Oil leak

[gbnbrb123]

My son has a 76 k20 chevy 350. We purchased the vehicle and the individual we bought it from stated it had a rear main seal leak, well we replaced that and there appears to be no oil leaking from that spot. However, the leak appears to be mostly coming from the driver's side just above the oil filter on the uppermost bolt in the picture below. When it is cold it doesn't leak, but once it gets warm it starts to drip out pretty quickly. I would assume there would be a seal there but not sure what the name of the gasket would be called. Plus looks like a bunch of stuff in the way to replace it and possibly having to move the transmission backwards, the other side has the starter and exhaust in the way and appears to be a much smaller leak from that side. It is pretty much above the flexplate, any help would be appreciated, thanks. Nick

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[Memaloose]

I can't see very well but put a mirror on the back end of the intake manifold and check that out. It may be running down. If you can, spray the area off with brakekleen and blow it real clean with compressed air, it will give you a better idea from where it's coming from.

 

[gbnbrb123]

I was kind of thinking intake manifold but it appears that either the previous owner or the one prior put a new intake manifold gasket on it, not sure how long ago, because you can see the red high temp silicone all around. It really looks like it is coming from the upper bolt in that last pic, the problem is when your underneath it when it is hot the oil is dripping down on the headers and yourself, which leads to burns, lol. We will try the mirror method tomorrow and see what we can figure out. Thanks

 

[PrairieDrifter]

The only places that can leak oil are the rear main, there's three oil gallery plugs back there as well that requires removal of the trans, those typically don't leak, more like rusted in. Could be a distributor gasket too.

I guarantee it's one of these three
-Valve covers
-intake
-oil pressure sending unit

Edit- there's a soft plug for the cam on the rear of the block as well, inside the bell housing.

 

[gbnbrb123]

Well unfortunately, we believe it is coming from the driver's side head. Definitely not from the distributor or valve cover gasket, but pretty sure it isn't coming from the intake manifold to.

 

[PrairieDrifter]

Well unfortunately, we believe it is coming from the driver's side head. Definitely not from the distributor or valve cover gasket, but pretty sure it isn't coming from the intake manifold to.

Don't think it's possible to come from the head. Only head bolts, or intake bolts. I'm fuzzy right now, but im pretty sure the lower bolts on the outside of the head go into the coolant passages. The other head bolts are under the valve covers...

So either the options in my last comment or the head is split in two lol...

If it's coming from that high up it's one of the three, don't forget about the grommets for the pcv and oil fill cap. I'd bet it's valve covers.

 

[DrPrepper]

Oil pressure fitting/sending unit...line?

 

[gbnbrb123]

We got new intake manifold and valve cover gaskets, got all the bolts taken out, only thing left to do is pull the manifold off and the valve cover, it was getting late so we stopped at that point. This truck doesn't appear to have an oil pressure fitting, I looked at some videos online at it's location near the distributor, which we have removed and there is nothing back behind the motor with the exception of what looks to be a brake line fitting going from the motor to the brake booster. Will let you all know how everything turns out but from what we can now see behind the motor the leak appears to be from the manifold and not the valve cover. Suppose to rain here tomorrow in VA, so we will see what we can get done.

 

[Rusty Nail]

Nah nah nah..

Remove the oil filter baseplate too while you've got it in pieces. Adding that one more gasket or O ring won't break the bank and it's good insurance.

Doesn't leak until it gets warm? Bypass.
Reseal filter housing.
If the intake manifold has orange stuff around the entire perimeter - it requires correct installation which includes actual gaskets. Silicone is only used for the end seals.
AND!
I reckon there are TWO holes for pressure between the intake and the pan..
You find a bolt with the correct thread and length, seal it in there. Plug it up since you arent using it. I assume aftermarket parts store electric powered oil gage, right? Requires 12 volts?
Yes, need to look at the original factory mechanical gage that fed from a tube that " looks like a brake line next to the brake booster" ? That's the OE oil pressure line and right near the root of your trouble I imagine.
Follow that down until you find the leak.

You'll findThe other end is behind the gage cluster in the dash. The oil is definately NOT leaking out of the cylinder head - you can breathe easy.

A better option may be to repair the correct setup and gage?

This thread needs pictures.
Welcome to the internet.

 

[gbnbrb123]

Here are your pics, lol. Not sure what you mean by bypass when leaks when warm and yes it has red stuff all around plus the edelbrock gasket which will be replaced with felpro permadry. You are correct in that the oe oil pressure line is near the root of my problem but I don't think is the culprit. Just took the pics about 10 minutes ago in the dark, tomorrow will clean around the back of it a little better since the brake cleaner seems to have taken some of the paint off things back there.

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[Rusty Nail]

Great block. Keep that one forever.

Bro. Oil comes out of THIS hole..it IS the feed to the factory, mechanical , oil gage.

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If you're not gonna repair the gage, you MUST remove that brass fitting and find a way to fill the hole.
A bolt or a plug.
You must.

The oil "bypass valve" (in the block above the filter) bypasses the filter when the engine is cold - that's why. Requires a certain amount of PRESSURE to open the valve.

Deep breath man, this is neither hard nor expensive but it could be a fun learning experience between dad and son.

See how great the pix are?
Don't strip it. Lefty Loosey.
The Rear main seal likely was leaking,probably still is, but it wasnt the problem..we'll get over it. They all leak.

 

[Rusty Nail]

 

[gbnbrb123]

Dude your hilarious, I have an 85 that I have done extensive offroad suspension/gear/body work to, so i do know my way around the truck in regards to suspension. I didn't say anything was hard, just hard climbing into a pickup truck that has way too big of a tire, being short doesn't help. Yes my plan is to put the fitting back in the hole, lol, why would I not put it back. I haven't really done motor work on a chevy, with the exception of the rear main seal which is just time consuming when working with old gaskets.

I bet you never heard of anyone using tacoma leaf springs for the rear of a chevy, allpro expedition leaf springs are perfect, modified bushings and shackle flip has about 6-7" of lift but flexy enough to make 33" tires hit fenders in the rear, then off-road design custom leaf springs for front, ford front shock mounts, lockers, and it goes about anywhere you point it with swampers.

 

[SquareRoot]

Holy Jesus! Get rid of the red silicon spaghetti mess and those horrible Edelbrock intake gaskets.

 

[SquareRoot]

I have had those fiber gaskets de-laminate and cause oil to get sucked into the runner. Swapped to the Fel-pro O-Ring style and never looked back.