Low oil pressure after cam swap
05-17-2008, 06:14 AM
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Low oil pressure after cam swap This is a LS7 engine with <2500 miles. Swapped cams, didn't like the grind so I removed it and installed another cam. The swap also entailed replacing the lifters with a set of the GM Cadillac Race lifters. After the swap on cold start the dash gauge reads 33 PSI which is half of what it usually is on cold start. Tore it apart again thinking I got something in the oil pump that had hung the bypass valve up, replaced the pump and same thing. Tore into it again, mic'd the cam, inspected cam bearings, and found NOTHING. Same pressure, but this time, I installed a manual gauge on the oil galley port on the left front side of the block, got 65 PSI there. So I removed the intake replaced the sending unit, and SAME DAMN THING 
Next I removed the intake, installed the gauge there and same pressure on the manual gauge I got 33 PSI there. I am pulling my hair out, I removed the heads last night, and I am in the process of replacing the lifters. That is the only other thing that could have done this.
Anyone else have an problem like this?
Next I removed the intake, installed the gauge there and same pressure on the manual gauge I got 33 PSI there. I am pulling my hair out, I removed the heads last night, and I am in the process of replacing the lifters. That is the only other thing that could have done this.
Anyone else have an problem like this?
05-17-2008, 07:13 AM
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I wish that was the case, but the LS7 isn't like the LS1/LS2 or LS6 engines. It has a dry sump oil pump that seals against the oil pan where it has several O ring seals that it seals againts. The pump still resides in the same place, but when the oil pan is secured it seals tightly against the bottom of the oil pump.
05-21-2008, 09:17 AM
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Problem fixed! The problem that caused the low oil pressure issue was found and fixed. The cause was the new cadillac race lifters that I installed with the new cam. Replaced the lifters and instant oil pressure increase! My advice, DON'T USE THE CADDY LIFTERS!
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05-21-2008, 11:09 AM
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Well, I don't know exactly why they did what they did in my car. I was a little pissed off to say the least. GM is replacing them and paying me for R&R time, and please don't ask how I arrainged this, lets just say I have an extremely good working relationship with the dealer where I get all my GM parts from. In my engine perhaps it was the combination of cam lift and the lifters I have no idea why, because the physical demensions of the lifters are the same, the only reason I can think of is the lifters internal oil metering that is different than the standard LS7.
I am just glad that its done and fixed and now I won't have to explain to my wife why the engine my $80k Z is apart and not running in my shop
All this was done in search of the perfect cam for my car, the first cam which I HATED was replaced with a different grind that was ground on a hours notice by my cam grinder runs sooo much better and gained 5 in/hg more engine vacuum but is 4 degrees longer in duration on the intake lobe. I will be strapping her down on my chassis dyno soon for tuning 
I am just glad that its done and fixed and now I won't have to explain to my wife why the engine my $80k Z is apart and not running in my shop
All this was done in search of the perfect cam for my car, the first cam which I HATED was replaced with a different grind that was ground on a hours notice by my cam grinder runs sooo much better and gained 5 in/hg more engine vacuum but is 4 degrees longer in duration on the intake lobe. I will be strapping her down on my chassis dyno soon for tuning
05-21-2008, 11:30 AM
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from looking at your sig, it looks like you have way too much money. Feel free to share any extra with me.LOL
Glad you found your problem. wonder how many people out there would have just blew this off and drove it with the low pressure..
Glad you found your problem. wonder how many people out there would have just blew this off and drove it with the low pressure..
05-21-2008, 11:58 AM
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That is very correct, if one had moved the EOP sensor to the oil galley on the left from the block one would never know there is a problem. The pressure at that poing read 65 PSI, after that point oil flows to the oil filter then through the oil cooler then to the mains, cam bearings and lifter galleys and last the EOP sensor behind the intake. Ideally you need the volume, and as a rule of thumb 10 PSI of pressure for every 1000 RPM of engine speed. So figuring a LS7 has a redline of 7000 RPM a theoretical 70 PSI is needed along with the proper flow volume.
