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91 cougar low oil pressure

Hey all, reader of both groups, hoping someone can help.

I have a 91 cougar XR7 5.0L HO that has recently started showing low oil pressure on the gauge. Needle used to read straight up-and-down between the R and the M of NORMAL, now the needle sits at the N or lower. Sometimes it will go to about the O but that is as high as it ever gets. Most recently it is a N or lower. I was running 5W-30 with 1/2 a quart of Marvels, I've since changed the oil to castrol 10w30 only, still no change. Next stop is a new sending unit. I tried cleaning the connections but couldn't get to the connection inside the wire clip, too tight in there. I know that these electrical gauges can be iffy if the connections aren't clean, should I be worried? Looks like many in the 'stang NG have seen this with no real issues. Engine has 160K on it but runs great, no noises and still a ton of power. I might occasionally have to add a quart between changes, but not often if at all.

Any ideas?

Reply to
John
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Generally speaking, dont worry about it.

Changing the sender might be a good idea,... but sometime around the early nineties Ford stared using "foolers" which is a switch for an idiot light and a 20 ohm resistor.

If your sender is compact and you can get a socket over it to take it out, it's a fooler. Esp if the needle went to a certain reading when you started the car and stayed there, no matter the rpm or how warm engine is.

I run nothing but Mobil 1 synthetic in my old engines... might add a quart of regular oil if it's just before my regular 10,000 mile change.

Try 15w-50 or a combo of mobil 1 (what I do if the engines loose) weights to keep the pressure where you like it.

What oil were you using BEFORE the Castrol?

"John" wrote in news: snipped-for-privacy@comcast.com:

Reply to
Backyard Mechanic

Yup, even thought how easy it would be to change because of that. Do I need to drain the oil to change this?

Esp if the needle went to a certain reading when you

Not much change if at all. It may move down a little as the engine gets hotter since the oil is thinning out, but other times it may go up a tiny bit, but not much at all. Generally at idle or at 3500 rpms the needle will not change more than half a letter at most. However, when I change the oil, it does take a second or two for the needle to move from dead bottom to the current pressure reading. For this reason I had thought it was a real sensor.

It has only had dino oil, Penzoil, Quaker, Valvoline, Motorcraft, always

5w-30.

John

Reply to
John

"John" wrote

From my personal viewpoint based on facts observed in 60's and carried on as unreasonable, unsupported bias to this day....Pennzoil and QS are crap!

- - - - - - - - -

S, then you DO have an idiot gauge.

I suggest finding a way to hook a 12 volt troubleshooting light to the ender and the other lead to 12volt pos.

If it flickers, while running you have problems... But it MAY be the sender itself got oil in it, thus a resistance when it's closed (running). Otherwise, Remove the lead from sender and ground it, ign on.. I'm guessing it will go to where it used to.

If it does... change sender. If it doesnt, problem is in your guage cluster or the wiring to it (doubt that last though or it would show erratic.)

If the gauge shows normal, grounded, but changing sender doesnt fix your problem, then you may indeed have low oil pressure... though needle should not vary when it is cold.

You MAY also have a bad engine-frame ground though this should affect the temp gauge, too

Reply to
Backyard Mechanic

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