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1979 dodge mobile traveler 360cl wont pass emissions

zerxyx
Explorer
Explorer
Hi guys, I have a 1979 dodge mobile traveler with a 360cl engine, and i cant get it to pass emissions. The CO2 level is the issue.

I have changed the oil and the spark plugs and things improved but it still fails on co2.

any ideas on what to try next?

Scott
33 REPLIES 33

MEXICOWANDERER
Explorer
Explorer
The OP abandoned ship. I passed the NIASE test for emissions in 1979. Curing the alphabet stew of emissions complaints had to be studied then tested. As a 6-month stint for MoPar line mechanic I have lots of experience with 360 and 440 engines.

That was 40-years ago.

Are any forum members capable of a factory quality rebuilding of a Carter Thermoquad carburetor? Or emissions test qualification? I had access to Factory Technical Tip Bulletins when the carburetor was brand new.

The OP asked a specific question and he specified CO2 not CO. I responded to that question. He since disappeared. Waste of time, except to folks that actually own and use and register that era's motor vehicles. High CO2 is a CLUE to troubleshoot OTHER emissions problems.

I should have known better than waste my time. Shame on me.

Dave_H_M
Explorer II
Explorer II
I know this is apples and oranges - BUT

When I had an ole dodge Dakota that thing would never pass emissions, even after dropping money at the stealer and they swore it was OK.

So long comes an idea that is out in left space. it was the time that AMACO was advertising the ultimate grade that you could see thru in the glass full of it.

i drove the vehicle down to as much as I dared towards empty. Even carried a little spare gas if i got empty.

Then drove into the AMACO station and dumped some ultimate in it. Took it out and let her eat on the free way for some miles. Then zipped into the station that was always flunking the test and it passed with flying colors. i did the same for the following years.

just my story and I am sticking to it. good luck with that beast.

BTW at the time they even sold snake oil that was supposed to help, but that didn't work on my Dodge.

Gdetrailer
Explorer III
Explorer III
Airdaile wrote:
You should investigate the requirements and restrictions if you were to register your motor home as an antique.


That WOULD most likely make the vehicle as designed IMPOSSIBLE to use for its intended purpose of camping.

Antique plates in many states WILL add considerable usage restrictions like a max mileage per yr, no or limited operation at night, only one day per week usage, only allowed to be driven to and from car shows or events, ect.

I suspect the DMV most likely would not accept a motorhome for antique plates..

OP simply needs to find a good quality old school mechanic with some diagnostic equipment to measure CO2 while making carb adjustments.. It should be do able but finding a mechanic now days that doesn't need to plug into OBD ports to fix things is getting to be very rare..

Not sure why the OP hasn't been against this wall before.. New in the state?

For all the hassle in such an old MH, perhaps it's time to move on?

After all, we ARE talking about a 40 yr old vehicle, with 40 yr old emission technology which was totally experimental back then.

Something newer will have considerably more powerful engines with fuel injection much improved emission systems and so on..

Airdaile
Explorer
Explorer
You should investigate the requirements and restrictions if you were to register your motor home as an antique.

landyacht318
Explorer
Explorer
The OP is in Utah, It would be nice to see a printout of all the things they are testing for, in Utah, to make any guess as to what might be the issue.

In California, which is likely the strictest of any state regarding allowable exhaust emissions:
---CO is measured as a percentage, and my TBI '89 LA 318(5.2l) Dodge is allowed 0.5% at 15mph and 0.64% at 25mph.

----CO2 is given as a percentage, but no maximum or minimum allowable % is listed, mine just measured 13.3% at both 15 and 25mph.

------O2 is listed as a percentage, but no min or max allowable % is listed, Mine measured 2.4 an 2.5% at 15 and 25mph.

It is difficult for me to imagine that Utah has stricter requirements than California in regards to CO2%, and that California does not state the allowable limits clearly, while Utah does.
So I urge the OP to recheck whether the CO2 or the CO is the issue as many people confuse the 'two'.

HydroCarbons, in California, are measured in PPM and the max allowed for my vehicle is 102PPM at 15mph, and 120PPM at 25mph.

NO is measured in PPM, and my vehicle's max allowed is 1010 at 15mph and 870 at 25mph.

Yes, the drive axle is put up on rollers during the test on OBD1( 1996) or older vehicles in my county/zipcode in this state. More rural areas likely are not.

They do visual inspection of the presence all the original smog related components, but they do not test the actual output of the smog pump, or see if the pintle is moving as it should on the EGR valve.

The Intake crossover is designed to heat the carb/throttle body of a cold engine faster, and should have no effect on the smog numbers once it is hot. All vehicles should be at full temperature when smog tested. Note that while the engine coolant might take 10 minutes to read its maximum, the oil takes much longer to warm up and it is much better if it is at full temperature when the vehicle is Smog tested.

The intake crossover is designed to allow better driveability and lower emissions with a cold engine, while it is warming up, and should have zero effect on hot smog numbers. If they were testing for the function of this feature as to the Smog numbers, they would have to start with an overnight cold engine. Obviously they cannot, and do not.

The bimetal spring operated valve on the passsenger side exhaust manifold of my 1989 318, which redirects gasses through the intake manifold on mine is broken, I have clamped it off fully open, and it never redirects any air through my intake manifold. It has been this way for my last 7 California smog tests(14 years), all of which I have passed the first try. It is visually inoperable, with hose clamps compressing aluminum foil on the shaft to prevent it from rattling or leaking.

A well running engine should have little issue passing a smog test.

My Smog test cost 73 dollars yesterday, and they knocked off money to this total, after I told them I would have the engine cover removed when I brought it in. Forcing the smog tech to do this is not going to make them happy, and they might not spend the time to make sure it is as hot as it should be for the sniffer part of test. When smog techs see an RV or a VAN and especially conversion vans with teh frou frou engine covers, they sigh audibly, and most stations charge significantly more for these vehicles because of the engine cover removal and return, can be a tedious and annoying, time consuming process.

There are all sorts of products, Like CRC 'guaranteed to pass' which are primarily designed as fuel and combustion chamber cleaners which should help lower the CO NO an HC's. These fuel add products have high levels of poly ether amine, PEA, which is supposed to clean the intake valves and combustion chamber without leaving any residue of its own. Other Fuel system cleaner type products have PEA, not all of them do. These are said to be most effective in cleaning the combustion chamber and intake valves, when heat cycling the engine, hot and cold, as opposed to a long drive on the highway. They are not add to the tank and then immediately take it to the test facility style of products. One needs to burn them though ~15 gallons of fuel so they have the time to do their job.

Some swear by adding ethanol to the gas to help pass smog tests immediately. DeNatured alcohol is Ethanol, with toxic denaturants added to keep drunks from swilling it, and government from taxing it, yet at ~8$ a liter is hardly inexpensive. One might be able to simply add some E85 to their gas tank and be able to pass the sniffer test.

Lots of people swear by water decarbonization of intake valves and combustion chambers which will help the engine to run cleaner and more efficiently. To do so, One needs to mist distilled water into the intake, while feathering gas pedal to not allow the engine to stall while doing so. One must be careful to not allow it to hydrolock. Obviously there is a huge risk if done improperly. I've never done so.

The smog tests are a bit asinine in some ways, as the smog pump itself injects so little air into the exhaust stream that its intent to help further burn any unburnt hydrocarbons is likely ineffective, and all it does is add parsitic drag to the engine making it less efficient. My spark timing is to be set at 10 degrees before top dead center and needs to be within 3 degrees of this to pass smog. They do test this with a timing light. My engine runs so much smoother and better with timing set at ~16 degreees. I have no proof it is more efficient and makes lower smog numbers at 16 degrees BTDC, but I do bust out the timing light every two years, twice, once before and once after the test.

My Smog pump tends to seize quickly if disconnected, so I just leave mine operable to make extra putt putt noises, and rob my engine of HP and torque, and in general irritate me.

MEXICOWANDERER
Explorer
Explorer
If the old spark plugs you changed had pure white insulators with perhaps blisters on the center electrode then the system is running too lean. That eliminates the ignition system.

Get a can of starting fluid, and if you can find a tip that fits that takes a plastic straw. Set the engine idle to 1000 RPM. CAREFULLY squirt around the base of the carburetor.
bit by bit check the carb throttle shaft bores, Then around manifold fittings.

If there is ANY noise change or RPM stumble from the engine speed, you've found your culprit.

There are a ton of tiny vacuum tubes on the intake manifold and carburetor. Go to the parts store and buy a three feet piece of this hose.

Disconnect one-by-one the hoses that lead to the choke pull of diaphragm, the secondary of the Thermoquad and the vacuum advance on the distributor.

Suck on the hose. No resistance -- is the culprit. That's a vacuum leak.

No push-back on the brake pedal after pumping it several times then holding it down hard and starting the engine is a "tell".

Leaks in the air injection reaction system will cause a lean high CO2 reading.

A tachometer will "tell" when noise is too high to hear subtle engine speed changes.

All of this will take longer than an hour. I vigorously encourage the use of a tachometer. Take your time being meticulous. I used a vacuum hand pump with gauge instead of my mouth to test vacuum components.

Good luck to you.

Chum_lee
Explorer
Explorer
First things first. ALL gasoline fueled vehicles produce CO2 when they are running. Period. Generally, for emissions testing, CO2 content is noted as a %, but, not tested. You probably mean CO, or, carbon monoxide, not carbon dioxide. (CO2) Very different animals.

In order to be helpful, you have to post the actual tested CO content in the exhaust gas to make a meaningful diagnosis. Your failed emissions test results must tell you what that value is. You should also post the maximum allowable CO content in the exhaust gas, usually as a PPM value. (Parts Per Million) It's helpful if you post ALL the test results along with their MAX allowable values. If you don't do that, chances are you are wasting your time in this format.

Chum lee

EDIT: Your test results should look similar to what landyacht318 posted above. I don't know if Utah still does the same but there should be two sets of test results. One at 15 mph (low speed/load) and one at 25 mph. (higher speed/load) California is one of the most restrictive states in the USA. You must pass both low and higher speed tests to pass the test. (at least in California) Utah may vary.

Gdetrailer
Explorer III
Explorer III
Should be very little "emissions" systems on that vintage to tinker with.

If I remember correctly 1980 was the last year of Cat converter exemptions for gas vehicles exceeding 10K GVWR (my Dad bought a 1980 Ford 1ton pickup with 400CID engine, had no cat converter, 1981 was first year that all needed cats).

However, it was equipped with a SMOG AIR PUMP system.

I suspect your 79 Dodge most likely will or should have a smog air pump.

The smog air pump would add pressurized air into the exhaust system, this would have the effect of thinning out the emissions at the tail pipe.

A malfunction of the pump and or valves, missing /removed pump or no belt to the pump will result in higher than expected "emissions".

You also should have a EGR valve and passages which tends to clog or get stuck.

Others have mentioned carb tuning which also can affect emissions, clogged passages in the carb or incorrect setting will effect the emissions.

Most vehicles of your age, folks have removed and discarded much if not all of the "emission" related stuff, most times it failed or caused poor running conditions and not to mention killing power and mileage.

Sadly, you are on a uphill battle trying to find a old timer who knows a thing or two about proper carb tuning, doesn't take much misadjustment to mess with the emissions.

Quite frankly I am surprised that there is no exemptions for that age of vehicle. At least in PA they simply look under the hood and under the vehicle for known emissions equipment (doesn't need to work, just be in place) that belongs on it for the age in most counties that are not required testing.

Vintage465
Nomad
Nomad
To my recollection, all CA vehicles 1976 and newer need to pass smog every two years. Problem is, most places that do smog aren't really mechanics and don't know squat about carburetors. I had a Ford Ranger with 380,000 miles on the engine that I could get to pass smog every 2 years. It was never a "burning oil" issue. It was always related to combustion. That cross over in the manifold may need to be cleaned. The carburetor should either be replaced with a re-man unit from National Fuel Injection(lifetime warranty), or do your own rebuild with some real Berryman's Carb(Amazon)dip..........not the junk environmentally suitable crud they sell in the parts stores. Not sure if Mopar used a version of a Thermactor set up like Ford did. If so, that is good place to look at for sure. One thing is for sure and try to remember this....All vehicles that passed smog once, can pass smog again. There is not a vehicle made that "can't pass smog". You just have to find out what the issue is and correct it.....not always easy, but is always possible.
V-465
2013 GMC 2500HD Duramax Denali. 2015 CreekSide 20fq w/450 watts solar and 465 amp/hour of batteries. Retired and living the dream!

landyacht318
Explorer
Explorer
Just passed California smog test with a 318.

@25mph and 1415rpm
%co2 13.3
%O2 2.5
Hc 83ppm---max allowable 102
CO% 0.09-----------------0.64
NO 118------------------870

markchengr
Explorer II
Explorer II
The OP said CO2 not CO. Emission tests require CO2 OVER a certain level, not less.

time2roll
Nomad
Nomad
CO is the air/fuel mixture. Need a good carburetor adjustment or better just get a new one.

MEXICOWANDERER
Explorer
Explorer
No exemptions for commercial vehicles.

DATA allows perspective. List HC, CO, and NOX data. it will have max/min + your numbers listed. One such example a VACUUM LEAK will raise CO numbers. Can we see some numbers, please?

D_E_Bishop
Explorer
Explorer
1984 was the first year for mandatory use of converters, prior to that it was optional but if the vehicle came with one it is required. Test on vehicles are a little schety to beging with.

A cat actually makes C02.

Check and see if you can get a vintage vehicle exemption at that age you just might.
"I travel not to go anywhere, but to go. I travel for travel's sake. The great affair is to go". R. L. Stevenson

David Bishop
2002 Winnebago Adventurer 32V
2009 GMC Canyon
Roadmaster 5000
BrakeBuddy Classic II

enblethen
Nomad
Nomad
Common problem with 360 is the exhaust cross over passage in the intake manifold. Ackward job to clean without taking manifold off.
Odd that the vehicle needs emission testing!

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker