Finn Lassen wrote:

It finally dawned on me that when I moved the [oil] filter down near the
front outlet (home made adapter plate), I had reversed in and out to the
filter! Apparently the oil is supposed to come in on the outer circle and
out through the center?

Yes. RK

So here's the question: can you think of any liabilities with flowing the
oil the wrong way through the oil filter (obviously can't use the one with
the one-way "valve")?

There are a number problems:

  1. The one-way valve (which you've already experienced) acts to prevent oil
     flow.  Even if a filter doesn't have a "valve", it may be designed to
     inhibit reverse flow.
  2. The filter elements are designed to resist deformation from the forward
     flow.  There is no assurance that the filter elements will resist
     deformation from pressurized reverse flow.
  3. The filter elements are designed to maximize surface area for forward
     flow.  Think about how most filters are pleated.  Larger "chunks" would
     obstruct substantially more filter area if the oil is flowing in reverse.
  4. Some filters have obstruction bypass valves.  These are essentially
     pop-off type valves that let oil continue to flow in the event that the
     filter clogs up (lots of sludge, or possibly filter element structural
     collape).  The obstruction bypass valve may not function if the filter is
     run in reverse.

Finn, I think it is your best long-term interest to correct the plumbing to
your oil filter.

Could this be the reason I've had to turn the engine so long before getting
oil pressure the first and earlier times I changed oil?

Perhaps.  The older filters, while not having true "backflow preventers", may
have had backflow inhibitors that you were fighting (by running the filter
backwards).  Also, they would tend to allow backflow (which looks to them like
forward flow) when the engine is off, making startup pressurization take that
much longer.

Russell Kent

 
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