Multiple lawsuits against Caterpillar for chronic failures of its 2007-2010 ACERT diesels go beyond heavy trucks, and include school buses and motor coaches as well as at least one marine engine, according to news reports, while a wide variety of problems have been chronicled in discussion groups on the Internet.

At least 15 suits are now pending over Cat C13 and C15 engines, reports say, and some have been consolidated by a federal court to make them more manageable. Some suits are in state courts.

Law firms have filed suits on behalf of trucking and bus companies and at least one owner-operator, news reports say. A common complaint is that the engines are unreliable and repeatedly break down, leaving trucks, drivers and loads stranded while mechanics at truck dealers and Cat’s own distributors struggled to repair them.

Some fleets claim they lost hundreds of thousands of dollars in repairs and lost revenue; many disposed of their Cat-powered trucks early and bought vehicles with other engines. A boat fire in Florida prompted one suit, while a motor coach owner in California sued there.

Stories in the Wall Street Journal and the Journal Star of Peoria, Ill., Cat’s corporate home, said some suits have been settled with judgments ranging into the millions of dollars.

A school district in San Antonio, Tex., won $900,000 over engine failures and fires that destroyed at least two buses, reports said. Those presumably involved midrange C7 diesels, which used pollution-control equipment similar to those on the larger C13 and C15 engines.

Complaints on internet chat sites include vibrations, fuel starvation, injectors, cooling systems, diesel particulate filters, and the “seventh fuel injector” that provides heat for burning soot out of the DPFs. Some complaints date prior to the implementation of ACERT equipment.

ACERT, which stands for Advanced Combustion Emiussions Reduction Technology, was a key feature was the piping of filtered exhaust gas to combustion chambers instead of using unfiltered gas, as competitors did. This, too, was troublesome, users have claimed.

Effects on Cat’s financial performance are not known, but the huge, multi-national corporation earns billions of dollars a year and is probably in no danger. Cat’s main businesses are manufacturing machinery and engines for construction, mining, electric power generation, ships and boats, and railroad locomotives.

However, “The suits are a potential embarrassment for a company that regularly says the reliability of its products justifies premium prices,” noted the WSJ.

As is common in lawsuits brought against corporations, Cat has not commented on specific filings and complaints. In a statement last month, the company said, “Caterpillar Inc. is addressing various claims relating to alleged performance issues with emissions technology in some of its 2007 EPA-compliant C13 and C15 ACERT on-highway engines.

“Caterpillar has worked diligently to deliver operating cost improvements and other value-added features in its engines to enable our customers to benefit from this technology,” the statement said. “Our customers have utilized and had success with the performance of these engines in trucks, buses and RVs across millions of miles in North America.

“Caterpillar looks forward to addressing these allegations now that they have been consolidated in one forum.”

Cat left the truck- and bus-engine business at the end of 2009 when ever-tighter federal emissions limits made compliance increasingly expensive. Meanwhile, the market for vendor-supplied diesels was shrinking as truck builders used more of their own engines. Cummins is now the only independent engine supplier to commercial truck makers.