No oil pressure when pulling away hard from a standstill

[AWSOM50]

When I hit the gas from a stand still, my oil pressure gauge drops to a big fat ZERO from around 50 for about 3 seconds. 

It happens every single time I pull away but only if I use a lot of gas.  If I drive off slowly, then its fine.  But if I hit the gas hard from a stand still then the oil pressure always goes to zero.

I am using an autogauge oil pressure meter.  I think its mechanical but I'm not sure. 

Anyone know why this is happening and how to fix it?

appreciate any help.

[Chryco Psycho]

you may have an oil slosh problem in the oil pan , but even so it should not drop instantly , possibly  the oil pick up tube is bent up or there is too low level of oil in the pan or the bottom of the pan is pushed up

[squeakfinder]

Did you figure it out yet? So this doesn't happen when you sit still and rev the engine?

[AWSOM50]

thanks chyrco... so my first course of investigation should be to get the sump off and have a look?

Rotssports, it does not happen when I rev it in neutral.  It never ever happens in any circumstances except for going from 0 to about 20 mph under heavy acceleration.

So I am guessing the oil is sloshing to the back of the pan.. but if thats the case why doesnt oil pressure drop when kicking down hard from 2nd to first gear?

[BrianShaughnessy]

Do you happen to know what kind of oil pan and pickup you have?     Was the pan modified from stock if it is a 402?   Is the windage tray installed?

[AWSOM50]

Thanks Brian, but unfortunately I don't know the answers to any of those questions

Except that it's a 440, not a 402

[BrianShaughnessy]

402 is the number stamped on the stock oil pan.

[firefighter3931]

Make sure you have enough oil in the pan.

Ron

[AWSOM50]

oh right lol..

I'll have a look at the oil pan as soon as I get the opportunity.

Firefighter, I just did an oil change and its showing full on the dip stick.  I had this problem before and after the oil change.

[squeakfinder]

I was checking if it was warn main bearing's allowing oil to flow freely through the engine without any pressure. But its sounds like what Chrycho Psycho said.

[TylerCharger69]

Sounds like you MAY  (notice the emphasis on MAY)  have a main bearing problem.  When they lose their crush (tightness against the saddles) it causes oil pressure to drop.....been there....done that.   BUT.....that usually happens at all speeds  and sitting still,  but  stranger things have been known to happen....on a lighter note.....Your pressure sending unit could be faulty.   I really don't believe it's a sloshing issue though.b  Also.....one more thing......does your temp gauge  and fuel gauge seem to be working properly?   Just another area to investigate.

[Steve P.]

Can you hear lifter clacking when this happens?

Do you have a manual or electric gauge??

High volume oil pump with stock pan??


Need more info..........

[resq302]

You said  you had this problem before and after the oil change.  Are you sure you have the correct dipstick in there?  When you did the oil change, how much oil did you add quart wise? 

[oldkimmer]

I had that same problem with a 383 in a 68 dart. I added 1 qt over full and it seems cured. Ofcourse this was after another new pump+ pickup.All clearances were to spec+ there was never any ticking. This engine has made 50,000 street strip miles.The old pump+pickup went into a good used motor and it doesnt have any issues.WTF?

[rt green]

if it a mechanical gauge, check the  routing of the line. the engine moves more when under load, than when standing still. also, look real close for leahs along that line.  bruce

[Steve P.]

I would install a manual gauge and see if you are REALLY losing pressure.

[AWSOM50]

hi guys, sorry for not replying. I appreciate the help but I have been too busy to look at the car recently.

I added another litre of oil above full, and guess what.. the problem is reduced significantly.  It doesn't hit zero anymore.  But it drops to about 10-20 psi from around 60 when I floor it.  Then after about 2 seconds it goes back up to the 50-60 mark

Is it normal and safe to drop to around 10-20?

thanks

[BrianShaughnessy]

   You never answered how much oil did you put in at your oil change or verify which oil pan you have.

[AWSOM50]

about 5 litres of oil initially got me about 2 cm over the full line on the dip stick, so I had to drain some out.  So I don't really know exactly how much is in there.  I couldn't see a number stamped on the pan, I'll have to have another look but I just got a flat tire and the car is in the garage (very small) so I can't check right now   However I will do so ASAP

[BrianShaughnessy]

You can follow this link to see 440source's selection of oil pans...  http://440source.com/oilpans.htm as a reference.

Offhand I'd probably guess you have a hi volume oil pump and / or  a stock depth pan that may have had it's baffles removed.    Possibly the oil pickup is incorrect or bent. 

[Carl1]

If you keep testing it you'll be on here asking how to rebuild your engine. This  type of problem won't fix itself. You better start at the begining and check your pan/pickup combo.Your pickup should be close (about 3/8") from bottom of pan. If you have a stock pan I wouldn't run a high volume pump, you run the risk of pumping the pan dry at high RPM or extended high speed driving, especialy if you have to panic brake or swerve. Make sure you have the right dipstick and tube.

[hemigeno]

A similar problem is what roached the original engine in the Daytona I now own.  The first owner flogged the engine hard, and bragged to me that he had travelled from North Kansas City to St. Joseph, MO without lifting the throttle 

He ended up trading it in shortly after it started developing problems, and the second owner didn't notice the oil pressure problem until a couple of days after he had bought the car.  In that instance, the oil pressure dropped to zero at any RPM over 3,000.  As it turns out it was the main bearings about to go out on him.

I would be very careful about assuming that overfilling the engine oil has "fixed" your problem.  In my opinion, the oiling system was/is the achilles heel of big block Mopars, especially if you're using the stock pickup and pan.

[TylerCharger69]

I agree with hemigeno.....Like I posted before...I believe that it is a main bearing wear issue.  This problem happened to me once due to extreme driving habits 10 minutes after assembling the engine.  (I know...pretty stupid huh?)  Anyway...I had fun  and I just happen to have a new crank kit at the time so there was really no loss other than the time it took to pull the engine  and rebuild it again.  The way I checked them was...I dropped the oil pan,  took off one of the main caps to see if there was any crush (tightness in the seats).  Well...there was none at all...in fact, there was actually about an 1/8 inch gap on either side between the bearing  and the cap itself.  Don't roast the motor...It may take time to check that,  but at least you will know.  I'd check them all, but in my case...the first one I pulled was bad  and actually  all 5 were the same way.  They should fit tightly in the seats and main caps...same as the rod bearings as well....Another   

[Carl1]

If the bearings are pounded out enough to lose their crush you probably need to have the block main bearing bores resized or your problem will soon recur. This will be accompished by your automotive machine shop by line honing or boring. Remember the connecting rods get their oil by way of the mains, so if the mains are shot probably the rods are too. You are also risking pin/ piston problems as they get their oil from the spray between the rods. Geno hit the nail on the head, the oiling system was the weak point in the big blocks hence a lot of cars without their original engines.

[Runner]

run it a quart over full and see what happens.    not all pans have baffels. 

[TylerCharger69]

He said he did that already....made a difference, but not significally.   When I toasted my main bearings as I stated above,  It wasn't necessary to re-align bore my mains.  The dial caliper still said it was perfect.  (You can actually still see factory etching on them)  I put in a new set,  let it break in properly this time,   and I have great oil pressure 7 years and counting.  The only reason I would see the need for an align bore is if you actually spun the bearing,  which this is not the case. Just 2 more cents...

[AWSOM50]

Man, I feel really stupid. 

At least I figured it out.

The sending cable was getting caught on the throttle linkage when the pedal was pressed.  There is no loss of oil pressure on this car...  Why it never happened when flooring it when driving I don't know.  And I guess the adding more oil and the improvement was a coincidence.

Looks like I have a good engine after all.  40psi at idle, 60-80 when driving.

So thanks to everyone, maybe the info in this thread will be useful to someone doing a search another time.

[RECHRGD]

Cool!!  No need to feel stupid.  The thread had a lot of good information in it and nobody thought of that one.  Nice CHEAP fix. Bob

[TylerCharger69]

It's sometimes the littlest, simplest, things when things occur.  Glad it wasn't a major problem!!!

[andy74]

my electric oil pressure guage suddenly dropped to zero while i was at 4400 rpms,and i almost had a litter of kittens,turned out the wiring was faulty and a short caused it,man did i feel some relief there!

[TylerCharger69]

Good to hear it was a electrical malfunction and not mechanical!!!    That's why I converted to manual mechanical gauges.  I just don't want to rely on electronics to tell me what my engine is doing...well....except for my AMP gauge of course.

[squeakfinder]

I use the VDO copper tubing kit part number 701 2154 for my mechanical oil pressure gauges. I've seen those plastic tubes break.

[1968Dodge]

I have the opposite problem. I've put probably less than 1,000 miles on my 440 since I built it and it holds high oil pressure all through the RPM range, but once the motor gets a good hot soak and it returns to idle, pressure drops to 10 psi and sometimes below. It will continue to idle at very low oil pressure unless you spike the throttle to pump it up every few seconds. Thinking this may be an oil pump issue, I put on a brand new Melling high-volume pump; same problem. Porosity problem in the block? I doubt any bearings are bad but I suppose it's possible- weird behavior for a bearing though. Any ideas?