My 2.8 will start, redline, then die. I took off a bunch of stuff to replace the thermostat and thermostat housing and when i put it all back together it wouldn't start... well is starts then dies instantly. Heres a link to the thread from when i was replacing the thermostat.

https://www.thirdgen.org/forums/v6/6...ml#post5489954

Ill post a video soon of what my car does when i try starting it. As soon as I figure out how to post videos...

 

stop trying to start it , its reving to redline because u have a massive vacum leak , did u unhook the brake booster hose ? also did u use rtv or gaskets on the intake manifold . if u used rtv get rid of the crap and use the correct gaskets

edit im surprised at some of the ppl who told u to use rtv for the intake gaskets as i figured the would know better, yes it can be used but its not the right way , just go buy the gasket set for 17$'s or whatever it is and do it the right way

did u happen to remove the injectors for any reason , if so u could have torn the orings on them which will also cause a bad vacum leak


on the 2.8 the pcv valve hooks directly into the intake manifold base so if u left this unhooked u will also have a massive vacum leak

 

i almost forgot if u dont have the rubber plug plugged intot he back of the throttle body were the vacum lines for the fpr and other stuff was hooked up thats also a massive leak.

i do belive the one air passage that that rubber block goes into is about 1/2 inch in diameter so it would be a pretty substantial leak

 

Thanks for the info and speedy reply. Ill go and buy the gaskets and correct sealant. Ill probably just take everything apart again then make sure there are no leaks as I put it back together. I REALLY appreciate your help. Thanks for throwing that knowledge at me but I have one question. I tightened the plenum really tight. and did end up using RTV silicone. Do you really think it would cause a big enough leak to cause all these problems? Or is it more likely its some hose i forgot to reconnect? I didn't remove the brake booster hose and I feel like I put all the hoses back in there place and I also feel like it woudnt leak cuz of the gasket just because i tried so hard to make sure that it wouldnt leak but clearly I'm wrong about one of those two.

 

when u use rtv u have to let the rtv start to dry before u tighten it down or it just squezzes out and will leak


the only reason the motor would goto redline soon as u start it is either the throttle is stuck open or u have a very big leak


the only thing u did remove was the upper plenum correct?

if so pull it apart carefully clean off all the rtv and use gaskets, get some hi tak spray and sray one side of the gaskets and then lay them in place on the plenum or on the middle intake and let the glue dry .


by doing this they will be glued to one side of the intake and if u ever need to remove it again the gaskets will come off with the plenum and not tear and can be reused


before u rip it all apart just double check all the vacum connections


few years back i did a carb swap on my iroc went from edelbrock to a single plane manifold and holley 670 had almost the same issue went to rip it all apart and found a big vacum port on the carb that was hidden i forgot to cap

 

I left the hose on the back of the plenum unplugged
It starts, now im off to go fix my coolant leak. Someone told me about letting the rtv dry before tightening it so luckily I already did that. Thanks for the help.

 

its usually somehting stupid like that, never hurts to dbl and triple check

 

TGO to the rescue again!