Problem Skunks the Technical Experts

Times Staff Writer

Question: I have a 1985 Corolla that emits a bad odor--something like rotten eggs. Can you tell me what can be done about this?--E.N.

Answer: The odor you smell is hydrogen sulfide, an exhaust emission that Toyota is working feverishly to eliminate. So far, they’re skunked and their top technical experts say there is essentially nothing you can do. Meanwhile, a lot of Toyota owners are hopping mad.

Hydrogen sulfide is a very active chemical that moves through the air very quickly, much like skunk odor or perfume. So, when you idle at a traffic intersection or park the car, the odor envelops the car and seeps into the passenger compartment.

The hydrogen sulfide is produced by new three-way catalytic converters, which treat hydrocarbons, carbon monoxide and nitrous oxide. Earlier two-way converters did not treat nitrous oxide. At certain temperatures and accelerations, hydrogen sulfide is produced.

Toyota blames the problem on high-sulfur fuel. The problem seems to be worse in the Western United States, where high-sulfur Alaskan crude is refined for gasoline. You might try experimenting with different brands of gasoline, because some brands may be refined from a lower-sulfur crude.

You also should have the engine checked to make sure the ignition is properly set. The carburetion adjustment screws are sealed to prevent tampering. On some two-way converters, however, the screws can be drilled open by a dealer and adjusted to minimize the problem. The objective is to enrich the fuel mixture until the carbon monoxide level of the exhaust is just below 3%, as compared to 1% at the factory setting.

Q: I am a senior citizen and have no one else to turn to. A gas station owner thought he was doing the right thing when he disconnected the heater of my 1977 Oldsmobile Cutlass, because there was a fishy odor in the car. Now he wants $150 to repair the heating system, which entails removing the whole dashboard. I am very upset and anxious to hear what to do.--N.S.

A: The fishy odor undoubtedly was caused by leakage of radiator coolant into the passenger compartment, as a result of a hole in your heater core. It’s not an uncommon problem but it is expensive to fix, as you have found out.

The heater core is a smaller version of the engine radiator. If you disconnect the heater hoses going into the core, you obviously will stop leakage of fluid. The mistake is that you won’t have any heat in the winter. Even if you can survive that problem, you are going to find occasions when you need heated air for your windshield defroster. And that’s a safety consideration.

Q: My 1985 Thunderbird has developed a fairly loud “clunking” noise, which seems to come from the rear and is synchronized to my foot on the brake pedal. Here’s the strange part: The noise totally disappears after driving five to 10 minutes. I have had this checked out twice to no avail.--R.K.L.

A: That’s a tough problem because there aren’t many systems in the rear end that could clunk and also are affected by the car warming up. You should have the rear brakes inspected. Possibly the backing plate or the brake shoes are hitting the brake drum. Once the drum heats up and expands, it may be missing whatever was hitting it before. You should also have the rear radius arms, part of the differential, checked.

Ralph Vartabedian cannot answer mail personally but will respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, You section, The Times, Times Mirror Square, Los Angeles 90053.