02 Sequoia - lost both camshaft/timing pulley shear pins at once

My 02 Sequoia shut down on the highway. Toyota service discovered left intake camshaft had sheared (pin) from timing pulley. They replace the camshaft only to find that the same thing had happened to the right side. Having replaced both camshafts, they now find that the engine has a low end knock and oil pressure reading is L. They are blaming both problems on low/ thick oil. I have both camshafts and see little to no wear - bearing surfaces are perfect. There is a known problem with the oil pressure sensor so I don’t even know if that is working. I never had any indication of low oil level or oil pressure. Mechanic told me that the diagnositic when I towed the car in did not show any oil pressure problem.

Their recommended fix is to either buy a short block (Toyota $5100) or a new or refurb engine ($4500).

So, does it make sense that old / thick oil would cause the camshift shear pin failure? How do I know whether the oil pressure is really low or a sensor problem? Mechanic is currently flushing the engine with transmission fluid to clean sludge, in hopes that helps the oil pressure problem.

Who’s been doing your oil changes? Do you know for sure they’ve been using the right weight oil? 5W-30 I’m guessing. How much sludge did they find?

The incoming diagnostic would not show an oil pressure problem because the motor has to be running to measure oil pressure.

The low end knock and low oil pressure indicate worn bearings, likely from oil starvation.

If you turn on the ignition without cranking the oil light should come on. Then when you start the engine the oil light should go out within a second or so. That tells you if the oil pressure sensor is at all functional.

The top of the engine is generally the first place to go completely dry in cases of oil starvation. That’s why the cams locked up.

The cams might look OK to you, but galled metal can look shiny.

Thanks for the response. So, all of this seems to fit together, but would I not be getting any warnings or indicators, if the oil situation is this bad? Never got oil light or any indication of low oil pressure.

If a secondary oil passage gets clogged the oil pressure sensor won’t see it. It’s probably located near the pump outlet.

Google ‘toyota sludge’