Mazda Repair: poor peformance, blown head gasket, hydro carbons

Question
Chris,
a family member has an 86 B 2000 with 200K miles. I put a reman head on it 3 years ago and it hs run great until last week. It was brought back to me running very poorly with the middle top hose that comes up off the exhaust back to the air cleaner housing burned off. I replaced plugs, checked compression 75,90,150,150,replaced rotor button, replaced oxygen sensor, and timing is fine.

Have you ever seen this before? At this point truck won't make it out of driveway. I'm stumped.

An

Answer
Hi Lee thanks for asking
Those compression test readings are actualy very poor, i would suspect a bad valve(s) or a blown head gasket, The next thing you should try is a cylinder head leak test or check for hydro carbons in the coolant. generally compression test readinds should NOT vary more than 10%
Good Luck
Chris P