Oil pressure drops on acceleration??

[HT413]

Hey fellas, just took the car out for a cruise and noticed something. Oil pressure is steady 70 or so when driving around, maybe 40ish idling warm. Under heavy acceleration, I noticed the oil pressure drops almost to zero, heck it might even go to zero if I let it. I thought maybe the pump was sucking the pan dry so I sat there and roasted the tires (for science, ya know?) and the oil pressure was a steady 70-75 psi right up to 4500rpm, when I let off.

So now I'm thinking the oil is sloshing back away from the pickup on acceleration. Motor is a 413, car is a street driven 69 belvedere. the pan is a cheap chrome after market. I do have a windage tray. Perhaps the pan has no baffles?

Any ideas on a course of action or a possible cause?

Thanks and happy Easter.

 

[Pops1967GTX]

Have you checked the oil pressure with a different mechanical gauge ... Could be filter or pressure relief valve...

 

[66chargerpat]

My383 was out of a 67 c body. The pan didn't have baffles and sucked air anytime I got down on it. I changed to hemi pan and run 6 gt. of oil. That stop it for me. If you do change the pan, get the correct pickup for that pan.

 

[HT413]

Have you checked the oil pressure with a different mechanical gauge ... Could be filter or pressure relief valve...

Hmm, I do have a 2nd mechanical gauge I could rig. One thing, one time it got down under 10 psi and the oem dummy light came right on, so I think issue is real, but I might hook up that 2nd gauge to confirm.

Could you explain about filter? Are you thinking it might be plugged and need a change? Thanks pops.

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My383 was out of a 67 c body. The pan didn't have baffles and sucked air anytime I got down on it. I changed to hemi pan and run 6 gt. of oil. That stop it for me. If you do change the pan, get the correct pickup for that pan.

I might just keep an eye out for a baffled pan then. Sounds like you had the same issue I'm having.

If it turns out a pan swap is in order, is it possible to swap pans without a hoist and with the motor In the car?

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I've read about swinging oil pickups, do the oem pickups swing? Could it be the pickup is the issue?

 

[66chargerpat]

You just have to drop the draglink and maybe lift the motor just a little. Not to bad of a job. Good thing you have a aftermarket gauge. The factory gauge is to slow to let you know if your sucking air.

 

[Pops1967GTX]

I have seen it a few times a restrictive oil filter.... I think you could be right. on acceleration oil going to back of pan......

 

[Rocketman]

this combo took my oil pressure from 35-40 to 75-80 at all times:

http://www.milodon.com/oil-pans/street-oil-pans-chrys.asp

http://www.summitracing.com/parts/mel-m63hp/overview/

 

[Garys1969RR]

If your oil pressure drops under hard acceleration, then the pick up is most likely being uncovered, and your sucking air. DANGER! Try adding an extra quart of oil to it. May help. I over fill mine by 1 quart for drag strip use, and have had no probs. Boy your motor must be putting out some torque to accelerate hard enough to lose pressure! Does it do it in 2nd and 3rd, or just 1st gear?

 

[MarPar]

my first thought was windage tray, but you have that covered...so im with Gary; im thinkin your "cheap pan" may be just deep enough where it will slosh the oil back and suck it dry under acceleration. add a quart of orl and see if that cures it.

 

[HT413]

If your oil pressure drops under hard acceleration, then the pick up is most likely being uncovered, and your sucking air. DANGER! Try adding an extra quart of oil to it. May help. I over fill mine by 1 quart for drag strip use, and have had no probs. Boy your motor must be putting out some torque to accelerate hard enough to lose pressure! Does it do it in 2nd and 3rd, or just 1st gear?

I'll try the extra oil for sure. I don't think it's the torque lol, it's just a low compression 413. Gotta be the pan. Just another thing to add to the Carlisle list.

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It only happens off the line.

 

[Meep-Meep]

I'd say you are correct in that the oil is moving away from the pickup. You could add an extra QT and repeat the test because the extra QT might be enough to keep the pickup submerged during acceleration. Also the pickup should be about 3/8" from the bottom if you get to the point of pulling the pan.

 

[bigmanjbmopar]

3/8" seems like a lot? I don't know just asking. My 7 qt pan with 1/2" pickup said to make sure you were no more than a 1/4" away from the bottom. What is stock for a 413?

 

[Meep-Meep]

1/4" - 3/8" or even touching the bottom won't make any difference with a factory style pick up, but if you have one of those pickups that has the perforated steel at the bottom you better have a reasonable gap so as not to restrict the inlet. I think the OP's problem is lack of effective baffling or low on oil.

 

[Garys1969RR]

Use a 68 to 70 pan from a 383 or 440 Magnum. Its a 4 quart pan thats baffled front and rear, and use a windage tray. My 1973- 400 oil pan is physically larger than the Magnum pan, but it has no baffles. I checked it with water, and it holds 6 qts to bottom of windage tray. And it also has a long straight pick up tube. So I put in 6 qts with a filter change. That puts the level just below the tray. Never had a problem. Launches hard at the drag strip, and the oil pressure stays right up there.

 

[Cranky]

If your oil pressure drops under hard acceleration, then the pick up is most likely being uncovered, and your sucking air. DANGER! Try adding an extra quart of oil to it. May help. I over fill mine by 1 quart for drag strip use, and have had no probs. Boy your motor must be putting out some torque to accelerate hard enough to lose pressure! Does it do it in 2nd and 3rd, or just 1st gear?

Doesn't really take that much power to uncover the pickup. I learned this with my first mild 383 that only ran 14.80's. A buddy noticed the gauge dip when I took off from a light. Yeah, I floored it but the car wasn't exactly a ball of fire but 14.80's wasn't too shabby in 1970.