Paul, I guess the major question is how quickly did this condition
occur? Did this happen suddenly, or over a period of months, or right
after you changed the filter? If it happended suddenly, then I might be
inclined to check for a stuck oil pressure relief valve first since its
easy to do, but if that doesnt do the trick, you may have a more serious
problem. You might want to think about having a closer look at the
engine, because I'm not sure I'd want to run the engine long in its
current state. Not that the pressures in and of themselves are
abnormal, but if it happened suddenly then I'm inclined to think
something serious occurred. Assuming your not leaking oil out of your
pressure guage line, then perhaps its a bad bearing somewhere or a blown
head gasket, although I cant say I've heard of too many blown head
gaskets that exhibited loss of oil pressure, ususally coolant will go
into the oil or into the cylinders. Also less likely is the oil pump
since they generally dont go suddenly. If you've exhausted all
possibilities and if this is indeed a "sudden" problem, I'd seriously
consider removing the valve cover, run the engine, and look for oil
shooting out of a rocker arm somewhere. Next I would consider removing
the oil pan and having a look at the bearings, measure their clearances
with plastigage, and also check the oil pump.
If the problem happened after your filter replacement, then perhaps you
got a bad filter (which I've never experienced before). Having said
this, I had a similar problem with a car I bought many years ago. I
changed the oil and shortly thereafter experienced sudden low oil
pressure. The oil pump was bad, which led me to believe that the DPO
put some motor honey in it prior to selling. Put in a new pump and
pressure was great. But it sounds like you've owned this car long
enough to eliminate the possibility of some dastardly deed a PO did.
John - 1976 TR6
Paul Barlow wrote:
I have just experience a loss of Oil pressure. i was running 70 psi at
start up (cold) dropping to 50 when hot (running) and 30 or so at idle.
Now I obly get 50 at start up, 35 running and 20 at idle. I burn 20-50
Castrol, jsut changed oil & filter (not leakes anywhere, Yes it's hard
to believe. Now the hard question WHY? Oil pump packing it up? Cylinders
shot or??? The car still fires up perfect and runs great, no missing
etc.
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