How do I fix carburetor / exhaust system on top of engine?

[Maldoror]

Short story: recently got a part fixed in my RV, and it seems they didn't put back my engine and carburetor back together properly. I've tried my best to figure it out, but don't have enough mechanical knowledge to figure out the parts and what I need to do to get it back to its original form.

Long story: I have a GMC Vandura 3500 Elite, and I am not completely mechanically inclined, but I did have some people explain to me what's going on here. It seems that the carburetor distributes air. There is a kind of pancake air compressor or exhaust control on top of the engine or carburetor. When I got the engine back, it didn't seem to be sealed properly. When I drove my RV, kind of like a hi-hat cymbal, if I put too much pressure on the gas, it would open up the pancake part on the top, and it would pop or make a bang like popcorn. I eventually tried to seal it with tape, and then I ended up using a part to do so. The other problem is there were these hoses that almost look like tin foil that were ripped apart, and it uses a lot of fuel and smells like gas when I drive. I tried to buy some of the 'hoses' and refit them on, but they're incredibly sensitive and they break.

In any case, I'd like to figure out how this engine and parts above the carburetor work, and how I can put it back together how I got it, so it can drive functionally, and so I don't have to use mickey mouse parts to shut the exhaust system or pancake looking part on top. I've included pictures of what's going on for reference.

Thank-you for reading!














EDIT: Resized the images for you.

[MitchF150]

Grit dog wrote:
And be more descriptive. What was wrong before…what “part” got fixed…’cause I don’t see any new parts around the carb or ignition.
And what’s up with the booger green spray paint on the brake rotor dust shields?
That’s “custom” too.

I had to go back and look at that again! So many "Custom" things on that deal I can't imagine any shop would send that out the door after charging for 'fixing it'??

Had to be done by a prior "DIY Guy" and you bought the rig that way?

Good luck OP with it! Mitch

[ScottG]

Even if everything is 100%, with a carb you are going to smell fuel at times. Ethanol blended fuels exacerbate the problem and you will have never ending problems with driveability, idle, etc, running that junk with a carb in a MH.

[opnspaces]

Unfortunately you are in over your head on this one. I would try to find somebody with a bit of knowledge to help you out and get it running correctly.

As Grit dog said the pancake thing is your air cleaner. It should be held down by a center wing nut which I see in your first picture. If that nut is tight the cover should not be lifting.

The foil tube you can pretty much ignore. It is only there for emissions when the engine is first started to make it run a little better. After the engine is warm the foil tube does nothing. Plus the top end of the tube that it is supposed to hook to looks like it isn't set up correctly.

If you're interested though, the foil tube is a heat stove tube to bring warm air up to the air cleaner when the engine is cold. The bottom of the foil tube should connect to the heat shield off the exhaust manifold. So basically the bottom of the foil tube should slide over a round piece of thin steel to bring heated air up to the top of the engine. The top end of that foil tube should go to the air cleaner housing.

In your last picture there is a round can with a red wire laying on top of it. The top end of the foil tube goes to the bottom side of that round can. It goes underneath the can, not on the open side that we can see in the picture. That open side just stays open so the engine can get some air. But you are hooked up wrong. The foil tube is on one side of the engine and the air cleaner opening is on the other side of the engine. So either loosen the center wing nut and rotate the air cleaner until the part with the small round can is over the foil thingy. Or move the foil thingy to the other side of the engine.

[ScottG]

It's missing the carburetor stud that secures the air cleaner. A universal part can be purchased at any auto parts store or you can just get some 1/4" all-thread from a hardware store and cut it to length. Top it with a 1/4" wing nut.
This will work unless the threads inside the carb are stripped.

[MDKMDK]

Agree with Tyler and sadie. Get it to a repair shop (or GM dealer) before you do irreparable damage.

[Grit_dog]

And be more descriptive. What was wrong before…what “part” got fixed…’cause I don’t see any new parts around the carb or ignition.
And what’s up with the booger green spray paint on the brake rotor dust shields?
That’s “custom” too.

[Grit_dog]

Oh and smelling like gas and leaking gas could be 2 different things. Either way yes figure that out before some wrecker is picking up the charred remains off the side of the road on your dime.

[Grit_dog]

Looks like some “custom” work there….
The pancake thingy is just the air cleaner lid. It’s held down by, well you know.
The “foil” is also custom, lol.
The popping is backfiring. Tape ain’t gonna help that….
Backfiring can be caused by several different things. But focus on what changed since before , assuming it wasn’t backfiring then.
Potential causes:
Poor vacuum or cracked broken disconnected vacuum lines (any of them).
Carb out of adjustment/accelerator pump worn out.
Mis adjusted timing.
Worn distributor components.
Firing order or spark plug wires out of order.
PS you’d maybe have better luck asking about a Chevy small block on a site that’s more engine related than this one. Your issues have nothing to do with the fact that it’s a RV.
Good luck.

[Tyler0215]

Take it to another shop before you start a fire or hurt yourself. You are in over your head.

[midnightsadie]

#1 you should have never touched it. I,d have taken it back the same day. now that you,ve moved things around ,its on you.