Another Oil Pressure Question
Another Oil Pressure Question Ok this is what i have, this is a fresh build, LQ9 block, standard crank, rods and wiseco pistons, machine shop checked the crank and all it needed was polishing, they supplied the bearings, all standard size, it has a pump from Precision oil pumps, the medium volume version, double row chain with the oil pump spacers, Cam Motion solid roller cam with Morel 4737 lifters, Cold start idle oil pressure is at 45-50, fully warmed up < about 205 engine temp, oil pressure is at 32-35, the problem comes when the rpm's are raised, the oil pressure might go up 5 pounds at the most, just stays at 32-35, this is what i done so far, pulled the pan, checked the pickup 0 ring, it had a small section on it that looked like it had rolled and pinched a little bit, removed the oil pump and timing chain, installed a new cam retainer, pan had some small metal particles in it, then i saw where the pump was rubbing the timing chain even with the spacers, so I'm guessing thats where the metal came from,, clearanced the pump then completely dissembled the pump to check for a possible stuck relief valve, found nothing wrong with it, installed the pump, sealed the pump spacer plates, while the pan was off i can see that the rear barbell was in place, put everything back together, might have gained a few pounds more but the pressure still does not rise with rpm's, before i pull the engine, Advise needed...., I'm also feeding a S480 turbo from the plate on side the pan thru a 6AN hose, no restrictor. HELP
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
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From: Central Cal.
What shape is the turbo bearing in? A 6AN hose can pass a lot of oil if there is low restriction on the other end. A turbo needs a lot of oil, but should pose enough of a restriction so as not to endanger the oil supply to the rest of the engine
The turbo is new, besides one trip just a few blocks down the street just to see if the oil pressure would rise under a load, it didn't , the whole setup only have idle time.
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,615
From: Central Cal.
I still wonder if too much oil is going to the turbo. I will be first to admit total ignorance on how a turbo oil system needs to be done. I just know it needs oil, and a good way to drain it back. I know how it is done on a diesel. That's it. You probably know whether it needs a restrictor or not. I hope this mystery gets solved! You need to start having some fun with this setup! Best wishes!
polished crank with stock clearance bearings maybe? Allows more flow but less pressure? I have a similar issue with my motor.. Hot idle i'd get to around 25-28 and maybe hit 45-50 at WOT.. Cold start idle it is around 45 and over 50 lightly cruising.. Once warmed up it doesn't really climb like it should at WOT, but its within spec.. My motor was also rebuild, and aftermarket bearings were used. I just recently went from 5w30 to 10w40 oil and gained 5-10 psi maybe but still need to verify on a hot day. My thoughts are the clearances are different in the motor than they used to be... i am rolling with it because i've had multiple people give me the thumbs up, but i'm not a huge fan. I did the billet oil barbell, new cam retainer plate, and new oil pump and o-ring. If you figure out something i'd be curious to see what you find, even though i'm non-turbo. I still have not verfied mine with a mechanical gauge and the sensor has 130k on it but it was reading normal before the heads and cam swap.
Today or tomorrow ill know for sure if its the turbo, my next check would be the solid lifters bleeding off too much oil pressure, not sure if its a test for them besides solid push rods, lol
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Yes... Also, I use a second bolt/girdle on the pump pickup.
The last install,, I found the pump p/u tube support brace was twisting the tube. I "clearanced it", and all was well.
My long tunes were only about 2 inches away from the oil filter and really messed up my oil Temps and hot oil pressure. My oil Temps also messed with the oil pressure readings and the switch wouldn't register the correct pressure until I let off the throttle
i haven't had time lately to mess with it but considering I already had the pan off 2 times, I'm going after the rear cover gasket next, I didn't replace it, it could be leaking internally bleeding off my pressure, going to try an replace it this coming weekend. Any thoughts??
What was the cause for the additional clearance? The size of the lifters in general? What lifters and what PSI do you have when at operating temp? Do you run it this way or did you make changes to correct it?