1997 Ford Explorer, Low Oil Pressure On Gauge

This 1997 Ford Explorer came in with a complaint of low oil pressure reading on the gauge and sometimes the engine would rattle. Well this one is not an electrical problem but I thought I would share it with you anyways. The first thing I did was to check the oil to make sure there was enough in it. There was but the oil was filthy. Time to drain the oil and see what comes out.

The oil that came out was dirty and thick and it got thicker and grittier as the pan emptied. Time to remove the pan and see what is going on. Thankfully there is a lower drain pan on this vehicle that makes inspection very easy.

Wow, what a mess. The oil really was not that light brown in color. Just a lighting effect from the flash on the camera.

This is closer to the real color. Can you see the hump at the closest edge of the pan. That is actually sludge build up.

It is not good to find loose pieces in an oil pan. This piece is actually part of the timing chain guide assembly.

That looks really bad.

Now just what happened other than general engine neglect? There are a few clues in the pictures.

1 The sludge that was in the bottom of the pan was not chunky. Rather well mixed.
2 Broken timing chain guide in pan.
3 Some very clean parts in a very dirty engine. Notice two thirds of the oil pump pick up screen is very clean. Also the main oil return paths are clean where large amounts of oil flow over the metal.

And the answer is the timing chain guide had already broken and the engine rattles a lot at start up. To “help” this condition some one put an oil treatment or synthetic oil in a high mileage poorly maintained engine. The “treated oil” started cleaning the sludge build up and washed and mixed the sludge with the engine oil. This washing also brought the broken piece of the timing chain guide down into the pan, where it was sucked up against the oil pump pickup screen, thus blocking oil flow.
The two lessons of this story are number one change your oil and filter on a regular basis and number two never put synthetic oil or a high detergent oil treatment in a high mileage engine unless you have already done a major sludge clean up and gasket change.

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