North American Turbocoupe Organization



Low oil pressure
TC1987 Offline
Junior Member
#1
I have had my 1987 turbo coupe for 32 years.  It's back on the road again after sitting in my garage for 17 years.  While in storage (if you can say that a garage is storage rather than just a dry place ) I would start my turbo coupe once a year and pull it out into the sun.  But it did not go anywhere in it

Now that my turbo coupe is back on the road, I have the oil pressure gauge saying that the pressure at idle is perfect.  But as I put a load onto the engine as I accelerate, the oil gauge drops into the red zone.   I parked the car 1 month ago to take off the wheels for reconditioning, and last week i went to change the oil before restarting.  There was no oil in the oil filter, as if it all drained out.

Questions: what could be causing the low oil pressure?   A weak - worn out oil pump?  A bad oil pressure sending unit?
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anasazi4st Offline
Senior Member
#2
(04-13-2019, 03:07 PM)TC1987 Wrote: Now that my turbo coupe is back on the road, I have the oil pressure gauge saying that the pressure at idle is perfect.  But as I put a load onto the engine as I accelerate, the oil gauge drops into the red zone.   I parked the car 1 month ago to take off the wheels for reconditioning, and last week i went to change the oil before restarting.  There was no oil in the oil filter, as if it all drained out.

Questions: what could be causing the low oil pressure?   A weak - worn out oil pump?  A bad oil pressure sending unit?

The very first thing you need to do is hook up a “real” oil pressure gauge. As has been noted on here, the stock gauges are reportedly notorious for inaccuracy.

While I personally have not noticed this, you can bet that as soon as a gauge started demonstrating odd or unusual readings, I’d be putting a “proper” gauge it to 1) see if there really was a problem and 2) check the accuracy of the stock gauge. (And, you could make the case that my gauges ARE inaccurate, and I’ve just never noticed it, they’ve always seemed fine to me.)

YES, low oil pressure is a real problem. As for the oil filter appearing “empty”, many factors could contribute to this, such as: what is the quality of the filter? Most of the better ones are supposed to have a feature that prevents oil drain-back into the engine. What viscosity is your oil?

First, you’d install a tee fitting to an oil connection and run the line for the test gauge off that. The trick is being able to view it whilst you are driving. You could run a line through one of the grommets in the firewall and have the gauge in the car with you...or you could figure out a way to somehow attach the thing to the outside of the hood near the cowl and watch it from there.

In the past some have managed to do both. If you do a site search here (use the SEARCH button at the top of the page) you’ll see some posts and the results they had. You might have to do some digging and scroll through some pages, but that’s probably a better answer than trying something on your own, if you are unsure.

If after all this your stock gauge is reading properly, then it’s time to try an new sending unit. SPOILER ALERT: this is not an easy task with conventional tools. Go to Harbor Freight and get a set of SAE (standard) crow’s foot wrenches—you’ll need the 9/16” one, and a long extension. It becomes a much easier job using these.

I had a similar situation, lower than I thought it should be, so I replaced the sending unit. Problem is, when I was done, turns out the issue was that the oil seal in the turbo was going bad (which caused severe exhaust smoke at deceleration), not the sending unit.  Hmpf. Rebuilt the turbocharger, installed it, gauge reading is back up near the top.
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 T5OD full rebuild, 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
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TC1987 Offline
Junior Member
#3
Thank you for the advise. I will post what I do and the results.
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Jeff K Offline
Administrator
#4
I have had similar problems before on a several Fords with oil pressure gauges and it always turned out to be the oil pressure sending unit or a loose or corroded push on connection to the sender. Senders are relatively cheap and available.

Of course, check the actual oil pressure as a first step as noted above. many years ago, I put a T fitting on the oil pressure port with the stock sender on 1 leg of the T, and the other leg of the T going to a mechanical oil pressure gauge I mounted under the hood. That way if the dash gauge reads strange, I can just pop the hood and see what the actual oil pressure is.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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