Oil Pressure loss in 2000 Tundra


Okay, 2000 Tundra (185,000 miles) starts out with usual pressure. After driving a ways pressure drops down to dangerously low and stays there (not detectable when driving, other than gauge). Mechanics measure same pressure drop using alternate pressure gauge at engine. They assumed oil pump, which would mean pulling engine ($Yikes$), but were advised bad oil pump is very unlikely on that Tundra (and I don’t think the symptoms quite suggest that), and also advised that oil suction tube could be clogged, also necessitating pulling engine, but oil has been kept fairly clean. Car also sits for long periods. Any ideas?
Dan WIllard


Save up to replace the engine or replace the truck. It’s days are definitely numbered. You could change out the oil to a heavy weight oil, like 20w-50, and see if the pressure improves. It may buy you some time. Since it sits for long periods, I assume it is just an extra vehicle you have.


I think a bad oil pump or clogged pickup would result in low oil pressure as soon as you started. I agree with @bustedknuckles . Tine to save for a replacement engine or a replacement vehicle.


Oil pumps spend their entire lives bathed in fresh oil. They’re the best lubricated and least stressed parts of the entire engine. It ain’t the oil pump.

Low oil pressure at idle when warm is a classic symptom of engine wear… as long as the idle is within specs. Oil pressure is the result of the pump forcing the oil through the wee spaces between the sleeve bearings and their corresponding wear surfaces. When the spaces wear too large, it becomes like trying to keep a balloon blown up that has a pinhole in it. The pump has trouble maintaining the pressure when the oil is hot and thin and the engine is at idle.

Unfortunately, the only was to conclusively verify this is to drop the oil pan and pull a bearing cap for inspection. If it were mine, I’d just try a higher base-weight oil and see if that helps. And I’d keep driving it until it developed more serious symptoms, like bearing knock.


Ask your mechanic if putting in a high weight of oil would help diagnose the problem. If the oil pressure was higher when warm when using the higher weight oil, that would be consistent with an engine wear problem. Also ask if a wet vs dry compression test might be a good idea.