Oil Pump maybe?

[nagodwin]

I just bought a 78 bronco with a 400 motor. i have an electronic oil pressure gauge that I just installed. The truck revs good but when it idles the gauge reads zero. When you give it gas, the pressure gets up to 50. when driving, If you try to accelerate more than half throttle the engine makes a clank noise and tries to die. Does my oil pump need replacing? Or, do I have bigger problems?

 

[86Bronco]

Ford is famous for oil pumps that work half the time.....is the gauge that you put in OE, or aftermarket....

 

[nagodwin]

It's an aftermarket gauge, how hard is changing the oil pump on these engines?

 

[SrATEX]

It's an aftermarket gauge, how hard is changing the oil pump on these engines?

25891[/snapback]

​

dont know too much on changing one on a 78/9 but in an 88 you gotta lift the motor to drop the pan. i gave up and am letting a shop do it right now.

try a mechanical guage and see what it gives you...you can pick up a cheap one from a parts house. dont even have to run it into the cab, just hook it up and crank it up and read.

 

[79shortbus]

Mine did the same thing would hold good pressure about 50-60 lbs then as it warmed up the pressure would start falling until got to 0. Mine never made a clank as you say yours does. Mine also would never start ticking like was low of oil so I pull valve covers off and ran I still had oil pumping so I replaced the gauge with another. Still same thing. Like you said you could give it gas and it would go back up for a little while. Mine just got to where I went back up less and went down faster. From what I can tell and what shops have told me the 351-400M is bad about that. The pump is not hard to change, least mine wasnt. I have mine lifted so the axle was not in the way. I just crawled under, pulled pan off, and changed. If you do this I'd recommend changing the screen as well. The only problem I had was the parts store kept ordering the wrong parts, if I can find my boxes I'll get you the part numbers to help out. If urs is not lifted you could prob just jack it up, thats another plus to having a lift, easier to fix stuff. Since then I've had mine rebuilt b/c mine would still drop after awhile just not as low. After being fully rebuilt twice it still did the same. So I'm putting another engine in now, I've had it with that block. Well I hope it goes ok for ya.

 

[BLADE262US]

Oil pressure is made from the tolerance between the bearings if there very worn you can have really good oil pressure wnen cold because of the oil viscosity it is thick and when it warms up and the oil thins out it goes through the tolerance in the bearings very easily causing the lack of pressure . I have seen when the oil level is low the pump will **** air and it causes the guage to go up and down due to the cavitation . I would guess more than likely if the motor has alot of miles the bearings are worn causing the loss in oil pressure . /emoticons/[email protected] 2x" width="20" height="20" />

 

[79shortbus]

Oil pressure is made from the tolerance between the bearings if there very worn you can have really good oil pressure wnen cold because of the oil viscosity it is thick and when it warms up and the oil thins out it goes through the tolerance in the bearings very easily causing the lack of pressure . I have seen when the oil level is low the pump will **** air and it causes the guage to go up and down due to the cavitation . I would guess more than likely if the motor has alot of miles the bearings are worn causing the loss in oil pressure .  /emoticons/[email protected] 2x" width="20" height="20" />

27958[/snapback]

​

That didnt fix mine.