Oil Return Restriction?
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Cargo Master
Joined: Jun 2001
Posts: 2,571
Likes: 22
From: Oxford, Indiana
Oil Return Restriction?
I've got a 30K original mile 302 that has been sitting around the shop for a couple of years. I recently sold it to a buddy for his project. He wanted to install an RV-style cam before we put it in. After the cam swap, we poured five quarts of oil in over the valve train as I've always done before we put the valve covers on. I noticed that the left rear oil return through the head is draining very slow. You can look down it all the way through the block and there is no obstruction or buildup. I'm just curious if it drains past or through the cam bearings and there is a possibility that the thick break-in lube we used for the cam might be slowing it down. Anybody know for sure? I'd hate to dump this thing back in with trouble brewing!
Batman
Batman
Laughing Gas
Joined: Nov 2002
Posts: 1,198
Likes: 9
From: Fairmont
Oil Return Restriction?
Seem if I remember right the drain hole just dumps down into the lifter valley. I know some older engines the valve seals will break up and find there way into the drain back hole, but you said you could see all the way to the block, correct?
Thread Starter
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Cargo Master
Joined: Jun 2001
Posts: 2,571
Likes: 22
From: Oxford, Indiana
Oil Return Restriction?
Yep, sure can. It doesn't drain into the lifter galley. The return down throught the block is a passage that is actually cast into the block - the casting protrudes out the backside into the bellhousing area and ends around the rear cam plug. That's why I'm wondering if it's got anything to do with our cam lube. I can see all the way down through the passage to the point where it heads north into the innards of the block.
Batman
Batman
Laughing Gas
Joined: Nov 2002
Posts: 1,198
Likes: 9
From: Fairmont
Oil Return Restriction?
I checked out a customer block we have here. The oil drain from the head does go into a seperate drain in the block. The drain dumps out in the crankcase area. From what I see here, the restriction is somthing in the block part of the drain, or is it possible the head gasket is somehow restricting the drain.
