454 intake question

86bigtrk · December 20, 2004

Ok, I have a question, hopefully someone can help. I have a 2000 K3500 Crew Cab Long Bed 4WD with a 7.4 liter V8. I just purchased it about 1 month ago. I think I got screwed. It was VERY clean under the hood, but the whole truck was that way. Well, to make a long story short, it is now leaking antifreeze all along the intake gasket area, down in the corner mostly, where the block, intake, heads come together. I'm sure I'll probably have to replace the intake gasket, hopefully that will be all. Here's my question. While I have it torn apart, would it benefit me to put in a new intake? Any other suggestions while I have it apart? I can't really afford more than a few hundred dollars in new parts. I'm new to Big Blocks, so any help would be appreciated. I'm having a hard time finding info, because I still have the old style truck, even though it's a 2000, because they didn't change over the 1 ton's for a few years after the 1/2 tons. Most of the info I find is on the New engine's also (5.3, 6.0. 8.1) There is much info about 454's that are fuel injected. I'm not even sure what kind of fuel injection I have. I'm a carburetor guy up until now. Thanks for any help you can offer. Andrew R.

LikeaRock14 · December 21, 2004

It's known that the newer 454 and even some 5.7's to have the intake gaskeet go after a while. I personally know a few people who had this problem. So it's not that you got screwed off buying it, it just happens

As far as a new intake manifold, I don't know what is available for these trucks...Edelbrock might have one I think...

86bigtrk · December 21, 2004

Thank you for the encouragement. Hope you're right. Just seems a little funny that it happened less than a month after I bought it. Thanks for the info. Andrew R.

vhato · December 21, 2004

Congratulations on your choice of truck and engine.

Your particular engine puts down 290 HP and 410 lbft of stump ripping torque. It is by far no slouch. As Likearock14 stated, this is a common problem with the Vortec 5000/5700/7400 Series of engines. I am unsure as to why, but the general consensus is that it is not IF these intake gaskets will leak, but WHEN.

Chances are it started to leak so the owner decided it was time to sell or trade in. Make no mistake, you still made a GREAT purchase. This gasket change can be done at home with lots of patience or a professional can do it quickly.

Performance wise, you have an Intake that develops great power and not much can be done to improve, so no one has. Feel confident knowing your stock Intake Manifold is doing its job and not restricting power.

The only "While the Intake is off" upgrade you could do is polish the intake ports and combustion chambers in the heads. However, if you do this you might as well change the valve springs and yada yada yada, you have spent some $$$$. Since it is Christmas time and you do have 410 lbft torque on tap, I would just fix the Intake Manifold gasket and learn to LOVE your Fuel Injected Torque Monster.

Shaners · December 21, 2004

My friend has a 2000 OBS K2500 7.4L. He hasn't had the leaking gasket problem yet, but he only has about 50K miles on it.

On another note, he did install a Westers PCM on his truck (about $400). You would not believe the power that can be released from that monster under the hood!!!

86bigtrk · December 21, 2004

Is a Westers PCM better than something like a hypertech? Like I said, I know nothing about these big blocks, but I sure like the power.

vhato · December 21, 2004

Is a Westers PCM better than something like a hypertech? Like I said, I know nothing about these big blocks, but I sure like the power.

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A Westers PCM upgrade can bring the Vortec 7400 almost into the same power realm as a stock Vortec 8100. And you can still run 87 Octane Fuel. So yes it is better than a HyperTech.

beat taco · December 28, 2004

would it be worth while to have the fuel injectors cleaned and re-0-ringed while the intake is off? or do you even have to take the intake off to get to the fuel rails? im a new owner of a 7.4 vortec motor too, so im anticpating the job, thanks.

whitesnake01 · December 28, 2004

Check oil to make sure its only an external leak. If internal, too, your "to-do" list may be a bit longer.

86bigtrk · December 28, 2004

Check oil to make sure its only an external leak. If internal, too, your "to-do" list may be a bit longer.

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I'm not sure what you mean by an internal leak? Can you explain?

C/K Man · December 28, 2004

An internal leak would be when the intake manifold leaks water into the engine, not outside where you can see it. An internal leak, if bad enough, would cause that milky-white sludge that you see when a head gasket blows. Coolant mixing with oil. As for intake manifold gasket problems, they are very common on 1996-2000 5.0 and 5.7 small blocks, much less common on the big blocks, but sometimes it still happens. One difference that I have noticed between small block intake gaskets and big block gaskets is that the big block gaskets have steel washers around the bolts, which make over-torque not a problem. Also, the big blocks still have 12 intake manifold bolts, the newer small blocks only have 8. My guess is that the small block maniflold is moving around when it heat cycles, beating up the gaskets. In any event, not a big deal. I don't think I would bother with the injector O-rings. You only need to remove the upper manifold to replace them. Also, they seem to last a long time, and to replace them you do run the slight risk of knocking the injector clip locator knobs off of the composite fuel rail.

86bigtrk · January 3, 2005

Does anyone have any suggestions on replacing the intake gasket on a 454? I have done this a few times on a 350 with a carburetor, and it's not too bad. Looks like this shouldn't be much worse. ONly thing different really is the fuel rail and the a/c hoses. As far as the gasket itself, any suggestions to make sure it doesn't leak after I'm done. That would REALLY suck. I was reading the shop manual, and it doesn't list using as RTV or anything on the intake bolts. Do any of these bolts pass through the water jacket? Do I need to use any rtv? Just a little in the four corners where the rubber end gaskets meet the side gaskets right? How about the big flat side gaskets? Before I used this red gooey liquid on those gaskets. Is that needed? Just hoping not to do this again. I checked at the dealer, and they wanted $800 for the intake gasket replacement. There's no way I'm gonna pay that much when the gasket set only costs about $60 at the dealership. Also, is the gasket at the dealership any better/worse than one at say NAPA? They want about $80 for the same gasket set. Is theirs better? Thanks for all your input. Andrew R.

Ok, I have a question, hopefully someone can help. I have a 2000 K3500 Crew Cab Long Bed 4WD with a 7.4 liter V8. I just purchased it about 1 month ago. I think I got screwed. It was VERY clean under the hood, but the whole truck was that way. Well, to make a long story short, it is now leaking antifreeze all along the intake gasket area, down in the corner mostly, where the block, intake, heads come together. I'm sure I'll probably have to replace the intake gasket, hopefully that will be all. Here's my question. While I have it torn apart, would it benefit me to put in a new intake? Any other suggestions while I have it apart? I can't really afford more than a few hundred dollars in new parts. I'm new to Big Blocks, so any help would be appreciated. I'm having a hard time finding info, because I still have the old style truck, even though it's a 2000, because they didn't change over the 1 ton's for a few years after the 1/2 tons. Most of the info I find is on the New engine's also (5.3, 6.0. 8.1) There is much info about 454's that are fuel injected. I'm not even sure what kind of fuel injection I have. I'm a carburetor guy up until now. Thanks for any help you can offer. Andrew R.

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86bigtrk · January 4, 2005

Does anyone have any suggestions where I can find answers to my questions?

Does anyone have any suggestions on replacing the intake gasket on a 454? I have done this a few times on a 350 with a carburetor, and it's not too bad. Looks like this shouldn't be much worse. ONly thing different really is the fuel rail and the a/c hoses. As far as the gasket itself, any suggestions to make sure it doesn't leak after I'm done. That would REALLY suck. I was reading the shop manual, and it doesn't list using as RTV or anything on the intake bolts. Do any of these bolts pass through the water jacket? Do I need to use any rtv? Just a little in the four corners where the rubber end gaskets meet the side gaskets right? How about the big flat side gaskets? Before I used this red gooey liquid on those gaskets. Is that needed? Just hoping not to do this again. I checked at the dealer, and they wanted $800 for the intake gasket replacement. There's no way I'm gonna pay that much when the gasket set only costs about $60 at the dealership. Also, is the gasket at the dealership any better/worse than one at say NAPA? They want about $80 for the same gasket set. Is theirs better? Thanks for all your input. Andrew R.

Ok, I have a question, hopefully someone can help. I have a 2000 K3500 Crew Cab Long Bed 4WD with a 7.4 liter V8. I just purchased it about 1 month ago. I think I got screwed. It was VERY clean under the hood, but the whole truck was that way. Well, to make a long story short, it is now leaking antifreeze all along the intake gasket area, down in the corner mostly, where the block, intake, heads come together. I'm sure I'll probably have to replace the intake gasket, hopefully that will be all. Here's my question. While I have it torn apart, would it benefit me to put in a new intake? Any other suggestions while I have it apart? I can't really afford more than a few hundred dollars in new parts. I'm new to Big Blocks, so any help would be appreciated. I'm having a hard time finding info, because I still have the old style truck, even though it's a 2000, because they didn't change over the 1 ton's for a few years after the 1/2 tons. Most of the info I find is on the New engine's also (5.3, 6.0. 8.1) There is much info about 454's that are fuel injected. I'm not even sure what kind of fuel injection I have. I'm a carburetor guy up until now. Thanks for any help you can offer. Andrew R.

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