I own a C5 and my dad has a C4 Collectors Edition and has the LT4 in it. Ive been babysitting it for a few weeks and took it out today. I smelled oil burning but no smoke, Dad told me that the intake manifold is leaking on the back side of it. He asked me to fix it. Is this a common problem? Also is there anything on taking the intake manifold off and re installing it? Thanks for any info!

 

Intake leaks are very common on the LTx engines, and fairly easy to fix.

 

Yup.. not a big deal to replace it... just make sure to follow proper torq proceedure on the intake bolts..
-=Rick

 

Thanks, thats good to know its easy. But is there any instructions on removal and installation and torque specs? Thanks Again!

 

Disconnect battery ground cable, then drain cooling system.

Remove throttle body air duct, then disconnect electrical connectors from fuel injectors.

Disconnect left and righthand wiring harness and position aside.

Remove accelerator cable bracket and disconnect cable from throttle body.

Disconnect hoses from AIR diverter valve.

Disconnect ground strap from intake manifold.

Remove retaining bolts from fuel rail.

Disconnect vacuum hose from fuel pressure regulator.

Relieve fuel system pressure then disconnect and cap fuel lines at fuel rail.

Remove fuel injectors and fuel rail from intake manifold and position aside, Fig. 2.

Disconnect vacuum and PCV hoses from intake manifold.

On VIN P models, remove EGR solenoid bracket and fuel vapor canister purge solenoid bracket.

Remove EGR valve.

On VIN 5 models, remove EGR cover plate, gasket and nuts.

On all models, disconnect air pipe from intake manifold and righthand exhaust manifold.

Remove alternator brace.

Disconnect coolant hoses from throttle body.

Remove throttle body to intake manifold mounting bolts, then remove throttle body and gasket, Fig. 2.

Remove intake manifold to engine block attaching bolts and studs, then remove intake manifold and gasket, Fig. 3.

Reverse procedure to install. Prior to installation, apply a 3/16 inch bead of sealer 1052366 or equivalent to front and rear of engine block.

Extend bead of sealer 1/2 inch up each cylinder head to seal and retain gaskets. Install manifold and tighten bolts to specifications in sequence shown in Fig. 4.

 

1st pass ~6ft/lbs 2nd Pass 35ft/lbs

Below is the picture of the Tq Sequence.
-=Rick

 

just a fyi.. the LT4 doesn't have EGR nor does it have a ground strap. Everything else looks correct.

You going to have to disconnect everything on the left and right of the intake. harness, MAP, etc.. I would take pictures before you start removing parts and cables. that way you know how the harness is routed. Unscrew the gas cap to release the pressure and you can remove the 4 bolts holding the fuel rail to the intake. I place a towel on the windshield and set the fuel rail with injections and lines still connect/attached on the towel. You shouldn't loose any gas. Make sure to torque the bolts in the proper sequence as vettetech said. Clean the "chain walls" before applying RTV. GM sells two different gaskets for the LT4. Don't use the 7777 gasket. I'll lookup the part number for the other gasket and post it here. Gaskets should be installed dry.



rob

 

VetteTech81 and Bluewasp THANK YOU VERY MUCH! Im not sure when I'll start on it but I will soon. Ya'll just made my job a lot easier!

 

No problem! Right on about the EGR on the LT4 I just grabbed the info quickly from the service info I had availble.

Good Luck! It's a good project for a weekend, probably a couple hours or so at most depending how quickly you work.. take your time and have fun with your car.
-=Rick

 

Prep is the key. Clean off all the old sealant. Use some brake cleaner on the surfaces to ensure oil free contact. Make sure you run a 1/4" bead of Permatex Ultra-Black at least a 1/2" up on the heads.

Once you've torqued it down to 35 lb/ft let it sit for 24 hours if possible. This is helpful if you used a bit of extra goo and it may have pushed itself into the lifter area. This allows the sealant to setup and not fall into the valley where it could potentially cause problems.

 

Replacing the intake gaskets on an LT4 is super easy, especially if you have already bypassed the coolant flow through the throttle body. If you have, there is no coolant that will be lost in the process.

I think it took me about 3-4 hours to do mine. Good luck.