I noticed on the air cleaner hose to the engine i also have a small yellowish colour (oil line?) hose that has cracked and broken in two.
Anyone know if this is important and should be replaced?
thanks...
91 300e with M103 engine.

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I had the sam hose break. Thanks to others on this forum they identified it , I bought a new hose at PEP Boys and replaced it. Good Luck. (My first picture wasn't as good as yours but it was the same hose.

Broken hose? What is it

It's the vent line from the fuel pressure regulator, and they all seem to break there on 103s. You can replace it or splice it together with a short piece of 1/8" ID rubber tubing.

It appears to be nylon material. The ID is 2 mm, OD is 4 mm, and total length is 11" on a 103.

Duke