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For the last couple months my 76 has started to leak oil. Only a few drips at first, but it has slowly evolved to the point of needing to add a quart after only an hour and a half of driving. Before I go broke buying oil and getting kicked out of my apartment for stains in their parking garage I decided to do something about it.
Investigating the engine bay I’ve narrowed it down to either the intake manifold China wall or the timing chain cover. My money is on the China wall because I spent extra time making sure to not warp the timing chain cover and using a good quality gasket and sealant.
When I previously installed the intake manifold I didn’t use the China wall gaskets because I’ve heard nothing but bad things about them. Instead I used a small bead of silicone slightly manipulated to look like a weld bead. I’m guessing the issue was not letting it sit long enough before starting the engine. I thought a couple hours would be good enough, but this time I’m taking no chances and letting it sit for at least a day.
So now I’m here waiting for my NAPA order of the gaskets to be ready to pick up. Since my apartment doesn’t allow me to work on my car at my apartment I’ll be driving it to my parents house and working on it there. Only issue is I won’t have a car there to get back to the apartment since I want the Vette to sit. My girlfriend offered to pick me up, and she gets off work at 3. So in the next 5 hours I have to:
Get my gaskets
Grab my tools and everything else
Drive to my parents house
Reseal the fittings on my Quick-Jack
Drain the coolant
Drain the oil
Remove the Carb
Remove the intake
Strip the old paint and give it a fresh coat of aluminum Hi-temp paint
Little bit of porting if I have time
Clean the sealing Surfaces
Put down a GOOD bead of silicone
Torque to 25 ft lbs in sequence
Reattaching everything else can be done another day, but I’d like to get this all done and have it driving again for this weekend.
If you're using a quart in an hour and a half, I'm thinking it should be obvious where it's leaking.
I don't use the china wall gaskets either. Make sure you use a good quality RTV designed for exposure to oil, and make sure you use a generous bead on a clean surface. It should be about 3/8" thick before you drop the manifold.
Good luck.
If you're using a quart in an hour and a half, I'm thinking it should be obvious where it's leaking.
I don't use the china wall gaskets either. Make sure you use a good quality RTV designed for exposure to oil, and make sure you use a generous bead on a clean surface. It should be about 3/8" thick before you drop the manifold.
Good luck.
Will do, I got a brand new tube of Permatex Ultra Black, not the 90 minute kind.
It’s hard to tell where the oil is coming from, only because there’s so much of it! Once it’s all sealed back together I’ll be doing a full engine bay detail.
Got the manifold off and sitting covered in paint stripper, I’m not sure if I want to repaint it or just leave it raw aluminum.
Everything has gone fairly smoothly so far. I’d hope so considering this is the third time I’m taken the intake off in the last year.
As arrived
Everything disconnected from the carb
Goodbye Quadrajet
Cap removed and rotor pointed near the #1 tower. An offset 9/16” wrench is very helpful for removing the distributor.
Everything unplugged and ready to pull.
Oops, forgot the coolant temp sensor. Now she’s ready to pull.
Inside the lifter valley everything looks good. You can see the previous silicone on the China wall all smudged though. The black I used when I installed the manifold, and the gray when I tried and failed to reseal it from the outside.
I saw a thread recently talking about if the bolts on the intake go into the water jacket on the four corners of the manifold. I can confirm they do not. They’re blind.
It’s a nice shade of old VHT paint and stripper mixing together.
Cleaned up with a razor blade, scotchbrite pad, and brake cleaner. Any advice on cleaning out the holes?
Last edited by Piersonpie; Mar 17, 2026 at 10:57 AM.
Since you are using RTV i would not worry too much about cleaning the holes out. you could just run a drill bit in them with your fingers if you want. seems like an awful lot of oil to be losing from the china wall and like stated above that much should be easily to track down.
Pat
Piersonpie
Not sure where you're at now but if you're still going to the store pickup some RIGHT STUFF 1-minute gasket maker..... It is about fantastic. Works fast but I still let things sit anyway..... BUT if you were in a real hurry you wouldn't have to wait much.
It has worked fantastically (sp?) anytime I've had to use it. Well worth the expense.
Piersonpie
Not sure where you're at now but if you're still going to the store pickup some RIGHT STUFF 1-minute gasket maker..... It is about fantastic. Works fast but I still let things sit anyway..... BUT if you were in a real hurry you wouldn't have to wait much.
It has worked fantastically (sp?) anytime I've had to use it. Well worth the expense.
Looking at their offerings as I’m typing this. Not seeing it on the shelf sadly. I’ll keep that in mind though if/when I have to do this again lol
Getting the gaskets took longer than anticipated. It always goes this way when working on cars, something happens.
Fel-Pro 1204 intake manifold gasket with heat riser block off. My thermostat hosing gasket was probably fine to reuse, but for $4 I got a new one.
Busted out the power washer in the 40 degree weather to clean off the intake and hardware. Only splashed myself a little bit. Next comes drying it off and prepping for paint.
Last edited by Piersonpie; Mar 17, 2026 at 10:58 AM.
Looking at their offerings as I’m typing this. Not seeing it on the shelf sadly. I’ll keep that in mind though if/when I have to do this again lol
If you use Permatex The Right Stuff, there won't be "another time redo".
I think you are getting in a hurry and not allowing products to do their job.
Some Intake gasket sealants should sit overnite such as Edelbrock Gastenich. And any RT for the water-ports.
However, The Right Stuff has a short working time and that will be the last thing applied to the china walls.
Eye-ball the bolt holes and "just set" the Intake. Install all bolts with thread sealant, but just snug. Again, slow down and torque them later to specs.
FYI: The Right Stuff is Permatex Black. But not in a squeeze tube but rather an applicator that lays down the perfect bead, like welding.
It comes in several different ounce package.
Last edited by HeadsU.P.; Mar 8, 2024 at 06:51 PM.
The above statement is actually incorrect. "The Right Stuff" is actually also available in a squeeze tube as well. And is a different product then "Ultra Black" And also different from just black silicone.
I like to glue my Intake gaskets to the head to make certain perfect port match is achieved.
I use 3bond 1104 , just a very thin smear around all the intake ports on the head. And the waterpump type silicone around the water ports. set the manifold in place. Let it sit over night. Next day, lift manifold and make certain gaskets are exactly where I want them. then a thin smear of 1104 around the manifold side of the intake ports, proper coolant resistant silicone around the water ports. Then The Right Stuff on the China walls. Set manifold carefully into position. Install all bolts finger tight.
Wait for the Right Stuff to set up. At least an hour. I usually give it a few hours. Then torque up the bolts and install distributor, carb, etc.
Take your time and you won't need to redo it.
FYI: The Right Stuff is Permatex Black. But not in a squeeze tube but rather an applicator that lays down the perfect bead, like welding.
It comes in several different ounce package.
Funny that you mention welding, my beads reminded me of one.
Intake painted and gaskets trimmed around the top so you don’t have a big piece of gasket visible on the cylinder head.
Installed and torqued to 25 ft/lbs.
Nice visible bead in the front
And rear
Thats where I’m leaving it for today. I’m not trying to rush anything, just trying to give the RTV as much time as possible to dry. The rest will go on later this weekend.
Last edited by Piersonpie; Mar 17, 2026 at 10:59 AM.
The correct method is let the silicone setup first. Then torque to spec. Yes, it does look like your going a bit fast.
Gasket trimmed along the top is no where near as important as perfectly centered on the ports.
This photo. Clearly shows silicone on the china walls. Intake gaskets not glued in place. Sealant around Intake ports? Correct sealant around coolant ports? Certain they didn't move?
these old engines don't have dowel pins to hold alignment like newer style engines. I do think your going way to fast.
Too late now, but if you really want that whole set-up to pop, toss the Ace Hardware ten cent bolts and splurge for a set of ARP Intake bolts. $28.
They come in stainless or black. Very sharp looking and are 12 point with built-in washer.
Ultra Black along with The Right Stuff are both made by Permatex.
Basically, one is an aerosol type applicator and has 10 X the density as Ultra Black.
Both have oil resistance and blow-out proof.
The big difference is the squeeze tubes need 24 hrs to cure.
The Right Stuff is ready in minutes and was invented for quick-turn-around in the automotive repair business according to Permatex.
Got a lot of little things back on. Brackets, thermostat housing, distributor.
Redid the braided loom on the upper radiator hose too. Doesn’t do anything, just looks neat.
Lifted the car with the Quick-Jack with the first time, very handy. I’ll definitely be using it again when I detail the undercarriage to get that leaked oil off of everything. The jack stand isn’t supporting anything, just there as insurance.
Got the oil drained and changed. Radiator is filled with coolant, only needs to be topped off after the car gets started.
That’s where it’s sitting for today. I’ll be doing things to the carb while it’s off, hopefully have it back on and running by the end of the day tomorrow.
As for the ultra black vs right stuff argument, everything I’ve seen on the internet says they can be used interchangeably. Only difference is the curing time, which at over 48 hours I should be fine with either. I used ultra black, let it sit for a day, and was leak free in the past. Only issues began when I pulled the intake again and resealed it without giving it time to cure.
Last edited by Piersonpie; Mar 17, 2026 at 11:00 AM.
Intake manifold leak fix
Before I go broke buying oil and getting kicked out of my apartment for stains in their parking garage I decided to do something about it.
