Flooded cars can cause a flood of problems down the road.

Pennsylvania has 20,000 vehicles — specifically 3,751 in nearby Pittsburgh — that have been reported as flood-damaged but are now back on the road, according to Carfax. But their unsuspecting, maybe misinformed, owners may not realize the potential consequences.

Recent flooding from Hurricane Matthew in the Carolinas and heavy rains in Texas and in Iowa means more flood-damaged cars are likely to flood the pre-owned market here.

“They are a big bee nest waiting to be cracked open,” said Byron Dreher, an automotive instructor at Butler County Area Vocational-Technical School.

Larry Gamache, communications director at Carfax agrees, calling flooded vehicles a “buyer’s worst nightmare.”

“They’re ticking time bombs because when you least expect it, the electrical, mechanical or safety systems on these cars will fail, often without warning,” Gamache said in a press release. “Consumers everywhere need to be vigilant about checking a vehicle’s history for flood damage and getting a pre-purchase inspection to avoid buying cars that rot from the inside out.”

While floods are inarguably less common in Pennsylvania than in places like New Orleans, the northeastern state has more flooded vehicles on the road than both Louisiana and Florida. Pennsylvania is second only to Texas, which takes the gold in this inauspicious game.

Dreher, who has taught at the Vocational-Technical School’s automotive technology program for 11 years, warns that while formerly flooded vehicles can be rebuilt reliably, he has seen many that don’t meet that standard. He was working at Kelly Chevrolet, where he gained 24 years experience, when someone brought in a used Chevrolet vehicle because the four-wheel drive stopped working. It was a result of flood damage that occurred before they owned it.

“If you’re purchasing a used car, just be careful,” Dreher said. “They (flood cars) do slip through.”

When looking at a used car, Dreher urges people to always be cautious. He suggests looking under the hood for mud and checking the interior for a musty smell before making any used car purchase. If something seems “off,” prospective buyers should ask questions.

“If it sounds too good to be true, you should have red flags going up,” he said.

There are used cars, and then there are reconstructed used cars; buyers should be cautious with both.

Used cars without reconstructed titles shouldn’t have flood damage. Yet, a savvy shopper could proceed with caution by probing into the car’s history: asking questions and getting a Carfax. (It is free to check for flood damage at carfax.com/flood.)

If concerned, that person might also consider having the car inspected by a mechanic of their choosing before the purchase.

Reconstructed used vehicles are ones that have previously had a salvage title, which PennDOT defines as a vehicle that doesn’t meet inspection or vehicle equipment standards and would cost too much to repair.

“A lot of times they are sold at an auction really cheap,” Dreher explained.

That’s how people can afford to purchase and rebuild them.

Once it is repaired and passes an enhanced inspection, the vehicle is awarded a reconstructed title, which tells customers that a certificate of salvage was issued for it, but it has since been restored to operating condition.

To get a reconstructed title in Pennsylvania, the vehicle must pass an enhanced inspection.

Not all reconstructed vehicles have been previously flooded; they may have earned the title because of hail damage or vandalism, or they might be recovered from a theft. In Pennsylvania, the reconstructed title should be specifically labeled “flood,” but the requirement varies by state.

“If it’s an R-title and they can’t tell you why, I’d be walking the other way,” Dreher said.

He used to work part-time flipping vehicles, even flooded ones, at Ray’s Auto Sales. He would replace the transmission, engine, computers and anything else that even might cause trouble in the flooded ones, “right down to the radio.”

When repaired properly, he says they are reliable. During the process, he took photos and kept receipts to show buyers proof of the repairs.

Once Dreher even helped rebuild a flooded dump truck, at the request of an insurance company, as it was less expensive to fix it than replace it.

“But after working around them, I frown upon buying a flood car,” Dreher said. “I myself stay away from them.”