Low oil pressure on freshly rebuilt engine

Luke.T5R · Post by **Luke.T5R** » 23 Aug 2021, 06:50

Over the past 6-8 months my dad and i rebuilt a T5 from a 96 850R and put it in my 96 850 Turbo wagon. we went all out with speed parts we had, reverse intercooler kit, ipd turbo control valve, ipd short ram intake, auto trans cooler, etc. We did fresh rings, bearings lifters, valve seals etc. The engine block and head were machined and cleaned. I dissasembled and cleaned the oil pump which all looked good, and put it back together and ran it. I put in fresh 10w30 for the break in and first 70 miles, and it will develop about 70psi when idiling cold. The issue is after it has been running and gotten hot the oil pressure will drop to around 14psi at idle, making the idiot light flicker on and off, driving it will be around 25-30 psi. I then changed the oil for fresh 10w30 for the next 1000 miles, and it is still doing the same thing. I bought the wrong radiator and the oil cooler was on the wrong side so rather than buying a new radiator (i waited too long to return) i enlonged the hoses using some an fittings and some modifications. I was wondering if possibly my low oil pressure issue is because of the extra length, or maybe i have the hoses reversed and they are not flowing correctly, not letting oil to the cooler to cool it off. do you guys have any thoughts? obviously this is very worrying for me and I would like to figure out the issues if i can. Thanks for reading!

Post by **abscate** » 23 Aug 2021, 07:51

Good news is that the spec on the oil pressure sender going to ground is 5.6-8 psi, so your 14 psi at idle is fine.

I think a new sensor might do the trick

Luke.T5R · Post by **Luke.T5R** » 23 Aug 2021, 19:22

abscate wrote: ↑23 Aug 2021, 07:51 Good news is that the spec on the oil pressure sender going to ground is 5.6-8 psi, so your 14 psi at idle is fine.

I think a new sensor might do the trick

This reply made my heart flutter like I just made it to second base for the first time again, I did replace the sensor while it was apart because it was cheap and it was apart. Do you think I got a bad sensor? (it was cheap, like under 10 dollars cheap). Is it possible in your mind that using a tee off of the stock oil pressure port to accommodate the oil pressure gauges' new sender is causing my problem?

Post by **RickHaleParker** » 25 Aug 2021, 04:50

You could get a quick answer with confirmation if you switch back to the Original Equipment sensor.
Did you compare the electrical profile of the Aftermarket sensor with the profile of the OE sensor?

You dumped all that time and money into it. Why would you go cheap on something that there to protect your investment?

Post by **Chuck W** » 25 Aug 2021, 05:20

So, you deleted the stock trans cooler? Then decided to run the oil cooler lines over and use the trans cooler side of the rad for an oil cooler?

Buy the proper radiator.

Luke.T5R · Post by **Luke.T5R** » 01 Sep 2021, 17:13

RickHaleParker wrote: ↑25 Aug 2021, 04:50 You could get a quick answer with confirmation if you switch back to the Original Equipment sensor.
Did you compare the electrical profile of the Aftermarket sensor with the profile of the OE sensor?

You dumped all that time and money into it. Why would you go cheap on something that there to protect your investment?

I will check both of them, should be pretty easy. Figured a pressure switch is a pressure switch, and the OE one that came visually looked crusty so i elected to replace it. I still have it so I will give that a look. Thanks!

Luke.T5R · Post by **Luke.T5R** » 01 Sep 2021, 17:17

Chuck W wrote: ↑25 Aug 2021, 05:20 So, you deleted the stock trans cooler? Then decided to run the oil cooler lines over and use the trans cooler side of the rad for an oil cooler?

Buy the proper radiator.

I thought about buying the proper radiator, but I'm not swimming in money. I deleted the stock trans cooler with an IPD external one, thus having an unused cooler element on the wrong side. Being outside the return period for the radiator, I used some hydraulic wire reinforced hose we had at work and crimped ends on it. used the hardlines and had a friend tig threaded adaptors on them, then pressure test them for me. all of this cost me a case of beer.

Post by **Chuck W** » 01 Sep 2021, 19:08

I would think that IPD trans cooler would cost more than a rad. (Looking at their site, it's $325...)

Are the internal passages for the built-in coolers on the radiator the same? I haven't looked at them personally to compare, but a difference in size might cause issues.

What size hose did you use for your extensions?