I hope this is the right forum.

On the way to the jobsite today, I happened to glance down at the instrument panel and noticed oil pressure was around 40psi. I found it a bitstrange since the oil pressure usually floats around 50-60psi. I gave the car some gas, and rather than the PSI going up, it remained at 40.

Within a few seconds, it dropped to 30. About a minute later, down to 20psi. I got worried so I immediately took the nearest exit off the higheway and just then, oil pressure went down to ZERO Nothing at all regardless of whether I was giving it gas or not.

The place where I bought the car was about 2 blocks away so I literally shut off the motor and coasted down the street in neutral so as to not possibly cause any serious damage.

After pushing the car into the parking lot and into the shop, we put the car on the hoist. My first guess (and hope) was that it was something small, like a possibly malfunctioning sending unit.

I ordered a new sending unit from GM ($30CAD) and it arrived 20 minutes later. We replaced it but it solved nothing. Oil pressure still read zero.

The strange thing was, the car ran and idle'd fine. No signs what so ever that there was something wrong. No unusual noises, no studdering or loss of power. Nothing. Just no oil pressure.

We eventually hooked up an external oil pressure gauge (we would have done that first but my mechanic lent it out to the guy next door and he didn't show up till later)

and sure enough, it show the car making 40psi at idle. We let the car run for a while, reved it a few times and pressure went up a few psi.

I drove the car home at the end of the day, with the oil-pressure gauge in the car reading ZERO. Obviously, it doesn't work as the car is infact, getting oil-pressure. But even after the sending unit was replaced, shouldn't that have fixed the problem with the factory gauge? What other part has to be replaced? The gauge itself?

Also, is 40psi about normal for these cars? How about 45-50psi under WOT? Is that about the average?

I'm kind of worried that 40psi is a little low and since the factory gauge reads zero, I'm worried if there is a problem and the PSI drops down, I won't be able to tell untill it's too late and I destroy the engine.

Are there any tell-tales signs that the motor is down on oil-pressure? Some sounds/noises I should be looking for?

ANy input on the situation I'm in right now would be greatly appreciated.

Thanks in advance.

 

take a valve cover off and run the engine see if oil is up there, also put a manual gauge on if you have 1

 

well the lifters will usually get noisy first which is a sign of something like that. it will be an overall niosy valvetrain.

it could be the guage in the dash.i cant tell you how many GMs ive owned that have had the infamous "dancing" oil pressure guage..also weight of oil can play a part in oil pressure but only marginally. for instance when i ran 20w-50 in my DD GMC Jimmy. pressure hung just over 45 or so PSI.now with 10-30 in it its almost 100% of the time just under 40 PSI at idle. 40 PSI i believe is more than enough pressure for a stock motor. IT could be something like a pump going out which would be a bad thing.

However use this for an example..at an old shop i worked at.. a kid did an oil change and never put a drop of oil back into it..just installed the filter and shipped it..the car then idled for over 20 min and went on about a 10 miles drive before finally locking up. so keep an eye out for you pressure.

how many miles on car?

 

Yeah, my oil pressure gauge has been "dancing" since I purchased the car last summer. It starts off fine, but after a few minutes starts jumping up and down really fast and continously untill I give it some gas. That's always been the case on this car.

I seriously hope it's not the pump going south on me 'cause that would cost a fortune in labour to install a new one and I just don't have the cash right now. The car has about 180k on the odometer (We use km here in Canada, not miles) but the car runs like a champ as it's been regularly maintained (motor-wise)

The trip home from work is aproximately a 30 minute drive doing about 110km/hour and the whole time, the car ran fine. No overly noisy valvetrain noise that I have noticed.

I have to figure out how I', going to repair the factory gauge as I curently have no way of checking oil pressure. The stock still reads zero.

I'm still tring to figure out what part of the oil-pressure gauge system is malfunctioning. I would have thought the sending unit would have solved the problem. What else could it be?

I hope the motor itself is fine. I guess I'll find out tomorrow on the way to work. If it is a problem with the motor, I'll surly find out tomorrow on the long drive to work....

 

You can buy a junkyard dash from a wrecked car and use the pressure gauge from that cluster. And you'll have a couple of spare gauges. Or you can just buy an aftermarket gauge and mount it on the dash or steering colum. Either way will run you about the same price.

 

I dont know about the pigtail on the sender unit but check all wiring. I had a dancing temperature gauge for my coolant. Because some how or another somone unhooked/knocked loose the pigtail from the knock sensor (this happend on both of my formula 350's) I'm assuming somone did it whilst changing the spark plugs. Anyhow aparently the grounding of the pigtail against the engine every now and then caused it to jump. After snapping it back onto the sensor it worked fine to this day.

 

it might be easier in the long run to just purchase an Autometer Oil pressure gauge...either mechanical (cheaper) or electrical (a lot more expensive) either just get a small guage pod or put it in the vent of your formula. this method may be easier than anything else.

 

scratch that vent idea..though you had a 4th gen

 

Yeah, I also have a 4th gen and have used the vents as gauge holders (pretty sure I was the first one to do it )



But yeah, I may just have to buy another oil-pressure gauge and mount it somewhere inside the car until I get something a little more permienant.

I've been looking at getting one of those 82-92 camro digital instrument panels by Nordsgog for a while now. I may just have to buy one sooner than I thought....

 

How long ago did you do the swap??? I retro-fitted the 4th gen interior into my 3rd gen a long time ago and the filling of vent holes with guages was just part of the deal



Back on topic, if the mechanical guage showed you have oil pressure but your electrical factory shows nothing, and you replaced the factory sending unit all it leaves is the actual guage itself by process of elminiation and everybody knows factory stuff leaves much to be desired for accuracey anyways. Getting a donor cluster and swapping guages would be the next avenue IMO. My Autometer oil pressure sender failed on race day once and scared the crap outta me LOL!! Pulled out the sender and fired it up then had a oil gysert so put sender back in and finished my day racing and ordered a new sender. Just does'nt feel right with a "dead guage" on such an important aspect of engine monitoring Also your psi is fine too. My motor would cold start at 50psi and once hot idle would drop to 20 psi and then go upto 50-75psi depending on how hot motor was, so dont let that worry you a bit. Swap out the guage, make sure all grounds are good and you should be golden.

Also, even if it was the pump going out, if you have a cherry picker and 3 hours you can replace it yourself pretty easily, you just have to tilt motor to get pan off which is just a matter of removing 1 motor mount and jacking it up...not a big deal in anybody;'s book.

 

I installed the gauges in the air vents about 8 or so years ago. It was by accident really that I came up with the idea. I was origionally going to mount them on the a piller and as I was holding one up around the area I thought looked best, I had the other two gauges just resting on the dash........right above the air vents.

I wasn't too happy about how they'd look on the a-piller and when I reached over to grab another gauge, it, and the air vent below it, suddenly caught my eye.

Hmmm...... 3 gauges......3 air vents......... The rest is history

I'm pretty sure I was the first as I had never seen it done before by anybody, nor did I ever see anything like it done in magazine's either.

Anyways....

As far as eventually replacing the oil pump... you make it sound so easy I have to get a cherry picker one of these days. They really are a great tool to have.

Hopefully though, the oil pump will last a good long time.

The particualr jobsite I was at today, was a good 35-40 miles away and the same distance back. All in all, probably around 70-80 miles I ran the car today and nothing out of the ordinary happened with the motor. Even ran the car up to about 160km/h for a 4-5 minute stretch and it ran like a champ.

If there really was no oil pressure, or not enough of it, I would have know by now for sure

I plan on ordering a Nordsgog instrument panel as they're direct replacments for the factory panel. Until then, I'll probably just pick up a cheap oil pressure gauge and run it inside the car just to be safe.


Thanks to all those who took the time to respond to my questions.

 

My only recommendation when considering a picker is to measure and base purchase-ESPECIALLY for 3rd/4th gen cars-is to pick the hoist with the longest reach. First motor swap I used a buddies run of the mill $199 picker and crushed the nose of my car due to arm being too short even being fully extended. I then bought myself one, AC Delco brand unit from O'Rielly's and was ALOT longer than my buddies and I had plenty of clearance when dropping the 388 between the fenders. The 6 casters is also a nice feature when it's all folded up for storage and moving around the shop.

Changing the oil pumps is that simple with the right tools....just like any job, you can make it as hard on yourself as possible by only having a 80 piecec craftsman tool set or as easy as possible by having tool overload to take care of anything that pops up....I used to get alot of chit from buddies cuz I'm a tool *****-constatnly buying tools for no apparent reason even if I only need to use a $100-200 tool for 10 minutes, but guess who ALWAYS gets a phone call when they're working on their cars or houses....yep, the tool ***** LOL!!!! Quickest oil pump change was at the track on buddies G body, dropped the pan, changed pump, put back together in under an hour. F bodies are a little toughter since everything is soo tight, but still not a huge mechanical feat by anymeans!!

 

but my main recommendation is get an oil pressure gauge, A REAL ONE!!!!! mechanical oil pressure gauges have never failed on me, unless you leave nylon tube lie on a header.... dont do that, but electrical, I've had sending units kill cruise nights, sending units plug, wires short out, gauges grounds fail, gauges simply die for no apparent reason... and then when i assumed the sending unit died AGAIN it was really working, and bye bye 2.8L, with a mechanical, if there's pressure it sees it, and you can hook up a warning light... if there isnt, shut down, that simple, no questions

and generally 10 psi per thousand is considered good, high volume oil pumps mess that up though... i've hit 100 psi cold : ( that's too much pressure... as in, you'll fill your valve covers and run out of oil to pump because it doesnt flow back fast enough, but 40 psi what are you worried about? my fresh rebuild ran more but now when she gets hot she runs 20 at 600 rpm and 60 at around 5000

also IHI is right, oil pump isnt a big deal, with a picker (but dont forget to drain oil lol that would suck), i just borrow one from a friend when i need it (no garage space really), otherwise they can be rented, and i have had the no reach picker problem too, two things first is to complete pull second is to raise.

if you need to use a short one to pull the motor i have used rags to save the paint and assign a person to nose protection detail if it's only a few inches shorter than needed otherwise.... yea when that motor picks up, the picker pulls in and your nose will lose, f-bodies and vettes have LONG noses, if you're gonna buy, get the longest arm you can buy the extra cost will be negligible compared to the body.

for a rental or borrowed picker, if it's short. just pull the hood (you'll want to anyway, 6 bolts) and come in from the fender for the lift, all ya need is to pull a mount pin, get some possible wires and hoses out of the way and pull straight up. so what if the picker is sideways? just a thought

 

and IHI, I love that interior, it's flat out sex appeal and SWEEET, I wanna do it WINTER PROJECT