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oil pump question

2K views 17 replies 8 participants last post by  sixfifty 
#1 ·
I was at a local car show today and got to talking to a fellow Mustang owner whose car is set up similar to mine ('66 with a 302 in it). We are both experiencing low-ish oil pressure at idle and low RPM (mine shows10-15 lbs., his is dropping down to less than 10 lbs., close to zero indicated on gauge when it is really hot). I was behind him in the line to register and get parked and the cars idled for 5-10 minutes while we waited, that was when his gauge dropped close to zero. When my engine is revved to 2000 RPM or above my pressure rises to about 25 lbs. and stays there (again, this is a thoroughly hot engine). Several longtime Ford owners there said that 302's were notorious for low oil pressure readings like this due to the oil pump gears being manufactured with some kind kind of coating or material that wears down and causes the condition.

So my questions (finally- I know I'm being long winded but I want to give as much info as possible) are these:
1) Is this good information? Is this a known issue with these engines or was I given bad info?
2) If it sounds reasonable- Can the oil pump in a 302 equipped '66 be replaced without removing the engine from the car?

Thanks in advance folks!
 
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#2 ·
A 302 is a 289 with a slightly longer stroke. There is hardly any difference at all in the two and Ford built both engines at times using the same blocks. There is nothing strange about the oil pump in these engines and they do not have any particular problem. Oil pressure will always be lower at idle and when the oil is hot but I have never seen a 289 go to zero under any conditions unless it was low on oil. The pressure at 2000 RPM should be 55 psi when the engine is hot. Ford allowed it be 35 psi for warranty purposes but that in reality it should be 55. If yours never goes over 25 then you have a problem somewhere. There is no coating of any kind on the gears of a stock oil pump; its steel against steel. I have always replaced the pump at overhaul time only because they are dirt cheap. I don't know that I have ever worn out an oil pump, just replaced them 'just in case'.

Yes, you can change the oil pump with the engine in the car. However, the oil pump is one of the last things to go bad. If you have low oil pressure its likely due to something other than the pump wearing out.
 
#3 ·
Excessive rod and main bearing clearances are most likely to blame. How old are the bearings? If they have high mileage or 30+ years on them, they should be replaced. Yes, bearings go bad with age. Over time, the acids in the oil peck away at the super fragile babbitt layer(babbitt is an adjective btw) and cause de-bonding of that layer. Because the babbitt layer is so thin(~.001"), it often goes unnoticed until the copper layer underneath starts allowing insoluables to damage the crank and really open up that oil clearance. I always, ALWAYS recommend replacement of old bearings; today's bearings are made much better with better alloys anyway.
 
#4 ·
Between my me and my family we've had about 15 pre-80's daily driver fords and I've never seen oil pumps fail on them.
I changed out oil pump on 72 ford truck with engine in place one time, I wanted to smash someone's face in afterwards but it can be done.
First keep "know it alls" and other annoying people at a 500 foot minimal no trespassing and no question zone
Get distributor at #1 cylinder and remove.
Remove motor mount bolts.
Jack up engine.
Remove oil pan bolts.
Drop pan (it won't come out completely).
Remove oil pickup, leave in pan.
Remove oil pump with oil pump drive shaft.
Install new pump with driveshaft.
Re-attach oil pickup.
Re-install distributor(you can use a wrench or pliers to turn oil pump driveshaft left and right to get distributor to drop completely).
Install new oil pan gasket.
Re-secure motor mounts.
It helps if you are now, or have ever been, a contortionist, or a straight jacket escape artist, and if you have arms like spaghetti.
Good luck.
 
#5 ·
I have 2 289s from my '67 Cougar. They both had low oil pressure at idle (0-5 psi). I replaced rod & main bearings, oil pump in the first one. The oil pressure came up to 5-10 psi at hot idle. The second one I replaced rod, main and cam bearings and oil pump. The oil pressure came up to 10-18 psi at hot idle and 30-35 at 1500 rpm. The 289s tend to lose oil pressure via worn cam, rod and main bearings. I still have the 289 that didn't get cam bearings.
 
#6 ·
My first thoughts, pull a couple rods and mains and inspect. I agree with the rest of the crowd, the pump is the last to go. Although there are tolerances within the pump that can be checked.
 
#7 ·
What oil are you using ? Mobil 1 15w-50 might be heavy enough to add some more oil pressure. A Melling HV oil pump will also provide an inexpensive bandaid until you can get the engine overhauled, as it sound like the bearings are too loose, as pointed out by others, this is the most likely scenario.

NOTE: I use the Melling HV pumps, and the Mobil 1 15w-50 routinely on my SBF overhauls.

Z
 
#9 ·
Nope, it won't . I just mentioned it as a bandaid in case the OP needed some time before an overhaul could be arranged, and wanted or needed to be be able to drive the car in the meantime. These big expenditure needs seldom happen at a convienent time.


Z
 
#10 ·
Z I knew where you were going Can you imagine how much oil will be flying around with a HV pump and loose bearings? The OP might want to add a quart to the pan fill. You and I would pull the caps and check the shells while the pan was off and go from there.
 
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#13 ·
Well, darn. I should have known not to listen to car show 'experts' and get my hopes up. I'm not going to be driving the car a lot this summer, just local shows and cruise-ins. It looks like the transmission swap to automatic will have to wait; an engine overhaul just moved to the top of the 'to do' list.
Thanks to everyone that replied, I appreciate the input.
 
#15 ·
All is not lost here! The fact that the oil pressure is low does NOT mean oil is not flowing. That is important to remember. Now to build confidence , I suggest a heavier weight oil or ( seriously) an oil thickening agent like STP. Guys will poo poo that idea but oil viscosity has an effect oil the pressure a gauge will read. This will "band aid" the engine until you can get it rebuilt. These additives are fine for a short term fix like this. Additional film strength is required when clearances increase to avoid more damage due to the additional pounding. They become a problem when used for long periods or in excessive quantities. I don't normally recommend them.
Randy
 
#17 ·
I'm researching buying a rebuild-able 302 engine for the car and building it while I drive the the car gently this summer; I'm going to go to a thicker oil and an additive to help with the pressure issue short term.
I've located a later model 302, out of an '89 Lincoln Town-car that has good compression. Of course, it is an EFI engine.
So. I know I have to change the oil pan- will the pan and oil pump pickup off my old 302 fit and solve the problem? Will this engine work without huge modifications? Can I pull the EFI off and drop my present carb and manifold onto it? Are there any other changes/modifications that I need to know about?
thanks
 
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