High's and Low's

[myk r sanchez]

Hello everyone.

I changed the oil and filter out in the Charger yesterday. Like all of of my oil changes, I do them hot and drive the car for a good half hour or so to get the oil as hot as possible; at this point the oil pressure was fine; reading about 20-40 on the gauge. I had used Castrol full synthetic 10W40 with a K&N filter and then went with Castrol SynBlend 10W40 and a Wix filter as a replacement.

After startup the oil pressure registered between 0 and 20. I listened for noise and I don't think I heard anything so I figured it was just my unreliable gauge which will show random readings from time to time, and went out for a drive. The oil gauge never did quite get past 20, and again I tried listening for noises up front but with that booming exhaust I can't really hear anything anyway. I parked the car and checked the oil level and its fine. The car did not run hotter or otherwise seem to be suffering any issues.

Now, my plan tomorrow is to verify oil pressure by sticking a gauge/tester where the oil pressure sending unit goes and to see what that reads. Is that the proper procedure for verifying pressure? I ask because I've done that exact same thing before and the gauge/tester read 50 psi at no matter what RPM, so I figured either my testing procedure is wrong or my car really is pumping 50 psi of oil at all speeds.

Another question: if I have lost oil pressure I've read that it could be a few things, such as a bad oil filter, or a faulty pressure relief valve. Checking the filter will be easy enough; I'm checking for a deformed or damaged filter, right? But, how do I check the pressure relief valve/spring? Where is it on the oil pump? Will I have to remove the oil pump to check it? I have a bunch of other questions about further testing as well, but I won't ask them until I see the need to if the oil pressure tests poorly tomorrow on the pressure tester. Any other recommendations or suggestions? The engine has about 50K miles on it since its rebuild, and unfortunately I have no idea what the specs on the internals are. Thanks in advance...

 

[Demonic]

Now, my plan tomorrow is to verify oil pressure by sticking a gauge/tester where the oil pressure sending unit goes and to see what that reads. Is that the proper procedure for verifying pressure? I ask because I've done that exact same thing before and the gauge/tester read 50 psi at no matter what RPM, so I figured either my testing procedure is wrong or my car really is pumping 50 psi of oil at all speeds.

So, the rule of thums is to use a good gauge, with full scale about twice what you expect. So use a 100 psi gauge if you expect 50 psi. There's sometimes two tapped 1/4" ports at the rear top center of a big block. Use either.

 

[Bad B-rad]

Do you have a big block or small block?
On big block oil pressure spring is under the hex cap on back side of oil pump.
If filter screws on to the front, its on the opposite side.

Do you have a priming shaft?
I would use that when checking the PSI with a gauge as directed above.



As far as checking the oil filter, I think you check the bypass spring, and disc, but IDK??

 

[Bad B-rad]

Are you adding in ZINC?
Or do you have roller cam?

Last time I found oil pressure issues on Big block, was worn lifters.

 

[33 IMP]

If it was fine before the oil change, and bad after, unless you used a mix of drinking water and cooking oil, it's the filter.
(That is, assuming it's not the gauge. Sure worth checking out. I trust mechanical gauges 100%.i trust aftermarket electric gauges10%)

 

[1 Wild R/T]

You won't see any problem with the filter, it internally bypasses....Replace the filter first, pretty cheap, easy & a common problem.... You didn't buy a Fram.. Thats good, but it doesn't mean your golden, other filters fail too... The only thing you changed was the oil & the filter.... That's the first thing to verify.....

 

[Pikser]

This has only happened once for me and was a new car. Took it to dealer for oil and filter change . They drove it around to the front of the shop and told me ready to go. I started it up and 0 oil pressure. They neglected to put any oil in.

 

[33 IMP]

That sort of thing happened to me too, Pikser!
My grandpa and grandma bought a brand new 64 impala and I rode home with them from the dealer. I was twelve. About half way home an idiot light lit up on the dash. I convinced grandpa to pull in a gas station and we checked the oil level. Took four quarts to fill it. Four quart plus 1/2 qt filter system. I still don't know how the light wasn't on at the dealer.

 

[myk r sanchez]

I typed a wall of text and forgot to mention it's a 440 lol. Ok thanks guys, I will change the filter tomorrow and see what happens.

As for zinc, no I never added any.

Finally, for the pressure check, was what I listed correct? Attach a pressure tester to where the sending unit screws into?

 

[Kern Dog]

I always add a half bottle of Comp Cams break in supplement at oil changes. It is C H E A P insurance. I am running a solid cam with EDM lifters too.
I have ran a variety of filters over the years in my cars and trucks. For all the bad press that FRAM gets, I've never had trouble with them. I often use their HP1 in my Charger or a NAPA/Wix.
As far as pressure, it is directly proportional to engine temperature, outside temperature, rpm, oil viscosity and bearing clearances. The first three are always changing but the bearing clearances usually change slooooooowly as the engine wears.
My beater '67 Dart with a basic re-ringed 360 idles at about 30 psi (cold engine) in the Summer and drops to around 20 once it is warmed up. It rarely goes over 50 psi at speed. My Charger cold idles just shy of 80 psi and drops to 30 at idle. It moves around with the engine speed. What really shows proper operation is to see it move with engine rpm. All engines that I have seen that have a real oil pressure gauge indicate oil pressure increasing momentarily after rpms rise.

 

[1 Wild R/T]

I always add a half bottle of Comp Cams break in supplement at oil changes. It is C H E A P insurance. I am running a solid cam with EDM lifters too.
I have ran a variety of filters over the years in my cars and trucks. For all the bad press that FRAM gets, I've never had trouble with them. I often use their HP1 in my Charger or a NAPA/Wix.
As far as pressure, it is directly proportional to engine temperature, outside temperature, rpm, oil viscosity and bearing clearances. The first three are always changing but the bearing clearances usually change slooooooowly as the engine wears.
My beater '67 Dart with a basic re-ringed 360 idles at about 30 psi (cold engine) in the Summer and drops to around 20 once it is warmed up. It rarely goes over 50 psi at speed. My Charger cold idles just shy of 80 psi and drops to 30 at idle. It moves around with the engine speed. What really shows proper operation is to see it move with engine rpm. All engines that I have seen that have a real oil pressure gauge indicate oil pressure increasing momentarily after rpms rise.

The HP1 isn't made to the same low quality as the FL1A

 

[Kern Dog]

I agree.
I used the PH30 in my Chevy for YEARS. I ran that 305 to 369,000 miles before it spun 3 rod bearings.

 

[Demonic]

Finally, for the pressure check, was what I listed correct? Attach a pressure tester to where the sending unit screws into?

Yes. Big block, right? Some years had a second pipe plug, so two next to each other. You'd need a short nipple and a coupling.

 

[myk r sanchez]

Yes. Big block, right? Some years had a second pipe plug, so two next to each other. You'd need a short nipple and a coupling.

Pretty sure on my 440 there was just the hole where the sending unit screws into...

 

[33 IMP]

If you have a second tap for oil pressure, you would likely know. The plug would be about two inches away from the one you are using, just the other side of the center rib.

 

[myk r sanchez]

Ok I'll check again. I just picked up the new filter and will put it on now and see if the engine grenades or not...

 

[myk r sanchez]

Got another K&N filter and at startup the oil pressure on the dash got up to 20#'s pretty quickly. Once the car was warm the oil pressure got between 20 and 40 on the dash gauge. I was pretty relieved at seeing this, but I always believe in verification so I put on my oil pressure tester/gauge into the hole that the oil pressure sending unit goes into. This time, the tester/gauge read about 48 psi at idle. Feeling safe, I took the engine up to about 3K rpm and the tester/gauge read a little over 50 psi. No matter what speed the engine was turning, the tester/gauge only registered at about 48 to 51 psi.

So, I guess I avoided the end of the world, unless you guys have anything different to say about it. I do have some questions though:

*Isn't it odd that the pressure only reads between 48 and 50 psi? On my 90's Mustangs and F bodys, the pressure gauges will read at about 15 psi at idle and will shoot all the way up to 50 at higher rpms. Is my testing procedure wrong? Is there something wrong with my pump or the oil system? Could that relief valve be stuck somehow, only permitting that amount of psi?

*I hate my oil pressure tester. When I try to screw in the fitting the entire hose and the gauge spins with it, making it a complete pain in the *** to screw into where it needs to go. I need something with a coupler that will rotate independently of the hose and the gauge. What do you guys use?

Thanks to everyone again...

 

[Demonic]

What do you guys use?

I think your oil pressure is fine, no worries. If it was a race motor, I might want a bit more at 6K, but most don't need to twist that hard.

Since piping is my trade, I have a nice selection of fittings. A 6" long 1/4" npt nipple with a coupling at the end is handy - I use a 8 pt socket to remove the plug at the block, and the long nip is easier to spin in with a dab of LeakLock one thread back from the end. Then just add the gauge to the end. I have 45's and 90's for where space is tight, then another short nipple and coupling. Black iron pipe is relatively affordable in 1/4", and easily found. I have 0-60, 0-100 and 0-300 gauges with 2" face or larger, all are 1/4" mpt bottom connection.

This has come up in topics before, but it bears repeating: Do NOT get pipe dope or Teflon over the end of the fitting. It doesn't take much to clog a 1/8 vinyl tube to an oil gauge. Good practice with pipe threads is to keep sealer 3/4 to one thread back from the end.