Strong exhaust smell during and after driving, engine sounds tired

[Varyk]

I'll try to be detailed.

1980 Winnebago Brave

3 month old fuel pump
Engine oil change last week
new starter and house battery last week,
4 month old thermostat and gasket
Fuel filter 4 months old, filter is full of fuel
New transmission fluid
New power steering fluid.
New starter solenoid(remote relay next to battery) as of a month ago carb fuel filter replaced four months ago

No coolant, engine oil, or fuel leaks since some cleaning and parts replacement.

2 issues have shown up this month: sluggish startups and strong exhaust smell

We generally move in the morning and in the evening from spot to spot, but almost never drive for more than fifteen minutes since we staying in one city right now for two months so far. Half the time, the engine starts up great, stuff sounds new(only has 46k miles) and half the time it turns over successfully, but much quieter, sounds sluggish and doesn't kick in until I drive around a few minutes.

The motor usually starts up fine the first time in the morning and in the evening, but anytime within a few hours of having been started up,
often sounds very tired starting up again and doesn't kick in until I drive it a couple minutes.

All the parts above I replaced myself and the bago kept running better and better with each replacement for eight months going, then about a month ago, there was an exhaust smell that showed up after I parked and the brake warning light(bright red rectangle in the middle of the dashboard reading "brake") turned on. I reversed and went through gears and the light shut off, but turned back on two days later and has stayed on. The brakes do not squeal when braking and function normally. Could the light be from brake fluid being low, which I don't know how to check yet?

If I turn off the engine as soon as I park, the engine sort of rumbles as it's shutting down, the carb sometimes belches some sort of exhaust and the exhaust smell is stronger. If I wait ten seconds after parking, in park, then turn off the engine, the engine dhuts down quietly and normally and there is usually not an exhaust smell or it is very faint)

The exhaust smell is there while driving as well, much less strong since I changed the oil but still strong enough that I want to fix it.

There is a second solenoid right above the engine I have not replaced but easily could, I haven't replaced the spark plugs since I bought the Bago mine months ago, the starter motor and alternator are supposed to be new, the alternator looks new but I haven't checked the starter motor because I didn't know where it was(I have an idea now after some YouTube videos).

I am wondering about the possibility of the catalytic converter being clogged since we don't drive long distances(or because it's forty years old) or there being a leak somewhere in the exhaust system since it's 41 years old and the screwed up pressure is messing with the engine running properly until it warms up.

Any ideas will help, I'm having trouble pinning down anything else to look at.

Thank you for any suggestions!

[HarryStone]

What engine/chassis is it on? Carb? You could have a leaking float needle, causing it to run rich. If it was a bad cat, it would probably be bad all the time. Have you checked timing, and make sure the advance is working? Your brake light likely is low fluid.

[Varyk]

Originally Posted by HarryStone

What engine/chassis is it on? Carb? You could have a leaking float needle, causing it to run rich. If it was a bad cat, it would probably be bad all the time. Have you checked timing, and make sure the advance is working? Your brake light likely is low fluid.

Thanks. Carbureted engine. I can adjust the electric choke with a dial after I unscrew three screws apparently, but I understand even twisting the dial is a fine process and I don't want to muck with it until I'm comfortable. oh- leaking float needle, didn't notice that in the beginning, I'll look into that.

It says in the manual it's a Chevy 454, and all the parts I get are for a 454 and they fit and run perfectly, but the guy who sold it to me says it's a Mopar engine. I can't find the mopar stamp or the 454 stamp anywhere on the engine body, though.

I just went with 454 for all parts because it says 454 on a decal on the back of the 'home and it's worked out so far.

The smell is pretty much all the time during and after driving these days, maybe in the last couple weeks. We won't smell it all the time, but that's because we're inside which is sealed pretty well since I redid the seals.

Another clue is that the smell is much stronger on the passenger side than the driver's side, and the exhaust runs along the passenger side so I'm thinking that is a clue to the converter.

If it is the converter, can I go on a long drive, an hour or something, and hopefully that burns off gunk that built up since I usually drive it such short distances.

What should I look at to check the timing and the advance? I'm not familiar with those terms. Timing of the spark plugs?

Thanks again.

[TheCatsRV]

What's the smell? Sulphur? Rotten eggs? That's usually the sign of a bad cat.



Chrysler made either a 440 or 460 engine, not a 454 IIRC.


Timing/advance is ignition timing. Measured in degrees before top dead centre (BTDC) that the ignition occurs. Engine should have a label (on radiator maybe) about what it should be at idle (also known as initial timing). You need a timing light. May have to disconnect the vacuum advance. There is also advance curve. Timing (BTDC) increases as RPM increases. The increase is determined by weights and springs in the distributor. Spring could weaken as they age hence timing increases more than optimal. You also need to lube these components. Computerised ignitions only require initial advance setting.


Brake fluid level is checked in the reservoir by the brake vacuum canister.

[D Gardiner]

Very long post. Took me a while to digest.

I have a few thoughts, on the engine running, and sluggish starting.

I'm wondering if the vacuum advance is not working correctly, and/or the mechanical advance is sticking.

Going to with your statement, that you have a Chevrolet 454. If so, your distributer should look like the one below.

If (for example) the mechanical advance is stick, or sluggish to advance, it will cause, poor acceleration.

If the mechanical advance does not quickly come to rest at idle speed, it will cause the engine to run-on (as you described).
It will also advance the timing, (upon quick restarts) where the starter will be fighting the timing advance. This is when the spark plug ignites too soon, making the starters job much more difficult, causing slow engine cranking speed.

Grab the advance and make sure it moves very freely, and returns quickly (and fully) once you let go. If not add some light oil or WD-40 if rust is visible. Work it back and forth until it moves freely.

The vacuum advance. Make sure the diaphragm hold vacuum when you suck on it. I leaking advance diaphragm will kill power, and gas mileage. Also it should move freely as well.

This gentleman, does a great job of explaining timing, mechanical advance, and what it does.

https://www.youtube.com/watch?v=msHlcjrnjV0

Best bit 0:00 - 4:45

Originally Posted by Varyk

I'll try to be detailed.

1980 Winnebago Brave

2 issues have shown up this month: sluggish startups and strong exhaust smell

We generally move in the morning and in the evening from spot to spot, but almost never drive for more than fifteen minutes since we staying in one city right now for two months so far. Half the time, the engine starts up great, stuff sounds new(only has 46k miles) and half the time it turns over successfully, but much quieter, sounds sluggish and doesn't kick in until I drive around a few minutes.

The motor usually starts up fine the first time in the morning and in the evening, but anytime within a few hours of having been started up,
often sounds very tired starting up again and doesn't kick in until I drive it a couple minutes.

If I turn off the engine as soon as I park, the engine sort of rumbles as it's shutting down, the carb sometimes belches some sort of exhaust and the exhaust smell is stronger. If I wait ten seconds after parking, in park, then turn off the engine, the engine dhuts down quietly and normally and there is usually not an exhaust smell or it is very faint)

Thank you for any suggestions!

[Winemaker2]

Agree that timing (advance) could be the cause.
I had similar issues on a boat engine once.
I kept checking and setting timing but it ran crappy unless I timed by ear and it ran better. It turned out the return springs in the distributor were rusted through and not returning timing when idled down. What took so long to diagnose was due them being hidden below the plate in the distributor.
Worth considering if still stumped.

[twinboat]

Shut the engine off after its warmed up, remove the air cleaner and see if wisps of smoke are coming out of the carburetor.

If yes, the carb is leaking gas internally.

[vseasport]

1980= no catalytic converter. My bet is sticky choke and advanced timing. That vintage of motor was built before unleaded fuel and needs high octane. It will never run good on todays regular gas and will probably sputter on premium. 1980 was before ethanol which will attack all the rubber fuel lines, carb accelerator pump and other components.

If the motor is original the true fix is lower compression pistons and less aggressive cam shaft. That said it can be fixed to run well enough to get by. If the rubber fuel lines are original they should be replaced ASAP. Todays fuel will melt them and cause a hazard. The carburetor should be rebuilt with components for todays fuel. Ignition timing should be retarded to accommodate low octane. Also, the brakes should be addressed by first changing all the fluid.

A lot of things need to be addressed to make a 42 year old drive train run in todays world no matter how low the milage is and how good of condition it is in.

[Varyk]

Originally Posted by TheCatsRV

What's the smell? Sulphur? Rotten eggs? That's usually the sign of a bad cat.



Chrysler made either a 440 or 460 engine, not a 454 IIRC.


Timing/advance is ignition timing. Measured in degrees before top dead centre (BTDC) that the ignition occurs. Engine should have a label (on radiator maybe) about what it should be at idle (also known as initial timing). You need a timing light. May have to disconnect the vacuum advance. There is also advance curve. Timing (BTDC) increases as RPM increases. The increase is determined by weights and springs in the distributor. Spring could weaken as they age hence timing increases more than optimal. You also need to lube these components. Computerised ignitions only require initial advance setting.


Brake fluid level is checked in the reservoir by the brake vacuum canister.

I'll YouTube about the timing and advance adjustments.

Okay, probably not the cat then, I'm getting a regular exhaust smell, not sulphur.

I can't actually locate my brake fluid reservoir, I've located the cylinder, but don't see any reservoir attached. Do master cylinder sometimes not have reservoirs with older cars?

[craigd853]

Originally Posted by Varyk

I'll YouTube about the timing and advance adjustments.

Okay, probably not the cat then, I'm getting a regular exhaust smell, not sulphur.

I can't actually locate my brake fluid reservoir, I've located the cylinder, but don't see any reservoir attached. Do master cylinder sometimes not have reservoirs with older cars?

Hello sir, it sounds like your knowledge of mechanics and how a motor works is very limited. I applaud you for asking for help but it might be better to have someone who knows what they are looking for take a look at your motor home. Your latest picture of your master cylinder is also the resevoir for this particular model. You have to use a screw driver in order to pry the the metal clip holding the top of the master cylinder cap in place and the fliud is housed underneath the cap. Again if you don't understand this it may be best to have someone with a little more experience take a look at these issues. Good luck and hopefully you will get the answer or help you need.

[HarryStone]

The picture you took is actually the brake reservoir, it has a baling wire on top to keep it closed. I agree with Craig. you're better off taking it to an "old school" mechanic.

[Varyk]

Originally Posted by craigd853

Hello sir, it sounds like your knowledge of mechanics and how a motor works is very limited. I applaud you for asking for help but it might be better to have someone who knows what they are looking for take a look at your motor home. Your latest picture of your master cylinder is also the resevoir for this particular model. You have to use a screw driver in order to pry the the metal clip holding the top of the master cylinder cap in place and the fliud is housed underneath the cap. Again if you don't understand this it may be best to have someone with a little more experience take a look at these issues. Good luck and hopefully you will get the answer or help you need.

Ha, I realized that was the reservoir right after I posted that.

Pretty limited, all the parts I replaced were one at a time and after watching youtube videos.

The larger chamber of the reservoir is almost full, while the smaller chamber is almost empty

I'm leaning toward a mechanic as well, but since I'm already here, do the two chambers of the reservoir correspond to different sets of brakes and does the near empty smaller chamber indicate a leak or that the brake pads are almost out?

Thanks

Thanks for your answer.

[Varyk]

Originally Posted by twinboat

Shut the engine off after its warmed up, remove the air cleaner and see if wisps of smoke are coming out of the carburetor.

If yes, the carb is leaking gas internally.

Okay, thanks, I'll do that. I did check before while I was fixing the carb fuel line/filter and didn't see any smoke coming up. But maybe it's a new development.

[Varyk]

Originally Posted by Winemaker2

Agree that timing (advance) could be the cause.
I had similar issues on a boat engine once.
I kept checking and setting timing but it ran crappy unless I timed by ear and it ran better. It turned out the return springs in the distributor were rusted through and not returning timing when idled down. What took so long to diagnose was due them being hidden below the plate in the distributor.
Worth considering if still stumped.

Everything I've replaced so far has looked ancient, so rusted springs is definitely looking into, thanks for the idea.