Oil Presure... need some help!

When I’m driving, my oil pressure is perfect. At idle, it sits at around 20-22 psi and when cruising, it sits at round 50-55 psi. But when I slam on the gas and go WOT, it'll jump to around 55-58 and then drop to 20-30 and then climb back up to 40-50 psi... the fluctuation always varies, it's never the same... I don't know what to take of this. I don't know if it's the sensor or if something's seriously wrong. Once it even showed it dip down to 15 psi for not even a second before climbing up to around 45 or so. It's always sparattic when it dips, it usually goes down between 20 and 30. The car hasn't been tuned yet since I put the dart heads, comp cams 503 cam and the HSR w/ 58mm TB, but I don't think this would have anything to do with the oil pressure acting retarded. What would cause such a thing to happen? Thanks for all your help in advance :)

Sounds okay to me

15 sounds a little on the weak side...but 20-30 at idle is fine

sounds like to me the oil pump pickup (piece with the screen in it) has fallen off the oil pump.

i wouldnt worry about it until the motor needs to come out,but when that happends pull the pan off and see if its on there or laying in the pan.

robvas, it hit around 15-18 not at idle but when i let it loose on WOT, and then went back up to around 40-50 psi. u think it won't cause a problem if i continue to race the car with this problem?

I definately don't like what it is doing. If the pickup fell off, I would definately fix that asap. If you can't, keep the oil level up(maybe a 1/2 quart high or so).

how would i go around at fixing that?

T-money,
Mine did the same thing. I took the stock one off and put in an autometer. The stock unit is ridiculously wrong. I would try the new gauge (maybe a reason to get a triple A pillar pod) and if it still acts up then you can point your finger at the pickup/oil system.

T-money,
Mine did the same thing. I took the stock one off and put in an autometer. The stock unit is ridiculously wrong. I would try the new gauge (maybe a reason to get a triple A pillar pod) and if it still acts up then you can point your finger at the pickup/oil system.


When you replaced the stock unit, what did the autometer read? I think the majority of oil pressure problems are caused by the sending unit on third gens.

lol t-money... your too funny chris

yeah man... i was thinking about getting a new guage, but i dunno... how would the stock one go up to good oil pressure, then drop, and go back up... wouldnt that have to do with the sending unit itself and not the guage? where is the sending unit located btw?

right above the oil filter

hmm... well let me throw this one at ya so you can tell me what you think. i've been noticing that there was some oil coated over the oil filter... and it looks like the top of where the oil filter connects to is shiny, like if it itself is covered/coated in oil. would this have anything to do with the problems im having?

Well, if the sending unit is somehow leaking, I would definately start there and see if your problems went away. If after that and a gage you are still having problems, you might want to check your pickup. In response to your earlier question, you will need to take the pan off and reinsert the pickup and tack weld it to the pump body. Even if it is not the problem, a small weld would be good insurance for the future.

right above the oil filter
If your engine has a one-wire sensor behind the driver side cylinder head to the right of the distributor, and a two-wire sensor above the oil filter, then:

The one-wire sensor is the oil pressure gauge sending unit. Don't put anything on the threads that will prevent it from grounding properly through the block.

The two-wire sensor is the fuel pump switch, you can safely use teflon tape, or liquid sealer, it doesn't need a ground because it switches power. The tan/wht wire goes through a junction to the fuel pump & fuel pump relay, the orange wire goes through a junction to Inline Fuse #2 (hot at all times.)

The fuel pump switch, and the fuel pump relay switch are in a parallel circuit, as long as one is closed the fuel pump will work.

I'd go ahead and replace the oil perssure sender. It's cheap, not too difficult (especially if you're changing the oil anyway,) and it's the most failure-prone part of the system. If it doesn't make a difference, buy/borrow/rent/steal a mechanical gauge and see if it matches the readings.

You might try overfilling it a bit for a couple days too. The sudden acceleration may just be slinging the oil to the back of the pan and allowing air to enter the pickup.

edit: It's a '90 model, so unless it's a swap or something it should have the single 3-wire unit above the oil filter.

My autometer reads about 40 on start up and will hit about 50 or 60 at WOT and completely burried on a juiced run. TPI motors have the fuel pressure safety switch which is located on the base plenum by the Dist. Tommy your probably seeing oil around the lip of the filter because they didnt oil it when they put it on. The stock sending unit sucks bad like every other sensor on 3rd gens-go figure. Change your filter and dip your finger in oil and spread it on the the o ring on the top of the filter. That will stop your leak. There is a plug in the block right above the oil filter where you have to run the line for the gauge. I ran mine there, covered it in loom till it hits the trans tunnel then zip tied it to the gas lines and ran it through the shifter hole and into the console. Thow out the ****ty plastic and use the copper lines. I used copper lines for a couple reasons. IHRA rules require it. No plastic lines in the car, and if that **** sprouts a leak say good bye to your nice interior and leather seats. So go get your auto meter and be done with it. Let me know how it works out bro bro. BTW me and my buddie joe are trailoring our cars down there for fun ford weekend, i know boo ford but hes paying for it, see ya then.

TPI motors have the fuel pressure safety switch which is located on the base plenum by the Dist.

Third gens don't have a fuel pressure safety switch, but they do have an oil pressure safety switch, which is probably what you are thinking of. He has a 90, which will have the sender/OPSS combo part right above the oil filter, unlike earlier model third gens that have the sender near the distributor.

trust me... when i put the oil filter, i always put oil around the o ringon the top of the filter. i somehow think maybe the oil pressure sending unit is either loose, comming loose, or broken. im going to replace it, clean up the bottom end from all that oil and see if that works any. i dont think it's the guage though because it doenst boune around or act retarded at any time other than WOT.

when you're down here give me a call man... i should have the iroc tuned by then... she's running hard :)

so the oil pressure sending unit looks like an over sized O2 sensor right above the oil filter, right? any special way to take it off, or is it fairly simple? i can remember my d!ckhead friend trying to take it off cuz he thought that was the O2 sensor.. but that was about a year ago when i was replacing it. hmm... now that i think about it, ever since he tried taking it off, thats when i started to notice my oil filter coated with a thin layer of oil. when i went under the car to replace the tranny mount the other day i noticed that the cover that sits between the engine and the tranny was soaked in oil and atf (atf because my old mechanic put too much atf and everytime i run it on the streets, atf comes out of the dipstick, onto the valve covers and down onto the headers and the cover). thanks for all the help guys

ATF coming out the dipstick tube generally means the vent tube is clogged up. It's a small tube about 3-4" long right on the top of the tranny case.

The oil pressure sender is the black can with the metal base and the 3-wire connector. Unhook the connector and it just screws out. Screw the new one in, don't use thread tape, and you'll be good to go.

thank you sir :)

anyway, yeah... i was thinking there was too much tranny fluid in there because, first off, the tranny wasn't shifting correctly when i manually shifted the car. it would slip a little when shifting into gear, i'd have to let off the gas for it to shift right, even though it shifted perfect when i was at WOT in D[3], so i put in a bottle of that lucas transmission crap to see if it would help any, and ever since then, when i run it hard, the tranny fluid comes out the dipstick... im installing a transgo kit in my car, so maybe that'll help everything (and im sure the right ammount of tranny fluid will, too)

Third gens don't have a fuel pressure safety switch, but they do have an oil pressure safety switch, which is probably what you are thinking of. He has a 90, which will have the sender/OPSS combo part right above the oil filter, unlike earlier model third gens that have the sender near the distributor.

Thanks,
Thats wat I meant but you know how it comes out when ur tired. Good luck Corporate T. :cool: :cool:

i was looking by the oil pressure sending unit and it's pretty tight on there.. but thats where it seems to me that the oil is leaking out because it's covered in old oil and with some new oil too. thing is that i noticed on the driver side on the block where the head meets the back of the block, it looks like an oil stain but it isnt new... it's not there on the pass side though. i dont know if this has anything to do with my problem, but i was going to ask, if i replace my sending unit with a new one, and i still have the same problem, then is it deffinately the pick up, or could it be something else? thats where the oil seems to be... and like i said, it's got some new oil on it too so it cant be when i spilled oil all over the valve cover about a year or so ago. could it be the rear main seals? thanks for the help

Rear main will usually drip out the bottom of the torque converter cover. The stain on the back of the heads is likely a leaky intake end seal....SBC's are known for that.

If there's fresh oil around the sending unit change it. They're prone to blowing the diaphragm and leaking through the middle of the sensor. Unhook it, and if there's oil in the connector it's definitely shot. Don't use a GP Sorensen unit....they're total junk and will go out within a year. Get BW if you can.

lol i just installed a GP sensor and it's giving me even worse readings than before! ill go back and change it... hopefully that'll solve the problem. if not... ill get a guage. and if that doesnt work, i dunno wtf is going on. and btw... i didnt find any oil on the sender, just around it. weird...

also... i was thinking maybe there was coolant in the oil by a possible leak in the intake gasket... how would i tell if the coolant mixed in with the oil?

lol i just installed a GP sensor and it's giving me even worse readings than before! ill go back and change it... hopefully that'll solve the problem. if not... ill get a guage. and if that doesnt work, i dunno wtf is going on. and btw... i didnt find any oil on the sender, just around it. weird...

also... i was thinking maybe there was coolant in the oil by a possible leak in the intake gasket... how would i tell if the coolant mixed in with the oil?

Ur oil will look milky if it mixed in or u will be able to the see it in the oil. You will be able to tell, it wont look like normal oil should.

why would the new sensor be giving me even worse readings? now it doesnt even go up to 50.. it's always chilling at 40-30, and when i step on it, it drops to 15. wtf? lol

i just changed the oil and about 2 quarts came out while i let it drain for an hour. the dipstick read normal and only 2 quarts came out? anyway... i filled her up with 5 qts of mobil 1 10-30w (1qt in the filter, 4 in the engine). now the guage reads past 60... WAY past 60, and doesnt move. any ideas? this is a new sensor too lol

Either your oil pump bypass spring is jammed shut, or your not getting a good ground at the oil sender. Or you got a new-BAD sender, it happens.
Pegging the needle proves a loss of grounding in the circuit or faulty sender..

yeah i have a bad sender... im going to replace it.

i gotta figure out where that oil is comming from! i cant figure it out... i ran my finger behind the china wall where the intake meets the block, and there's no oil. under the area where the heads stick out from the block, no oil. but the oil filter is covered with oil and so is the part that holds the oil filter and the sender. where could this oil be leaking from? because i know when i put my engine back together 800 miles ago i put 5 qts, and now there was only 2. i dont think ive spun a bearing because the car never overheats and it doesnt make any weird noises or anything. im stumped :(

i just changed the oil and about 2 quarts came out while i let it drain for an hour. the dipstick read normal and only 2 quarts came out? anyway... i filled her up with 5 qts of mobil 1 10-30w (1qt in the filter, 4 in the engine). now the guage reads past 60... WAY past 60, and doesnt move. any ideas? this is a new sensor too lol

Still up for that autometer eh?

im up for it, but only until i figure out why the oil went from 5 qts to 2. maybe that has something to do about the crappy oil pressure. i figured out i snapped off one of the leads on the sender and thats why it wasn't giving me a reading... a soder gun and some 'afro engineering' and i've got it working... but i think the new sensor's shot because it doesnt go past 40 now, even on wot... and before when i changed it, it did... it would go up to 50 and then do what the old sender did and drop to 20 or so on WOT. now i dont think it helped any that when i tried to change the oil, i couldnt get the filter out without having to beat the crap out of it and then drill three holes into that black fitting that goes on it to get it off with a rachet, put nails through it into the filter and struggle to get it off. that sh!t was ON. but if the filter was leaking, why is there oil on top of it near where the sender is... but there's no oil on the sender? :( this sucks asssssss

Hmm, only thing I can think of is a leaking valve cover gasket?

yeah... well... where do i start? went and bought a new sender... and when i was installing it i noticed some coolant (verry little) on the filter along with some oil. yeah... you guessed it. blew an intake gasket (you can see it from the front of the block) and the new oil i put in was freakin' black. went and did some more investigating, and i think the oil is comming from the back of the block on the driver side under the head... there's some coolant leaking from there along side with some oil... but it's not much... just noticeable when you pass your finger through it. if you can look at it with a light you can see the block is stained by there. so yeah... going to have to take off the heads and everything... =\ sucks ass. thanks for the help though guys, i really appricaite it. lets just hope i didnt bust a bearing lol