Oil pressure goes to zero on hard breaking 69/383

[KENTON]

Do you have the correct oil pickup for the pan? How far is the pickup off the bottom of the pan? If it is a stock pick up it should just touch the pan bottom.

I will check that when I have the pan off. It should be the stock pick up & pan, as this was a #s matching one owner car. Nothing else was messed with. I had the motor rebuilt, when they put it together they had one pan gasket and decided to leave the windage tray out.

 

[KENTON]

I had the same problem...no baffle to stop the oil from rushing forward on hard braking....

windage tray will not cause or stop this, but it's a good idea to install one while you have the pan off

Thanks I will do this.

 

[KENTON]

Install a baffel in the front and rear of the pan. Will keep oil from slushing out of pan on acell and decell. Also make sure the pickup is aligned with the botton of the pan before assembly. If tillted it increases the chance of pulling air.

I was wondering if the 402 pan came with baffles already? And if it did will it be hard to get off the motor with out raising the engine?

 

[gdrill]

It's small, but it's there.

 

[IQ52]

I will check that when I have the pan off. It should be the stock pick up & pan, as this was a #s matching one owner car. Nothing else was messed with. I had the motor rebuilt, when they put it together they had one pan gasket and decided to leave the windage tray out.

Oh boy, it's pretty damn hard for them to go all the way to the parts store and pick up that other gasket........for sure.

 

[KENTON]

After getting it up where I can see it,I can tell the windage tray is there. When I drained the oil I could see the pick up tube was there and at the very back of the pan. Good place for hard acceleration, but not so good for hard stops. Also with the added rake from larger tires on the rear, the pan sits at an angle to put the pick up in less oil. Thanks to the picture from gdrill, I'm going to bet it has the baffel in place too. So i think with the 20/50 oil, and HV pump there is a couple of quarts hanging around the top of the motor when she's running. Leaving me with 2 quarts in the pan. So I think I'll try some 10/40 and throw another quart in like the first poster said and see what happens. If it still loses oil then I'll put a 7 quart pan on. If I can find on that won't hit every driveway approach I come to.

 

[Ranger16]

When I drained the oil I could see the pick up tube was there and at the very back of the pan.

Isn't the pick up supposed to be in the front of the pan?

 

[KENTON]

Isn't the pick up supposed to be in the front of the pan?

I think the rear is where they are.

 

[Ranger16]

Looks like the front to me.

 

[miller]

Actually sits about middle of the pan drop.

 

[KENTON]

Well, wherever it sits it is close enough to the drain hole to see it is at the bottom of the pan and level. Like IQ52 said.

 

[66Satellite47]

If my dim memory is correct, I agree with Miller, with my 402 pans & stock style pickups, it was in the middle of the sump. Pickup does need to be close to the bottom of pan, again if it's a stock pickup. Does your motor build (bearing clearances etc) need 20-50? If not, a lighter weight oil is better.

 

[Hemirunner]

If it's an old MP windage tray, they keep oil from reaching the sump quickly and hold it on top of the tray defeating the purpose of running one in the first place.

 

[miller]

Besides the oil pickup needing to be around a 1/4" from the bottom of the pan, baffles should be there. Both front and back, to keep the oil in place, no matter what the circumstance...braking, or power on. That's the whole purpose of it.
Next time you pull the drain plug, look...if baffles are there, you can see them.

Oil weight? In my younger years (lol), I ran 50 wt in my 69 RR...no problems at all. Why, you say? Simple...those motors were advertised to be built 'loose', or bigger clearances. All those parts float on a coat of the oil you use! 10 wt don't cut it. But, that's just my opinion.
Just for grins, I'll toss this in. 50 weight oil (used 40 during cold time of year), oil weight drops to about half, once at operating temp. 50 weight goes to around 25 weight, once hot.

 

[KENTON]

If my dim memory is correct, I agree with Miller, with my 402 pans & stock style pickups, it was in the middle of the sump. Pickup does need to be close to the bottom of pan, again if it's a stock pickup. Does your motor build (bearing clearances etc) need 20-50? If not, a lighter weight oil is better.

It's just a stock build. I put 10/40 in it this time & will see what happens. I figured the worst case i'm only out some oil.

 

[KENTON]

Besides the oil pickup needing to be around a 1/4" from the bottom of the pan, baffles should be there. Both front and back, to keep the oil in place, no matter what the circumstance...braking, or power on. That's the whole purpose of it.
Next time you pull the drain plug, look...if baffles are there, you can see them.

Oil weight? In my younger years (lol), I ran 50 wt in my 69 RR...no problems at all. Why, you say? Simple...those motors were advertised to be built 'loose', or bigger clearances. All those parts float on a coat of the oil you use! 10 wt don't cut it. But, that's just my opinion.
Just for grins, I'll toss this in. 50 weight oil (used 40 during cold time of year), oil weight drops to about half, once at operating temp. 50 weight goes to around 25 weight, once hot.

Next time the oil is out of it i'll take a better look for the baffles. I can't remember what oil the factory said to use in them, but this motor had 110,000 miles on it when we rebuilt it. The worst cylinder had .003 wear and the crank was right on factory specs. So we put new rings and bearings in it and a new cam. The rest is what it came with.

 

[KENTON]

If it's an old MP windage tray, they keep oil from reaching the sump quickly and hold it on top of the tray defeating the purpose of running one in the first place.

I thought it was left out, because I have one sitting on my shelf. But I see it is in there. I can see what your saying might be the case, especially with the 50 wt. oil. before I pull the pan I thought I'd try a lighter oil.

 

[miller]

I can see what your saying might be the case, especially with the 50 wt. oil. before I pull the pan I thought I'd try a lighter oil.

Understand. Just thinking things out. For what it's worth, gotta use what works for you.
I'm too old school for my own good! But, also falling back on what I've learned through the years. Almost funny nowadays, but when I first got into messing with motors, learned things from the 'old hands'. One thing, back in 40s-50s, new cars had break-in oil in 'em. 10-20 wt oil! 500 miles later, go to 30 wt..
Ever work with hot oil? I had to all the time, using it to heat interferance (tight) parts. 30 weight oil, about 180 degrees...like water.

 

[66Satellite47]

I have always modified my windage trays to help drain back. Still don't think that's your problem. Pickup location or some baffle problem. My 2 cents.

 

[KENTON]

Well I finally took the pan off yesterday, I'll post some pictures later. It has the same pan & pick up as in grill's photo. The baffles are in place. I didn't drive it much this summer so that's why it's been awhile. I noticed it has 60-70 PSI when cold and drops to 50 after it warms up at hi way speed. At idle it goes down to 20, this is with 10w40. I know all the bearings are new. So I'm thinking the 7 quart pan would help, but also wondering if the oil pump might be weak? It is new, but I had a friend get a bad one that quit pumping all together. I don't know what brand they put on, but I have a new telling on the shelf I could try.