2003 E150, 4.2 V6 - 135,000 miles - planning to drive this cross country and back.

So I need to replace my isolator bolts, and with all the reports of coolant leaking into the engine through the intake manifold gasket I plan to do that too so I can have the peace of mind given this vans milage.

But there are two intake manifold gaskets

1 - Fel-Pro MS94452 Manifold Gasket Set

#1 is the one shown in most of the Isolator bolt instructionals

Which one is the culprit for the coolant leak issue?

if it is #2, how much more difficult is it to access if I am already replacing the isolator bolts?

 

These can get confusing. You have an upper intake manifold gasket set(#1) that seals the intake manifold to the plenum. Then you have a lower intake manifold gasket set(#2) that seals the manifold to the heads.

#2 is where a coolant leak would develop, the upper manifold gaskets are dry and never see coolant.

 

thanks for this explanation and the picture, very helpful. Does anyone have any opinion on how much more of an effort it is to replace the lower intake manifold gasket?

Like, If I'm already doing the upper, and the isolator bolts, can I just as easily remove this intake manifold and do the gaskets? I just want to go into it with realistic expectations about time/effort.

 

I haven't done one on a 4.2L, so keep that in mind...

It's not much more of a job. You already have the majority of the disassembly completely if you are at the upper manifold gaskets. You'd have to drain the coolant and remove the bolts securing the lower manifold to the heads to remove. Be careful not to let ANYTHING drop down those intake ports. Any small nut or bolt that falls down there could prove to be a MAJOR headache.