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Valve Cover Gasket Visible

Daysanator

Daysanator

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Hey, I had a pretty significant (steady stream) leak on the rear of my ‘86 SBC 350. Well, I go for the low hanging fruit. Changed the oil sending unit and valve covers with the best gaskets I could find. I went from a stream to a quart of oil right now on the driveway directly after that. It’s hard for me to see and I can’t find my snake camera. There’s oil everywhere starting high. Anyway, should I be able to see the valve cover gasket from underneath? Maybe I don’t have an ‘86 and got the wrong part?

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Have you checked to see how flat your valve covers are,
remove them and wipe them down real good, lay them down on a true flat surface to see how flat they are.
no matter what brand valve cover gasket you use, if the cover isn't flat It will leak..
also are you using spreader bars to help distribute the downward tension from the bolt holding them down
 
Yeah, these were a lot flatter and true than I expected from an after market cover. They were very thick material so I’m glad I didn’t have to mess with them out of the box. I did use the spreader bars that came with the gasket. Everything seemed to fit up and it doesn’t appear that the oil is coming from there. It seems to be the distributor/rear intake manifold area. I can’t confirm that yet though.
 
I've had gaskets under the dizzy leak before
Also was there any changes to the oil pressure/sending unit. Those are notorious for leaking
If you can wipe everything down with a rag ie side of valve covers as well as behind the block.
Oil leak from there can be from either the inrake gasket (rear valley) dizzy.
If if was in the other side I would blame the oil sending unit.
But from your pic of rhe valve cover I still say the valve cover itself is warped around were the mounting bolt is
 
I appreciate the responses. I’ve never claimed to a be an auto mechanic but I’ll do whatever it takes to get this thing into leak-free road worthy condition.

Even though the exposed gasket seems “obvious” there’s no fresh oil coming from there. I fired it up again and it’s like it’s directly on top of the transfer case. It pours out on both sides and everything is oil wet. Frustrating. I’ll upgrade and change whatever it takes.... I just haven’t figured out what it takes....

I’ll have some time to dig deeper tomorrow. My dad is the mechanic and Chevy expert but his back is terrible so I hate asking him questions because he always Says “let me take a look”. Farming has destroyed him enough for me to ask about a weekend toy.
 
It does look like the back side is not completely flat, might have a wire or something caught. Also make sure the side of the gasket with the 4 hole is on the intake side of the head.
 
if you find your snake cam look at the back of the intake to block gasket/silicon. You may need an extra gasket under the distributor.
 
Haha, no I don’t think I’d make it very far. This thing isn’t leaving the driveway until it’s leak free and all the wires are put where they need to be. Hopefully tonight I can work on tracing down my leak. It should be obvious with my camera. Mosquitoes about carried me away last night and the PTO on my mower decided it didn’t want to be in a relationship with the engine anymore. So, it fell off and broke. It’s always something, I swear.
 
Daysanator said:
Haha, no I don’t think I’d make it very far. This thing isn’t leaving the driveway until it’s leak free and all the wires are put where they need to be. Hopefully tonight I can work on tracing down my leak. It should be obvious with my camera. Mosquitoes about carried me away last night and the PTO on my mower decided it didn’t want to be in a relationship with the engine anymore. So, it fell off and broke. It’s always something, I swear.
Click to expand...

a leak in the distributor shaft gasket or the back of the intake can make oil come out like that. I’ve had both. Valve cover leaks usually run down the sides of the motor.
 
Whelp... I took the distributor off. Just to change the gasket and get a better look overall. So here’s order of operations.
Small Leak:
Change Valves covers w/ gaskets

Leak goes to massive leak:
Pull sending unit. Sending unit has JB Weld all over it. Take out the offset fittings because they aren’t needed and re insert sending unit.

Major leak continues:
remove distributor and sending unit. The block is blown out on the back side of threads.

My guess:
block was cracked at sending unit threads. Guy put JB weld on the sending unit for a typical fix (why?! They are $12). Didn’t work. Found the cracked block. Used offset fittings because they go deeper into the block beyond the crack. I bumped it with the valve covers and turned the crack into a break.

I’m going to get a new offset piping kit since this one was bent (maybe causing the crack). Thread it until bottomed out with my monster tape/dope. JB Weld the broken block section. Cross fingers. Thoughts?

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not sure I got all that, You are saying the threaded part of the block where the oil sender screws in is cracked ? if so that sucks. I guess it would depend on how deep the crack is if tape or liquid Teflon would work. I would have thought the sender would crack b4 the block.
 
I think it was cracked when it was a small seeping leak. Now the block has busted out about ¼” of threads or so and made a gushing leak. I’m going to try everything I can before I throw in the towel on this block. We’ll see how it goes.
 
You can try and tap it deeper, 1/8" pipe thread. Put grease in the flutes of the tap to collect metal chips from taping. Clean and regrease often.
 
Wes Harden said:
You can try and tap it deeper, 1/8" pipe thread. Put grease in the flutes of the tap to collect metal chips from taping. Clean and regrease often.
Click to expand...

Good info. I might try get a few more threads out of it then. I hate tearing things apart more than once....
 
I've seen a few small blocks that had that happen,probably caused by the sending unit snagging on the firewall during removal ,or hitting it due to a busted motor mount..

Maybe you could drill & tap the sender's port to 1/2" x20 and use one of these piggy back style oil drain plugs in the block,that has a 1/8" NPT thread for the plug..you'd need a flat sealing surface under the plug though for it to seal up good (or maybe locktite would seal the threads well enough,and prevent it from loosening if you ever need to replace the sending unit..oil drain plug piggyback.jpg

One SBC engine we sold a guy at the junkyard got the sending unit whacked and it took a chip out of the block casting and it leaked..
The customer drilled the port out and tapped it for a 1/4" NPT pipe plug and then brazed it in, after it still weeped there,it had a hairline crack,and he used another 1/8" npt port above the timing cover the engine had to hook up his oil pressure gauge to..
 
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