No oil on startup

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Oct 30, 2009 | 01:38 PM

mb87

Thread Starter

Intermediate

Joined: Jul 2005

Posts: 25

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From: Floyd VA

No oil on startup

I have an 87 L98 that was professionally rebuilt 5 months ago. I have 3000 miles on it and I have trouble with oil leaks at rear of engine and when car sits overnight, on start up it has no oil psi with valve noise until psi builds up, which only take a couple seconds until its up to mid 50's. I changed the oil this past weekend and found the oil adapter was cracked to the point that the cooler/filter was close to falling off. I replaced that and re-installed the cooler and PF454 oil filter, which I understand has an anti-drain back valve. Still no change. Engine still dry starts when it sits overnight and is leaking into the flywheel cover, transmission pan, etc. The intake manifold was installed by the engine builder, I installed the sending unit and switch. If either of these leaked, would this cause the engine oil to drain down over night?

Oct 30, 2009 | 04:50 PM

0Paul Ruggeri

Former Vendor

Joined: Nov 2006

Posts: 2,482

Likes: 3

From: Carmichael ca

Take the car back, something is wrong if there's no oil pressure and the lifters are clattering on start up.

Oct 30, 2009 | 05:00 PM

Pete K

Race Director

Joined: Feb 2004

Posts: 12,518

Likes: 19

If is has been happening since it was first assembled, ask the machinest if he installed the 1/2 inch cap plug under the rear main bearing cap.
If you wish to check for yourself to see if he did, let me know, and I will explain how to do it. It involves disassembling the oil pressure sending unit, and sticking a piece of threaded rod down the hole.

Oct 30, 2009 | 06:16 PM

redrose

Melting Slicks

Joined: Feb 2006

Posts: 2,753

Likes: 15

From: backwoods upstate ny

Quote:

Originally Posted by mb87

most engines 'drain down' in a very short after shutdown...'wet sump' engines rely on 'good' drain down to keep the oil pump 'pumpin'...lt1 owner manual that comes in glove box notes that lifter noise on start-up is normal for a few seconds...my guess (need tons more info for point of pin) is that you have 'anti pump up lifters' (most cam vendors push these) which are really 'controlled' high rate leakdown, and you're too observant (aka, like me, ****)

disconnect your 'ninth injector' ( cold start injector, 85-88 only) to delay start up a bit and give the oil pressure time to build...or, as we do with race motors, always 'crank for oil pressure' before flipping on the switch for ignition (you will need to add an 'interrupt' switch to your vette to do this)...'instant start' is a great marketing ploy but worst thing by far for engine wear.

oil leak at engine rear or front is often caused by assembly too soon after application of 'RTV' at ends (always allow 10-20 minutes for RTV to take initial cure, varies with temp and HUMIDITY, before 'setting manifold), some just not torqued properly (many otherwise good mechanics scorn using a torque wrench for manifold bolts)

Last edited by redrose; Oct 30, 2009 at 09:39 PM.

Oct 30, 2009 | 07:22 PM

383vett

Race Director

Joined: Apr 2003

Posts: 17,700

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From: moraga ca

It's not unusual for a motor to take a couple of seconds for oil pressure to build up after an evening. Any more than that is not normal. Are you sure you aren't hearing piston slap on startup?