Seven problems related to manifold/header/muffler/tail pipe have been reported for the 1999 Chevrolet Tahoe. The most recently reported issues are listed below.
Intake manifold cooling system leak.
Smells of antifreeze in cab. Took to mechanic, intake manifold gasket must be replaced. This is due to bad part installed. This is a known problem with GMC.
Intake manifold leaked at gasket and at stub out for heater hose. Coolant leaked out of intake manifold. Intake manifold had to be replaced.
My husband and I were in route one evening when the check engine light came on. Following the manual's instructions: check the coolant gages, it had a reading of nearly 260. We pulled over at the next exit, into the parking lot of a gas station. We checked the coolant recovery tank, it was empty. Inspected the engine fan, it was operating normally. Waited 1 1/2 hrs to let engine cool down. Removed radiator cap. Radiator was dry. I asked the gas station for the recommended brand 'dex-cool'. Fortunately, they didn't carry that brand. (the reports I've read today, indicate brand dex-cool coolant is the #1 cause in gasket corrosions, it eats plastic. Added a 50/50 coolant and arrived home without further incident. The following morning I took my vehicle to a reputable mechanic. After giving him a very brief description of what we'd experienced the evening prior, he immediately stopped me in mid-sentence and said "vickie, you don't even have to finish telling me. I know exactly what the problem is. It's common for this engine in chevy's from 1996 - 1999 to leak coolant from the intake manifold near the rear firewall" he went on to say, that their service center has had many customers come in with the same complaint frequently. He estimated the cost to replace the intake manifold gasket is between $250 - $300. If this is such a common problem, then gm should not only be required to notify the owners, but should assist in the cost to replace the defective gaskets. The mechanic also stated, if the fluid enters the engine, which could very well happen, then the engine would lock-up. This is a safety issue, and can easily be prevented. Need there be a fatality before gm voluntarily notifies the owners and rectify this problem? I demand that gm inform current owners of this problem, reimburse owners who've already paid to have their vehicles repaired, and finally, stop recommending the use of dex-cool brand coolant in the owners manual!!!.
Composite manifold is leaking, cause unknown. Dealer notified.
The manifold leaked water into the engine. The dealer has been made aware of the problem. Ph scc.
The exhaust manifold was falling out causing vehicle to lose gas mileage. Vehicle experienced pulsated brakes when driving on the hwy at 55 mph. Dealer replaced brakes and surfaced rotors to correct the problem. Brakes failed after serviced. However, the calibers got very hot which boilded the oil in the brakes system which caused the failure.