4.3L Vortec Lower Intake Gasket Replace and MPFI Upgrade

[Cadcom]

Man, thanks for this. I have a 1999 S10 Blazer that my kid drives and need to do some of these updates.

 

[Sharps40]

Yep. If they loosen up again, I'll do that. For now, they seem good with about 1000 miles on them since tightening. No leaks. I suppose the next frost plugs to go will be the old factory press in ones that are on the Passenger rear and drivers front (under the DS motor mount). If those let go, I'll have to raise the motor. Probably put in 4 new ones at that point. With luck, the motor is buttoned up good for the next 50k or so miles.

 

[Sharps40]

Just ran 6 hrs to north va no issues. 19.6 mpg at an average 70 mph.

 

[Shotgun Jeremy]

Thanks for the great write up! I've got an 04 blazer that seems to have developed a pretty good oil leak from the lower intake gasket. I'm about to tear into it as well as the valve cover gaskets. This seems to be a bigger job than I was hoping for, but with your write up I think I'll manage. I know this is a borderline necropost, but I wanted to let you know that even 8 months later, you're still helping those of us who choose to use the "search" function of the internet.

 

[acastillo457]

I have 2002 Chevy Silverado 4.3, literally have the same problem like yours. Squeezed one of the hoses, heard it hiss and bubble up in the same spot you had. Currently following your procedures! Everything is going well. Thank you so much! Glad I found this.

 

[haole396]

Great write up. I’ve lost count of how many of those 4.3 and 5.7 intakes I’ve done. Those damn plastic/silicone gaskets just never lasted as long as we hoped. That was a great idea changing from the spider to the MPFI. Those poppets were often unreliable/unpredictable.
Great job!