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George H.
George H., ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 18817
Experience:  ASE Master tech 15+ years
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Is a defective crankshaft that break the bolt???? It is the

Customer Question

Is a defective crankshaft that break the bolt???? It is the second time that The crankshaft bolt is broken in my montero and I can't find the solution
JA: What year is your Montero?
Customer: 2002
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I changed the bolt, the pulley and the gear of the crankshaft
JA: How many miles are on the car? Have you noticed any fluid leaks lately?
Customer: 145k it have an oil leak on the pulley area
JA: Anything else you think the mechanic should know?
Customer: The bolt usually broke or loose off when I turned-on the air conditioner
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  George H. replied 1 year ago.

Hello I will help you with your question,

The bolt will break if it is overtorqued. With a properly calibrated torque wrench and a dry bolt and seating surface torque a new (from the dealer) bolt to 133 ft lbs.

If it breaks after that check the fit of the balancer to the crankshaft

Let me know how I can help

Thank you

Customer: replied 1 year ago.
I have a calibrated torque wrench and I applied the 133ftlbs, but the bolt was broke. The last time only the bolt was damaged and the balancer was intact. In the past when the bolt was broke the balancer was very worn on the mating surface with the gear, and also the woodruff pin of the gear was broken. The mechanic suggest to me that I must change the engine or the crankshaft, but I don't know if it is necessary. I want try changing the AC compressor because this problem happens when I turn on the AC system in the car. Usually the AC works for some minutes and then suddenly the bolt breaks or loose.
Expert:  George H. replied 1 year ago.

If the balancer does not mate properly with the crank then you will have repeat failure. You need to determine which is the problem, the crank or the balancer. If it is the crank replacing the engine is less money than doing the crankshaft as I would not replace just the crank I would rebuild the engine.

The Compressor does put more strain on the balancer but it would be the fit of the balancer that is the weak point. If the compressor turns normally by hand, the system is not overcharged a new compressor would not change the situation.

Let me know how I can help

Thank you