59a oil pressure drop hard braking

D

Daveyjonez

Member
Hello All:

Searched, didn't really find a specific answer:

59a, has 60 lbs unless I brake really hard. Pressure drops to 7lbs for about 10 seconds then right back up. Has five quarts, mechanical gauge, no baffle. Seems obvious that the oil is sloshing away from the pickup- my question:

Is this common/ do I need to be concerned??

Thanks in advance,
Dave
 
You are most likely partly uncovering the oil pickup. If the oil level is correct you would need to add baffles to the oil pan or stay away for situations requiring hard braking.
 
Binx said:
Here's a thread you may want to read that had a happy ending...

http://www.fordbarn.com/forum/showthread.php?t=156951

Lonnie
Click to expand...

This was a thread I started and to make a long story short, if you remove the intake on a 59 engine there's a pipe up front that has a large flat bolt in it. I removed that bolt and inside there is a spring. After so many years these springs weaken and they are involved in oil pressure. I changed that spring to a new 50 lb unit (there is also an 80 lb one) and I never go below 30 lbs of oil pressure now and I am usually 40 lbs or more hard braking or no.

Reading the last several posts will describe it better than I remember but it definitely worked ....
 
Wow, thanks for the quick response. I will have a look at that- logic was sending me to no baffle/ pickup problem since this only happens when I hammer the brakes. Thanks Again!

Dave
 
Hey Tom:

If I am reading correctly, you indicated just changing the spring did not fix the problem- you felt that an accident caused damage to the oil pump which was the culprit. Did I follow along incorrectly??

Thanks again for the help,
Dave
 
I don't think the pressure spring has anything to do with your issue as discribed. Braking is not related to the pressure spring and you posted 60 psi except during hard braking. The hard braking is causing the pressure issue and most likely because it is uncovering the oil pickup. This is a common problem on race engines because of the g-loads. On our race engines we used a swinging door type of arrangement. That stop oil flow in one direction (away from the pickup) and free flow in the other direction (toward the pickup).
 
Yes, I understand what the relief valve is designed to do so I was very curious as to how it would be involved in keeping pressure UP under hard braking (or how it knows when I hit the brakes...). In reading the link, I believe the problem was solved when he changed pumps (not the spring) so a bit confused. Again, common sense says oil moving away from the pickup under braking, I'll pull the pan and have a look. Thanks again for the input!
 
Might want to take a look in the oil drain hole before you pull the pan. See if you can see the pickup might give you an idea where it is in location to the bottom of the pan.
 
You can get this sort of behaviour if you have an air leak in the pickup tube, or (I had this once) fatigue cracks in the top face of the pickup can. Any problems in this suction side of the pickup can be unnoticeable when under the oil level, but when the oil surges forward during heavy braking, the leak path gets uncovered and the pump sucks in air and the pressure drops until the leak gets covered again.

The standard pan should have a single transverse baffle. Is that in place? (To be honest, I don't have that in place in my roadster and haven't noticed a problem.)

If you hadn't stated that you have 5 quarts in it, I would have said add more oil. Sometimes the dipsticks can become mismatched and the oil quantity and level are low, even though the reading on the stick is ok. This also happened to me.

As stated, the pickup being bent or mismatched or somehow sitting high relative to the bottom of the pan is also a likely cause.

Hope you find what is causing the problem.

Obviously at least there's nothing wrong with your brakes!

Mart.
 
Thanks Mart!

Yes, the brakes work like an s.o.b.!!

I am going to have a peak in the drain plug hole and see where the pickup is. I strongly suspect it has a mismatched pickup somehow.

Best from Texas,
Dave
 
You must log in or register to reply here.
Back
Top