Custom lq4/ls2 engine oil issue
06-16-2019, 02:53 PM
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Custom lq4/ls2 engine oil issue Hi!
i’ve been reading a bit on my issue and I was wondering if you guys would have a good answer to me.
ok so let’s start with the engine.
it is a fully rebuilt LQ4 with the LS2 componments. So I basicly reused the block, pistons, connecting rods, heads, and valley cover from the LQ4.
Everything else comes from the LS2 engine (crank, cam, sensors, intake).
I’m running the 58x crank sensor and 4-1 front cam sensor. I reinstalled the original LQ4 cam sensor to avoid leakage at the back of the engine.
here’s the problem. When oil is cold I have full oil pressure all across the rpm range (sits close to the middle of the guage on a trailblazer ss). When it gets warmer I lose pressure to the point it will read 0 on the guage at idle only. As soon as I give a bit of gas it goes up right away to the good pressure.
This lead me to think the oil pump is working good. The rear plug was installed at the back of the engine. I was careful when I reinstalled everything and made sure the oil sump oring was not pinched (but its hard to verify now).
oil change was made at 400km after break in. Block got honed and cleaned. Oil was 5w30 if I recall good.
From what I’ve seen I do have a bit of a "rocker arm noise" coming from the driver side if the engine but it’s not too loud.
Common culprits I’ve been reading about are:
- failed oil pump
- pinched oring on suction tube
- missing rear block plug
- obvious oil leak (nothing that I could see, and oil level is still very good after 3000kms)
- blocked/collapsed oil filter
i know the oil pump have a pressure relief valve, maybe this one is stuck open and don’t allow pressure to build up, but I guess it would affect cold oil too.
I haven’t worked on it yet since right now I’m working 6days a week on night shift and got my truck to go to work anyway.
What do you guys think? I’ll probably be able to work on it in a month or so but I’m trying to get prepared before starting the work on it.
Thank you
i’ve been reading a bit on my issue and I was wondering if you guys would have a good answer to me.
ok so let’s start with the engine.
it is a fully rebuilt LQ4 with the LS2 componments. So I basicly reused the block, pistons, connecting rods, heads, and valley cover from the LQ4.
Everything else comes from the LS2 engine (crank, cam, sensors, intake).
I’m running the 58x crank sensor and 4-1 front cam sensor. I reinstalled the original LQ4 cam sensor to avoid leakage at the back of the engine.
here’s the problem. When oil is cold I have full oil pressure all across the rpm range (sits close to the middle of the guage on a trailblazer ss). When it gets warmer I lose pressure to the point it will read 0 on the guage at idle only. As soon as I give a bit of gas it goes up right away to the good pressure.
This lead me to think the oil pump is working good. The rear plug was installed at the back of the engine. I was careful when I reinstalled everything and made sure the oil sump oring was not pinched (but its hard to verify now).
oil change was made at 400km after break in. Block got honed and cleaned. Oil was 5w30 if I recall good.
From what I’ve seen I do have a bit of a "rocker arm noise" coming from the driver side if the engine but it’s not too loud.
Common culprits I’ve been reading about are:
- failed oil pump
- pinched oring on suction tube
- missing rear block plug
- obvious oil leak (nothing that I could see, and oil level is still very good after 3000kms)
- blocked/collapsed oil filter
i know the oil pump have a pressure relief valve, maybe this one is stuck open and don’t allow pressure to build up, but I guess it would affect cold oil too.
I haven’t worked on it yet since right now I’m working 6days a week on night shift and got my truck to go to work anyway.
What do you guys think? I’ll probably be able to work on it in a month or so but I’m trying to get prepared before starting the work on it.
Thank you
06-16-2019, 06:11 PM
#2
TECH Senior Member
I think it's your stock gauge sender. If it's good everywhere EXCEPT idle, it's not the oil system. Change the sender and report back.