super67

Hey this is my first ls1 I had it mildly built a while back it was reading lower oil pressure than i woulda liked. The machinist said it would be fine less than a year later cam bearings went out. I took it back to the machinist had it rebuilt again as soon as i got it back together it was reading even less oil pressure than the first build with a high volume pump. My machinist has never touch a modern ls block before is there any kind of machining error that could be made on these to cause this issue?

ls1 1990 VN

Never let anyone who has not worked on an LS motor near one...they will *** it up 'every time'.
oil pump O ring has probably been pinched allowing pressure to pass.
Use the search button...read as much as you can about the LS motor from mods to maintenance & all the pit falls the guys have come across....there are many!

All your oil pressures hot & cold, cams, heads, exhausts, manifolds etc.
You have many hours of reading ahead of you & a huge amount to digest....Goodluck

super67

checked the o ring it was fine... is it possible that the high volume pump draws more oil than the pan hold causing low oil pressure?

ls1 1990 VN

Only at constant high rpm like road racing, High pressure pump is not ideal, ported yes. What pressure are you showing.

super67

once its warm basicaly zero at an idol never breaking more than 1o psi

ls1 1990 VN

Get it looked at by someone reputable that knows the LS motors...
If it was mine, I would be having the pump changed and a new O ring fitted.

senor_camaro

iTrader: (1)

The pressure of the oil depends on the efficiency of the oil pump and the clearances through which the oil flows. also lack of oil, plugged oil pick up screen, weak or broken oil pressure relief valve, or low engine oil viscosity.

what is the engine mileage and viscosity engine oil are you running?

I would suggest performing an oil pressure test. check your oil pressure at the specific RPM range according to engine model. if the oil pressure is low it is most likely the oil pump.

also make sure to remove the pick up and clean it out, sometimes it can be clogged not allowing it to suck up engine oil. once the pump is removed check the snout of the crankshaft for wear, if the snout that makes contact with the oil pump is worn that may be your cause. there is not enough contact to spin the pump since it is a rotor style pump.

hope this helps

ls1 1990 VN

Thinking you need to list exactly what was done to your engine & parts used, mileage thats been done on the build, What it was like before the bearing issue & after.
As much info as possible always helps.

senor_camaro

iTrader: (1)

I actually researched into this further, I saw that you mentioned that you had a high volume oil pump. i think that is the cause of your problem. if your using the stock pan I dont think theres enough oil in there to keep refilling the bottom end once its pumped thru. you should look into what size pan that pump is rated for, you might have to buy a higher capacity pan or maybe a remote reservoir.

ls1 1990 VN

He's got no pressure with a warm engine at idle....A high pressure pump won't empty the sump at idle & he would show oil pressure

senor_camaro

iTrader: (1)

you would have to know the flow at certain RPM to be sure, but it could empty the sump at idle, remember its a higher volume oil pump which means hes pumping more than double what the stock pump would, plus hes probably running the stock pan. his pump is sucking so much oil his pan cant compensate and doesnt have time to refill. while its getting pumped it goes into the system and circulates through the oil galleries thru the engine. it makes sense why you would need a higher capacity oil pan to run a higher volume pump. the more you pump the more fluid you need.

you should put the stock oil pump back on and see if your oil pressure changes.
unless your doing some hardcore racing, have a higher capacity oil pan, and dry sump your just setting your engine up for disaster. your gonna starve the bottom end and damage your engine.

what where your oil clearances?they should be on your engines build sheet from the machine shop.

chrisfrost

iTrader: (8)

No , the high volume pumps don't pump 2 times the stock pump and if it emptyed the pan the gauge would go from showing oil pressure to zero oil pressure and there would be bearing damage . sounds 2 Me like bearing clearance issues but 2 b more certain it needs 2 b checked with a mechanical oil pressure tester b-cause the electronic 1's can b unreliable .

super67

yea it was tested with a mechanical oil pressure testor and it matched what the gauge read i researched the pump and the only issues i found were under high rpm pulls pressure dropped. Its a pretty mild build mild cam shaved heads for a little extra compression double roller chain the machinist said the main bearings where in spec. Is it possible the new pump could be deffective ?

senor_camaro

iTrader: (1)

absolutely, its possible that the pressure relief valve is stuck open or deffective rotor. change the pump like I mentioned and you will definetley see a difference in pressure. make sure to prime the pump before installation

bczee

iTrader: (12)

yeah.. o-ring is usually the most common problem. but also if the oil pickup is not seated correct and flush in the pump, it well also cause problem.

Did you check your oil pickup / tube to the bottom of the pan clearance..?.. put some clay on it and then put the pan back on. to check it. if it is too close to the bottom, it can cause problems. I have about 3/4" on mine.

I would also check the relief valves (dumb bells in the block) and valve in the pump.

brett walker

iTrader: (6)

I would be willing to bet, since he has never done an LS motor that he doesnt know you have to "center" the cam bearings in the bore. Not just push them flush with the face of the cam bore. If you search EPIC low oil pressure thread on here you will see what im talking about.

777

iTrader: (21)

No high volume/high pressure pump will run the pan dry of oil (especially at idle). If you are truly getting 0-10psi of oil pressure I don't even know how your engine is still running. You should be getting ~40psi warm idle with a stock pump, ~50psi if you have a ported one.

Gray86hatch

iTrader: (83)

Pick up should be no more than 3/8 to 1/2 from the pan. Another thing is the pick up screen can be to restrictive. I run my stuff 1/4" and have not seen a oiling issue

I am guessing this is a alum block. The mains need no more than .002 rods can be .0024 or so.
cam bearings can be the issue but a competitent machinest should be able to handle this. Some cant even get them in straight and this will tighten the clearance up.

My engine makes 60 psi cold idle and 30 hot. The block grows a bunch and if you don't have the ability to overcome that with extra volume you will have issues

Tim

fastazzls1

also they are differnet size cam bearings that help align the camshaft in its bore i work for gm as a tech guy next to me ordered all the sam size camshaft bearings, and if you read the service manual they have differnet diameters to help keep the camashaft as straight as possible in the bore due the machining process like everyone else is saying i would try new pump and o ring before i would start changing bearing and remove the engine also drain the oil and inspect for debris and cut the filter open and inspect filter element

Gray86hatch

iTrader: (83)

Another thing is did you alighn the oil pump when you installed it this is something else that needs to be done

Tim