifold. Some of you may know General Motors made these 5.7 litre Vortec engine with bad manifold gaskets from 1996-1999. Yes, they used silicone on the block..front and rear between the heads....

So, it come to this. I'm going to tackle the job or replacing the intake gasket, as I'm sort old shade tree mechanic. I don't see any problems, just a lot of wiring and cable that need to be labeled and move aside to perform the chore.

I have plenty tools...Craftsman products from 1956-2012...But, one tool I have is a Craftsman "Beam" torque wrench. I'm thinking of getting a "digital or chick type torque wrench to use here. But, there's a problem here with these wrenches. The torque spec's on the '96 Tahoe intake manifold are....3 stages....50 inch lbs, 100 inch lbs, and 132 inch lbs. (11 ft. lbs) on the last torquing.
Does mosts of these new digital and clicker wrenches can be set for 50 inch lbs. and up to 132 inch lbs.?
 
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Ridebutter

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My craftsman 3/8 clicker goes 25-250in-lbs. should be fine. I have done this job twice before on 2 different 350s it's not too bad even with hand tools in a parking lot. Good luck!
 

wafrederick

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Plus mark the distribitor before pulling out,the timing is not adjustable set with a scan tool.FelPro does make the upgraded metal intake gaskets,MS98000T
 

bluechevy94

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Its a simple job to do.I have replaced about 7 or so on those engines and could almost fo it with my closed.Make sure you get the updated gasket.It has metal inserts around the bolt holes to help keeping the gasket from crushing.I use my 1/4 drive inch pound torque wrench and have had no problems torqing the intake bolts.The biggest problem is settung the timing after you reinstall the distibutor.It needs to be set at +/- 2 degrees btdc.You really need a scan tol to get the timing set right.If you dont have a scan tool you can limp it to a shop to get it set.
 

chris142

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Plus mark the distribitor before pulling out,the timing is not adjustable set with a scan tool.FelPro does make the upgraded metal intake gaskets,MS98000T

This! We got burned last year by this. Stealer charges $300 to connect the scan tool and make the engine recognize the timing then adjust it.
 

wafrederick

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I have done a few, made a mark on the distribitor before pulling out.Includes the vortec 4.3s.The part inside the distribitor tells the computer when to fire the fuel injectors.
 
OP
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FD611V

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I have the Fel-Pro #MS98000T gasket set, and Fel-Pro #VS50293R valve cover gasket. One valve cover gasket comes with the set. I'm marking the distributor in two locations, plus marking the rotor in two locations to make sure I install it back in same position before removing it. If I do it correctly, there shouldn't be any problem to have it scanned.
 

roblouvasz

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Somewhere between the end of the line and the midd
I've done this on two different 99 suburbans. A friend of mine (mechanic) told me to get a die grinder with a carbide burr bit and notch out the AC pump mounting bracket to get access to one of the manifold bolts near the front of the engine so you don't have to go through the trouble of removing the whole bracket assembly. Use a shop vac as close to burr as possible. I like to get the same type of bolts that hold the manifold in place and cut the heads off, insert them into the heads and use them as guides when you set the manifold down. Then just unscrew them and put the original bolts in. Works great when trying to line up a transmission or water pump.
 
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FD611V

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Most would think it would require removing the power steering plump assembly to get to the front manifold bolts. There are 4 bolts on the P/S bracket that one must remove and nut on a bolt that needs to the looseing.
Doing this, you can slide the P/S pump and A/C bracket out about 1-1/2" as this pictures shows.

The bolt nut shown top of the P/S tank cap is all one needs to slide the pump out from the engine block.

l_17_acbracketdetail.jpg



l_16_acbracketdetail1.jpg
 

Diffident

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If your replacing the intake manifold gasket, this would be the perfect time to get rid of that nasty Dexcool coolant and replace it with a universal (Any color) style coolant.

And depending on how much longer you plan to keep the truck, replacing the "Spider" fuel injection system while you have the intake apart might be a good idea. Your approaching the end of life span of the fuel injection system. Mine lasted 170,000 miles before it left me stranded.
 

KinzeMech

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And depending on how much longer you plan to keep the truck, replacing the "Spider" fuel injection system while you have the intake apart might be a good idea. Your approaching the end of life span of the fuel injection system. Mine lasted 170,000 miles before it left me stranded.

Please elaborate. Is there an updated design, or are you recommending replacing it with the exact same thing?
 

Diffident

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Please elaborate. Is there an updated design, or are you recommending replacing it with the exact same thing?

There are performance spider injectors available, but I was suggesting replacing it with a stock one now since it is located in between the upper and lower intake manifolds. With over 120,000 miles on the vehicle the injectors aren't going to last much longer. With the intake already apart it would be better to replace it now, than have it go bad in another 10 to 20,000 miles and have to take the intake apart again.
 

KinzeMech

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Thanks.
I thought at one time (back when I drove a truck with one of those engines), I had read something about a MPFI replacement system for them, but when I searched, could not find details.
 
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NUTTSGT

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KinzeMech

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Does your '96 Suburban still use that crappy *** coolant connection at the back of the intake near the heater core ? (passenger side) Those have been known to rust and corrode away, enough in fact that most dealers will carry the replacement part in their inventory.

The original one is some kind of crappy pot metal type POS. When I did mine, I got a steel one from O'Reilly's. Much better. Definitely a part to replace. Be prepared to extract it if it breaks off during disassembly.
 

Tribalvision

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Actually the quick connect heater hose connection is just behind the alternator. Mne just recently corroded and broke in half. I drilled and picked the old one out and went back to the old school standard fitting and a hose clamp. Might as well do that while you have it apart. The fitting is cheap pot metal and i can guarantee it will break upon removal.
 

Tribalvision

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I was replacing the fuel pump on my Blue Tahoe when i ran out to grab a fuel filter. On the way home I smelled antifreeze and found this. it stinks when both of your trucks are broken.
https://sphotos-b.**.fbcdn.net/hphotos-snc6/603545_4253884996226_1462837633_n.jpg

the fitting just rotted from the inside out.

https://sphotos-a.**.fbcdn.net/hphotos-ash4/417268_4254080441112_740200744_n.jpg

stuffed a small rag in the hole, then I drilled and chipped the old fitting out. Ran a pipe tap down to clean it up. I used a shop vac to vacuum the old fitting pieces out. Then I removed the rag from the hole and installed the old style ******.

https://sphotos-a.**.fbcdn.net/hphotos-ash4/306496_4254310726869_395176199_n.jpg

replaced the hose, flushed the crappy coolant out and went back to the old school green coolant.
 

NUTTSGT

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Thanks for posting those pics, that is the exact part I was talking about, they used to be towards the rear of the intake. I was wondering if this is where the OP's leak is coming from and why I brought it up.
 

bigcaddy

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I've done both of those repairs that you are suffering from right now. When i worked with my dad, i, among other things, had to service a fleet of aging chevys and a few new ones. By age 20 i had replaced 6 of the Vortec intake manifold gaskets and i have no training as a mechanic. I was always told, "just get them fixed":lol: They always seemed to blow out around the distributor hole making it hard to somewhat diagnose:shocking:

They are fairly easy to do and i would suggest taking some pictures as a final reference for the hose/wiring layout. Tagging lines with tape and marking bags of hardware is a must too. Some of those hose/wire assemblies get shorter if you don't retrace the exact route they used from the factory.

As far as the busted coolant fitting goes, replace it with a brass 7/8? thread/ barb fitting. The factory ones are cheap pot metal that gets attacked by the coolant and fails from the stress of the hose pulling on it.


Good luck and make sure to have cold beer handy to drink when you finish. You are going to need it!:beer:
 

wafrederick

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The aftermarket from Dorman is made out of steel which lasts longer.Lisle sells the tool to remove the broken part out of the intake.
 

sabercatt

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you arent setting the ignition timing with the scan tool, you are setting the cam timing.
 

bgott

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Drain the water jacket from the left hand side (driver side) block drain plug. That will drain the whole engine down far enough, through the water pump, that you won't have to jack with the knock sensor, which is the right side plug. You'll also have to get underneath and unplug the crank sensor and the power steering pressure sensor to pull the wiring harness out of the way. Be sure and blow the **** off of the intake or you'll have a bunch of stuff fall into the engine when you pull it up and out.
 

sumner52000

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Great thread guys. I should have shown it to my mechanic. I have a 98 Silverado with 5.7L 170,000 miles. Had one intake gasket 4 or 5 years ago. Needed another one now. My mechanic had finished and had it sitting outside running when he saw water running out. He thought the gasket had slipped. Went and got another gasket set and put another intake gasket on before he saw what was really leaking, and of coarse it broke off like the pics above show. He didn't charge me anything extra but it cost him a lot of time. I spent a little under $1400, $500 was labor. Intake gasket, new A/C compressor (seal bad), belt, hoses, heater hose fitting.
 

Toolhorder

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This! We got burned last year by this. Stealer charges $300 to connect the scan tool and make the engine recognize the timing then adjust it.

Here we go again with the stealership comments. Buy a scan tool next time and see how you like that price....better yet buy a better made product and avoid the whole mess. I hear Toyota makes an intake gasket on their V8 that doesn't leak.
 
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29Sedanman

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Guys, Just for extra info. If you are in need of the Spider fuel injector replacement, Jim Linder at Linder Fule injection here in Indy sells them. He is a leader in Fuel injection training, rebuilding, cleaning and troubleshooting. Cant remember his number off hand but if you google Linder Fuel injection you will find him. He is a Ford Barn member, and a long Time HAMB member goes by GMCBUBBA.
 

mrjaw14

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I have a silverado with a 4.8L vortec that the intake gasket went bad in. Manifested itself in the winter. Ran ok when warmed up, but I had to keep my foot in it when cold to keep it cranked. I wasn't having to add a lot of coolant, but much more than normal. Took it in, had the gasket replaced and had the coolant flushed.

The shop I went to they all have chevy products for their personal vehicles and they recomended NOT putting dexcool back in, but the older style green. I've since done that to all my GM vehicles and couldn't be happier.
 

uhcrandy

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I just replaced the Poppet valves with the new Injector type. I found the best price on Amazon.com. Just FYI!
 

camarotoolman

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Not to steel the tread, but I had on those motors that got water in the oil after a guy replaced the head gasket. Did he cause the eng. to distroy its self.
 

Heavy Metal Doctor

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And depending on how much longer you plan to keep the truck, replacing the "Spider" fuel injection system while you have the intake apart might be a good idea. Your approaching the end of life span of the fuel injection system. Mine lasted 170,000 miles before it left me stranded.


Side note on the spider assy --
I think my 97 5.7L made about 200k before is started messin' up. It still ran ok when running , but leaked down making it flood the cyl's after shutoff - this made cold start fine, but hot restart would crank for 20 /30 second to clear flood.
The indy shop I use when lacking time or problems seem deeper than my limited automotive ability covers was nice enough to print me the service page on spider assy replacement and told me to go home and do it myself....part was basic Napa stuff - not overly expensive......I also found it funny that the instruction said to drain coolant just for spider assy job - but the upper half of the manifold has no coolant in it.....and yet noone, by phone or interweb could verify that fact for me. Not even the Chevy oriented forums. I took a chance based on pic's of the parts and said "screw it" and pulled the top half of the manifold off without draining. All done in less than 2 hours and no coolant mess. Still running fine 2 or 3 year later at 240K.
 

KinzeMech

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ethanol does cause some problems in some instances, but it also gets scapegoated alot.

These vortec engines had this problem since before ethanol fuel was commonplace.
 
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