Air Intake Problem

Robert and Linda Grindahl had an interesting event happen to them on their annual cruise to the North Channel of Lake Huron. The wind was light and they were behind schedule so they decided to motor sail. While doing so, they heard a sharp metallic click, but couldn’t determine its source. A short time later, they were alarmed to notice the engine (VOLVO MD2B, S/N 31422) was not running well, saw that the engine temperature was red-lined, and immediately shut the engine down.

After opening the engine compartment, it was apparent there was a problem, since unburned diesel and diesel particulate matter coated the area. It was encouraging that the engine started since that indicated that it wasn’t damaged by the overtemp, but it ran very roughly.

After removing the air intake "horns" and hand cranking the engine while holding a hand over the air intake; first #1 cylinder, then #2, one could feel a "sucking", followed by a slight "poof", while on #2 one could only feel the "sucking". They speculated that the intake valve must not be fully closing. Subsequently, the #1 cylinder head was removed and it was noticed that there was something stuck in the intake valve.

The object was about 2 cm X 6 cm and looked like expanded metal. It turned out that a portion of the expanded metal grid holding the air cleaner element (in the horn) had been ingested into the cylinder head.

The valves were removed and appeared not bent, but the exhaust valve seat was burnt and leaking (which helped explain why the engine had been difficult to start). Following a bit of machine shop work on the head and awaiting the delivery of the necessary gaskets and air intake horn, the engine was placed back into satisfactory service. Bob mentioned that the cost of the parts and labor was approximately $300 US.