This morning when I started my car (1991 350SD) I heard a loud thud and then all warning lights came on. I popped the hood to find the Serpentine belt off the pulley system and the power steering pump broken clean off the engine. I took it to a mechanic friend he said that I needed another pump and it was a relatively easy fix. All other devices on the system did not appear to be seized in anyway.

My concern is why would it break off like that? It would take a considerable amount of force to break the P/S pump off the engine like that. I'm worried that if I replace the pump that I'm not addressing the real problem. I am looking forward to your replies.

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Martin Gecelovsky

'91 350SD 75500 MI

Maybe the P/S Pump locked up and thus the belt which has extremely strong grip on the pulley, twisted it right off. Its a possibility. Does the pump rotate? If not...then theres your problem.

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Its rare but I have heard of that happening before. I think its the casting on the bracket failing.

What exactly broke?

The serp belt is self tensoning thats not going to cause it to fail.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I distinctly remember checking all systems the Serp belt runs (including the P/S pump) and they all rotated relatively freely. Is it possible that the P/S pump locked up momentarily and tore itself right off its mounts?

The part's that ultimately failled were 1- the arm holding the bolt closest to the cooling fan, broke in half. 2- the second top mount, was split in half around the bolt.

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Martin Gecelovsky

'91 350SD 75500 MI