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Oil pressure drop on idle @ operating temperature.

1llustriou5

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Hi guys, have a VX 5.7L LS1
Firstly to give some background on the situation the car has had work done, including a cam, ls7 lifters, rods etc. along with transmission work.
Car drove fine for months and was very happy, one day out of the blue the oil pressure light came up on the dash while i was sitting at a light, revved it, oil light off, sit for another 2 seconds oil light back on. Installed a guage so i could read what exactly was going on and basically car was losing pressure after it was warm on idle.
Figured it could be Oil pump or o ring or something within that vicinity. So off comes the sump and timing cover to check out whats going on. Oil pump looked to be fine, oil and pan was clean, not a piece of metal shaving to be seen, o ring isn't pinched, barbells were in place. Figured it was possibly a fault in the oil pump even though it all checked out. Swapped the melling 10295 out for another melling 10295.
Put the car all back together, still the same problem is occurring. Cold idle pressure sits at 15-20psi, after it warms up drops down to 10psi and hovers in-between 5-10psi on idle @ operating temp. On load car is hitting good pressures around 50-60psi.
Currently running a semi-synthetic 10w-40 oil.
Spoke with my mechanic and he says the only thing he sees possible for this behaviour and knowing what we know is that the lifters are bleeding off.
Car also doesn't tick or tap.

I just want to ask for more opinions, similar experiences and what options i can take to confirm the issue.
Once again it is not the o ring, it is not the pump, it is not the barbells, and more than likely not the cam bearings...
Thanks guys any help would be greatly appreciated.
 

Immortality

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Hi and welcome to the forum.

Did you check the oil filter? Some drop in oil pressure is expected from cold to hot, the drop does not seem excessive but I'm also no expert on the LS. This is the downside of only having and idiot oil light, if you don't know what is normal (from seeing an actual gauge) then it's hard to judge what is not.

If you find nothing than you may get away with trying a thicker oil and seeing what it does and monitor oil pressure. If the pressure comes up and no strange noises try driving it but I'd be monitoring the oil pressure and if it continues to drop it may be time to pull the engine and check things like bearings.

Also, I wouldn't discount the cam bearings. Worm cam bearings does seem to be a bit of a thing and once you disturb something mechanically (like swapping a cam) it can accelerate wear and tear.
 

someguy360

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Most likely cam bearings are worn, thats the most common cause of oil pressure drops at idle on the LS engines.
 

Jezza

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How many kms has the car done? Any LS engine with over 180k kms will need the cam bearing replaced when changing the oil pump. The only reason you wouldn't is if you wanted to flip the car/ sell it once oil pump is replaced. I know this because i bought a LS1 and had this exact issue and bought a replacement oil pump and then discovered that it's not just replacing the pump when its done 210k kms. The workshop asked if i was keeping it or selling and $4500 later i had a new oil pump, cam bearings and the rest of the bottom end fixed up.
 
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