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I have a ls7 that was a wetsump. It's in a C5 and I've converted it to an Aviaid LS A setup. Tank is mounted where the battery was. It's the 7.5 x 16 "2 gallon" tank. I have two -12 lines from sump to pump (XRP lines with head shields and no sharp bends). Then a -12 line from pump to tank. Then a -12 line from tank to oil pan and the meiling high volume internal oil pump. I have a -16 but have tried for hrs to route it down there and it just doesn't fit. So the issue is it will stop scavenging and run the tank dry. But not all the time. Sometimes it does it after 30 or 45 mins of idling. Sometimes it does it in the 1st min or two. I've been lucky so far and caught it every time as the pressure starts to drop and shut it off. I haven't been brave enough to drive it more then around the block. Of which it seems to happen the moment it comes back to idle after driving. I'm not happy with the size of the tank and have ordered the next larger tank but I'm not so sure that's going to solve it as it shouldn't be draining the tank. 5L fills the tank to the 2/3rds mark. Start the car and fill back to the 2/3rds mark and it looks like total system. Capacity is around 6L. Which I think is much to small. I'm not sure that's what's causing my issue. I just don't understand how logically it can be absolutely fine for 30mins or more. Then just stop scavaging. It looks like at idle my oil pump pumps brought 4 GPM which means if I've got 5L in the tank it will suck the tank dry in about 15 seconds. The information I haven't been able to find is how much oil actually stays in the motor. My theory I've got is that the oil is still all draining back to the pan and therefore not being scavaged. Is it possible my system just plain doesn't have enough capacity and all the oil is simply stuck in the motor? If so.... Why does it work for very long periods then stop working. The pump is run off the serp belt and it keeps spinning. I don't see how a pump could just stop pumping. When it does run out of oil, if I shut it off then turn it back on it instantly fills the tank. This had lead me to believe the original Redhorse performance lines I was using were simply sucking shut. I had XRP make me lines that are a lot stiffer and I stalled them last night only to find it made no difference. John at aviaid had aoa theory that i might need to increase the pump speed or raise the idle speed. Current idle is 900rpm. I'm just doubtful the large tank will be the fix. Has anyone run into anything like this? Pic to show routing.
Last edited by Mrsideways; Jul 18, 2020 at 02:45 PM.
NO expert on these things but one bit of info you reported made me think.
If the tank runs dry and the oil is just building up in the sump, and the scavenge is not happening.
Since you are using a stock type melling to pressurize the oil system in the motor. You should NOT be losing oil pressure in that scenario. The melling should still be pulling oil from the motor sump and you should have oil pressure. I assume you are measuring oil pressure from the normal spot on the motor oil circuit.
It seems like there almost has to be something wrong with the scavenge pump. I wonder if it would be worth sending it back to Aviad to test?
Another thought - seems unlikely - with the pump mounted high like that, if the scavenge looses prime their has to be a suction to re-establish prime.
Could there be a problem or opening in the crank case vent system some where (or other leak) that is preventing the system from developing good suction. An air leak? Maybe when the oil is cooler it is thick enough that it can maintain the vacuum but as it gets hot and thin it allows "channels" that prevent the vacuum from building up and no suction.
NO expert on these things but one bit of info you reported made me think.
If the tank runs dry and the oil is just building up in the sump, and the scavenge is not happening.
Since you are using a stock type melling to pressurize the oil system in the motor. You should NOT be losing oil pressure in that scenario. The melling should still be pulling oil from the motor sump and you should have oil pressure. I assume you are measuring oil pressure from the normal spot on the motor oil circuit.
It seems like there almost has to be something wrong with the scavenge pump. I wonder if it would be worth sending it back to Aviad to test?
Another thought - seems unlikely - with the pump mounted high like that, if the scavenge looses prime their has to be a suction to re-establish prime.
Could there be a problem or opening in the crank case vent system some where (or other leak) that is preventing the system from developing good suction. An air leak? Maybe when the oil is cooler it is thick enough that it can maintain the vacuum but as it gets hot and thin it allows "channels" that prevent the vacuum from building up and no suction.
Well the stock pump is blocked from sucking From the sump because it can only suck through the -12 line coming into the pan. But I think your on to something about the scavage pump loosing prime. Question is how to fix it. Smaller scavage lines maybe? It does not happen when motor is stone cold. From cold start I have a good 5 mins to not worry about it. Seems to happen. A lot more often as it gets hot. In order for that theory to be correct it would mean a majority of the oil is stuck up in the motor and the sump is fairly dry and sucking mostly air. I just don't see 5qts stuck up in the engine.
I have the stock PCV from valley to intake still hooked up. I have a check valve from valve cover to dry sump tank. I do still have the stock dip stick installed as I haven't come up with a good way of pressing the little freeze plug into the dipstick hole to block it off. I just trimmed the dip stick shorter and stuck it back in. But there is every possibility that that is a vac leak. I didn't think a vacuum leak could be the culprit. That's a good thought. I'll double my effort today to try to seal that off. I wonder if I should be removing the valley cover to intake manifold Vent?
Thats the frustrating part about this. I feel like a serious lack of information and absolutely zero instructions. Questions like "is a 2 gallon tank enough" are anwsered with... Hmmm I dunno, depends...
Last edited by Mrsideways; Jul 19, 2020 at 11:43 AM.
That could be it - the scavenge is loosing prime - most of the oil is in the sump - i think you want a mild vacuum with a dry sump, wont the PCV prevent a vacuum from forming?
That could be it - the scavenge is loosing prime - most of the oil is in the sump - i think you want a mild vacuum with a dry sump, wont the PCV prevent a vacuum from forming?
This is why I came here.... Will it. I don't know. When the car was wet sumped it pulled a vacuum at idle. I guess next step is to seal off that dip stick tube and block off PCV.
Last edited by Mrsideways; Jul 19, 2020 at 12:39 PM.
I want to say all venting to be out the tank. No other vents. My understanding is a PCV is to take pressurized crank case breather fumes and put them back in the intake so they will burn - less emissions - you dont have this concern.
What about a crank case breather? That should be sealed off and only breathing out the Dry Sump tank (I think).. I would think their is a tech line at Aviad that would easily answer that type of question.
I guess you cant mount the pump below the engine sump :-)
It would be interesting to run a thicker oil and see if the scavenge worked for longer. Best not to mess around with an expensive motor.
Something interesting that makes me discount the pcv theory is that Aviaid told me I didn't need a check valve on the breather hose to the drysump tank. Without the check valve is have no chance at crankcase vacuum as I'd have a -10an hose venting freely both ways to a catch can.
And yes the more I mess around with it the more I worry about hurting the motor. I won't let it idle without someone watching the oil pressure. Requires 2 people around to try to hunt issues. First time it happened the car had been idling 10 mins or so. I was alone and looking for oil leaks after seeing good pressure. Peaked inside the car to look at the water temp just as the low pressure light flashed on and I shut it off.
Last edited by Mrsideways; Jul 19, 2020 at 12:56 PM.
Where are you picking up the scavenge from? I have hade avaid, ARE and now Dailey, they all have issues. What size is the scavenge? 1.5? What oil pump do you have the standard flow or the high flow?
Also looking at your scavenge pump, you have one of the circuits blocked off, and are using the rear circuit, it may be causing a problem. I would try to put a Y on both the inlet and outlet so that it won’t cavitate.
that pump is basically 2 pumps, and the front one is not getting any oil, that pump may be the problem.
Last edited by c5racr1; Jul 19, 2020 at 03:09 PM.
Reason: Info
Where are you picking up the scavenge from? I have hade avaid, ARE and now Dailey, they all have issues. What size is the scavenge? 1.5? What oil pump do you have the standard flow or the high flow?
High flow. Not sure about scavage pump it's what they sent me. About the two lines. This was how the diagram said to do it. I'll ask him about it tomorrow when I call.
Where are you picking up the scavenge from? I have hade avaid, ARE and now Dailey, they all have issues. What size is the scavenge? 1.5? What oil pump do you have the standard flow or the high flow?
High flow. Not sure about scavage pump it's what they sent me. About the two lines. This was how the diagram said to do it. I'll ask him about it tomorrow when I call.
the scavage lines are pulling from Front and rear port on the ARE pan.
The pump you have is for a 2 stage scavenge and you have 2 lines going to the pump and one line going from the pump to the oil tank. If I’m not mistaken, that pump is actually 2 pumps separated by that silver aluminum joint. That being the case the way you have it set up it is causing the pump to go static because the front side is actually going static with oil flow in and no way to pump it out. Put a y exit on that top port and see if that solves the issue or just put a exit on it and pump it to the fill port of your tank to see if it flows oil out.
Where are you picking up the scavenge from? I have hade avaid, ARE and now Dailey, they all have issues. What size is the scavenge? 1.5? What oil pump do you have the standard flow or the high flow?
The pump you have is for a 2 stage scavenge and you have 2 lines going to the pump and one line going from the pump to the oil tank. If I’m not mistaken, that pump is actually 2 pumps separated by that silver aluminum joint. That being the case the way you have it set up it is causing the pump to go static because the front side is actually going static with oil flow in and no way to pump it out. Put a y exit on that top port and see if that solves the issue or just put a exit on it and pump it to the fill port of your tank to see if it flows oil out.
Ill give that a try tomorrow. I have enough fittings and hoses that should be easy to do. Report after work tomorrow.
bAffle broke in the are pan, mostly filling the catch can or not creating vacume in the crank case. Ahhhhh put a vacume gauge on the valley port and see if it is creating vacume in the crank case. If the scavenge pump is not working then you won’t have any vacume. Put a rubber plug on the dip stick tube.
bAffle broke in the are pan, mostly filling the catch can or not creating vacume in the crank case. Ahhhhh put a vacume gauge on the valley port and see if it is creating vacume in the crank case. If the scavenge pump is not working then you won’t have any vacume. Put a rubber plug on the dip stick tube.
It has to be scavaging some. It will run fine for 30+ mins. It just seems to have a hickup and stop scavaging. Should I have pcv from valley to manifold blocked?
Aviaid Dry Sump help.
