Coolant loss without signs of leak. Loss of oil with no signs of leak. Lifters chattering on cold start. Puff of white smoke on start-up. Loss of oil pressure. Defective cylinder heads made by castech.

- Dayton, OR, USA

2004 Chevy Tahoe with castech heads has a history of running hot or overheating with little warning. In the cooler months, will fail to heat the interior of the vehicle without warning. Can leave drivers and passengers (likely children) without transportation in a harsh environment.

- Virginia Beach, VA, USA

The engine cylinder heads for the 5.3L GM motors built by castech leak coolant into the engine causing engine overheat and internal engine failures. GM has issued a technical bulletin #060601019B to address the issue and diagnose the issue. GM will not offer customers any financial help in the replacement of the defective parts. This issue effects the safety of the vehicle and the safety of the persons in and around the vehicle. The fouled engine oil causes the lifters to fail, the oil pressure to drop and the engine to lock up due to lack of lubrication by the fouled oil and the driver has no way of knowing this is happening as there is no external indicators.

- League City , TX, USA

Consuming oil and water - needing 1-2 quarts of oil and 1 gallon water/coolant per 900 miles. No leaks, no dripping, no spots on garage floor. At start up, there is a large cloud of blue/white smoke from exhaust. Sometimes there is a very loud tapping in the engine until well after reaching normal temperature. Oil and water is being consumed internally - due to crack in cylinder head which is a known issue with certain engine blocks.

- Raleigh, NC, USA

2004 Tahoe, 79,000 miles. Engine overheated which could have caused fire if I had not noticed and stopped. GM dealer says overheaing due to crack in cylinder head and confirmed tsb 06-06-01-019B (06/12/2007) applies to vehicle, which admits there is known manufacturing defect in certain cylinder heads which can cause engine coolant to leak internally causing overheating and potential engine failure. Dealer refuses to cover repair. I have pending complaint with GM customer service to pay for damage. I think this should be a recall as it can lead to overheating, engine failure and potential fire. There are multiple reports on internet of same problems by other owners.

- Little Rock , AR, USA

2004 Chevy Tahoe speedometer quit working. Stays on 55 mph even when engine is off. Told it would be about $800 to fix. Now oil gauge is not working properly. It does not drop to zero. Oil in engine is at proper level.

- San Antonio, TX, USA

So many... where do I start? 1) at 9,000 mi. Intermediate shaft was replaced due to a popping feeling in the steering, at 16,000 mi. It is doing the same thing again. 2) at 9000 miles the instrument cluster was replaced due to a faulty tach motor making a buzzing/rattling sound, started making noise again at 13,000 miles took to dealer and said there is nothing wrong. 3) headlights flicker on and off on turns has been to the dealer 5 times since it had 9000 mi. 1st 2 times replaced a plug on alternator and said it was fixed, was not then said the found a bad connector still did not fix the problem. The problem still exists contacted GM and they were no help. 4) exhaust has been popping since new and sometimes after cool down sounds like something exploded 5) engine makes a noise when warmed up took in for service at 12000 miles and they cleaned oil pump pickup tube and said the oil pressure was not correct. This did not fix the problem took back in at 15000 and they stated no problem was found I was told the engine noise was normal. 6) the brakes pulsated when new took back at 59 mi. I was told to drive it and it would get better. Started again at 9000 mi. And they turned the rotors. Brakes started making a cracking noise in the front took in 3 times found no problem yet when I picked the vehicle up the last time at 15,000 mi the noise went away only to come back a week later. 7) when idling the vehicle vibrates bad!!!! dash will rattle and you can feel it in the steering wheel. I was told this was normal when the A/C was on yet it's worse when the A/C is off. Now that A/C is making a terrible noise from inside the engine compartment and inside the climate control box area. 8) engine has a miss at idle.

- Morgantown, WV, USA

Loud popping/pinging sound coming from front of vehicle when the vehicle is idle position or when it has been turned off.

- Sacramento, CA, USA