1993 4.3 Intake Gaskets

[Kkortman112]

I'm going to be doing intake gaskets and some other work on my 1993 4.3 this coming weekend, but I'm wondering if I have the correct intake gaskets. I went with Felpro's but the rear coolant port is blocked off on them and on my truck the heater gets fed from the rear crossover passage in the intake, so I don't see how the heater will work with these gaskets. I just spend a good half hour up at my local NAPA after work today and they come up with the same exact gaskets as I did from Rock Auto. They did find that 1991 trucks used gaskets that have those rear ports open so I do have a pair of them coming just in case I need them. But I figured I'd ask the brain trust on here if anyone knows which style I need? The only oddball thing with my truck is that it was spec'd with California emissions when it was built so I have found a few odd things on it, such as even though it's a 93 it uses a heated 3 wire O2 sensor instead of the 49 state 1 wire style and also has an all electronic EGR valve instead of the 4 state vacuum operated one. So I'm not sure if that would make a difference for the intake gaskets too. I'm just trying to make sure I have all parts on hand so that I can get this job done.

 

[PlayingWithTBI]

I went with Felpro's but the rear coolant port is blocked off on them and on my truck the heater gets fed from the rear crossover passage in the intake

Yes, it should have a little steam hole there. My 5.7L is the same. The previous time I did the intake gaskets I used Mahle gaskets which came with that block-off insert for both styles. This last time I used the same Felpro gaskets as you got.

I wonder if your 93 is a late year model with some newer sensors/controls from a 94?

 

[Kkortman112]

Yes, it should have a little steam hole there. My 5.7L is the same. The previous time I did the intake gaskets I used Mahle gaskets which came with that block-off insert for both styles. This last time I used the same Felpro gaskets as you got.

I wonder if your 93 is a late year model with some newer sensors/controls from a 94?

I just ordered some Victor gaskets that show a metal restrictor deal in the back holes. As to my truck according to the factory parts book and a VIN research I did on it, it has the NB2 California emissions setup and the NRQ close coupled exhaust system which also goes along with that emissions setup. I did find out this same electronic EGR valve is the same/similar to what is used on later model trucks with 49 state emissions. Although this truck was made in Ft. Wayne, IN and went to California it is now back in IN about 60 miles from where it was assembled lol!

 

[Kkortman112]

Oh, I forgot to mention this truck is an early 93, build date of November 1992.

 

[Schurkey]

The heater isn't fed from the back of the cylinder head supplying the rear corner of the intake manifold.

The heater is supplied by hot coolant from the thermostat area, routed to the rear corner of the manifold using a passage IN the manifold.

Thus, only a steam hole in the gasket between head and manifold.

Using hot coolant to warm the intake gets it hot enough to vaporize the fuel, without being so hot that it bakes the oil mist in the lifter valley.

 

[Kkortman112]

The heater isn't fed from the back of the cylinder head supplying the rear corner of the intake manifold.

The heater is supplied by hot coolant from the thermostat area, routed to the rear corner of the manifold using a passage IN the manifold.

Thus, only a steam hole in the gasket between head and manifold.

Using hot coolant to warm the intake gets it hot enough to vaporize the fuel, without being so hot that it bakes the oil mist in the lifter valley.

I didn't know there is an internal coolant passage. The current Felpro gaskets don't have any kind of opening or steam hole for the rear passages though, they are completely blocked.

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[Kkortman112]

Well job is complete. No major issues other than #6 sparkplug was loose for some reason. While it was down for the intake gaskets I went ahead and did valve cover gaskets, new module in the distributor, replaced my leaking oil pressure sending unit and put a new water pump on. Considering I think the engine has 250K on it, the insides didn't look too bad.

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[Schurkey]

Fel-Pro version for 5.7L TBI, along with a conventional gasket:
http://hbassociates.us/K1500_ZZ4_Intake_016.jpg

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[Kkortman112]

Fel-Pro version for 5.7L TBI, along with a conventional gasket:
http://hbassociates.us/K1500_ZZ4_Intake_016.jpg

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V8 engines have the heater core feed up at the front of the engine correct? On my 4.3 it's off the passenger side rear, maybe that's why my original gaskets and 2 of the replacement sets (Felpro and Victor) both had the rear ports completely blocked off.

 

[PlayingWithTBI]

V8 engines have the heater core feed up at the front of the engine correct?

Not on TBIs the heater hose quick connect fitting is on the rear too.