Manifold Clean-Up

This afternoon I spent some time cleaning up the intake and exhaust manifolds to prepare them for paint.
I started with the washers and engine-lifting bracket, which I sprayed with Simple Green and scrubbed with a Scotch-Brite pad.

After a fair amount of scrubbing they came pretty clean and revealed the original paint underneath the grease and dirt.

I used some Metal Prep to treat the raw metal, applying it also with a Scotch-Brite pad. The Metal Prep removes light rust chemically but also leaves a protective coating on raw steel to fend off new rust.

Next I turned my attention to the manifolds. I removed the hot spot gasket from the exhaust manifold. It’s thin and impregnated with metal.

I used a drywall knife to pry off the carburetor insulator from the intake manifold without too much trouble.

Here is a look at the thickness of the insulator.

I sprayed and scrubbed the exhaust manifold.

And I sprayed on scrubbed the intake manifold.

Then I turned my attention back to the manifold mounting washers and engine-lifting bracket, which had dried nicely in the sun. I sprayed on a coat of Rustoleum Clean Metal Primer.

After they dried, I slipped them over to prime the other side.

The exhaust manifold is cast iron, and it had more surface rust than the steel parts. I used a wire brush in my drill to remove some of the pitting.

Before…and after.

Here is the wire brushed outside of the exhaust manifold.

And the before and after of the inside of the exhaust manifold.

I applied some Metal Prep to the exhaust manifold.

And I also applied some Metal Prep to the intake manifold.

Intake/Exhaust Manifold Removal

I spent most of today removing the intake and exhaust manifolds from the engine.

Here is a shot of the intake manifold as it sits on top of the exhaust manifold. The light blue shop towels are still in place from when I removed the carburetor and stuffed them into the intake.

As shown below, the manifolds attach to the head by a combination of six bolts and washers. In the first picture, on the end toward the firewall is the bracket one can use to lift the engine out of the engine bay.

I used some PB Blaster and a 1/2″ socket to loosen the bolts.

I removed all of the bolts. The second left-most mounting point was actually a stud.

I removed the 1/2″ nut and the washer from that stud.

Then I did the same from the right-most stud, which also mounts the engine lift bracket.

Here are a couple of shots of the engine lift bracket.

I used a ratcheting wrench to loosen the inside bolts because there was no clearance to get a socket into the space.

And did the same on the other side.

The top of the manifold came loose from the engine, but the bottom was still mounted to the exhaust below. The truck came without a full exhaust system. After a brief downpipe with a resonator the exhaust terminates under the truck and never makes it to the back bumper. At first I tried to loosen the bracket that clamped the exhaust manifold to that short pipe, to no avail. So, with nothing worth saving south of the manifold, I took more drastic measures.

The exhaust pipe didn’t put up much of a fight.

So with the manifold liberated from the exhaust pipe below, I was able to extract the intake/exhaust manifold successfully.

Then I pulled that short length of exhaust pipe from the exhaust manifold.

Here are some pics of the combined manifold, still assembled.

These two pictures show the four nuts that connect the intake manifold (upper) to the exhaust manifold (lower).

This is a look down into the two intake ports below the carburetor. There is an insulator and gasket that sits on those four bolts between the manifold and carb.

Here are a couple of shots of the engine on the driver’s side. Now with the manifolds and carburetor/air cleaner stripped away it looks pretty bare.

Next I separated the intake manifold from the exhaust manifold. I used a 7/16″ box-end wrench to loosen the nuts from the four studs at the corners of the intake.

After breaking them loose I was able to turn all four off with my fingers.

With those four nuts and washers removed, I was able to pull the intake manifold up and off the exhaust manifold.

The underside of the intake manifold that mates to the exhaust manifold has a cool, accordion shape. In the picture below is is caked in black carbon from combustion. Also between the two manifolds is a hot spot gasket that thermally separates the hot exhaust manifold from the cooler intake manifold above.

Here is the free intake manifold. It appears to have originally been painted Datsun blue like the engine.


I decided to take some pics of the interior as it stands now. I don’t have big plans to do anything to the interior until the truck is running (and stopping!), but thought it would be worthwhile to document how everything looks for posterity.

Steering wheel and gas/brake/clutch pedals.

Here are a couple of the heater box under center of the dash.

And here’s one of the driver’s side under the dash.