oil pressure question
09-20-2010, 08:52 PM
#1
oil pressure question What should the gauge read 4-6k? I always thought it raised when I was in it, but tonight it would only read 40psi even at 6k. Idle at the light around 800rpm, it holds at 20 nice and steady. 55mph in 5th, around 2k, maybe around 30-35 psi. Is this pump getting weak? Approx. 35k miles on the pump. I'm not sure if it was a GM pump or a Melling, seems I tossed all my PM's from when The_Merv had told me what he put in this motor. Only time I saw it go above 40psi tonight was on a 4-3 downshift.
I changed the oil a few weeks ago, ran a K&N filter this time due to Advance Auto's oil sale. Don't know if this could affect anything.
Well let me know if things are normal or I'm just getting paranoid! My truck is still down, so this is all I have to drive, if something is starting to go I'd like to address it before it becomes a serious issue.
I changed the oil a few weeks ago, ran a K&N filter this time due to Advance Auto's oil sale. Don't know if this could affect anything.
Well let me know if things are normal or I'm just getting paranoid! My truck is still down, so this is all I have to drive, if something is starting to go I'd like to address it before it becomes a serious issue.
09-20-2010, 09:35 PM
#4
Looking at lethalbirds thread on the same thing, can a new opti really slow down the oil pump? I did an opti install about two or three weeks ago.
Oh yeah and it has always had 20psi at idle, its just above 4k rpms now that it has me concerned. 5w30 Castrol Syntec was put in this oil change.
Also tonight I was running no A/C. I notice that most of this month with the A/C on the engine would bog a lot on initial acceleration. I have a six puck clutch, so that sucker grabs violently and sometimes the motor bogs when the A/C is on.
Maybe this has been like this for a long time and I'm just noticing now, or maybe the bogging had weakened it? Now I'm trying to remember if my sending unit is up behind the intake manifold or if on this car someone had installed it down low by the oil filter.
I know about the 10psi per 1k, that is why all of a sudden I'm worried.
Oh yeah and it has always had 20psi at idle, its just above 4k rpms now that it has me concerned. 5w30 Castrol Syntec was put in this oil change.
Also tonight I was running no A/C. I notice that most of this month with the A/C on the engine would bog a lot on initial acceleration. I have a six puck clutch, so that sucker grabs violently and sometimes the motor bogs when the A/C is on.
Maybe this has been like this for a long time and I'm just noticing now, or maybe the bogging had weakened it? Now I'm trying to remember if my sending unit is up behind the intake manifold or if on this car someone had installed it down low by the oil filter.
I know about the 10psi per 1k, that is why all of a sudden I'm worried.
09-20-2010, 10:38 PM
#5
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oil pressure when i bought my lt1 383 it had the same oil pressures as you state. before the first open road race with that engine i decided to change the rod and main bearings. the engine before my ownership was drag raced but i dont know how much. i removed the pan and dropped the bearings one at a time and found every rod bearing into the copper layer and the mains into the copper. after changing them and the oil pump, (m155), the pressure went to 70 psig at idle cold and 40 psig at idle hot and 65 psig at 5800 rpm during the race. i clearenced the oil pump gears to end plate at .0015 to .002 and cleaned up the inside of the pump. i hope that the bearings are not your problem but it bears looking at if the mechanical gage reads the same as the cars gage. i can send you pictures of the old bearings if you need them. see ya
09-21-2010, 09:15 AM
#7
My car almost pegs the gauge. I'm probably going to try some thinner oil.
http://s86.photobucket.com/albums/k1...=VIDEO0011.mp4
http://s86.photobucket.com/albums/k1...=VIDEO0011.mp4
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09-21-2010, 12:11 PM
#9
That was some 10w40 redline I had sitting around for a track day. Now I have M1 10w40 high millage in it. I'm probably going to switch to 30w high millage since its on the thicker side of a 30w. I'm too cheap to spend $8/quart on german castrol when I can get a 5 quart jug of mobil 1 for $22 at walmart.
09-21-2010, 12:12 PM
#10
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I would guess windage since you state during downshifting the pressure is higher at the same rpm. Reason being is my stock gauge did the same thing. It would go to 40psi or just above and stop. It was not reading the dramatic fall the pressure took when the pump started to cavitate. Lots of people have experienced this with the stock oil pan and tray.
09-21-2010, 01:14 PM
#12
OK while at a light today I rev'd it up to 6k, oil pressure was around 58psi. Yeah I think its just starving on rapid take offs from a stop and low speeds. Don't know on the windage tray, once again The_Merv will have to say yes or no.
When he sold me the motor all I did was swap valve springs and rockers, stuck it in my car. I've never had the pan off.
I wonder how long it has been doing this and I just haven't noticed?
Yeah a bit over two years I've been running this motor now, I'm racking up the miles!
When he sold me the motor all I did was swap valve springs and rockers, stuck it in my car. I've never had the pan off.I wonder how long it has been doing this and I just haven't noticed?
