Oil pressure drop under hard braking

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Aaron65

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This is a weird one...

My Dart's engine is a '74 225 with the original 170's pan and pickup. When I installed that pan, I modified the dipstick tube of the new engine to make sense with my new pan, and whenever I change the oil, it's spot on the full mark.

When I have to stop quickly, my mechanical oil pressure gauge (and the electric one before that) drops quickly, so I'm obviously uncovering the pickup under hard braking. I installed the pickup according to the shop manual and verified it with my borescope, so I don't think that's a problem. It seems to have the correct amount of oil in the sump.

I guess I'm not sure what to do...It's not like I'm stopping that hard; it has 9" drums on it. Should I add a half quart? Is this a slant six shortcoming?

I don't think it's going to hurt anything considering how infrequently I have to slam on the brakes, but every once in awhile it happens.
 
Where are you sensing your oil pressure? Are your tube/sender screwed into the port at the rear of the oil galley on the distributor side of the block, or into the port on the oil pump just below and to the rear of the filter?
 
OK. Checking because some '64-'65 cars had it at the rear of the oil galley, and they tended to light up the oil warning light under hard braking so the factory went back to the oil pump location and issued a TSB.

How many quarts of oil do you put in for an oil change? If less than 5, the dipstick still isn't right.

Just trying to eliminate the easy factors, because otherwise if you want to fix it the pan's going to have to come off for installation of some baffles.

As long as there's good oil pressure the rest of the time, and the pressure dropoff is brief and only under panic braking, you're probably best off not worrying about it. The money, time, and effort would be better spent on better brakes!
 
Honestly, with 8 cars to watch out for, I can't remember if I put 4.5 or 5 quarts in it!

Either way, I think you're correct all the way around (especially about just leaving it alone), and I thank you, sir.
 
My 64 170 3/tree Valiant 2dr post that I had in high school in the 80's would do this on occasion on hard stops. Really hard stops, and usually on a nice Pennsylvania downhill incline with a full stop at the bottom!
 
OK. Checking because some '64-'65 cars had it at the rear of the oil galley, and they tended to light up the oil warning light under hard braking so the factory went back to the oil pump location and issued a TSB.

How many quarts of oil do you put in for an oil change? If less than 5, the dipstick still isn't right.

Just trying to eliminate the easy factors, because otherwise if you want to fix it the pan's going to have to come off for installation of some baffles.

As long as there's good oil pressure the rest of the time, and the pressure dropoff is brief and only under panic braking, you're probably best off not worrying about it. The money, time, and effort would be better spent on better brakes!
Wouldn't improving His brakes make the problem worse??:D
Just get it hot & keep adding oil 1/2qt. at a time until it stops doing it!!
 
This is a weird one...

My Dart's engine is a '74 225 with the original 170's pan and pickup. When I installed that pan, I modified the dipstick tube of the new engine to make sense with my new pan, and whenever I change the oil, it's spot on the full mark.

When I have to stop quickly, my mechanical oil pressure gauge (and the electric one before that) drops quickly, so I'm obviously uncovering the pickup under hard braking. I installed the pickup according to the shop manual and verified it with my borescope, so I don't think that's a problem. It seems to have the correct amount of oil in the sump.

I guess I'm not sure what to do...It's not like I'm stopping that hard; it has 9" drums on it. Should I add a half quart? Is this a slant six shortcoming?

I don't think it's going to hurt anything considering how infrequently I have to slam on the brakes, but every once in awhile it happens.
------------------------pan isn`t quite right inside, you answered ur own question, about uncovering the p/u. believe it or not, my swinging p/u will do it , if its a qt. low !
 
------------------------pan isn`t quite right inside, you answered ur own question, about uncovering the p/u. believe it or not, my swinging p/u will do it , if its a qt. low !

Did you use the 170 oil pick up tube also?

Since the engine originally came from a Charger, I swapped the 170's pan and pickup. I'll probably add a half quart for now, and at the next oil change, I'll run the borescope through the drain hole and see if anything looks obviously amiss.
 
My 64 170 3/tree Valiant 2dr post that I had in high school in the 80's would do this on occasion on hard stops. Really hard stops, and usually on a nice Pennsylvania downhill incline with a full stop at the bottom!

That's the only time it does it, although we have few hills in Michigan. :)
 
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