Oil Pressure?
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Oil Pressure?
I have 77' F-100 4x4 with a 400. I know once it warms up the oil pressure drops a lot. Sometimes its not even on the scale. It may be a bad gauge seeing how they are original and 2 other gauges do not function. I will be putting an aftermarket one on soon and see what it tells me.
Any idea what could be the problem? Is low oil pressure common in these motors? ( I ask this b/c a guy I know who has owned a lot of old fords told me this)
Thanks,
Kyle
Any idea what could be the problem? Is low oil pressure common in these motors? ( I ask this b/c a guy I know who has owned a lot of old fords told me this)
Thanks,
Kyle
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Joined: Aug 2001
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From: Delaware
This is quite common, it is because the oil pump feeds the front of the motor, and the oil pressure sensor is in the rear. There are kits available that connect a line to an oil gallery in the front of the motor, and divert oil to the rear where the oil sensor is located.
Laughing Gas
Joined: Feb 2003
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From: In the woods of Oregon
As a side note these engines live for ever with so called low oil pressure. Since the sending unit is on the end of the oil galleys, its reading from the lowest pressure point. I would think that the guage reading is the lowest the pressure would be in the whole system. Cleveland style blocks only have legit oil system problems on the extreme end of high rpm's (say 9,000+) in pro stock drab racing, and so do other engine styles such as Mopars. Some people do modifications to the oil feed that are not needed, but they make them feel better. On a mild/hot street build, good machining tolerances and a HV oil pump is all that is needed.My 2cents.
P.S. Car Craft pg 64-68, March 2003, has a good article.
P.S. Car Craft pg 64-68, March 2003, has a good article.
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Joined: Aug 2001
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From: Delaware
I agree with kopfenjager. There is a better indicator of oil pressure than a gauge, however.
Since the last place to get oil is the valve train on the driver's side, if those valves are quiet at idle when the motor is hot, then everything is getting oil.
You should always get a gauge reading at cruising speed.
Since the last place to get oil is the valve train on the driver's side, if those valves are quiet at idle when the motor is hot, then everything is getting oil.
You should always get a gauge reading at cruising speed.
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Ya, the pressure only seems to drop low when it has warmed up but at idle. When driving it is where it looks like it should be. Glad I asked this question I feel a lot better about the truck.
Thank Guys!
Kyle
Thank Guys!
Kyle
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From: Brentwood,CA
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I believe it has 40 weight in it now (previous owner put it in). Its due for an oil change and I plan to put in 30 weight.
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10w30 should be OK. The weight of the oil does not seem to be significant when dealing with this problem. As far as the valves being noisy at idle, -that is a good indicator. When my valves started making enuf noise that I could hear them at cruise speed I finally retired my 400. The low oil pressure at that point caused overheating problems and a lack of power due to the valves not opening enuf. BUT IT STILL RAN!!!! 
When you rebuild the engine there is a huge oil passage at the #1 main bearing that needs to be plugged completely. There are some discussions on that here. I don't know of anyone that has been willing to try it yet tho.
When you rebuild the engine there is a huge oil passage at the #1 main bearing that needs to be plugged completely. There are some discussions on that here. I don't know of anyone that has been willing to try it yet tho.
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From: quarryville,pa
hi,
i got a 351m in a 79 f250 and it's been rebuilt in the last 2 years and it got the stock gauge and it does the same as yours, but it runs great with lots of power, and one more note to add, all the 400-351 i have had all did this too, good luck and injoy your engine, i love my, gene,
i got a 351m in a 79 f250 and it's been rebuilt in the last 2 years and it got the stock gauge and it does the same as yours, but it runs great with lots of power, and one more note to add, all the 400-351 i have had all did this too, good luck and injoy your engine, i love my, gene,
