Cody

I have a LS1 that I have swapped into an Astro van. The engine has sat for about 8 months without being run. I had to change the oil pan and pickup tube for one from a truck to clear my cross member. Now I'm ready to start it and I can not get any oil pressure when I crank it over. I changed the o ring on the pickup tube last week just to be sure. I believe the tube is all the way in as the plate around it sits flush with the mounting flange. Does anyone have an idea what might be wrong? I have heard of the pressure relief valve going bad, possibly mine is stuck from it sitting so long?

Cody

Sorry I forgot to mention that I pulled the oil filter off and it is completely dry.

Michael Yount

iTrader: (1)

Did you use pressurized oil to re-prime everything? How long did you try cranking it? Even with a pressurized prime, mine chattered the lifters for a good 5-7 seconds after first start up, then the gauge popped up to 55 psig or so and all was quiet. Mine took a fair number of revolutions to fill everything up and start generating pressure on the gauge. My sender is in the oil passage that runs from front to rear on the driver's side rear of the block right above where the filter sits.

Cody

Have not used pressurizing.
Cranked it for about 30 seconds.

Project GatTagO

iTrader: (7)

Did you use the right o-ring? I seem to recall some discussions about different pick-up tubes using different o-rings, and that you have to match them.

Andrew

Michael Yount

iTrader: (1)

Andrew is, as usual, spot on. Various vehicles (trucks/cars) use two different size o-rings. And the aftermarket pickup tubes have to have the proper size of these two as well. Having said that, I think using the wrong size for your pickup tube might result in reduced pressure, but not a complete lack of pressure.

To the OP - how do you know it had pressure from "before"?

Project GatTagO

iTrader: (7)

I know when I first fired up the engine in the GTO, I took the oil filter off, disconnected the coils, and cranked it until oil started coming out of the oil filter pad. It was back in 2008, so I don't remember it taking too long, maybe 20 seconds?

With the 5.3L in the Cougar, I didn't do ****. I hooked up my laptop, fired up the Holley software to monitor pressure, and cranked it. It fired up quickly and I had oil pressure almost instantly...

Andrew

ls1nova71

iTrader: (4)

Wouldn't hurt to put some oil in the filter before putting it on, I do that every time I change oil. I have also had engines that wouldn't build pressure just by cranking the starter, so like the others said, you may want to try pressurizing the system first. Haven't personally done this, but seems like it may be worth a shot. https://ls1tech.com/forums/tools-fab...nder-20-a.html

Michael Yount

iTrader: (1)

I bought a $9 AN fitting and used my Motive brake bleeder to put 5 qts. in at 15 psig through the port front of the driver's side passage directly below the temp sensor in the head - filled up the filter AND the oil cooler/lines. According to the paperwork that came with the new engine, failure to prime this way was a no-no for the warranty. This approach flowed oil through the system, up the pushrods and drained back into the sump until I had put 5 qts. into the sump. Then I added another 1.25 qts. to hit the full mark on the stick.

Cody

I installed a new o ring from Chevy. The engine and pickup tube are both from a 2001. The engine is from a Camaro and the tube is from an Avalanch.
I made an oil primer for my engine and pumped plenty of oil thru it. Turned the key and.................still non pressure. I'm sure the pickup tube and seal are good. The pressure relief valve might be stuck from sitting so long.

Michael Yount

iTrader: (1)

?? Relief valve OPENS on high pressure, otherwise is closed. Seems unlikely that it's stuck open against the spring.

RixTrix

Leave oil filter off and crank motor again with fuel pump disabled.

You can blow oil up to the pump (to wet the pump) from the oil filter flange. But it should pick up on its own, this is a clue that there is something wrong.

Oil pickup oring is a very likely suspect.

If the relief valve was stuck it would at least dribble oil to the filter.

Cody

The o ring is brand new I just put it in but you never know. Some forums say O rings others say relief valves.
My pickup tube is from a truck motor and the new o ring is the blue one from chevy. Is there some difference between the car and truck tubes? Can someone verify either way?

Michael Yount

iTrader: (1)

YES - there are two different o-rings -- I've had them both in my hand at the GM dealer parts counter as I returned the wrong one and bought the right one. One is made out of oring material that is a larger diameter resulting in an inside diameter of the ring that is smaller. It's not about how the OD of the ring fit's into the section in the block; it's about how snugly the o-ring fits around the indented portion of the tube. As I recall, from dealer - one is red and one is blue. Again - I don't think the wrong o-ring would result in no pressure at all, but rather, reduced pressure.

Cody

In looking online I seem to see that the LS car engine and LS truck engine (LQ4) have different colored o rings, so I assume maybe they are different sizes?

LS is blue, LQ4 is red

Michael Yount

iTrader: (1)

Read my post above yours....

Michael Yount

iTrader: (1)

And....what matters is what pickup tube you're using - especially since these things get so mixed up what with conversions, different oil pans, etc. I finally took my pickup tube with me (Mast Motorsports pan uses truck-type tube I believe) to the dealer to test fit and get the right oring.

Project GatTagO

iTrader: (7)

There is a thread on here about all this with pictures and actual dimensions.

Andrew

Cody

I'm going to try the other o ring next time i'm off work again. It's a definite b***h to change on mine as my pan is about 1.5 inches from my crossmember. I can't completely drop the pan without removing the engine from the van and it is a tight fit. Changing the plugs is gonna suck.

Michael Yount

iTrader: (1)

I'd sure try an external prime and more cranking before I assumed it's the oring. I know I'm a broken-record here --- but I think you'd have pressure with wrong oring - just less than it should be.