LQ4 No Oil Pressure
#21
A pre oiler would be quite easy to make but I am sure you should be able to rent one from an engine shop or sometimes auto stores have them for customers that buy a rebuilt engine. I figured my problem out tonight 4 sure and it was the O ring. I bought one at the local dealer today 12584922 red/orange. When I removed the pickup tube and looked it was blue slightly larger in diameter and a lil thinner. I did a little more research and I read somewhere there are 4 diffrent O ring sizes? This could be totally irrelevent to your problem just thought I would mention. As well as recommend you check that engine with a prelube tank. When you tear into the bottom end of one of these angines fasteners need replacing and there are a few other items a person has to be careful. If you replace rod bolts use Katechs or GM only! Stay away from other names as you WILL need to resize rods. Some guys will reuse the stock fasteners but they are all tourque to yeild fasteners and are not recommended to re use. If you have oil pressure with a preoiler you can narrow down your problem. Theses motors have an incredable bottem end If there is nothing wrong down there I wouldnt wast your time? Just my opinion I have torn a few down and it was piston problems in all but one. This engine by the way now primed itself within 3 5 second starter intravels and came up to 38 pounds.I am lucky enough to have put royal purple break in lube on all bearings on assembly so I can breath easy doing this . I hope you are able to find a preoiler get some pressure to it and see it hold pressure on its own and rule out bearings.
#22
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Depends on who you talk to from what I have seen? I would like to know GMs advice on that. I know that tourque to yeild bolts are meant to be tourqued once. Just like the cylinder heads bolts. I dont doubt you could re use them with success and guys do. But I beleive only because they are over engineered from the General. And well the bottom end duz have 6 bolt deep skirt block so mains arent as important as rods. Ask around . And If the pickup was not from that oil pump I would really want to varify its correct. Ask at gm what part # are from the two different years and see if they are the same?
#23
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I wish I could up load a pic here but I havent figured it out yet. There are different diameter pickups if you saw the picture i took of the two different O rings you would "see" what I mean lol. And they are close enough that it would be easy to mistake a good fit. I got my engine from the dealership with it having the wrong Oring and the wrong length pushrods.They were trying to figure out what was wrong with it too. You never know what youre going to find.
#24
I wish I could up load a pic here but I havent figured it out yet. There are different diameter pickups if you saw the picture i took of the two different O rings you would "see" what I mean lol. And they are close enough that it would be easy to mistake a good fit. I got my engine from the dealership with it having the wrong Oring and the wrong length pushrods.They were trying to figure out what was wrong with it too. You never know what youre going to find.
The LQ4 block showd signs of running, oil still in the whole motor, crank, heads, ect. so i know all plugs are in place. so what im thinking is either i cracked or did something to the pickup tube when installed into the 6.0. OR i just need to pull the OPSU and dump oil down there and threw the heads and try again lol
#26
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I'm learning a lot from this thread . . .
I was totally unaware about the need for shimming an LS oil pump. This thread has probably saved me a lot of frustration and, possibly, the new motor I'm preparing to build.
Your problem is really baffling, because the stock pump and the replacement pump are exhibiting the same problem, even though all of the pre-oiling and priming is being done.
I agree that it sounds like there is a "hole" somewhere . . . My "gut instinct" tells me that there is a cracked weld in the pickup tube that is allowing air to enter, causing the pump to be unable to draw oil from the sump even though the pump itself has been primed.
Just my thoughts . . . Good Luck !
I was totally unaware about the need for shimming an LS oil pump. This thread has probably saved me a lot of frustration and, possibly, the new motor I'm preparing to build.
Your problem is really baffling, because the stock pump and the replacement pump are exhibiting the same problem, even though all of the pre-oiling and priming is being done.
I agree that it sounds like there is a "hole" somewhere . . . My "gut instinct" tells me that there is a cracked weld in the pickup tube that is allowing air to enter, causing the pump to be unable to draw oil from the sump even though the pump itself has been primed.
Just my thoughts . . . Good Luck !
#27
any progress? im having similair problems with my 5.3 i just put a cam in, but im getting oil to the filter and in the tube to the mechanical gauge, just no pressure. going to pull the front apart and check o ring
#28
When I get time I think I'm going to pull pump and poor oil down into the tube to see if it holds it. If it does I'm going to poor oil in the opsu hole and all threw the heads and try again. Think there is only 3-4qts in the pan
#29
i swapped pumps last night to try and rule out the pump. i packed the pump with grease and it helped prime it right away i had oil moving almost instantly. still no pressure tho. i think im going to get a tsp ported ls6 pump. that truck pick up tube is a pia to seat. is it supposed to seat all the way up into the pump??? i would pry mine up into the pump but after i tighten the bolt it would slide back down an 1/8'' or so. same o ring as what i had before. i give up!
#30
found a cool pick up tube idea on another thread thought id pass it on to ya, i ordered one, they are made to order takes about 3 days gets rid of the o ring, comes with a flange and a gasket! way better designhttp://schumannsdynamicperformance.c...d/131436/LSPST good luck!!!!
#31
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i swapped pumps last night to try and rule out the pump. i packed the pump with grease and it helped prime it right away i had oil moving almost instantly. still no pressure tho. i think im going to get a tsp ported ls6 pump. that truck pick up tube is a pia to seat. is it supposed to seat all the way up into the pump??? i would pry mine up into the pump but after i tighten the bolt it would slide back down an 1/8'' or so. same o ring as what i had before. i give up!
#32
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i swapped pumps last night to try and rule out the pump. i packed the pump with grease and it helped prime it right away i had oil moving almost instantly. still no pressure tho. i think im going to get a tsp ported ls6 pump. that truck pick up tube is a pia to seat. is it supposed to seat all the way up into the pump??? i would pry mine up into the pump but after i tighten the bolt it would slide back down an 1/8'' or so. same o ring as what i had before. i give up!
#34
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opsu
The pickup tube, Pan, Tray, Lifters, Cam, Heads, Water Pump, push rods, rockers, and intake where all pulled. from my LS1 block that got trashed due to a broken head bolt, lets just say i have learned my lesson about TTY bolts lol.
The LQ4 block showd signs of running, oil still in the whole motor, crank, heads, ect. so i know all plugs are in place. so what im thinking is either i cracked or did something to the pickup tube when installed into the 6.0. OR i just need to pull the OPSU and dump oil down there and threw the heads and try again lol
The LQ4 block showd signs of running, oil still in the whole motor, crank, heads, ect. so i know all plugs are in place. so what im thinking is either i cracked or did something to the pickup tube when installed into the 6.0. OR i just need to pull the OPSU and dump oil down there and threw the heads and try again lol
#35
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oil pump pick up tube
I saw the same thing recently when I pulled the pan and changed the Oring on my L92 the pick up tube was not seating properly to the pump. I removed it and lubed it up and then it slid in with a lil tap. ANY amount of leakage at the Oring or on the pickup tube will prevent the pump from priming. But if you say it is moving oil out the filter location then that eliminates the oring or pickup and points to possible cam bearing instalation or cam bearings turning on cold dry start? I realize that you guys dont have the issues of starting a vehicle in -40 weather but you never know? Or an open gallery somewhere?
#36
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I saw the same thing recently when I pulled the pan and changed the Oring on my L92 the pick up tube was not seating properly to the pump. I removed it and lubed it up and then it slid in with a lil tap. ANY amount of leakage at the Oring or on the pickup tube will prevent the pump from priming. But if you say it is moving oil out the filter location then that eliminates the oring or pickup and points to possible cam bearing instalation or cam bearings turning on cold dry start? I realize that you guys dont have the issues of starting a vehicle in -40 weather but you never know? Or an open gallery somewhere?
#37
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Oil pressure with open galleries.
As I have mentioned I am a novice engine builder. But I have built quite a few engines in my life. When I was younger 20+ years ago I had an engine on the test stand that had O oil pressure. I was young and didnt do the checks that I would have done now but it came down to a missing plug behind the upper timing chain gear that hadnt been staked hard enough.? I again 15 years later came across another engine I built (embarresingly) that had the same gallery plug miissing this one put out 15 lbs oil pressure?? One of the reasons I doubted it was missing a gallery plug. I am sure the difference was oil pump volume/pressure. If the engine moves oil but doesnt make pressure there has to be a plug out some where like the two I had encountered earlier. But with these LS engines crank driven oil pumps and that long pick up tube it makes it a totally different animal to work on. A pre oiler is essential. Not like the old school chevys where you could take an old distributor and modify it to prelube the engine. This engine has to rotate in order for that pump to make pressure. From my recent adventure the engine after oil change should make oil pressure with spark plugs out no fuel within 5 x 4 second intravels on the starter. I dont recommend any one doing this unless necassary but I have Royal Purple assemly lube on every friction point in the engine not just the main bearings. The answer to my earlier question is yes these engines will prelube themselves without running, on the strater when everything is correct. And once the system is full the pump is supposed to friction lock with oil so it doesnt need to prime itself till next oil change??? Any one with oil pressure problems after changing oil should critic the o ring. A pre-oiler would be easily made by using an air tank and adding two valves off the drain side and gauge. Two valves work best like the one I borrowed from one of my customers that rebuilds engines his looked like you could put 1000+psi to it lol seriously over enginered. I wish I could put a pic up from this stupid phone but unfotunately still havent figured it out. One valve before the gauge on the bottom for tank pressure then one after the gauge to see what your engine is doing if it makes pressure you can shut either valve to read either sides pressure. Or lack of I like to fill the engine with 3 L of engine oil and add 2 to the pre oiler just so you dont over fill the engine. I always make a habbit of filling my oil filter before spinning it on even 7/8 full so not to make a mess. Sorry If I rambled? lol
#38
i dont wanna hi jack mista blazer's thread, this is my first ls cam swap. i was gentile installing the cam, used the comp cams pro lube, so im going to say the cam bearings are fine. but with out taking it back apart to inspect the cam bearings its only a guess. oil pressure was good on this motor before i tore it down. bottom end was left alone, so the barbell in the back is still there and the plug up front is still in tact. i'm hoping its an o ring problem. those pick up tubes are made to order, hopefully next weekend ill get it back together and fired up.
#39
Swapped pick up tubes, packed the pump with vasoline, had 30lbs in about 5 seconds!!!! i guess i suck at seating pick up tubes with o rings lol thank god for the aftermarket co.