Ford Mustang Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
I've recently purchased an 87 5.0 GT and while driving it around I noticed the stock oil pressure gauge fluctuates from the bare minimum line of normal to about the 2nd and 3rd lines. But once warmed up it stays around the bare minimum line of normal just above the red 0 line. I have read that the sending units are prone to going bad. The car does have what looks like an oil pan leak. Most of the pan is covered in oil. So my question is can an oil pan leak cause low oil pressure? The other question is can I replace the sending unit without draining the oil?
 

·
Registered
Joined
·
159 Posts
The sending unit can be changed without draining the oil. Oil pan leak won't affect the pressure the oil pump supplies to the engine. If you oil level is full, you are good. You can change the pressure sending unit, it could be the problem. Best way to know is to add an mechanical oil pressure gage, mine will drop to 20 psi when hot and idling, plenty for proper lubrication.
 

·
Registered
Joined
·
2,057 Posts
I have an 1987 xl and the oil pressure hovers
around 60 psi at an idle of 950 rpm and jumps
to around 80 psi at 2500 rpm. I run 20/50 wt
oil. 20 psi at an idle seems low to me. How many
miles on the engine?. Low oil pressure at an idle
some times indicates excessive bearing clearances,
or just a weak pump. Just a thought.
 

·
Registered
Joined
·
13,138 Posts
The sending unit can be changed without draining the oil. Oil pan leak won't affect the pressure the oil pump supplies to the engine. If you oil level is full, you are good. You can change the pressure sending unit, it could be the problem. Best way to know is to add an mechanical oil pressure gage, mine will drop to 20 psi when hot and idling, plenty for proper lubrication.
Correct.

Mechanical gauge is the only way to tell as the stock gauge is doo doo.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #6
So I went ahead and replaced the Oil Pressure Sender unit and I cleaned out the connector and the oil pressure gauge went up to the second white line under normal. Is this a normal read out for this gauge or should it be higher? It surges up to the third line when driving at higher rpms. I have attached a picture of the gauge at idle.
 

Attachments

·
Registered
Joined
·
2,057 Posts
So I went ahead and replaced the Oil Pressure Sender unit and I cleaned out the connector and the oil pressure gauge went up to the second white line under normal. Is this a normal read out for this gauge or should it be higher? It surges up to the third line when driving at higher rpms. I have attached a picture of the gauge at idle.
If you take a good look at the gauge you will see that
your needle is in the normal range, actually on the "A"
of normal. Mine hovers around the "R". If the gauge
is accurate which it probably isn't then according to
Ford you have plenty of pressure.
 

·
Registered
Joined
·
978 Posts
10 psi per 1000 rpm is fine for oil pressure when hot. Dont knock dont tap it is fine. IMO. Our street/ race car dont carry a bunch of oil pressure 15/20 pis at 1200 rpm hot. every time I tear it down to look at it the bearings looks great. Been reusing the same bearing for 5 years of running. But our engine was put together lose.
 

·
Registered
Joined
·
13,138 Posts
Like it was stated earlier the stock gauge will not give you any numerical value what so ever.

Only way to say how many psi will be with an aftermarket gauge.
 

·
Registered
Joined
·
2,306 Posts
My fox would always fluctuate from the 2nd bar when sitting at a light to 3rd line when I would get driving again. I wouldn't worry about it.
 

·
Registered
Joined
·
6,397 Posts
1 - 11 of 11 Posts
Top