Toyota said yesterday it has found in a handful of its much-hyped new Tundra pickups a defect that caused the engines to fail.

Toyota has reports of camshafts breaking in the 5.7-liter V-8 engines of about 20 Tundras so far. The flaw was due to a manufacturing defect by a subcontractor. All of the engines are being replaced.

Toyota spokesman Bill Kwong said he doesn't know how many engines were made and installed before the flaw was detected. But he said the problem was found early. It was fixed at the subcontractor's factory in February, the same month that Tundra launched amid a $100 million advertising blitz.

The company has not issued a recall. "We're still investigating it. We don't believe it was that many," Kwong said.

A cursory check of investigations under way by the National Highway Traffic Safety Administration didn't include one for Tundra engines, which it typically would begin if the defect involved safety.

The issue amounts to a rare embarrassment for Toyota. While problems aren't unusual in new models, Tundra is one of the automaker's most important launches in years as it attempts to break Detroit's lock on the full-size pickup market.

"I'm sure there are people agonizing over this in Toyota," said Jeffrey Liker, a University of Michigan professor and author of "Toyota Talent." "Toyota prides itself on zero defects."

Toyota said earlier this month that its pre-launch forecasts are on track for Tundra. It hopes to sell as many as 200,000 this year, up from about 125,000 of the old model last year.

Although optional, the 381-horsepower 5.7-liter V-8 has quickly become the most popular engine for the Tundra, which is depicted in ads as having brawny towing capabilities. About 65 percent of buyers opt for it.

Kwong would not disclose the name of the subcontractor. The engines are assembled in Alabama and installed in the pickups at Toyota's plant in San Antonio.

There are four camshafts in each engine. Two control the operation of the intake valves and the other two control the exhaust valves. The 32 valves move air and fuel in and out of the engine's combustion chambers.

The problem occurred in the later stages of the manufacture of the camshafts that control only the intake valves.

If a camshaft breaks, the engine will barely work or not at all. Rather than try to fix the affected engines, Kwong said owners are getting new ones that are shipped overnight to dealers.