Dodge 360 idle problem

[907blizzard]

I have a 1976 dodge transvan with a 360 in it. I bought it last summer and have had alot of fun with it so far. Recently it started to idle rough and sputter and low rpms. It seems to run fine at higher rpms. It still cruises fine at 55. When driving at 25-30 it really struggles. Sorry I don't have a tach so I can't give exact rpms. I am thinking about taking apart the carburetor and rebuilding it.

Also the fuel gauge recently stopped working. Possible fuel pump failure? And I recently had to remove the muffler because it was rusting away and I didn't want it to fall off in the road. It ran fine for a while with it off so im not sure if this is related.

Aby

[Dunner]

Check for loose or cracked vacuum hoses. Do a tune up.

[Diplomat Don]

They were notorious for burning engine valves. Before you start spending a lot of money, pull the plugs and do a compression check. If you're handy, you can do it yourself for the price of a compression tester ($20.00)

If the compression is good, the next probable culprit is probably the need for a tune up consisting of spark plugs, plug wires, distributor cap and rotor. The carburetor should be last.

[907blizzard]

I have receipts from a legit mechanic shop that the plugs, wires, cap, and rotor were replaced. This was about 6000 miles ago. I can also tell this is true because they look alot cleaner that the rest of the engine. I have had experience using a compression test. I will try that. Hopefully I can find one for a good price.

[Diplomat Don]

907blizzard.....Good to hear it was recently tuned. The compression check is still a good thing to do. It will give you piece of mind that the engine is okay. You should be able to find a cheap tester at Harbor Freight. Buy one with a length of hose on it, its easier to manuever.

You can also fire the engine up in the dark and look at the spark plug wires, making sure none of them are arcing. Even theough they are new, if they were routed incorrectly, they could get burned if they touch the exhaust. Most new plug wires are pretty high quality with good heat protection, but it odesn't cost you anything to look.

If everything checks out, the carburetor would be the next step. Those were pretty easy to rebuild. You may have a hard time finding anyone who still rebuilds them.

[TQ60]

Dried out carb gasket leaning out

Spray wd 40 at bottom gasket while idle, if leaking it will change idle.

A cheap and common easy to fix problem

[TQ60]

Will need to replace gasket

[TQ60]

If your fuel pump was the issue it would be the opposite, no power on higher demand for fuel.

Now I can type more, not using phone...

number one rule, safety, so try to have a helper nearby for these steps, also have a portable fire extinguisher handy.

Remove the air cleaner from the top of the engine.

Examine the choke plate, figure out how it moves so you can manually control it, or you can just use your hands.

Start the engine and either by using the choke or cupping your hands on the top of the carb you can make it rich to counter a vacuum leak.

If this makes it run better then a leak exists.

Here are times for finding the leak.

WD40 is the safest to use, starting fluid can cause a fire, simple water in a spray bottle also works but some folks argue spraying water may cause damage, if in tiny amounts it gets burned up.

What you want to do is spray small amounts of your fluid of choice at places that can be leaking.

Regardless of what you use, when you spray it on the leak the engine will run differently, faster with starting fluid, maybe worse with water, you get the idea.

Start the engine, first pull out the vacuum line that goes to the vacuum booster(s), it will be mounted by the brake pedal or under the coach, it will be about 3/4 inch in diameter, when you pull it off the motor will likely die, cover the end with your thumb as fast as you can, if the engine runs better you have a bad booster, no change then return to normal and start spraying.

First place is the gasket under the carb, these are likely "Thermo-Quad" the gasket is thick to isolate the carb from the heat of the engine, over the years they dry out if the engine is not a daily driver.

Spray along the bottom of the carb, if any change at all then the gasket needs to be changed, you can carefully remove the bolts and lift the carb with everything in place and slide out the gasket.

make a trip to the store and get a replacement.

Carefully slide it back in and tighten the bolts, re-test.

Next up will be the hoses that go to the smog controls, they are scattered on the engine as well as a possible cruise control module.

If you are using water then just spray small pattern of water on everything that looks like a hose, when you find the leak determine what is wrong and fix it.

You may be best off replacing the carb gasket and all of the small vacuum lines, they are cheap.

[Diplomat Don]

TQ60....gave you some great info. I haven't worked on one of those since the 80's when the father-in-law had one. The vacumn lines run all over the place and could even be bad under the dash. Most of the vacumn lines all start at the carburetor or the manifold. The most expeditious way is to block them at that point to see if there is a leak. If you block one port and the problem is resolved, you'll know to trace the lines from just that port.

TQ60 is right about the hoses being cheap. Replace them all now as he said and save future issues. Fuel lines may be ready for replacement too.