25 Oil p.s.i. how low is too low?

born2 · Post by **born2** » December 21, 2009, 8:18 pm

150,222 original miles...I've been noticing the (after-market) oil gauge slowly creeping lower over the last few drives. No longer in the high 30's to 40...now 25 p.s.i. tops. Dash panel oil light will occasionally flicker--never stays on solid red.

Any thoughts? Troubleshooting? Where is the oil pump on a 352 FE V8?

Note: The only thing I've done differently internally is add Amsoil Oil additive to the crankcase. Castrol 20-50W and new Oil filter every 2-3K mi.

ICEMAN6166 · Post by **ICEMAN6166** » December 21, 2009, 8:45 pm

the oil light comes on somewhere around 8 psi. some flickering at a low idle is not bad and considered normal.

1st thing i would do is check the gauge, it may be the issue.

the oil pump on 352 is inside the oil pan.it can be r/r without removing the engine, a bit of a pain getting the pan out but i have done it more than once

150K and still going is not too shabby either.

has it had any work like valve job done?

born2 · Post by **born2** » December 21, 2009, 9:06 pm

Thanks Iceman for your reply. We had a friend help us replace valve seals around 120K. The motor has never been into other than adding an Eldebrock manifold. I'd be happy to remove the oil pan myself and replace oil pump---if that's something a non-mechanic can attempt in the driveway.

Are Oil pumps for 352 V8s avail? or do they need to be rebuilt?

Thanks

Steve

ICEMAN6166 · Post by **ICEMAN6166** » December 21, 2009, 9:30 pm

Steve
new pumps are available.
there is no core charge , they dont get rebuilt.
i use the melling high volume (not high pressure) pumps.

laying on your back in the driveway plan for a whole day.

jack up the front of the truck, block the back wheels on both sides and set down on jackstands.
disconnect battery
remove air cleaner
drain oil
remove filter

remove nuts from engine mounts on either side

carefully jack up the engine from the harmonic balancer until the back is touching the firewall.
watch for things binding/hitting on the rear while raising the engine
put a couple short pieces of 2x4 wood between the mounts and towers

remove all the bolts from the pan.

drop the pan down as far as it will go. crossmember is in the way so it will only fall so far.

this is where the fun begins

reach in and remove the 2 bolts holding the pickup tube and screen to the pump.

remove the 2 bolts holding the pump to the engine and let it and the drive rod fall into the pan.

now you should be able to pull the pan out.

clean the pan, and the tube and screen.

you may find some crusty old pieces of valve stem seal or nylon timing gear in the screen or the bottom of the pan.

prime the pump by putting oil in the inlet and spinning the rod a few times.

assembly is the opposite of removal. you may need to spin the shaft a bit as the hex fits in the bottom of the distributor. do not force the pump up or try to use the bolts to pull it up, it must touch the mating surface before you do any tightening.

good luck.

64 f100 · Post by **64 f100** » December 21, 2009, 10:45 pm

If you are going that far, you might as well check the main and rod bearings. these can be replaced from under the truck.

Rich

Obsa · Post by **Obsa** » December 21, 2009, 10:49 pm

Thunderboy · Post by **Thunderboy** » December 22, 2009, 12:44 am

With cold weather and short trips, you may have diluted oil, which can thin the oil and cause lower than usual oil pressure. I agree with Ice, check pressure with a different gauge first, and I probably would change oil again to be sure.

Old rule of thumb for oil pressure is 10psi/1000rpm.

FWIW, oil pumps don't typically wear too much, and if the gauge and oil aren't the issue, I would bet there are some pretty loose bearing clearances. If you are going to pull the pan, you may as well install a high volume pump (which I would only use on an engine with greater than stock bearing clearances), and use some plasti-gage on the mains and rod bearings. You could just install the HV pump, and if pressure doesn't come up appreciably, plan on a rebuild in the near future.

or

depending on what you wanted to do next, I guess!

born2 · Post by **born2** » December 22, 2009, 8:09 am

Thanks again! I'll start with the oil change, pressure check with another gauge 1st. Oil pan removal got spooky for this non-wrench when Iceman let me know I'd have to jack motor out of mounts.

Thunderboy · Post by **Thunderboy** » December 22, 2009, 11:30 am

On something like a slick, all mechanical work is pretty easy. Try something like this on a late-model anything. It sucks!

That's one of the things that got me into Slicks - they are so darn easy to work on, and a (relatively) inexpensive(?) automotive hobby....really!

born2 · Post by **born2** » December 22, 2009, 8:39 pm

oil change got me back to 35-40 running and 25-30 low idle. Thanks again!