The 4.3 and 5.7 of that vintage is very well known for the intake gaskets failing. It is due to the plastic used to make the gasket and the poor clamping angle of the intake to cylinder head. In the earlier generations of them the intake and head were clamped together at a right angle using bolts. To make the engine faster to assemble they changed the angle of the bolts so that instead of clamping at ninety degrees they now clamp at a steep angle. They also reduced the number of bolts in the intake to four. Instead of the parts holding the gasket the intake now acts like a wedge and crushes the bottom edge of the gasket tighter than the top. Then they also switched the gasket design to a plastic that cracks as it ages.
Replacing them with an updated aftermarket gasket is a great idea. The image shows the stock plastic gasket on the bottom compared to a Fel-Pro replacement. If you look close at the left side of the stock gasket you will see the cracks at the bottom as well as the failure on the top.
The vehicles condition and mileage would determine if it was worth repairing it as well as if you are doing it yourself verses having a shop do them.
Image (Click to make bigger)
Sunday, June 24th, 2018 AT 12:19 PM
