Possible oil pressure problem?
Discussion
Just came back from a track day.
And my oil pressure is giving me wonders.
Example situation is as follows:
160 MPH 6th gear
Hard braking
Clutch 4th gear, still braking...
Releasing the clutch, about ~3000 rpm
turn in, oil pressure starts to drop to zero
slowly starting to accelerate towards the end of the turn (oil pressure is still below 1)
4000 RPM oil pressure's starting to raise
5000 RPM oil pressure's back at normal
This means my oil pressure bulb is shining for about 5 seconds (indicating the oil pressure is too low)
Is this normal?
Is this a sensor/display problem?
Any ideas?
It's probably conincidence, but I think it happens always when using the engine for braking.
Probably some kind of back pressure?
I have no idea if it was always like this.
I just noticed that now.
I will try to upload a video of it,
but it will take a few days to convert and upload my recordings.
And my oil pressure is giving me wonders.
Example situation is as follows:
160 MPH 6th gear
Hard braking
Clutch 4th gear, still braking...
Releasing the clutch, about ~3000 rpm
turn in, oil pressure starts to drop to zero
slowly starting to accelerate towards the end of the turn (oil pressure is still below 1)
4000 RPM oil pressure's starting to raise
5000 RPM oil pressure's back at normal
This means my oil pressure bulb is shining for about 5 seconds (indicating the oil pressure is too low)
Is this normal?
Is this a sensor/display problem?
Any ideas?
It's probably conincidence, but I think it happens always when using the engine for braking.
Probably some kind of back pressure?
I have no idea if it was always like this.
I just noticed that now.
I will try to upload a video of it,
but it will take a few days to convert and upload my recordings.
It's a dry sump LS7 with diamond forged pistons,
cylinder head modifications,
12:1 compression,
and a custom grind Camshaft made by Comp Cams.
I took a closer look at my video, and it seems the oil pressure falls whenever cornering.
I'll check the dry sump tank tomorrow.
I guess it's just not enough oil in there...
I suppose the missing oil pressure during the cornering did not harm the engine?
I mean the oil isn't gone, it's in the engine, but simply didn't flow?
cylinder head modifications,
12:1 compression,
and a custom grind Camshaft made by Comp Cams.
I took a closer look at my video, and it seems the oil pressure falls whenever cornering.
I'll check the dry sump tank tomorrow.
I guess it's just not enough oil in there...
I suppose the missing oil pressure during the cornering did not harm the engine?
I mean the oil isn't gone, it's in the engine, but simply didn't flow?
Edited by Mr.Snood on Saturday 11th September 05:16
missing oil pressure under load is always harming the engine.
Doesn't mean catastrophic, but creates extra wear somewhere, most likely the conrod bearings, because they starve first. the sleeves, valvetrain etc have enough splash to survive small oil pressure losses.
I once took an old car to the scrapyard and drove it there with no oil and water in the engine. It got about 10miles before meltdown. So from that point seen you're safe.
If it only occurs during cornering you could have a gauge problem but if also the pressure sensor kicks in.
This always scares the s
t out of me when the red bulb starts to glow. It means the end of the day for me.
Doesn't look promissing. The oilpressure sensor is the last warning of upcoming damage if you continue.
Things to do, replace or test the pressureswitch to see if it works.
You can easy test it with compressed air or a injectortestrig if you have access to it.
it's a normal contact probe. Take a battery a small lightbulb and witre it to the pressure switch. (Not the oilpressure sensor)I don't know the LS7 exactly, but it could be a combinationsensor with the oilpressure.
If sensor is ok look for surgeproblems from oiltank, and whatever is between that and the oilpump that could cause airlocks to occur
Doesn't mean catastrophic, but creates extra wear somewhere, most likely the conrod bearings, because they starve first. the sleeves, valvetrain etc have enough splash to survive small oil pressure losses.
I once took an old car to the scrapyard and drove it there with no oil and water in the engine. It got about 10miles before meltdown. So from that point seen you're safe.
If it only occurs during cornering you could have a gauge problem but if also the pressure sensor kicks in.
This always scares the s
t out of me when the red bulb starts to glow. It means the end of the day for me.Doesn't look promissing. The oilpressure sensor is the last warning of upcoming damage if you continue.
Things to do, replace or test the pressureswitch to see if it works.
You can easy test it with compressed air or a injectortestrig if you have access to it.
it's a normal contact probe. Take a battery a small lightbulb and witre it to the pressure switch. (Not the oilpressure sensor)I don't know the LS7 exactly, but it could be a combinationsensor with the oilpressure.
If sensor is ok look for surgeproblems from oiltank, and whatever is between that and the oilpump that could cause airlocks to occur
Mr.Snood said:
It's a dry sump LS7 with diamond forged pistons,
cylinder head modifications,
12:1 compression,
and a custom grind Camshaft made by Comp Cams.
I took a closer look at my video, and it seems the oil pressure falls whenever cornering.
I'll check the dry sump tank tomorrow.
I guess it's just not enough oil in there...
I suppose the missing oil pressure during the cornering did not harm the engine?
I mean the oil isn't gone, it's in the engine, but simply didn't flow?
My dry sumped SBC takes 2 gallons of oil,so how much did you put in it??cylinder head modifications,
12:1 compression,
and a custom grind Camshaft made by Comp Cams.
I took a closer look at my video, and it seems the oil pressure falls whenever cornering.
I'll check the dry sump tank tomorrow.
I guess it's just not enough oil in there...
I suppose the missing oil pressure during the cornering did not harm the engine?
I mean the oil isn't gone, it's in the engine, but simply didn't flow?
Edited by Mr.Snood on Saturday 11th September 05:16
It should be half full when engine warm and ticking over.
Dom
I don't think there's holes in the system.
I was driving ~100 miles home from track day (highway), and the pressure was fine.
Just took a look at the surge tank.
Engine's cold and the tank is quite empty.
Far far away from the mesh within the tank.
As far as I remember the oil needs to be slightly below the mesh? (in cold conditions?)
What kind of oil do I need to fill in there?
Is it bad to mix the type of oil? (no idea what's currently in there)
Changed the oil about 1000 miles ago.
100 miles of that is probably track day.
Seems I lost quite much oil in a short time?
I was driving ~100 miles home from track day (highway), and the pressure was fine.
Just took a look at the surge tank.
Engine's cold and the tank is quite empty.
Far far away from the mesh within the tank.
As far as I remember the oil needs to be slightly below the mesh? (in cold conditions?)
What kind of oil do I need to fill in there?
Is it bad to mix the type of oil? (no idea what's currently in there)
Changed the oil about 1000 miles ago.
100 miles of that is probably track day.
Seems I lost quite much oil in a short time?
Swiss_Toni said:
LS7 though dry sumped can suffer from oil pick up issues under high G (such as braking, though mostly long corners). Moslers have the same issue.
The chap who built my engine installed baffle arrangement in the dry sump pan to ensure this doesn’t happen.
I have a lot to learn yet about dry sump systems but surely the point of the system is that it does not matter if there is surge in the sump as the oil for the pump is coming from the tank. So as long as there is sufficient in there, or the tank is large enough, there will always be pressure. There may also be an accumulation of oil over in a corner of the sump but that will resolve itself when you come back out of the high G situation.The chap who built my engine installed baffle arrangement in the dry sump pan to ensure this doesn’t happen.
Am I missing something?
Steve
Swiss_Toni said:
LS7 though dry sumped can suffer from oil pick up issues under high G (such as braking, though mostly long corners). Moslers have the same issue.
The chap who built my engine installed baffle arrangement in the dry sump pan to ensure this doesn’t happen.
Probably the reason why my engine is not using the internal LS7 pumps and a billet crank bottom plate with new oil routings and a NASCAR approved DAILEY external pump. My pressure readings never go below 5 bar, only if i am idling, flooring means as high as 8-9 bar.The chap who built my engine installed baffle arrangement in the dry sump pan to ensure this doesn’t happen.
The LS's tend to be slow to return oil from the top, probably aggravated during g and when installed in a capeable chassis. The stock set-up includes breathers which do not assist the scavenge side of the system although they might help with emmisions rules etc. To maximise your scavenge side and thus keep a resonable level available in the tank Im pretty certain a breatherless system is the way to go. My 2pth
Thanks guys. Problem is sorted.
The oil tank was quite empty.
Had to fill 4! litre of "OMV" 10W-60 to get the oil slightly below the mesh (in cold conditions).
Pressure is fine again. Seem to never drop below 4,5 bar now.
I never checked the oil consumption during the past 1000 miles,
since the pressure at startup was always fine...
Guess I learened something new again :[
The oil tank was quite empty.
Had to fill 4! litre of "OMV" 10W-60 to get the oil slightly below the mesh (in cold conditions).
Pressure is fine again. Seem to never drop below 4,5 bar now.
I never checked the oil consumption during the past 1000 miles,
since the pressure at startup was always fine...
Guess I learened something new again :[
No idea where it's gone.
There's definitely no obvious leaks, my garage is clean.
Made the first service after 1000 Km, and the oil has been replaced.
Had 3 track days till then.
I was told it's not unlikely for such an engine to use some oil on the track.
I will keep an eye on the oil consumption in the future and report about the situation.
There's definitely no obvious leaks, my garage is clean.
Made the first service after 1000 Km, and the oil has been replaced.
Had 3 track days till then.
I was told it's not unlikely for such an engine to use some oil on the track.
I will keep an eye on the oil consumption in the future and report about the situation.
Mr.Snood said:
It's a dry sump LS7 with diamond forged pistons,
cylinder head modifications,
12:1 compression,
and a custom grind Camshaft made by Comp Cams.
I took a closer look at my video, and it seems the oil pressure falls whenever cornering.
I'll check the dry sump tank tomorrow.
I guess it's just not enough oil in there...
I suppose the missing oil pressure during the cornering did not harm the engine?
I mean the oil isn't gone, it's in the engine, but simply didn't flow?
Question does anyone else with a LS7 fitted with Forged pistons have high oil use issues ?cylinder head modifications,
12:1 compression,
and a custom grind Camshaft made by Comp Cams.
I took a closer look at my video, and it seems the oil pressure falls whenever cornering.
I'll check the dry sump tank tomorrow.
I guess it's just not enough oil in there...
I suppose the missing oil pressure during the cornering did not harm the engine?
I mean the oil isn't gone, it's in the engine, but simply didn't flow?
Edited by Mr.Snood on Saturday 11th September 05:16
Thats one reason I got pissed off with my old SBC, and one reason I haven't fitted forged pistons to my LS7 at present....
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