Droping to Zero oil pressure HELP

I wouldn't drive it anymore....

I just have the dummy gauges, but apparently they are more useful than many think they are.

http://forums.stangnet.com/showthread.php?t=724919

Yellow302 said:

Since my blown head gaskits, and coolant mixing with the oil my pressure has droped alot. As the car heats up the pressure drops which it should but it becomes very low under 10 psi and at idel will drop to zero.

I have the stock dummy guage and and after market that tells me the exact PSI.

Im wondering if my tubes are clogged from the oil pump or if something was damnaged because of the oil and coolant mix.

Both guages drop to zero at idle. Need suggestions.

Click to expand...

I think your rod/main/cam bearings were probably wiped out by the coolant-contaminated oil not providing adequate lubrication, so I'm afraid it's very likely you'll have to tear the engine down and replace bearings/oil pump.

Well for suggestions I recommend you:

1 - Replace your blown head gaskets

Adam

for me, that has been symotoms of a worn out oil pump...or about to go.
my bronco's 302 did that, and so did my current mustang engine....i replaced the oil pump and it has been fine ever since

pull the oil pressure sensor sender and make sure theres no coolant/water trapped in there and then go from there

If you try to change the pump in the car, you'll have to undo the motor mounts and jack the motor way up. It is a PITA though.

its possible w.o removing the motor. autozone sells pumps..... dont get a new pickup, but clean the old one......

remove the motor mounts and jack the engine as far as it will go, and read up on a few choice curse words before you begin.

There are two oil pump part numbers...

melling M68HV (high volume)
melling M68 (standard volume)

If I were you I'd take the standard volume pump (M68). Higher volume oil pumps should have a higher volume (aftermarket) oil pan.


I don't think it's your sending unit. You said you have the stock as well as aftermarket....so it seems unlikely both would be dropping to zero.

My guess would be that the coolant got into the pump and possibly messed something up in the pump. Since you say that you stopped driving it right after I don't think bearing clearance is you problem.

I wouldn't drive this car until I figured out the problem...you prolly know that already though.

raise the engine, drop the pan. take the two bolts from the pick-up to the pump and bag and tag. Then, take the two bolts out of the oil-pump to block and bag and tag. Pull the pump off. Pull the pump driveshaft out (take note how it went in). Put new driveshaft in. Clean gasket surfaces with some brake cleaner. Lay down the gasket that came with the pump (two come with the pump...one for the pickup side and one for the block side...take note of which go where. They look the same but they are different). line up the driveshaft with the slot on the pump (hex slot) and then torque the pump down. Put the gasket on the pickup side and bolt the pick-up to the pump. Put your oil pan gasket down and then torque the oil pan down (in inch/lbs). Drop the engine back down.

Oil Pan Mounting Bolts 110-144 INCH lbs.
Oil Pick-up Tube-to-Main Bearing Cap Nut 22-32 ft. lbs.
Oil Pick-up Tube-to-Oil Pump Bolts 12-18 ft. lbs.
Oil Pump Mounting Bolts 22-32 ft. lbs.

Oil pump driveshaft ARP-154-7904
Oil pan gasket (one piece) FEL-OS34508R
Oil pan Bolts ARP-254-1802
Timing chain set (if you get bored) FMS-M-6268-B302
All gaskets and seals for timing cover FEL-TCS45449

I would recommend using loctite on those bolts.

Don't forget to prime the pump before you start the engine

good luck and let us know how it turns out.

OH YEAH...I'd go ahead and buy an aftermarket pump driveshaft (arp one is about 20 bux). If you're feeling bored you can go ahead and change your timing chain stuff while you're at it. If it hasn't been done then it might be a good idea and it doesn't take too much more labor to do it...just more money cuz you'll have to buy more coolant and the parts.

Rick recommends the FMS oil pump shaft over the ARP as it has more room for clearances. You can read his post in the link I already posted above about my pump failing.

I have had pick up tubes split on me 3 times in my mustang days.Its always a very fine split and the symptoms are just as you are discribing,but the bottom end is also a good possibility.

I didn't have a problem with my arp shaft....but I've heard others have problems with the clearance issues. FMS might be a better choice. Good catch