fairly significant
Typical Repair Cost:
Average Mileage:
105,000 miles
Total Complaints:
2 complaints

Most common solutions:

  1. make sure to use 3rd gen aluminum lower gasket (1 reports)
  2. replace upper and lower intake manifold gaskets (1 reports)
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problem #2

Jun 012023

Bonneville SE 3.8L V6

  • Automatic transmission
  • 150,000 miles

Upper and lower intake manifold gaskets fail every 60,000 miles no matter what. 1st gen lower gasket made of rubber and would fail. 2nd gen lower gasket made of thicker rubber and would also fail, both around 50,000 miles. 3rd gen lower gasket made of aluminum and rubber would also fail around 50,00miles.

When replacing upper and lower gaskets. Make sure to put black RTV silicone in the 4 corners of the lower intake manifold where it meets the top of the head. You may want to set the lower intake manifold in to the RTV and torque an additional 2ftlbs over spec and let dry 24 hours as RTV needs air to properly dry.

For the upper intake manifold make sure you get a kit that has the metal tube that gets adhered to the upper intake manifold EGR port- one tube seats to the top of the lower intake manifold and the other tube/sleeve go's into the upper intake manifold.

- makjohnson, Sauk City, US

problem #1

Oct 042010

Bonneville SLE V6

  • Automatic transmission
  • 60,000 miles

Well, obviously, we know about this problem. The DexCool eats the gaskets and they leak and have to be replaced. And GM does nothing to (fully or even partially) reimburse its victims. Last GM car I buy.

- dusenshine, Trenton, NJ, US