Oil light turns on at idle

[87turbodance]

For the last couple months the oil light has been turning on in my Spirit at idle. The motor is still quite as ever and runs perfect so I have been ignoring it. I have been assuming that I've had a bad sensor because my gauge (factory) still shows normal pressure. I replaced the sensor this weekend and the light still turns on at idle when the engine is warm. Do you guys think I should bother investigating further or just drive the car until I can build a new motor next year? The motor has 220,000 km on it and is my dd

[Tim_K]

Run a heavier weight of oil. What are you using now?

[87turbodance]

Quote:

Originally Posted by Tim_K Run a heavier weight of oil. What are you using now?

I have 10W30 in it right now

[93sundance]

You probably don't want to run heavier oil than that. I don't see how the oil pressure could really be that low. If it was, the hydrolic lash adjusters (lifters) would probably start ticking. When you say you replaced the sensor, you mean the sending unit (right next to the oil filter) right?

[87turbodance]

Quote:

Originally Posted by 93sundance You probably don't want to run heavier oil than that. I don't see how the oil pressure could really be that low. If it was, the hydrolic lash adjusters (lifters) would probably start ticking. When you say you replaced the sensor, you mean the sending unit (right next to the oil filter) right?

Yeah, the one that screws in beside the oil filter. The motor is quiet so I think I'll just drive until it starts to make some noise. The motor does clatter a little bit at startup for a couple seconds. Once oil pressure comes up the noise goes away. I'm running a Fram PH8 filter

[c2xejk]

I would start by putting a good mechanical guage on the car and see what the real pressures are...

[87turbodance]

Quote:

Originally Posted by c2xejk I would start by putting a good mechanical guage on the car and see what the real pressures are...

Yeah, I agree. I'm going to pick one up this week. I remember when the oil light turned on at idle in TBI Sundance 2 months later of driving the motor was so loud I couldn't have a conversation inside the car while driving. The motor started out having 0 psi at idle and slowly ended up having 0 psi until 4000rpm. the motor refused to die despite my best efforts

[Tim_K]

10w-30 is too light for an old high mileage engine. I run 10w-40 in all my engines, for some old high mileage Slant Sixes that I used to have, I'd run 20w-50 with no problems.

Try a mechanical gauge and / or replace the oil pressure sensor.

And get rid of the Fram filter too. I switched to Purolator about 5 years ago and noticed a 2-3 psi rise in oil pressure just from that.

[lookin]

At least in the past, Fram oil filters were poorly constructed, and they went into bypass very easily. Maybe Fram has improved their product. I don't know. I have long used Purolator Pure-One filters with good results though.


Check out this page about oil filters. Bear in mind that it is old info though.

Engine Oil Filter Study

[Dusty_Duster]

Try replacing the sending unit. It's on the front of the motor.

[87turbodance]

Quote:

Originally Posted by Dusty_Duster Try replacing the sending unit. It's on the front of the motor.

I have already installed a new sensor and the light still comes on. I think I'll stick with my 10W30 and get a mechanical gauge.

I have ready that oil filter study in the past. The only reason I have Fram on my car is because it the most available. Here and Canada everyone seems to carry Fram. I'll try a different store next time for filters.

[RoadWarrior222]

This is supposedly "normal" on some vehicles. Though it would drive me nuts too until I got it to stop.

I know this sounds wierd, but I've heard of the light flickering at idle when the sump is a little overfull. What happens there is, at idle, there's just enough in the pan that the crank starts hitting it and foaming it up, so foamy oil goes through the sender and the bubbles and air gaps trigger it reading low. Then when the revs go up a little, there gets to be enough oil in the top end of the motor such that the pan level is low enough that it doesn't foam, and everything appears normal. If it was very overfull it would be foaming out of the dipstick at RPM. Now the gauge takes a while to react, doesn't have time to drop to 0 and go back up for every bubble, but if you look at the needle closely it might be shivering slightly, the light is more noticeable.

RW222

[lookin]

That is an interesting theory. Sounds plausible. Would using a good synthetic oil keep it from foaming though?

[RoadWarrior222]

Well keeping it below the full line would stop it foaming. I have heard some synthetics are good at not foaming but don't know which.

You might be more inclined to overfill slightly if you've had much to do with Fords, they often have a Full and an Add mark on their sticks, but the "Add" means "Add 1qt" so you add one qt, even when it's gotten an eighth below the add, and it ends up 2 inches over the full mark... and this is normal.

[87turbodance]

It's definately not overfilled and the light was on before my last oil change when the motor was nearly 2 quarts low (after 10,000 km between oil changes and nothing added between)

The motor runs like new and doesn't burn any oil. I do have leaks on both the front and rear valve covers, though.