fluctuating oil pressure?

[1970bowtie]

ok, i gotta question i put a fresh motor in my truck it has probably 200 miles on it. when first cranked in had 55 psi and 2000 rmp while breaking in the cam. now my oil pressure gauge bounces all over the place (ive tried a different gauge) and while driving back from town it went down really low. i pulled over and checked the oil and it was good. but psi wouldnt get over 25 driving back so i was babying it. psi is fine at idle it stays about 20-25. so does anyone know what my be the cause of this because i am lost

[1970bowtie]

need help with this

[The Big Green]

It's carrying between 20-25 at idle but drops when you speed up? Here's something to keep in mind, it's not the pressure, it's the oil volume, and that's checked by seeing, try pulling the valve covers and see for yourself. If it has the right dipstick and shows good on oil then it COULD be a bad pump, is it new? Is it a Mellings high volume pump? It's could have a gap in the pumps seat. I would see if you have enough oil volume out the rockers and go from there.

[pwderman]

Is the pump pick up welded or bolted on??? if not I'd check that

[jhow66]

Oil pickup tube may be off the pump.

[1970bowtie]

it has a mind of its own it'll idle at 20-25 and when you step on the gas it"ll jump up like it should. but driving down the road it stays at 20-25-30 until you mash on the gas fairly hard then it"ll jump on up to 55 i have no idea what the problem is.. i changed oil filter and that didnt help i didnt change the oil because the comp cams break in additive says to run the motor 1000 miles before changing the oil. i was thinking maybe there is something sticking to the pickup on the oil pump? and yes everything is new this is a crate motor from ledford performance in waco texas.

[The Big Green]

It should have a warrenty. I'll use this as an example. I have a Dakota with a 408 stroker, 600hp. I have 15-20 idle, 50psi highway. It's fine and some engines with cams carry low psi. Mine has 2000miles, it's fine. I have a 67, 350 with 454rv cam and Mellings pump, it has 60 idle and 70-80 driving.

[1970bowtie]

it did have a warranty but ran out before we got around to putting it in.. i just hope its nothing serious... ive had nothing but problems with this truck since i got it on the road

[WorkinLonghorn]

According to the original Data Book (for 1969,350ci) the oil pressure spec is " 30psi at 1170-1200 RPM"
That's about what mine has. At idle it's about 5-9psi when hot. Freeway,2500RPMs I get 35 (hot).
There should be a relief valve on the pump that limits pressure to about 60 on OEM type pumps.
Remember that as the oil heats up the pressure will go down and it heats up at a different rate than the coolant so even if your engine temp gauge shows it's up to normal,the oil might still be warming up.
But I can't explain why you would have 20-25 at idle and then low at cruise unless as mentioned above,there was a problem with the pick-up.But mine will be 55psi on the freeway cold and will drop to 30 after full oil warm-up on a real scorcher.

[1970bowtie]

me neither im lost i really dont wanna pull the motor back out.. i just graduated from high school and am flat broke, cant get to my job because the trucks always acting up

[The Big Green]

Run a gauge with lower numbers you can read. Watch you oil gauge religiously and just make sure it stays up. It's either that or pull the pan. I've pulled the oil pan in my 67 with the engine in the truck. I had a 454 and I put all new bearings in it too. That's what I would do but if you just want to keep an eye on the psi gauge then make sure it's in the ok. Anything from 10-15 is good, any lower is ok I guess but closer to 0 make it harder to catch if it drops to nothing. Just pull the engine mounts bolts, loosen the tranny bolts and jack it up but watch anything that gets in the way. You dont have to pull it out to get the pan off. You can reuse the oil pan gasket, only the intake and head gaskets can't be reused. That's your best bet but both are ok I guess.

[1970bowtie]

yeah ill have to look at it this weekend. i dont HAVE to drive it anytime soon i dont guess although it is my only means of transportation. im out of options and parts ive had this truck running maybe 3 months and been threw an engine and 2 transmissions... shop teacher snapped my cam in the other motor, and the transmissions were mostly my fault..

[1970bowtie]

went out and looked at the truck today and there is oil EVERYWHERE. its all over the transmission. intake manifold is leaking in one spot but mildly. valve cover arent leaking nor is the oil pan, oil pressure fitting is good. there was oil puddled on top of the fuel pump & trans cooler lines anyone have any ideas what might be leaking?

[The Big Green]

You checked the oil pressure fitting, but if it's a mechanical gauge then check the line if you haven't. They have a lot of pressure and it's a good reason for the crazy psi numbers if they are varying in psi. If that lines good then clean the oil good with a degreaser and then watch for oil coming out.

[72chevyk10]

Originally Posted by 1970bowtie

went out and looked at the truck today and there is oil EVERYWHERE. its all over the transmission. intake manifold is leaking in one spot but mildly. valve cover arent leaking nor is the oil pan, oil pressure fitting is good. there was oil puddled on top of the fuel pump & trans cooler lines anyone have any ideas what might be leaking?

are the front/rear main seals good?

[69GMCLonghorn]

You may have to clean everything off, then just run it a little bit and see where it's spewing from. If it's that bad, it shouldn't take too long to find the leak.

Just make DANG sure you don't let that motor run out of oil!!!

[The Big Green]

Does the engine make any tapping sounds? Is the intake useing the front and rear rubber seals? It may be, and they tend to smash and come out. You always throw them away and use a bead of sylicone. From the factory I bet on the seals being in there. They will be rubber and you'll know when you look.

[tranz am]

I had this same problem with my 350. Oil pressure was fine until about 2500 rpm, after that the pressure would drop the higher the rpms went.
Im willing to bet your pickup tube fell off the pump. These tubes should be spot welded in 3 spots imo.
Mine came off on a bumpy logging road in the forest. If you have a magnetic flexible probe you can stick it in the oil drain plug hole and fish around for it. Mine was laying right next to the hole, I could see it.
hope this helps.

[tranz am]

Did the motor come with the oil pump, pickup tube and an oil pan installed? If so and that tube fell off, then I would bring it back to them and ask for a replacement motor. Good only knows if the motor has been starved oil for too long. If they were the ones to put it together than its not your fault and I would be worried.

[1970bowtie]

the motor was complete oil pan to intake when i bought it. the rubber china wall things werent used. ive pulled the oil pressure line from the back of the gauge and cranked the truck and the oil runs out in a steady stream. and yes front and rear mains are good, not oil up in the bell housing and timing cover is also clean... i have a bad power steering leak.. maybe thats what im seeing... i could just be paranoid with the motor being new and all it'll drink lots of oil until the rings seal. but with the gauge fliping out im not sure. ledford says they weld their pick ups on, i know they build alot of circle track motors and are reputable, but im running out of things to check i may have to pull the pan..

[1970bowtie]

and i appreciate all of yalls help, thanks alot

[Willys47]

If your running out of things to check can ledford help track down your motors problem if you took it by there, I would think they would if they are reputable.

[tranz am]

Well you know what the funny thing is? I had my pickup welded to the pump initially too, and it still fell off. Thats why I weld mine in 3 spots instead of just one now. Im almost positive this is your problem.
just dump out the oil and fish around in there for it. If its loose in there you will feel it.

Originally Posted by 1970bowtie

the motor was complete oil pan to intake when i bought it. the rubber china wall things werent used. ive pulled the oil pressure line from the back of the gauge and cranked the truck and the oil runs out in a steady stream. and yes front and rear mains are good, not oil up in the bell housing and timing cover is also clean... i have a bad power steering leak.. maybe thats what im seeing... i could just be paranoid with the motor being new and all it'll drink lots of oil until the rings seal. but with the gauge fliping out im not sure. ledford says they weld their pick ups on, i know they build alot of circle track motors and are reputable, but im running out of things to check i may have to pull the pan..

[tranz am]

did you ever figure it out?

[treveiger]

interested also hope you figure it out.