# no oil pressure



## wingnutooa (Feb 4, 2009)

so here's the entire scenario

i ran a quart of ATF through the engine for about a week and a half 2 weeks.

then changed the oil/filter with a nice WIX filter and some DELO 40wt. 

(better oil, Diesel oil was exempt from a federal regulations that made manufacturers remove certain viscous qualities from automotive oil, if you buy a new cam it actually explains this and tells you to use rotella or delo while breaking in.)

this was about 4 days ago.

ever since, with increasing frequency, the oil pressure light has been coming on, upon startup.

i dismissed it as its an old engine and figured maybe the delo was a thinner oil than the last stuff that was in it.

well i get home last night and head upstairs to grab some karoake cd's and when i come back down to start the car the oil pressure light wont go off.

i suspected maybe a bad sending unit, as when i was down there, it didnt look to happy and the wire was old and brittle.

negative..

i get a block down the road and the standard issue valve clatter starts up.

so i shut the car off and coast for a while and re ignite. same thing.

i turn around, get some speed, and coast back into my parking spot at home.

try starting it one more time, no dice.


so now i get to sit at home alone, with channels 2-31, and no leftovers while my girlfriend is in hawaii with some friends for the Pro Bowl.

its okay though... i got to watch I-Robot in spanish....




So this morning i had a stinking hunch that i would have oil pressure.

so i head out there and sure enough.

immediate oil pressure

after about 3 seconds it stops missing and 80% of the clatter goes away.

i call my dad and tell him i'm driving out to storage to work on my 280Z and i'm going to leave it out there, he was my ride.

by the time i get out here, as i assumed would happen, the rest of the clatter went away.

i shut it off a couple times and re started and everything is peachy.






so here's the thing.


A: the ATF loosened up some grime that wasn't "quite" loose enough to make it out when i changed the oil, and now its causing havoc with the screen or oil filter.

B: An Intermittent problem with the oil pump, which as far as i'm concerned is completely unheard of. either they work or they dont.

C: This one i ruled out this morning. but: the slot on the oil pump for the distributor shaft (assuming its the same as a SBC) wore increasingly because of resistance/stiff oil pump. finally broke off one or both sides of the slot.

D: Time to pull the motor, flat top it, deck the heads and block. buy RPM Performer, throw a holly on it and a bigger bump stick.

and maybe i'll take a look at the oil pump while i'm in there


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## geeteeohguy (Feb 2, 2008)

Same thing happened to me with a 428 about 25 years ago. Turned out to be seilicone sealer in the oil galleries from a sloppy timing cover/water pump install. I managed to flush it out with the engine in the car and a lot of time and labor. Worked, though. You are dead right about the oil pump. They work or they don't. The drive on the distributor is the same: either it drives the shaft, or the shaft shears and you NEVER have pressure. I would change the oil yet again, to get rid of any straggling particles of crud, and run Delo or Rotella with a ZPDDP additive and go from there. You could also have worn cam bearings, etc. I suspect you loosened up some crud with the use of the highly detergent ATF, and cause the problem that way. I have seen this happen in industry with the use of unneeded "flushes" for everything from engine oil to coolant. Good luck. Jeff


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## wingnutooa (Feb 4, 2009)

i'll start with a fresh oil change again. but its parked for now.

what is zpddp?


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## geeteeohguy (Feb 2, 2008)

I screwed up on my typing (again). It's ZDDP. Google it. It's a zinc/phosporus metal additive that's been in motor oil a long time to cushion metal to metal contact areas like cam lobes and wristpins, etc. It is NEEDED in any flat-tappet engine. It was removed in 2006 by the oil companies because it was starting to foul out catalytic converters on 200,000 mile, worn out cars. EPA decided to remove it, and kill two birds: keep the old [email protected]@box smog cars running clean, and get our old, pre-cat cars (GTO's) off the road and into the crusher, where they belong. Seriously, google ZDDP, you will get schooled. BTW, the only two easily available oils that have SOME ZDDP are DELO and Rotella, as spec'd for diesel engines. You're doing right using them. I use 'em, too. Good luck with your ride, and keep us updated!!


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## Too Many Projects (Nov 15, 2008)

You don't have your local posted but if you are in a cold climate the straight 40wt diesel oil may have been too thick for the pump to pull up. When you change the oil try using the 15-40 grade. I've been using Delvac Super 1300 15-40 for 11 years in my Pete without any internal failures and the original cam has over 1 million miles on it.


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## wingnutooa (Feb 4, 2009)

no i guarantee thats not the problem.

even if i had issues when it was cold, once the car was warm it would work normally.

and the issues i've had have been after i've been driving and shut the car off. then try to start again a few minutes later.


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## 05GTO (Oct 6, 2004)

You can also use ZDDPlus.


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## yellow69 (Feb 1, 2009)

I think your idea about junk getting loose is the answer. It is very likely that a piece of grit got stuck under the bypass valve check ball in the oil pump. I have seen this several times, having owned a machine shop. I would suggest hooking up a mechanical gauge just for giggles. You can also do what the marine guys do for an engine that gets water flooded. Pull the valve covers and pour 2-3 gallons of diesel over the rocker gear into the crankcase. Drive the oil pump with a priming tool. This generally washes out the system of debris. 
According to Melling oil pressure should be 40# at 2000 rpm. This is kind of the GM standard. 15-20 at hot idle sound scary, but really is not. Anything over 60 hot as a max is really too much and only causes wear on the distributor drive gear. I am sure some will disagree, but for any street engine this is more than sufficient. Remember oil pressure is a measure of restriction, the tighter the clearance and the thicker the fluid the higher the pressure.


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## geeteeohguy (Feb 2, 2008)

10psi oil pressure for every 1000 RPM is the accepted minimum standard. I've heard this time and again over the past 30 plus years. I've no reason to doubt it. I HAVE seen 80 PSI pumps make a mess out of an engine, though!


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## wingnutooa (Feb 4, 2009)

i've put high volume pumps in TWO SBC's i've built and will never do that again.

they actually have a tendency to push oil out the rear main. nothing spells dissapointment like a fresh rebuild pushing oil out the rear main and coating the undercarriage and anything you happen to be towing at the time.


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## wingnutooa (Feb 4, 2009)

my dad was telling me last night that he remembered something about Pontiac engines having weak oiling capabilities to the lifters/valve train?

when he put a "Crower, Monarch" cam in his GTO he said he was either going to go solid or with the new style "pump up" lifter and he decided to go with those.

can anyone shine some more light on this?

we're debating what to do with the engine. i'd like to build it.

with a set of pistons, cam and an intake it'll break 350hp easy.


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## Rukee (Feb 8, 2007)

^^ That was true with the 326 engine. I missed what motor you have. But if it was a 326, changing the pistons, heads, cam, lifters, push-rods, guide plates (to the 389 style), should net you reliable 350HP easy.


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## wingnutooa (Feb 4, 2009)

ok so what about the 326 gave it weak oiling?

obviously was changed for the 389 right?


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## geeteeohguy (Feb 2, 2008)

Pontiac engines are NOT known for weak oiling to the top end. In fact, they usually get so much oil up there, there have been restrictor devices fabbed over the years by racers to keep more oil in the sump! If all is clear and free of gunk, it will be fine.


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## Rukee (Feb 8, 2007)

wingnutooa said:


> ok so what about the 326 gave it weak oiling?
> 
> obviously was changed for the 389 right?


The 326 top end was not oiled through the push rods. There are oil passages through the head that pass the oil through holes in the rocker studs to oil the rocker arms. The hollow rocker studs are weaker then that solid rocker studs of the 389. The top end oiling of the 389 is much better. You can convert a 326 top end to a 389 oiling system by changing the push rods, lifters and rocker studs, but you can't go the other way.


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## Mcantw (Sep 7, 2008)

I got some ZDDP right from Ames. Was getting a bunch of items and just added that one in.


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## Koppster (Jul 27, 2008)

Okay, you guys got me wondering. My oil pressure gauge indicates about 70 psi at 2700 rpm, seems high to me. The motor is a 76 400. Thoughts?


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## geeteeohguy (Feb 2, 2008)

Yeah. If it's a stock guage, they can read high. 70PSI at cruising speed is kinda high. How accurate is your guage? Do you have other sins of excessive oil pressure (leaks, etc)? How high does it get at 4000 rpm??? Generally speaking, a standard oil filter will bypass the element at around 60-70psi. Pontiac also has a bypass port and valve at the oil filter housing, meant to allow oil flow if the filter gets clogged. So if you're running 80PSI sithout a superduty valved oil filter flange, you will be running unfiltered oil. (the 455 Super Duty ran an 80psi pump). What viscosity oil are you running? 10W-30 should be fine. How cold is it running, etc. If you have no symptoms other than a slightly high guage reading, my advise would be to leave it alone. You probably do not have a problem.


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## Too Many Projects (Nov 15, 2008)

Koppster said:


> Okay, you guys got me wondering. My oil pressure gauge indicates about 70 psi at 2700 rpm, seems high to me. The motor is a 76 400. Thoughts?


Could be the builder put a high pressure pump in it... call him and ask what is in your engine for oil pump, cam, rocker arms, etc. he should've given you a complete list of the build with the car.


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## Koppster (Jul 27, 2008)

Gauge is a Classic Instruments quad, the fuel, temp and amps all seem to be reading correcty so I ass-u-me the oil pressure is as well.

I'm using Valvoline VR1 for oil, that's what the previous used and I'm thinking it may be good for the Edelbrock heads. I also remember the rule from "back then" about never changing oils...

I'll call the guy that built the motor, he put just about everything else in it so I wouldn't be surprised. I want to ask him about the pistons anyway, I know it was bored but don't know what kind of pistons they used.

Thanks Amigos & Apologies to Wingnutoaa for the "thread jack".

Rickster Sends...


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