• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Having Weird Oil Pressure Issue

  • Thread starter Thread starter PWR SHFT
  • Start date Start date May 22, 2014
P

PWR SHFT

New Member
Apr 9, 2014
2
0
2
May 22, 2014
#1
  • May 22, 2014
  • #1
New to the forum! New to 5.0s! Thanks in advance!

So normal driving, oil pressure is great. It is very steady around 60 psi. But under heavy acceleration, the oil pressure slowly drops. It does not drop to zero but goes pretty low to about I would say 20 psi. As soon as you take your foot out of it, it goes right back to normal. Factory gauge.

Here are the particulars on the car: 89 LX 5speed. I just bought this car a couple of weeks ago. It looks like an aftermarket block but its hard to tell. Was told it is a 306 with forged pistons at minimum. TFS heads, X303, original cobra intake with 70mm throttle body, Vortech V1, Aftercooler, FMU, T-Rex booster pump, MSD 6AL BTM, BBK Long tubes, off road h-pipe, mac 2.5 cat back. When I bought it, the car was way over the previous guys head. It had a wicked vacuum leak that was the plenum gasket and it ran like total crap so I never pushed it hard. That is till today after I fixed all that.

Thoughts?
 

MFE92

10 Year Member
Aug 25, 2010
1,094
373
124
Phoenix
May 22, 2014
#2
  • May 22, 2014
  • #2
Split block. You apply load, it opens up the clearances and lowers your pressure. Reduce the load, the clearances go back to normal, your pressure comes back up. Been there, done that.
 
P

PWR SHFT

New Member
Apr 9, 2014
2
0
2
May 22, 2014
#3
  • May 22, 2014
  • #3
Wouldn't you see leaking oil? Other than the rear main, everything is dry. Oil looks good too.
 

MFE92

10 Year Member
Aug 25, 2010
1,094
373
124
Phoenix
May 22, 2014
#4
  • May 22, 2014
  • #4
Not when I did it. Drove it 2.5 hours home from a track event, even took it to a dyno before tearing it down for a rebuild and discovering all 3 center main webs were cracked through. It's what they do. And it started like this http://forums.corral.net/forums/5-0...ips-around-2500-comes-back-up-rpms-go-up.html
 

FoMoCo17

Member
Apr 1, 2011
188
3
18
May 23, 2014
#5
  • May 23, 2014
  • #5
what was your fix for this problem a girdle? thats what i went with ... just curious?
 

mikestang63

SN Certified Technician
Aug 27, 2012
11,606
8,859
214
In the garage
May 24, 2014
#6
  • May 24, 2014
  • #6
It's either a loose wire on the sending unit or as MFE said, a split block. Remove the distributor and with a drill and a long 1/4" socket taped to a long extenstion, spin the pump - drill in reverse. Have someone look at the oil pressure gauge. You may be able to replicate the issue but it probably won't put enough load on the motor. Only way to know is to pull the intake and look in the lifter valley or the timing cover.

A girdle does nothing more than hold your broken parts in the pan. It's worthless in holding a block together.
 

FoMoCo17

Member
Apr 1, 2011
188
3
18
May 24, 2014
#7
  • May 24, 2014
  • #7
guess I'll remove it then since its useless ...
 

MFE92

10 Year Member
Aug 25, 2010
1,094
373
124
Phoenix
May 25, 2014
#8
  • May 25, 2014
  • #8
FoMoCo17 said:
what was your fix for this problem a girdle? thats what i went with ... just curious?
Click to expand...

Replaced the block when I had the engine rebuilt. And then had the rotating assembly carefully balanced and professionally built.
 
You must log in or register to reply here.

Similar threads

M
01 mustang 3.8 fuel pressure issue
  • Mhaley2006
  • May 29, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
94
1996 - 2004 SN95 Mustang -General/Talk- May 29, 2026
Mhaley2006
M
P
Weird Voltage & Oil Pressure Gauges
  • PNN
  • May 22, 2026
  • SN95 V6 Mustang Tech
Replies
0
Views
46
SN95 V6 Mustang Tech May 22, 2026
PNN
P
B
'03 GT Fuel Pump/Pressure/Delivery Issue
  • Brodach
  • Oct 21, 2025
  • SN95 4.6L Mustang Tech
Replies
8
Views
863
SN95 4.6L Mustang Tech Oct 31, 2025
gkomo
5
Hello Everyone !
  • 5150K
  • Friday at 5:34 PM
  • The Welcome Wagon
Replies
0
Views
41
The Welcome Wagon Friday at 5:34 PM
5150K
5
C
Engine Oil pressure issue
  • Cg’s 347
  • Jan 15, 2024
  • Fox 5.0 Mustang Tech
  • 2
Replies
27
Views
4K
Fox 5.0 Mustang Tech Mar 2, 2024
AeroCoupe
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?