Goodmorning,
new to all this forum stuff, thanks in advance for any help. I have a 99 F-150 4.2L V-6 rear wheel drive 146,000+ hard miles. I have been through more than seventy pages(started with search, FAQ for this forum and from link to post from google search) trying to find where the oil pressure relief valve is located. Got close a couple of times but no luck yet.
Replacing oil pump with melling oil pump, reason for replacement, stopped at light oile pressure went to zero and idiot light came on truck still ran fine.. got home started truck a couple days later pressure gauge came up after few seconds light went out and sounded like every lifter was tapping shut it down did some digging figured bad oil pump and setout to replace it.
had done oile change and replaced plugs week before.
Need help to locate oil pressure releif valve so I can reeplace it. Diagram in box for valve no real help, also chilton online manual no help either. Need to get truck going need it if start date for job comes through.

 

Isn't it part of the pump housing? External pump, correct?

 

It should be part of the pump (internal component).

 

it seems to be an external part, was included with the pump but seperat packaging with very limited instruction and bad diagram.
yes it is an external pump. Which I was very happy to find. All th info I can find indicates external part
thanks

 

FWIW, I personally know nothing about the 4.2L V6... But the 1997 shop manual shows removing the oil filter, then 6 bolts to remove the external oil pump. Then suddenly has a line drawing of a front cover (timing cover) laying on it's face, so the inside of the cover is up. An arrow points to an area on the lower driver's side inside of the cover, facing back towards the block. Says to remove cup plug, spring and ball. And to use new cup plug.

Not a word about having to take the cover off, nor putting it back on.

Since I know nothing about it, the poor line drawings leads one to believe that the oil pump assembly bolts onto the lower driver's side of the timing cover. And that the pressure relief valve is accessed from inside the timing cover.

But that's just what I see on a poor line drawing, that may have been drawn on a CAD doc system by a person who never saw the actual part.

 

Thanks for info sounds similar to the bad drawingthat came in the box. I hope it's not there cause that seems to involve taking apart half the engine. My gravel driveway isn't prepared for that and I'm not sure I am either.

 

For your V6, see Haynes 97-02 repair manuel pages 2A-15 &16.
Pay close attention to housing and plate wear.
If excessive the new gears won't make the pressure it normally would.
The pressure relief spring sets the 'bypass' pressure point according to oil viscosity and pump pressure.
Don't be surprised if the new pump parts don't restore the pressure as high as you would like to see it if the rod and main bearing clearences are greater from wear.
If the pump can't keep up with the flow rate, the relief valve will never open except when the oil is cold before warm up or heavier oil is used.
Good luck..

 

Oil PSI relief valve is inside the timing gear cover, consists of a ball and spring. If spring isn't broken you have suffered internal engine damage. By the sounds of it bad damage. Not yet broken though.

 

I'd guess a spun bearing. Might cost 50.00, and take a few days, but a place that does oil analysis will tell the story, without taking the engine apart. Check for oil distributors that offer the service, or call a couple of repair shops for larger trucks.

Dave

 

I appreciate all the information from everyone and am glad to find that my truck isn't dead, seriously wounded, but thanks to you all and and this forum I'm sure I can get her back on the road and keep her that way. Well. I guess I better get busy got alot to get done. Thank you all again.

Hawk

 

Just wanted to say thanks again to all of you for the help and ideas. I discovered that my oil pump wold lock up intermitantly as I spun the gears. Found out while I was debating about my next step when it was to hazardous to pull my oil pan while lifting the engine, gravel driveway and a floor jack that tilted the higher it went(was really too short) the 2x4 was barely in contact with the jack. Not good when you're alone and going to have your hand jammed up in there. Anyway swapped out the pump put the motorcraft filter in and oil cranked her up and the pressure came right up light went out and she purred contentedly. Had a slit tap which didn't really surprise me. Shut her down checked for leaks...no leaks. Started her back up pressure came right up and no tap. Took her for short ride no leak no pressure loss and no leaks. Longer ride purred all the way no leaks no taps no pressure loss. Thank you one and all.

Hawk

 

You had a great outcome.
Good luck.