Lost oil pressure

[gunslinger]

Got my new build running today.
Priming the pump with a drill gave me 70psi, and on initial start up, oil pressure was around 75psi.
I was breaking the cam in, running it at 2600rpm, and after around 15 minutes, oil pressure had dropped off to around 15psi. I shut it down to hopefully avoid damage.
All clearances were .0015-.002 on the rods & mains, and new cam bearings properly installed by me. It has a new TA cover, Melling SD pump with the 60psi spring in it.
I restarted it and idled it for a couple seconds to check oil flow to the turbo ,and there was some valvetrain noise, and the oil pressure gauge read zero.
I haven't dropped the oil or filter yet to check for debris. (I had to walk away from it for a while)
When building the front cover, the bypass valve was sticky in its bore. I cleaned it up, and had it moving freely, but if it stuck again, could it cause the low pressure?
I was running 10w40 with a bottle of ZDDP, and ZPaste on the cam.

 

[jpwalt1987]

The oil galley plugs behind the cam could have blown out. Unless they are NPT plugs of course.

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[turboclam]

I'd pull the cam sensor and try the drill again.

 

[750H.P.V6]

The oil galley plugs behind the cam could have blown out. Unless they are NPT plugs of course.

I was kinda thinking the same thing myself. Another thing you might want to look at is the pick up tube to make sure it's still in place. On a similar tangent, I heard of one instance where the bolts were overtorqued and the gasket split then the oil pump started sucking air.

Neal

 

[ek02]

X2. if your oil pressure cold when spinning the pump with a drill is lower than when you primed the pump the first time, you may have a loose oil pickup tube and it's sucking air, or like jpwalt87 said, oil gallery plug came out. The oil pressure relief valve is easy to check. Pull the plug and the valve should come out easily with the spring. Try another oil filter too, and cut open the old filter to see if it is plugged or has a lot of metal in it. If you have an oil cooler, could it be plugged from a previous failure? I hope it is an easy fix.

 

[gunslinger]

I doubt it's the oil galley plug. They're the originals, and they're still staked in.
When I get back the shop today, I'll check the oil pressure cold. If it's low, I'll pull the pan the check the pickup tube & gasket. If that's good, the pump comes back apart next, and if that checks out, the engine will have to come back out.

 

[Chuck Leeper]

Pump been "ported"? If so, CAREFULLY check the gasket coverage on the pump cover....
I made the mistake of buying a ported cover...Had the same fatal results. Ports were cut out so far that the pressure eventually ruptured the gasket. Initial psi was good. Made the break in OK. Got stranded on the way to a race....
Of course, the "pro" that did the pump, claimed he put it on his "personal GN", and drove it forever...

 

[gunslinger]

Just got to the shop & started it. 70psi again.
Turbo isn't spinning & is stiff to turn now.
So this seems to be a hot oiling problem.
The cover hasn't been touched. It's as it came from TA.

 

[gunslinger]

Put a different gauge on it. 80psi at 1500rpm, 65-70 idle but the needle flutters. I'm thinking the bypass valve is bouncing.
I backed it out of the shop to make some room for customers, and just for the hell of it, I tried to build boost, and the turbo started to spool, and is easy to spin again....WTF??

 

[Pronto]

Did you have a chance for it to get warm to see idle pressure? Maybe the turbo heated up when pressure went to 0? Does it spin freely when he engine is off?

 

[gunslinger]

Did you have a chance for it to get warm to see idle pressure? Maybe the turbo heated up when pressure went to 0? Does it spin freely when he engine is off?

The turbo stopped spinning while I was breaking in the cam. The lowest pressure I saw was 15psi. I started it again to check flow to the turbo and the pressure gauge read zero, but I had a nice stream of oil to the turbo. I thought it may have gotten hot, but when it was cold this morning, it still was hard to turn. Now it spins freely.
I'll let it warm up later today, and see what pressure does.

 

[Pronto]

Hope the bypass wasn't open and sent break in crud though it...

 

[gunslinger]

I just let the car warm up again. At idle I'm getting 15psi hot in gear. 2k rpm it's 50-60psi, but I'm still getting a 10psi flutter in the gauge at 2k rpm. The turbo still doesn't spin at idle, and is stiff to turn, but it will build boost. Weird. I'm guessing it needs a rebuild.

 

[TRICKSIXPA]

Did you dump the oil from the 15min break in period?? I would not let it sit in there!

 

[Pronto]

It's odd that the pressure gauge read 0 but you still had oil going to the turbo. They both come from the same fitting.

 

[gunslinger]

It's odd that the pressure gauge read 0 but you still had oil going to the turbo. They both come from the same fitting.

Different gauge. The first one was a 600 psi gauge. 15psi looks pretty low. I've got a 100psi gauge on it now.
Shit happens. I'm not having a good week. The alternator on my Altima died on the way to work today too.
If it's got tits or tires, it's nothing but trouble.

 

[Pronto]

Al's alternator on his T crapped out last weekend. Spring? Sucks so far.

 

[ek02]

Sure acts like a loose pickup tube sucking air sometimes. Worn out cam sensor gears or a really loose timing chain will cause a slight flutter in a mechanical oil pressure gauge, but since you just put it together, I doubt that is the cause. I would drop the pan before I pulled the pump off, since you need to change the oil anyway. You can also see if there is anything bad sitting in the pan.

 

[v6turbo87]

Just to clarify, the bypass has nothing to do with actual engine oil pressure. It's only purpose is to open at the pressure set by the spring and bypass the oil filter so it does not rupture it on cold start up or at high pump rpms.

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[earlbrown]

There are 4 bypasses in the oil circuit not just one. The one under the 1"nut with the long spring sets the max pressure the engine sees. There's also on in the oil filter adapter that keeps full pressure from collapsing the filter media. The filter itself also has a bypass for the same reason. And the 4th is in the sammich adapter to keep full oil flow out of the oil cooler.


A few month ago there was a huge thread where a member had the same 'sticky' turbo problem you're describing. His solution was a rebuild.


It sounds like you have a pre-pump air leak that doesn't manifest itself until the engine gets spinning good and can hemorrhage enough oil. Common places to check are the pickup for a crack, the pickup flange for warpage, and the pickup gasket. A less common problem is a crack in the block's oil passage from the pickup to the front of the block.

Another one that can be attributed to installer error is the timing cover gasket. The inlet hole on the cover is odd shaped and if the gasket isn't located correctly it can leave a very thin strip of gasket around the inlet hole on the cover. You might be pulling air from there when the pump pulls a depression in that area. Just for kicks look in that area and see if it's oily.