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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15133
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Starter motor. Turn on the ignition switch and get a "thunk"

Customer Question

Starter motor . Turn on the ignition switch and get a "thunk" sound . No "whirr" sound no "click" sound . Instruments and all electrical features work well . No sounds of "clicling", and no "grinding" while driving . Engine runs well , no fluid leaks . No oil in the coolant , no coolant in the oil , no fluid losses . New starter and flywheel ?
JA: What color is the fluid? What part of the car is the leak coming from?
Customer: There are no leaks.
JA: What is the model/year of your Chevy?
Customer: 199 Suburban 1500.
JA: What year is your Suburban 1500?
Customer: 1999.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Hoping to have it repaired by a local mech without it costing me a new engine.
JA: Anything else you think the mechanic should know?
Customer: It runs fine otherwise.
Submitted: 3 months ago.
Category: Chevy
Expert:  Jared D replied 3 months ago.

Does it sound like a hard metallic thunk; like the engine is locked up and the starter can't turn it?

Have you tried rotating the engine by hand (or with a socket and breaker bar)?

Customer: replied 3 months ago.
It's a soft "thunk" and we can "bump-start" the it . It runs fine.
Expert:  Jared D replied 3 months ago.

Ok. I would probably suspect a bad starter if that is the case. It probably is engaging the solenoid that slides the starter drive gear out, but not engaging the starter motor every time. Sometimes that's how the starters fail on these trucks.