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2G Oil pressure dropping upon braking

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ishnish

ishnish

10+ Year Contributor
940
152
Jun 26, 2011
Modesto, California
Hey guys, so after finally rebuilding my head, changing timing components, all belts, water pump, etc. I decided to drive the car for the first time in years to test it out. I drove just a short distance around the block to see how things would go.

What I noticed was that on my aftermarket prosport oil pressure gauge, the car sat at 10 psi @ 750 rpm (which I believe is normal enough) pretty rock steady. However, I noticed that every time I would come up to a turn and depress the brake pedal, and depressed very steadily at only 15-20% mind you, the oil pressure would drop below 10 psi and my gauge warning light and beep would go off. Also, this was around 15 mph or so. At one point, when I finally got 25 mph or so in 2nd gear and depressed the breaks, the oil pressure dipped all the way down to almost 0 psi if not 0 for sure and then my factory oil pressure light came on. I immediately shut off the car and popped the hood open to check it out. Everything looked perfect.

On the ground, I noticed a leak that trailed the entire route I took my car on and suspected it could have been my oil. It wasn't my oil though. I believe it was a puddle of coolant from pulling a coolant hose when removing my tb for a rebuild. My only guess is that is what it could have Been unless of course I could have a coolant line disconnected somewhere. Because the leak only happened when my car was moving.

Anyway, this morning I decided to check my oil levels. The dipstick read I was completely fine with oil so no problem there. It was full. I parked my car over a white sheet last night and checked to see if there were any spots on the sheet that may have been from sitting over night. NOTHING. Completely clean.

So, since I know an oil leak definitely isn't an issue, what could be causing this problem? Is this normal? Keep in mind, my car has sat for 4 years or so never even started. Could it be an oil pump issue?

Thank you
 
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That's the one thing I regret not completely paying attention to honestly. I put it in neutral every time I would press the brakes though. So I doubt it?? I really don't think it did. I'll have to check again when I get the chance to drive it. It's just hard to get time with work and school. Even if it did drop below 750 rpm though, isn't that wat too much of a pressure drop? I mean hitting almost 0 psi is really low. And my oil pan isn't dented either so I doubt it has anything to do with the pickup
 
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At idle take the oil cap off and observe inside, then rev the car lightly. Under rev it should sling oil out of the fill hole slightly to indicate your oil pressure is increasing.

My car started doing low pressure oil light at idle at a stop because the sensors were Coated in oil. My switch was also slightly damaged, but the gauge and switch were messing up at the same time.

Long story short if the oil pump was failing you would notice shavings in the oil
 
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Thank you very much for the advice and suggestions!

I do remember when working on the car that some old oil leaked down my oil pressure gauge wire and all over the sensor too so maybe I'll clean it and see how that goes. I really hope that is it. I've read a forum thread about some one questioning whether it could be the pressure relief valve but wouldn't that cause the issue issue?

My other concern (now) is the trail of leaks that followed the route I took my car in could possibly be oil. Like I said, I have no oil leaks whatsoever but that is with the car parked. And that leak happened when I was moving. I would like to say it is the little puddle of coolant that was on my block but the leak trail goes on forever and is very very long. It couldn't possibly have been that much coolant.

So now my question is, does coolant leave stains on the floor that are pretty much permanent? Because the stains have not went away. If it is oil that was leaking, then now I'm stumped as to where it's coming from, being that my car happens to spring a leak only when under load and moving. Very odd..
 
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@ishnish I have had issues with 2 Prosport gauges now...1 is oil 1 is EGT. IMHO they are absolute shiiiite.

I have had the same issue as you with my oil gauge (still installed). It was fine for a few months and then started acting up. I have it remote mounted on the chassis with a braided line and all wires are soldered and heat shrunk. I also have a Autometer gauge hooked up to my turbo oil feed pressure. Very often the Prosoprt gauge is reading a weird number that is low and then I look at my Autometer gauge and it reads higher than the Prosport one....which isn't physically possible since the turbo oil feed has a restrictor in it.

I have the same issue with my oil Prosport gauge at idle...says my oil is @ ~15psi and then suddenly drops down to 1-2 psi for a bit then back up. I look at the Autometer gauge and its rock solid....so I know my oil pressure isn't fluctuating at idle and its for sure the gauge.

I also have the same issue with the Prosport EGT except it goes the other way.....suddenly shoots up to 2000*F (usually while im cruising or at a light) and then back down to the 1200-1400's. I have an additional exposed tip fast response EGT probe about 1" away from the Prosport probe. The EGT's have never gotten to 2000F while crusing....not even close. And they have never swung wildly like that ever as its a shielded tip probe and they are so slow that it just can't move the gauge that fast which leads me to believe the issue is in the actual gauge and not the sensor.

From all this I know its the Prosport stuff that's not functioning. I have 2 different types of sensors displaying weird numbers that I have confirmed are false with 2 independent sensors.

Maybe there is a bad batch of Prosport gauges out there....I dunno, but I am personally steering clear of their products. Its too bad b/c the Autometer is so ugly and the Prosport is slickAF, but the whole point of gauge is the feedback its giving you so function over form.
 
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kmetiuk said:
@ishnish I have had issues with 2 Prosport gauges now...1 is oil 1 is EGT. IMHO they are absolute shiiiite.

I have had the same issue as you with my oil gauge (still installed). It was fine for a few months and then started acting up. I have it remote mounted on the chassis with a braided line and all wires are soldered and heat shrunk. I also have a Autometer gauge hooked up to my turbo oil feed pressure. Very often the Prosoprt gauge is reading a weird number that is low and then I look at my Autometer gauge and it reads higher than the Prosport one....which isn't physically possible since the turbo oil feed has a restrictor in it.

I have the same issue with my oil Prosport gauge at idle...says my oil is @ ~15psi and then suddenly drops down to 1-2 psi for a bit then back up. I look at the Autometer gauge and its rock solid....so I know my oil pressure isn't fluctuating at idle and its for sure the gauge.

I also have the same issue with the Prosport EGT except it goes the other way.....suddenly shoots up to 2000*F (usually while im cruising or at a light) and then back down to the 1200-1400's. I have an additional exposed tip fast response EGT probe about 1" away from the Prosport probe. The EGT's have never gotten to 2000F while crusing....not even close. And they have never swung wildly like that ever as its a shielded tip probe and they are so slow that it just can't move the gauge that fast which leads me to believe the issue is in the actual gauge and not the sensor.

From all this I know its the Prosport stuff that's not functioning. I have 2 different types of sensors displaying weird numbers that I have confirmed are false with 2 independent sensors.

Maybe there is a bad batch of Prosport gauges out there....I dunno, but I am personally steering clear of their products. Its too bad b/c the Autometer is so ugly and the Prosport is slickAF, but the whole point of gauge is the feedback its giving you so function over form.
Click to expand...

Kmetiuk, thank you so much for your reply. I've read a few of your threads on your holset set up and what you're doing is amazing. What a boss! Lol

I agree with you that prosport gauges are utter crap =/ and it's so true what you say. I got them back then because of price and they were the best looking! Mimicking the Defi gauges that I wanted. I have halo premiums so they were supposed to be the better and gauges. They were just released at the time. Autometer gauges are ugly but you're correct, function over form.

I will have to report back once I go for another drive with my car. The reason I guess this dilemma with the oil pressure Readings bug me so much is because I'm hoping it's not related to the leak I have, if indeed it is a leak!
 
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ishnish said:
Kmetiuk, thank you so much for your reply. I've read a few of your threads on your holset set up and what you're doing is amazing. What a boss! Lol

I agree with you that prosport gauges are utter crap =/ and it's so true what you say. I got them back then because of price and they were the best looking! Mimicking the Defi gauges that I wanted. I have halo premiums so they were supposed to be the better and gauges. They were just released at the time. Autometer gauges are ugly but you're correct, function over form.

I will have to report back once I go for another drive with my car. The reason I guess this dilemma with the oil pressure Readings bug me so much is because I'm hoping it's not related to the leak I have, if indeed it is a leak!
Click to expand...

Thanks man. The Holset build has been a lot of fun. :)

I'm not sure on the leak...I'm chasing one in my '12 F150 that I can't find too. I can smell it in the engine bay very lightly and its losing about 0.5-1L of coolant every 2-4 weeks....but its not leaving a drop on the ground. It's driving me crazy trying to find it so I feel your pain.

I really don't like my Autometer gauges....uglyAF. But they give me piece of mind so I can over look it....for now. Hahhaha.

Good luck with the leak. :)
 
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If the f150 is a 5.0 check the o rings for the upper rad hose and the t joint at the thermostat housing and rad hose connection. I'm a Ford tech this is a very common problem
 
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brian9397gsx said:
If the f150 is a 5.0 check the o rings for the upper rad hose and the t joint at the thermostat housing and rad hose connection. I'm a Ford tech this is a very common problem
Click to expand...

chrysler kid said:
Damn I forgot about that, yeah the pipe for the thermostat has an o-ring that likes to leak
Click to expand...

Thanks! I have been struggling on my truck which has been problem free for 6 years now so mos def appreciated.

ishnish said:
Well, nice to see you guys are figuring out your issues on MY THREAD.. Lol jk jk
Click to expand...
Hahha. Sry man, free advice is always welcome. ;P
 
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kmetiuk said:
Hahha. Sry man, free advice is always welcome. ;P
Click to expand...
I'm only kidding LOL today I get to work on my car and gonna try taking it for a drive again to see what's up. Real quick though, I thought about what you said and the thing is, my prospect gauge oil pressure gauge isn't the only gauge that read 0 or close to 0 when my oil pressure dipped. My factory oil gauge warning light came on as well the moment the prosport gauge dropped very low. You still think it may be the gauge?
 
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ishnish said:
I'm only kidding LOL today I get to work on my car and gonna try taking it for a drive again to see what's up. Real quick though, I thought about what you said and the thing is, my prospect gauge oil pressure gauge isn't the only gauge that read 0 or close to 0 when my oil pressure dipped. My factory oil gauge warning light came on as well the moment the prosport gauge dropped very low. You still think it may be the gauge?
Click to expand...


Hmmm.....not really then no. Now I am wondering b/c that is weird.

You said the oil level is fine but when you press the brakes the oil pressure dips....maybe check the pick up. Perhaps its not sealed all the way and when the oil sloshes forward it loses suction for a moment?

I dunno man but that is weird. :(
 
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ishnish said:
Real quick though, I thought about what you said and the thing is, my prospect gauge oil pressure gauge isn't the only gauge that read 0 or close to 0 when my oil pressure dipped. My factory oil gauge warning light came on as well the moment the prosport gauge dropped very low. You still think it may be the gauge?
Click to expand...

The oil light comes on at about 4.5psi. Even if your Prosport gauge is crap, it may still be reading correctly. Either that, or the gauge and/or sender may be bad along with the sender for the oil light. The sender for the low oil pressure light is less than $10 last time I checked.
 
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Do you have any tuning logs that we can look at while you drive? That would be an accurate way to see if the rpms are going way down upon braking. Ramen could of gave your answer in his post regarding the oil dip to rpm. I'd boost leak test to assure no place is leaking giving you non monitored air to make the car almost stall resulting in the oil light to pop on and go low on oil pressure since the car is trying to shut off itself. If your oil is full and if it is clean without any metal pieces, I wouldn't suspect oil pump but if you'd have time, just pack the oil pump with some vaseline and prime it from it sitting for 4 years without being started. That could rule the pump being the problem.

Also, prosport is butt for gauges. Autometer is definitely the way to gauge but yea they're all ugly. At least you can get different color condoms for their lights.
 
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