Hello I'm having problems with motor when cold I have about 25 to 30 oil pressure when motor gets warm I don't have any I changed the oil and filter its a fresh rebuild It only has 80 miles on it at first oil pressure was good but went down slowly when I give it gas the pressure goes up any ideas do I need to pull motor and take back to machine shop thanks
call the machine shop... who put the oil pump and pick up tube on it...who put the OIL pan on it...what weight oil do you have???are you running a mechanical gauge or an electrical gauge.. if electrical gauge.. did you hook up the ground wires from the back of the cylinder heads to the firewall.. and the ground wire from the negative battery cable terminal to the body??? why.. the engine is sitting on rubber mounts.. if its only grounded to the battery .. and there is no connection to the body where the gauge is grounded... you could have a difference in voltage do to the bad ground... do you have a hand held digital volt meter.. have you done a mechanical oil pressure test.?? please run the 4 numbered parts of this test..i can do the test in under a minute with the headlights on and the engine running..practice on a different car until you have it down...please post results by number1......................2......................3.....................4....................could the pickup tube be too close to the pan.???could the pickup tube have fallen off..do you still have the previous oil filter... can you cut it open and examine the filter element??some stores like harbor freight have oil pressure test tools.. a 140 pound gauge on a LONG high pressure hose with a set of adaptors to fit many cars..
lastly for tonight before i sign off..do you have a remote starter button????if you truly have no oil pressure... disable the ignition system so the engine cannot start...verify that when you push the remote starter button that only the engine cranks... does not start..remove the oil filter... yep.. place a drain pan under the adaptor.. i hope you don't have headers... while watching the oil filter mount.. use the remote starter button to crank the engine... do you get a significant amount of oil out the filter housing.. you can in some pans.. look through the drain plug hole to see if you have lost the pick up tube or if its too close to the pan...
Is the engine making noise of any kind.ie the lifters ticking, or a rod knocking.Before the machine shop gets blammed. If you have another oil pressure gauge install that to verify the low oil pressure. I would do that first. Theres a lot of things that could have gone wrong with a fresh rebuild. Verify the oil pressure first. Then call the builder! Bob
+1 wayne you always have a lot of good info. like bob said verify the oil pressure. i had the oil pump by pass valve stick open. it is a 3/4" steel ball in the oil pump. the only way to verify is to pull the motor, drop the pan and take the pump off. there is a large cap on the pump housing behind the cap is a spring and the 3/4' ball. the ball should roll out freely. if it doesn't get a new oil pump.my car had 3 to 4lbs at hot idle and 20 to 30lbs at 2000 to 2500 rpms with no abnormal noise from the motor.also had a bad mechical gauge one time due to somebody using too much silicone. if the machine shop put the motor together i would let them check the motor while it is in the car. i would not drive it. haul it! most shops will stand behind a bad part they provided and make it right. good luck!!
76 455/4spd TRANS AM69 GRAND PRIX 455/5SPD
+1 to everything mentioned above.. Two other items that may be of note. The oil pump will normally have an adjustable pressure spring off the discharge side. If it's set to low that might explain the variance in pressure after the engine is warmed up. Second one is- Pontiac installed a bypass metal diaphragm in the oil filter housing on the side of the motor. If that spring is either missing or the diaphragm is bent that would also explain the variance in pressures between hot and cold.
I'm using mechanical gauge autometer and used another just to verify same results the filter had a little debri but not copper after warm up it sounds like it starving for oil I haven't started the motor since the machine shop put the motor together all I had to do was put carb on and the motor has headers the shop told me to pull motor and bring to them I will let u know what they find thanks
you might want to YANK the distributer out...use a oil pump priming tool and spin the oil pump shaft with a speed handle..see if the pump is actually working by feeling for resistance..there are a LOT of reasons for things to fail..or rig your own..the idea is to spin it by hand... so you can feel how much resistance it has... you can see and feel the relationships with the torque needed and the oil pressure..engine rebuilders sometimes have a oil leak device.. they bolt the short or long block into the machine... attach a drive shaft to the crank.. hook up a oil pressure line to the proper fitting.. and spin the engine.. while observing oil pressure.. oil leakage from the bearings and lifters... sticking either a push in type compression tester or just their trained fingers to check the compression...i do agree with the NEED for a big honking drill motor to spin the pump..somebody gave me one of these with a #3 morse taper... should be strong enough to twist the pump right off the bottom of the block...another friend wanted to play who owns the biggest drill.. he pulled out his milwaukee 5/8 gear reduction hole shooter...i said.. i will play.. reached in and pulled out the #3 morse taper skil drill.. the look on his face was priceless.. and he did not want to play who has the biggest drill any more.. i should have pulled out the 220V milwaukee 3/4" chuck drill.. that would have really impressed him..
it takes a stout 3/8 drill to turn a oil pump. you can make a oil pump drive out of a 12" long peice of 3/8 fuel line, smash one end flat and slide a 9/16 socket over the line then chuck it in the drill and hold on tight. the socket will keep the extention on the oil pump drive rod. counter clock wise rotation.
76 455/4spd TRANS AM69 GRAND PRIX 455/5SPD
Hello machine shop took motor apart today everything looked good the only thing was check valve on oil pump was stuck open could that cause the problem
Yes that will cause a low oil pressure problem.
Engine builder,self taught auto body guy.Horsepower sells engines and torque wins races
Thats a good lesson, and good reason for guys that do their own engine building. Take the oil pump apart, and inspect it. On assembly just put oil in the pump to keep things coated with oil. Check that relief valve! I have used Melling pumps for years. If the pump is going in a race engine it is taken apart and we blue print them.(Even if purchased Blue Printed the pump is taken apart) it's all checked. Then we test them.I'm sure the oil pump was flow tested, but thats it. Flow test means that it flowed oil, and how much was the pump tested to the relief valve probably not.I have found metal burrs in some pumps. It doesn't matter who made the oil pump. That stuff happens. Just take it apart visualy inspect it and put it back together. Make sure the pump housing, and cover are flat that will ensure a good mating surface. Then when you reassemble it, the (2) mating surfaces will be flush, and not cause an internal leak. You can even flow test it yourself. Very simply put the pump in oil enough to cover the pickup. Spin the pump in the proper rotataion direction. Cover the outlet (so you don't get a bath of oil) with your hand,a piece of cardboard, anything, and spin the shaft by hand or with a drill. Bob
hello atleeyou have some xlnt replies so mine will touch on a different area. dont know how much you know so hopefully this isnt redundant for you.oil pump valve debrisdecent oil pumps virtually never fail unless they get debris in then somewhere. the debris should not be there in a properly cleaned, reassembled and broken motor. if all things are correct then it must be left over from the oil pump machining process. most people dont clean the pump at all. either way it may be possible to carefully remove the ball and locate the debris if you are that motivated. the purpose is to take a magnet and see if it is metal or aluminum. if its metal no problem just clean it and reuse it. if its aluminum then it is bearing material and you need to look at all the bearings yourself carefully to find the bearing and journal it was riding on. never assume the shop is 100% perfect. reassemblyif you did not keep the lifters in order you will need new ones or your cam may go flat. install new rings and rehone. others here may say its unnecessary. why take a chance? break it in with joe gibbs break in oil, preheat oil in cold climate. switch to vr1 after around 500 miles or less. do not add zddp additive. good luck with your project
barnett you missed a post he took the motor back to the machine shop. and i'll bet they only pulled the oil pan.
76 455/4spd TRANS AM69 GRAND PRIX 455/5SPD
HELLO ATLEEyor first post says you drove the car 80 miles, your second post says you haven'tn started since the shop built it. did they rebuild it between your first and second post? did they take your entire motor apart, please say yes?thanks