ok so i have a 96 se7 discovery 5 speed, it has had low oil pressure for a while. for example if im at low idle with the a/c on i will get an oil pressure light rarely, but it does happen. i recently switched to 15w-50 to try to buy some time before an engine rebuild and while i no longer have low oil pressure at idle, now at startup i have any where from 30 seconds to a minute of the oil pressure light being on at idle, to the point where the engine will start knocking till the light goes off. im going to try change to a better oil filter in case the drain back valve in this one is bad. i believe my oil pump is failing any thoughts ideas or places to look.
thanks in advance
-Jeff

 

Try a synthetic 5W40 instead, your too thick on the cold side unless it's a synthetic but I would still take it down a few notches. Your problem is more than just an oil pump, it's bearing wear and with the light being on for as long as your letting it rebuilding won't be an option.

Have you removed the pan to check the pickup screen? If not you should. If so then it's bearing wear.

I replaced all my lower end shells and gave the top end an excellent cleaning. No light with over 190k on it with original pump. Pumps do wear but they're stronger and can withstand much more than tin coated copper bearings.

 

I should mention, that the only time i have 30 ish second of knocking is when the truck sits for more then a day, if i drive it daily no oil light at all, and no knocking on startup. and no way am i going to put bearings in this engine, im planning a 4.6 swap in the next year or so, i just need this engine to last another 10,000 miles or so.

 

Do like scouts said go to thinner oil, I do in winter, my bearings were shot in mine all scored and to the copper and I had the oil lite staying on in cold weather starts , hell you could drop the pan and change the bearings if needed

We have not been real cold here yet so time will tell how my rebuild will do in cold weather for winter, as I have yet to switch to the thinner oil for winter

 

It don't matter Tom, free country. Funny thing is I paid more for two gallons of synthetic oil (Rotella 5W40) and a Napa Gold filter than for a full set of bottom shells......

 

It isn't the cost of the bearings, it is the three hours to drop the oil pan and replace the bearings. The previous owner ****ed the motor in this truck up, the valve stem seals leak, and i have this sinking suspicion that the head gasket is leaking coolant into the cylinders when i shut it down after a drive, its a dieing motor. The rover isn't my only car so if the motor dies and it is down till i can get a 4.6, so be it. I'm Just looking for ideas as to why I'm losing the oil pump prime after two - three days of not being driven so hopefully i can get it to last for now.

 

Either way I would go thinner on oil see if that helps, the oil pickup could be clogged, the oil pickup can be loose or have a bad gasket

 

Got it the first time. Looking at your morning temps I'm telling you, it's the oil. If it's cold and your using dino and not synthetic 15W50 your lucky it even primes...... it's like pulling grease and God knows what's stuck to the pickup screen cuz I've found wads of RTV stuck to mine. If the valve seals are leaking running vaseline aint gonna make it smoke less than baby oil.......

The pump has a by-pass on the oil filter housing and it'll have a snap ring at the bore plug. Relief valve is on the right side of and behind the crank pulley, same thing, snap ring. If you don't see a snap ring then no joy, just punch plugs. Some had em, some didn't. Plungers corrode and tend to stick in bore. Polish the plungers, clean the springs and give the springs a light tug. Don't have a length or spring pressure to give ya.

 

its fully synthetic 15w50 mobil one, and like i said it isn't every startup just when it sits, i started it this morning when it was 20 degrees no oil light or knocking, i started it yesterday when it was 65 and had been sitting for 5 or 6 days and the light was on for almost 40 seconds

that is exactly what i was looking for, thank you. when i get a minute ill take a look and let you know what i find.

 

i dont know if your making to much of it, most vehicle left for a few days will take a few seconds the get oil flow