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Lack of oil pressure, Crank-Cam position DTCs

Lack of oil pressure, Crank-Cam position DTCs

(OP)
So im on a car team at school where were integrating a hybrid powertrain into a 2016 Camaro. Were using GM's 2.0L LTG engine coupled with 2 YASA P400 electric motors. Our packaging forced us to use a dry sump for engine....problem was that at the time, no one made a dry sump for this engine, so we made our own. We spoke with Moroso regarding the oil pump, and they recommended this one: https://www.summitracing.com/int/parts/mor-22343/o.... The pump is driven @ 70% engine speed off of a custom sprocket on the crank that has the timing chain profile as well as the pump belt profile on it

For the pan design, we based it on this one:


Here's ours:


We did some tests of the oil system prior to startup to make sure we were getting oil flow and it does seem like we are (were getting oil pressure, oil is flowing to the top of the engine, and its circulating back into the reservoir)

Got everything ready to go last week, threw some 0W-30 in it and fired it up (BTW, this is a brand new engine). While it did start up almost instantly, it wasnt running well. At idle it stumbled (especially when cold), the oil pressure was low (at 800 RPM, we saw 100 KPa; a stock Cadillac ATS with the same engine at 800 rpm shows 300 KPa), and we were getting DTCs saying that both camshaft positions relative to the crank are out of whack (DTCs: P0016, P0017). We suspect the low oil pressure is causing the cam phasing to not work properly, causing the cams to not move to the desired angle, resulting in the crank-cam position DTCs. Our first course of action is to try thicker oil, either 5W-40 or 10W-60, and a new oil filter to see if we can bump up the oil pressure and solve the problem. If that doesn't work, we might check the timing chain to see if we installed it incorrectly or if it jumped a tooth or if the custom sprocket we had made is off, but that may only solve our DTC problem. Were not quite sure what to do to solve our oil pressure problem. We've also tried playing around with the pressure relief valve on the oil pump and that didnt do anything (kinda suspected it wouldnt but we tried anyways). If anyone has any ideas, that would be much appreciated.

RE: Lack of oil pressure, Crank-Cam position DTCs

Thicker oil isn't a way to fix this ... in my opinion, don't even bother. The system has to work correctly with the proper oil specified for the engine.

The photos of the parts that you showed tell me nothing about what their orientation is in the engine and where oil is flowing out of and to.

The oil pump that you have linked to is a scavenge pump for sucking oil out of the dry sump and sending it to the externally mounted (UNPRESSURIZED) oil tank. It is NOT suitable for generating the main oil pressure that is intended to supply the oil galleries inside the engine that lead to the main bearings and valve mechanisms and so forth. What pump are you using to do that?

Do you have a schematic of where oil flows to what and how it's laid out in the vehicle?

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)
That pump has a pumping stage and 2 scavenge stages. Shouldnt need another pump to create the oil pressure.

This is a schematic of the system (we have 2 scavenge stages, the pump in the schematic has 3; everything else is the same):

RE: Lack of oil pressure, Crank-Cam position DTCs

Have you got a level sensor or a sight glass in the oil tank?

Note the difference between the pan you copied and your version:
The 'base' pan has four rectangular ports, each draining one crankcase cavity.
Your pan has two much smaller round ports, each draining two crankcase cavities through channels that are joined, and the channel that drains two cavities is not larger than the 'base' pan channel that drains one cavity.

I can't help but conjecture that you are starving the scavenge pumps, causing the oil to accumulate in the block, and the oil level in the oil tank to fall until the pressure pump is pumping air and some oil. ... and things go downhill from there.

Mike Halloran
Pembroke Pines, FL, USA

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)
When we first tested the system, we did have the issue of oil accumulating in the engine, but it was due to a restriction in the pan at the front cover to oil pan interface; oil would pool at the base of the front cover and not drain into the pan quick enough. We opened up the pan at the interface and that seemed to solved the issue. We dont have a level sensor in the reservoir, but we have monitored the level visually every time we've ran the engine and were maintaining steady oil level (level maintained at around 3/4 full)

RE: Lack of oil pressure, Crank-Cam position DTCs

You need to monitor the oil level in the tank while the engine is running.

How much damping (restrictor or electronic filter) is in the oil pressure gage?
I'd expect to see it banging up and down, a lot, absent damping.

Mike Halloran
Pembroke Pines, FL, USA

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)
Not sure how much damping there is in the sensor, but we are using the stock GM oil pressure sensor, which has some electronic filtering. The values we were seeing were quite smooth

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)


From one of the later tests we ran

RE: Lack of oil pressure, Crank-Cam position DTCs

The filter and the cooler are both restrictions in the supply line of your schematic.
Moving the filter and the cooler to the return line is my first suggestion.
Next try a smaller pulley on the pump to drive it faster.

RE: Lack of oil pressure, Crank-Cam position DTCs

I suspect that you are underdriving the pump for your given restrictions.
But have you looked at the oil to make sure that are not foaming it?
If you have air trapped in the system or are starving the pump inlet you could be entraining air into the oil.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)
We have some in-line filters on our return line. Not sure if I would want to move the main oil filter to the return line as that would mean we have no protection for the oil entering the engine. Also, there would be no pressure to drive oil through the filter; it would rely solely on the vacuum created by the scavenge stages of the pump.

Were currently driving the pump at 70% engine speed. From the research we've done, it seems like the norm is around 50-60%, so were actually overdriving the pump.

We looked at the reservoir while running and the oil doesn't seem to be severely aerated. There is air in the oil coming into the reservoir but there are baffles in the reservoir to get rid of it before it circulates back into the engine.

RE: Lack of oil pressure, Crank-Cam position DTCs

You DO NOT want the oil filter on the suction side. It belongs after the high pressur pump where you have it. How did you come up with your 70% underdrive ratio?

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RE: Lack of oil pressure, Crank-Cam position DTCs

I'm on the design team with OP and helped design a majority of that system. The 70% drive speed was determined when contacting Moroso technical support regarding their pump. In our discussion regarding maximum drive speed and when cavitation were to occur, their team mentioned that we can run to 70%/80% underdrive without concern with cavitation.

RE: Lack of oil pressure, Crank-Cam position DTCs

A friend (Evelrod) recently had a low oil pressure issue in his race car.
(Pressure went low, and he shut it down)
When he inspected the car afterward, the oil filter was only half full.
His filter, as yours is, was between the main oil pump and the engine bearings.
Their best guess is that they were getting air in the oil, and when the aerated oil settled down over a few days, the filter was only half full of oil.
The remainder had been air in the oil.
(In his case, it seemed to be a fastener bottoming out and not quite sealing something on the suction side)
Check your filter - it might tell you of aeration?

Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: Lack of oil pressure, Crank-Cam position DTCs

One issue I can see looking at the oil sump design is the shape of the scavenge passages. They look like they could benefit from more careful profiling. Another thing to consider is that your high-volume scavenge pump mixes large amounts of air into the oil. So you should have some device to remove the entrained air from the oil before it is fed to the pressure pump.

RE: Lack of oil pressure, Crank-Cam position DTCs

That's the job of the tank. He said there's some provision in there, but perhaps it is not sufficient?

Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: Lack of oil pressure, Crank-Cam position DTCs

Where are you measuring pressure?

I'd be driving the pump with an electric drill, etc, and measuring the discharged oil volume with the main oil line disconnected. First before the oil filter. If the flow was good, then after the oil filter, and finally at the engine connection.

RE: Lack of oil pressure, Crank-Cam position DTCs

The oil pressure in your charts is closely proportional to engine speed. That is normal until the speed/pressure increases enough to open the relief valve.
This suggests that your problem is not a restriction but a mis-match ie the oil discharge at the engine is too high or the pump volume is too low. Can you
feed oil pressure to the engine (electric drill?) with the sump off, to see where the majority of the oil is coming from? You are looking for excessive clearances
somewhere or a leakage path - eg what did you do to disconnect the factory oil pump? Did you remove it and plug the gallery? If it is still in-situ and free to rotate
it will rotate backwards and bleed oil back to the crankcase.

je suis charlie

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)
@tmoose Were measuring the oil pressure via the pressure sensor on the engine block

@gruntguru The factory oil pump was completely removed. We did plug the gallery that fed oil from the stock pump to the oil filter (the oil filter is now remotely mounted). Unfortunately, we aren't able to run tests with the sump off as it would require a fair amount of time to remove it (our engine bay is quite crowded to say the least) and the vehicle ships for competition in a few days.

We swapped the oil filter and that had very little effect. We have been looking at potentially adding an air separator before oil goes back into the reservoir to help reduce foaming

RE: Lack of oil pressure, Crank-Cam position DTCs

Where are you actually feeding the oil? Are you pumping it back through the original filter location, or are you tapped into the block somewhere?

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)
Back through the original filter location

RE: Lack of oil pressure, Crank-Cam position DTCs

JMO but your oil pressure sounds normal for an idling aftermarket pump that appears to be "universal" to older engines. I would recommend separating the pump from the engine and driving it with an electric motor and VFD as common in dyno cells so you can independently control oil pressure. You can then crank up the motor speed/pressure temporarily to check if it solves your timing issue. You can also then troubleshoot the system without running the engine, looking for issues with foaming and pressure loss.

RE: Lack of oil pressure, Crank-Cam position DTCs

This may be an obvious one, but are you certain that your oil lines going to the remote filter housing aren't backwards? If using braided lines, are you sure they're not kinked?

You may want to disassemble the bypass valve and make sure nothing is hanging open. I'm just not sure that the pump curve at the engine speeds you're describing are going to get you there with such a thin oil. Those pumps on race motors do not uncommonly see upper teens to low 20's at idle. Granted, they're seeing much wider bearing clearances than many modern OEM engines, but they're typically running a 20W-50 oil. That puts them safely in the 10psi/1000 RPM category, but they don't have pressure-driven cam/tensioner characteristics to worry about.

RE: Lack of oil pressure, Crank-Cam position DTCs

Again. The pressure vs engine rpm relationship does not look like a restriction. Looks more like leakage or a supply/demand deficit.

je suis charlie

RE: Lack of oil pressure, Crank-Cam position DTCs

(OP)
@Mr168, we checked the lines and everything is routed correctly and there aren't any kinks. Some of the lines are a little long and have some bends which may introduce a pressure drop, but i would imagine they're not where the majority of our pressure loss is coming from. We believe that we are getting sufficient flow through the engine, given that the pump is spinning quite fast (and is adequate for this engine), however the low pressure could be due to what you mentioned, that these pumps are meant to run with thicker oils due to the higher clearances.

@gruntguru we do have some slow leaks in some of our fittings, but i dont think they're significant enough to reduce the pressure that much.

On the bright side, we do believe we have found our cam/crank issue. The timing chain was off a tooth on the crank side, which correlated to an 8 deg difference in the cams relative to the crank. Hopefully this solves some of the DTC's were getting and the engine actually runs properly

RE: Lack of oil pressure, Crank-Cam position DTCs

High pump clearance plus thin oil = leakage. You might be on to it. You probably don't need to worry too much about the oil pressure as long as it is on the relief valve when the engine is under load.

je suis charlie

RE: Lack of oil pressure, Crank-Cam position DTCs

I don't see any big issues with what how you built the system. So, step up the pump speed if you need or want more idle pressure. The pump should be fine as long as it doesn't have a maximum rpm limit you're exceeding. It has a pressure relief built-in to limit the maximum pressure so more rpm just means it circulates the oil internally more at maximum rpm.


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