alright... I think I'm going to replace my oil pump this weekend if weather permits.

I'm wondering if you guys think that replacing the oil pump would rectify my problem. My truck is a 67 F100 with a 390. I register what I would consider normal oil pressure when running cold (middle of the gauge). As the truck warms up, the oil pressure gets steadily lower. At full operating temperature, if I'm idling, the pressure drops to just a hair off the bottom of the gauge scale. If I'm cruising at 40mph for a sustained amount of time, it gets somewhere near the middle again. It's really scaring me, but the engine note hasn't changed, and I'm not having any trouble with overheating. I have a moderate oil leak as well, so I'll be killing two birds at once, so to speak, if I go ahead and replace the oil pump.

Should I put in one of those high pressure oil pumps, or a high volume oil pump, or should I just go with a stock one?

Also, why did Ford have to make it so darn difficult to replace the oil pump without removing the engine? It sucks to have to jack up the engine and remove the oil pump bolts through the tiny space you can get between the block and the oil pan. Another difficulty I've had is stabbing the pump drive shaft into the hole under the distributor while using two fingers through the same space in between block and oilpan. Does anyone have any suggestions for making this job easier?

Greg
67 F100 CCS 390 FMX

 

Quote:
>Also, why did Ford have to make it so darn difficult to
>replace the oil pump without removing the engine?

Are you implying that it's less difficult to change the oil pump on some other vehicle? I haven't run across one that's easy to change out, but my experience IS limited.

-j.banks-

 

Greg, Your guage may not be giving you a correct reading. As long as you are getting 20lbs on a well used engine you should be ok. Do not put in a high pressure pump. If you feel that you have to install a new one, go back with a standard pump.
While you have the pan off, and if you have the skills, you might want to plastigauge the crank bearings. If you or a bud don't have the skill levels, leave it alone.
My suggestion is that if the engine has high miles, and there is oil in the engine, and gas in the tank, just keep driving. If you only use it for local driving, you need not worry. IMHO
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I wouldn't count on replacing the pump only to bring the oil pressure back up. While you have the pan off you better drop the main and rod caps and inspect the bearings. It's more likely that they are worn to the point that you are losing pressure as the engine warms up. You can replace the bearings while the engine is in the truck. As long as the crank isn't damaged or badly scored you can get a lot of life out of an old engine by replacing the bearings. You'll almost have to wait until you get the bearings out to get new ones, in the event the engine has had work done to it before and the crank has been cut, requiring undersize bearings. As you install the bearings, check the oil clearance on each journal with Plastigage, which you can get at any parts store that would have the bearings. While you have the pan off it would also be a good time to slide a new rear main seal in. Doing any of this work while the engine is in the truck isn't really all that hard of a job, but it sure is a dirty one!

 

Not trying to second guess you or anything Jowilker, think we answered the post at the same time. Good advice on your part!

 

 

I have been told that the noise (knocking or rattle) that i hear when i hit 40mph are my bearings. I even have 20w 50 in there and it doesnt help that much. It isnt that hard for me to take my oil pan off, so i could put new bearings in from there? How hard is it and what is involved. thanks