installing intake manifold gasket, 94 ChevyTBI 350

[gmchevroletruck]

Got a remanufactured motor, about to install it actually right now, working on it as we speak. (some of you have seen my other thread about the project, and thanks for the help over there as well!) Project is behind schedule but I've hit a snag - the gasket set that came with the engine, included an intake manifold gasket that has the rear ports on the gasket blocked off with a little metal piece within the gasket. My actual cylinder head, and intake manifold (both stock) have holes in that location. The Haynes Manual says that "some models have the rear passages blocked off" and to make sure the gasket is installed that way on those models to ensure proper amount of coolant flow, but it does not specify which models this pertains to. From what I can tell, the intake would get coolant flowing through it either way, from the thermostat to the rear of the intake where the screw-in fitting is that goes to the heater core. What I want to be sure of, is that if I leave that passage blocked off by the gasket, if I am starving the cylinder head itself of coolant. I do not remember if the original motor I took out of the vehicle had this blocked off or not. There are coolant passages in the front of each cylinder head that mate up to the intake, I just can't figure out how else the cylinder head would get coolant flowing through it all the way to the rear of the cylinder heads without this hole open, but I admit I do not know much about these cylinder heads, or if they have some sort of other passages in them that line up with coolant passages in the block that would still specifically feed them in such a manner to allow flow all the way through them, with these rear gasket holes blocked off.

Can anyone help, with a definite answer? Would hate to mess up the motor, or have to do this twice.

Thanks in advance!!

 

[bullwinkle]

The block flows coolant up from the head from the rear, comes out the front by the thermostat housing (or the bypass)-my '94 350 TBI Suburban was the same way, if I remember correctly there was a small pinhole in the gasket (might have been by the exhaust crossover) in the blocked off port, they should be marked by the mfr. as well.

 

[gmchevroletruck]

Thanks for the quick answer!

Ohhhhh ok...I think I get it. So, the coolant is of course always circulating through the block and the heads, and the thermostat, when open, allows it flow through the intake to the rear threaded fitting and hose to the heater core and radiator.

So,...it's always circulating through the heads, and does not need that rear passage to be "unblocked" to work correctly? (I did see that pinhole, I wondered about that...what does that do?)

 

[gmchevroletruck]

I'm assuming that means, leave it blocked off then, correct?

 

[1993_VG30E_GXE]

I suspect you have the wrong gasket for your exact VIN#. Did you specify to the dealer your VIN# before they gave you the gasket?

Sometimes it's VIN specific and they'll have the same part code, but slightly different gasket depending on the yrs etc...

I wouldn't install any gasket that blocks anything. Maybe you can modify the gasket slightly?

 

[xxch4osxx]

I dont think I would attempt to modify the gasket. I would do as someone else said and go in with your VIN and get a vehicle specific gasket.

 

[mechtech2]

My definite answer is to try and get a look at a factory set of gaskets.
And any other name brand aftermarket ones that you can.
There are often changes made to improve things, so note this.