2005 4.3 MPI Intake Manifold Gaskets

[kvkon]

Found a trace of antifreeze in the lube oil while doing an oil change yesterday. Looks like intake manifold gaskets are a problem area. Agreed? Most of the replacement job looks pretty straight forward but I'm not clear on how to disconnect the fuel hoses from the fuel rail. Also is it necessary to separate the top manifold from the bottom? What make of gaskets are suggested? Gasket or RTV or both on the ends/corners? Thanks!

 

[Bt Doctur]

usually your just concerned with the lower intake gaskets .I use FelPro exclusively and RTV on the ends of the gaskets and I use Permatex Aviation around the water jacket ports and on the gasket

 

[kvkon]

OK, is it possible to remove both without separating them?

 

[Scott Danforth]

yes

 

[alldodge]

What's your engine serial number?

 

[kvkon]

what's your engine serial number?

0w068147

 

[alldodge]

Thanks
I don't have a manual which covers your motor, but think yours will use the fuel line disconnect tool. Think they are push lock. With fuel pressure off, put tool on line and push in in and under fitting, the line should come loose

https://www.amazon.com/Lisle-37000-...sed-search-10&pf_rd_t=BROWSE&pf_rd_i=15707681

 

[Lou C]

On those gaskets, this is for sure a Vortec engine, check the torque specs, the Vortec engines torque specs for the intake bolts are a lot lower, like 10 ft lbs IIRC, the older pre-Vortec like mine were 30 ft lbs.
I used Fel Pro on my top end overhaul and they sealed well. Like Bt Dr said just a bit of Permatex Aviation around the water ports. Sometimes on older engines there is pitting on the intake sealing surfaces or cyl heads.

 

[kvkon]

Thanks
I don't have a manual which covers your motor, but think yours will use the fuel line disconnect tool. Think they are push lock. With fuel pressure off, put tool on line and push in in and under fitting, the line should come loose

https://www.amazon.com/Lisle-37000-...sed-search-10&pf_rd_t=BROWSE&pf_rd_i=15707681

OK thanks for the link. After looking at the line I suspected there would be tool required. Just ordered it. Thanks.

 

[kvkon]

Quick update. Manifold gaskets had been previously changed by someone. Standard FelPro blue gaskets were in it. Installation was poorly done and leaking antifreeze into the lifter valley. There an upgraded FelPro gasket set available with multiple sealing rings around each intake and water port. Should help if there's corrosion around water ports. Part number MS98002T. Fingers crossed. [h=1][/h]

 

[Lou C]

Make sure the sealing surfaces of the intake are flat and level to less than .003" when checked with a straightedge and feeler gauges. Those better quality Fel Pros should seal well. I used them on mine and they sealed well even though its an old intake used in salt water. I have always wondered though if the Vortec engines had more trouble with intake leaks than the non-vortec because the Vortecs only have 8 bolts holding the intake on vs 12 on the non-vortec….

 

[kvkon]

Make sure the sealing surfaces of the intake are flat and level to less than .003" when checked with a straightedge and feeler gauges. Those better quality Fel Pros should seal well. I used them on mine and they sealed well even though its an old intake used in salt water. I have always wondered though if the Vortec engines had more trouble with intake leaks than the non-vortec because the Vortecs only have 8 bolts holding the intake on vs 12 on the non-vortec….

Yes and very light torque holding them.

 

[QBhoy]

Glad you found the issue, but naturally I’d maybe be doubtful about the intake of AF coming from there.
If this is a fresh water internally cooled engine, ignore me. But if it’s the usual 4.3 MPi with raw water and you mean af is getting into the engine over winter storage...mmm. I’m not so sure it would be common from there. More likely from the exhaust manifolds perhaps. Just another option.