I have a freshly rebuilt engine that I got running recently. MY oil pressure on the stock gauge was holding around 30psi at idle and would drop close to zero sometimes. Anyway, I replaced the sender unit with a friend's that was working perfectly in his car. When I put it in, it almost read 60 psi at idle, but then slowly went down to just below 30 psi at idle. If I blip the throttle to around 3k rpms, the oil pressure only slightly increases to just above the 30 psi mark.


Does anyone have any ideas as to what could be my problem? I am thinking that it is quite possibly a faulty oil pressure regulator, but have talked to a local rotary guru, and he says it is unlikely. By the way, I will have a Defi Oil Pressure gauge at my disposal in the next few days.

Thanks in advance for your advice.

 

Anyone?

 

You do really need to back up the stock gauge's reading with a mechanical oil pressure gauge - there's just too much that can go wrong with the electrical gauge.

You should see about 30psi at idle, and about 60psi at 3000 RPM. If it's a few pounds less or more, that's no big worry.

I had similar problems on my 1st motor in my FC - I used the wrong front cover O-ring (used one that was too big) and had about 10-15psi at idle, 45 at 3000 RPM. The o-ring was pinched, and oil pressure was spraying out inside the front cover.

I really hope it's just a sender/electrical problem - tracking down oil pressure problems is a MAJOR chore.

Good luck!
Dale

 

Thanks Dale. Yeah, I hope my new Defi gauge informs me it is an electrical issue.

Thanks,
Brad

 

FWIW,
I believe the FSM says minimum 55 psi @ 3K. I had/have symptoms as you described originally having, before changing your sender. I'm not trying to start a debate or make any recommendations, but indicated PSI at idle on my car (after warm-up) seemed to improved slightly after I switched to a synthetic oil...btwn 5 and 10 PSI. It also worsens gradually between oil changes, presumably from fuel dilution.
Jim

 

Alright, I finally got my Defi Oil Pressure Gauage in today and hooked it up. It reads 20 psi at idle and maxes out at 45 psi at around 3k rpm. After 3k the oil pressure drops down to around 25 psi.

Any ideas?

Thanks.

 

one of your pressure regulators stuck or not working properly?!?! or something could be wrong in the front cover as Sgtblue mentioned. Did you inspect the pump before assembly?

 

Who built the motor? I'd talk to the builder - unless you pulled the front cover or messed with the oil regulator, it's something they did. Unless you built it yourself .

Could be a front cover O-ring problem. Pain in the *** to fix, BTW.

Dale

 

Where is the sender unit located? Anybody have any pictures? Thanks.

 

Yes, I did build the motor myself, with the help of another board member that dubulup knows pretty well. . Anyway, I guess an o-ring could be pinched but I know it was flush and free when we stacked it.

However, the oil pressure regulator was reused from the 30 mile Atkins rebuild the car originally had, which suffered from bearing failure. The previous owner went WOT within 30 miles of his receipt of his Atkinks rebuild and did a number on the bearings. However, they might have used a faulty oil regulator which helped cause the premature bearing failure, since at high rpm, the oil pressure doesn't increase.

Thanks again, guys.

 

OUCH! I wonder if bearing/e-shaft material can get lodged in the regulator thats on the bottom of the motor?!?!

moehler - under the oil filter...the gold thing.

 

There was an awful lot of bearing shrapnel in the oil pan when I originally disassembled the motor, so I guess it is possible the oil pressure regulator is the culprit.

 

thanks dubulup!

 

Hope you flushed the oil cooler and lines. Don't ask how I know.
Barry