My oil guage is droping to 0 at idle sometimes. It does not always do this. I changed the oil with some 20/50 It did not help. Someone told me i may be losing pressure past the bearings and thicker oil would help. Up until 2 months ago my oil guage always read around 30. The most it will read now is 20. The car has been overheated in the past but runs good and usually wont run hot. plenty of power. it is a 305 with a cam and headers. the block is stock. there may be some crap in the bottom of the oil pan. I get some on the bottom of my dipstick sometimes. I have had the car 3 years and always change the oil every 2 or 3 thousand miles. if even. I can change the oilpump but am not sure if i need to. My oil pressure will read 20 for days and then out of the blue at an idle it will just drop to 0. Could it be the sensor or an electrical problem? Or do you think I may have replace the bearings. Thanks in advance for any help....FM

 

Hook up a mechanical guage and see what it does. If the mechanical guage still reads low then its time to try a new oil pump.

 

Just replace the sending unit. It's less work and less money than hooking up a mechanical gauge, and fixes the problem about 95% of the time, if it's the gauge system that's the problem.

If the sending unit doesn't fix it, get ready to put a crank kit in it. Oil pumps don't just "go bad". In all my days, I've never seen an oil pump fail in such a way that it worked but had low pressure. Either they work or they don't. Not that I've seen more than a few hundred or so, but still, that's pretty long odds.

 

Mine did, as did a few others I have replaced. It may not be an actual pump failure, the pick up screen may be partially blocked or the pick up may have come off. A mechanical guage is the best way to eliminate the pump/engine. Replacing the sender won't ell you if there is a problem with your Electrical guage or wiring to it. And a cheap mechanical guage costs about what a sender does and takes about 30 minutes to install.

 

Toss the CRAPPY factory gauges. I replaced the sender in my IROC, cause it spewed oil everywhere, then a few months later the gauge started reading near 0 psi at hot idle. ????? I finally got of my butt and installed the Autometer mechanical water temp / oil pressure gauges I've had sitting around.


It's nice to know that my oil pressure NEVER drops below 25 psi, even at 650 RPM idle. In fact, it holds well over 50 psi most of the time. Synthetic has a bit to do with that I'm sure too...especially once it's warm.

Also, it's nice to know the EXACT temp, not a guestimation with the factory "instrumentation"....


ALSO...throw the plastic oil line away that comes with the gauge, get a copper line kit, it's only like $15. Easy to install and won't burst or melt like the plastic line will.


HTH

 

just makin sure...you changed your filter when you changed your oil...right?

 

Thanks for all the advice. AND, yes I changed the filter. I change my oil all the time. It did it again yesterday. I have a 5 mile drive to work. The engine starts and drives fine. I had around 20 psi on the guage and when I got to work at an idle it would go to 0. when I left work 8 hrs later and on the way home it was fine. It was running hot when I got to work but I forgot to turn on my electric fan which has a manual switch but not too hot.
It seems that when the engine is hot the problem is worse. From what I understand the oil will be thinner when hot and pressure may be leaking through the bearings when the oil is thin. I am going to replace the sensor first, AND put in a good Mechanical guage with a metal line instead of the plastic one.
Someone else told me to flush out the motor in case it is a clogged pickup screen.
BUT I think I am going to have to put in a crank kit. While I am in there I will put in a new oil pump.
Talk about rebuilding an engine in stages...I did the top end about a year and a half ago....Thanks...FM...

 

I had a similar problem, i was fixed by replacing the oil pressure sending unit.
What oil weight is recomended for a modified engine?

 

I'm not sure. Probably depends on the engine. I have asked people over the years about what oil is better or what weight is better. I have used 10/40 in all the V8s I have ever owned. As for the brand I have found no differance in quality between expensive oil and cheep oil. As long as it is Says SAE on it. I just get a gallon jug for 3.69 at autozone and a quart for .89. Hell, It's going to be changed in 1000 to 2000 miles anyway, at least it should be. I do splurge on a good oil filter though. There is a huge differance in quality there. You do get what you pay for when it comes to oil filters. I use FRAM Sure grip. I know there are a few better ones but these seem to work good...FM....

 

Might wanna rethink all that you just said. Go with synthetics and ditch the fram, its a worthless piece of crap. Get an ac delco oil filter.

 

Na, I tried synthetic oil. I know some people like it. My engine ran a bit hotter. I stoped useing it. As for fram They make a good filter. AC is good also....

 

You have a lot of learning to do. I would suggest doing a search and you will never use fram again. As for synthetics, which were you using? There are many benifits to using them as well. I would suggest doing a search on synthetics too.

 

Hey man, We seem to have a differance in opinions about oil. but saying, and I quote you, "You have a lot of learning to do. " is kinda rude dude. I am well into my 30's and have rebuilt several cars in my life. I am not stupid. You on the other hand seem to have a a lot lf learning to do when it comes to people skills, and how not to say things that may insult others.
I Know a lot of people use synthetic oil. A lot of people don't like it. Also Fram is not what it used to be. I did do some research and found a few things i did not like about them. Thanks. I will use a differant one next time. Besides the original post here was to see if others have had an oil pressure problem like I am having right now. Do you have any advice there? I would like to hear it.
As for the oil, You can give your opinion but don't insult people. I really don't care what oil you use. Pour Jack daniels into your crankcase for all I care....FM PS. I'll Tell you what. Just to make you happy, next time I change my oil I will use royal Purple or mobil 1 and an AC Filter. Also I will look into synthetics again. I found this website about filters.
http://www.frankhunt.com/FRANK/corve...lterstudy.html

 

I didn't mean to come off as rude, I was just trying to help you out. If you do a lot of research on the different oils and filters you will always use synthetics and never use fram, lol. If you don't want to use what I recommend then you don't have to. You can stick with what you are used to, but I was only trying to help you out. Most likely using conventional oil and fram filters will not hurt your engine, but synthetics and a better filter can only help it. It's what I run in my cars and I try to let other people know why. That study is just one of the many reasons why I will never again use a fram oil filter. Oh and don't use royal purple, I havent heard good things about it. The viscosity seems to break down after only a couple thousand miles. I would suggest mobil 1 or redline oil. As for the oil pressure problem, it's probably the sending unit. I would replace that first and see if it helps.

 

Thats cool. I did look into the fram filters and You are right. The surface area of the filter is much smaller than the AC filter.
For some reason I started useing them and have for a while but I will try an AC next oil change. I have not tried Mobile 1 yet. The Royal purple I used at 5.85 per quart did seem to break down fast and my engine did run hotter. I may try the mobil 1 sometime. I have really had good luck with the cheep 10/40 at autozone. Seems to last a while....
ALSO , I did get a sending unit. I am going to put it in tomorrow. I am going to flush out the crankcase as well. It can't hurt.