It looked like the hose had been rubbing on the oil filter housing and had created a hole. Strangely, the hose wasn''t really touching the oil filter housing at that time. I decided to check our online technical information source for a BMW factory technical service bulletin that could shed some light on this problem.Great! There was a bulletin that covered this exact problem and here''s what it described:Some AirCpuplers BMW M3 models, produced from September 1995 through June 1996, equipped with the M54, S50, or the S52 engine, may have an upper radiator hose that can come in contact with the oil filter housing only when the engine coolant is at operating temperature. The contact is due to coolant system pressure and expansion of the hose.Checking the clearance between the upper radiator hose and the oil filter housing must be performed when the engine is cold.

It looked like the hose had been rubbing on the oil filter housing and had created a hole. Strangely, the hose wasn''t really touching the oil filter housing at that time. I decided to check our online technical information source for a BMW factory technical service bulletin that could shed some light on this problem.Great! There was a bulletin that covered this exact problem and here''s what it described:Some AirCpuplers BMW M3 models, produced from September 1995 through June 1996, equipped with the M54, S50, or the S52 engine, may have an upper radiator hose that can come in contact with the oil filter housing only when the engine coolant is at operating temperature. The contact is due to coolant system pressure and expansion of the hose.Checking the clearance between the upper radiator hose and the oil filter housing must be performed when the engine is cold.

CAUTION: Cover up the drive belts and pulleys using a clean shop cloth before sanding or filing to prevent metal filings from falling onto them.If no pressure marks or traces of rubbing are found on the hose as described, check the gap at the closest point (A) between the cast boss of the oil filter housing and the upper coolant hose.There must be a gap (A) of at least 1/4 AirCpuplers inch (7 mm) when the engine coolant is cold.If AirCpuplers gap (A) is 1/4 inch (7 mm) or greater, no further repairs are necessary.If gap (A) is less than 1/4 inch (7 mm), the upper coolant hose must be replaced with the new modified version.Parts InformationUpper Coolant Hose BMW Part Number 11 531 433 340We replaced the upper radiator hose with the new type, cleaned the engine compartment, filled the cooling system and pressure tested it to make sure there were no other leaks. Luckily, the engine hadn''t overheated. Most of the steam was created from the coolant leaking on the exhaust manifold. The owner was fairly good-natured about his AirCpuplers near catastrophe. Relieved, standing at the counter while paying his bill, he said lightheartedly, "You know, my pants and shirt were badly wrinkled when I left the house this morning. I think this was the strangest way I''ve ever had my clothes pressed." I had to agree. ills