Western Engine Supply They did a poor quality repair, ruined the part, and blackmailed me. Denver CO

I’m a Professional Engine Builder — They Ruined My OM642, Lied About Mercedes Specs, and Held My Parts Hostage

Complaint:  I am a professional mechanic with a degree in mechanical engineering, trained specifically in internal combustion engine design. I’ve rebuilt hundreds of engines over the years with my own hands. That’s why I immediately recognized that this machine shop is both dangerously incompetent and deeply dishonest.

I brought them a Mercedes OM642 engine block (standard bore 83.00 mm) and a brand-new set of NPR oversize pistons marked 83.50 mm on the factory box. I gave verbal instructions, through a fluent English-speaking friend, to bore the block according to the pistons’ actual measurements — with a proper diesel clearance of 0.06–0.07 mm.

But instead of working from actual piston dimensions, they started converting everything into inches and showed a clear lack of proper metric equipment. Their understanding of tolerances was so misguided that they presented me with a printed document, which they claimed was provided by a Mercedes-Benz dealer, stating that the correct clearance should be 0.128 to 0.140 mm.

They were extremely insistent:

They kept pointing their fingers at the paper,

Highlighted the clearance numbers in yellow marker,

Drew arrows and marks all over the page,

And told me with full confidence that "this is the correct data — straight from Mercedes — everything you read online is fake."

I still have that exact paper in my possession — complete with their company information printed on it and their markings, which I kept as evidence of their false claims.

Anyone with even basic diesel engine experience knows that 0.128–0.140 mm clearance is not acceptable for a 3.0L V6 Mercedes OM642. These values might apply to giant 15-liter commercial engines like Detroit Diesels — but not to a high-efficiency turbocharged light-duty diesel. Their numbers are wildly wrong, and their confidence only made it worse.

Once I pointed out their mistake and said they had destroyed the block, I told them they could keep the block — but I wanted my other valuable components back, including:

My brand-new NPR pistons

The main bearing cap bolts

The lower crankcase girdles

They refused to return anything unless I paid for the work they botched. That’s extortion, plain and simple — using my own property as leverage after destroying my engine.

I have photos, video documentation, piston box labels, and the fraudulent clearance document with their markings and highlights.

Do not trust this shop under any circumstances — especially with metric, diesel, or precision engines. They lack the tools, knowledge, and ethics to do the job right — and then blame you when they fail.