Eliot Silverman

Eliot Silverman

Tuesday, April 24, 2012

Emission Controls

The goal of the emission control system is simple, minimize pollution.

PVC Valve
The first emission control device was the positive crankcase ventilation valve, also known as the PCV valve.  It was federally mandated in 1963.  During the compression stroke a small percentage of the raw air/fuel mixture squeezes between the pitons and the cylinder walls and goes into the crankcase.  This raw mixture of air and fuel is very polluting.  Before 1963 these gasses were vented into the atmosphere.  With a PCV valve, these raw gases are put back into the engine where they are burned.  This reduces pollution while marginally increasing gas mileage.

EGR Valve
In 1972 the government mandated “Exhaust Gas Recirculation” valves, also know as EGR valves.  This valve opens when the engine is warmed-up and turning faster than the idle speed.  It allows a predetermined amount of burnt gases to be recycled back into the intake.  Over 98% of the exhaust gases are inert since they were ‘burnt’ in a previous combustion event.  Nitrous oxide is the main component of “Smog” and is caused by high combustion temperatures.  Mixing raw air/fuel with inert gas from the EGR valve decreases the combustion temperatures, preventing (limiting) the production of nitrous oxides.

Catalytic Converter
In 1975 catalytic converters were introduced.  Catalytic converters are very effective means to reduce air pollution.  When you burn gas, you produce H20 (water), carbon dioxide (C02) and Carbon Monoxide (C0) and some gasoline remains unburnt (HC).  H20 and CO2 are desirable results of combustion, but HC and C0 are very polluting and therefore undesirable. The catalytic converter converts CO into CO2 and converts HC into H2O and C02.  Catalytic converters can be destroyed instantly with leaded gas.  When they were introduced, the gasoline manufacturers also introduced lead free gas. 

Oxygen Sensor
Oxygen sensors are used to fine tune the air fuel mixture.  The ideal mixture is 14.7 parts of air to one part of gasoline.  This ratio is called stochiometric.  A rich running car means there is too much fuel for the amount of air, and a lean running condition means there is too much air for the amount of gasoline.  A very rich or very lean running engine will ruin a catalytic converter.  To keep the engine close to stochiometric, manufacturers added sensors to measure the amount of air going into the engine.  Knowing how much air is going into the engine, the computer can add the proper amount of gasoline.  The Oxygen sensor is a feedback device which tells the computer if the mixture is too lean or too rich.  Since the oxygen sensor helps the computer maintain stochiometric mixture it reduces pollution and increases gas mileage.

EVAP System
The EVAP system was introduced around 1996.  This system is designed to prevent gas vapors from escaping into the atmosphere.  Gasoline in your gas tank naturally vaporizes.  In older cars this vapor was vented into the atmosphere.  Since 1996 these vapors are collected in a canister filer.  When you are moving above a predetermined speed, two valves open up allowing the vapors in the canister filter to vent into the engine where they are burnt.  This devise increases gas mileage and decreases pollution. 

Wednesday, April 18, 2012

Be Paid $538 per month or $6256 to Keep Your Car In

Sounds too good to be true, but it is…. Let me explain.
A few months ago my niece sent me an article which stated the average car on the road is about 11 years old.  This is a record.  The article hinted that this was due to the recession.  It is NOT because of the recession!   
Let’s get started…. Growing up in the 70’s my parents, who were middle class, bought a new car when their existing car had about 60,000 miles.  This wasn’t because they wanted the new features, or they liked car payments, or they just wanted a new car. They bought a new car because they had to.  The existing car was falling apart. Inside and outside everything was breaking. 
Since then the quality of cars as skyrocketed.  What I call revolutionary, not evolutionary quality improvement.  I opened my business in 1986 and I saw first hand the quality improvements. 
My 1993 Oldsmobile, with over 230,000 miles, ran like new – until an Audi rear ended my car – it was parked.  My 1996 Oldsmobile similarly runs like new and all I ever do is maintenance.
Cars made after 1995 were designed to run like new, with just regular maintenance, for over 200,000 miles.  This isn’t pie-in-the-sky praying, this is for real.  I see it every day.  Cars with over 100,000 miles are the new normal, not unusual.  I believe in a few years, cars with over 200,000 miles will be the new normal as well.
So how do you get paid $538 per month or $6256 per year NOT to buy a car?
Insurance on a new car is at least $600 more than insurance on a 6 year old car.  Cars over 6 years old, on average, cost $500 per year to keep in like-new condition.  Since you save $600 on insurance, it is like the insurance company is paying you $100.00 per year NOT to buy a new car.
Also, the average car payment is $438 per month.  Keeping your car is like the auto companies paying you $438 per month, or $5256 per year to keep your car.  These are real savings, but you must maintain your car.

Thursday, April 12, 2012

Anti Freeze, More Complex than you might think

Your Anti Freeze (also called ‘coolant’)
It has four jobs:
1.        It keeps the engine at a constant temperature
2.       It lubricates the water pump
3.       Cool the automatic transmission oil
4.       It provides heat for the heating vents.

For coolant (water) to work, it must be able to flow from the engine to the radiator and back.  Outside air passing through the radiator cools the ‘coolant’ inside the radiator. 

An anti freeze agent (ethyl glycol) was added to the coolant(water) to keep it from freezing.  Ethel glycol lowers the freezing point of water, which is important in the winter.  Additionally, it raises the boiling point of water, which is important in the summer.  Your water pump cannot pump steam so it is very important that the coolant doesn’t ‘boil.’

Your engine gets extremely hot from burning gasoline.  To maximize gas mileage, and reduce pollution, anti freeze needs to keep your engine at a predetermined temperature, normally 275 degrees Fahrenheit.   If the temperature of the anti freezes gets too hot, the air/fuel mixture will combust too soon, and if the temperature of the anti freeze is too low, the gas does not completely burn.

The temperature of the anti freeze is controlled with a thermostat.  Your car’s thermostat is NOT an on or off type of switch.  It can open up a little, or open up a lot depending upon how much cooling is needed.  Highway driving creates more heat than stop and go driving.

One of the reasons a car overheats is the thermostat does not open up or does not open up enough.  Either way, not enough coolant is allowed to pass through it to the radiator, so the coolant overheats.

If the thermostat stays open, the anti-freeze continuously circulates through the radiator, which means it takes a long time for the engine to heat up to its normal operating temperature.  This causes excess pollution, poor gas mileage, and increases the amount of time it takes for you to get heat out of the vents.

Some of the additives in your anti freeze lubricate the water pump and others prevent impurities from accumulating inside the radiator.  Many cars have engines made of cast iron and aluminum.  With two different types of metal in water (anti freeze), ions from one metal want to go to the other metal.  This causes pitting, and if the pitting gets very bad, the anti freeze escapes the engine through gaps created by this pitting.  Manufactures add a “Dielectric Inhibitor” to their anti freeze to prevent pitting.

A few years ago GM and others introduced a “Long Lasting” anti freeze.  The old standard anti freeze (green) is replaced every two years or every 24,000 miles which ever comes first.  GM’s long lasting anti freeze is colored ‘hot pink’ and Fords long lasting anti freeze is colored ‘yellow.’  Color is added to the anti freeze so we don’t confuse one with the other.  Long lasting anti freeze, we were initially told, is replaced every 5 years or 150,000 miles which ever comes first.  When long lasting anti freeze was introduced it was considerably more expensive then ‘regular’ anti freeze.  Now they cost me about the same.

Sounds good but…..  Under normal condition a small amount of water boils out of anti freeze.  It shouldn’t happen, but it does.  This will not create a problem with the old style green anti freeze.  However, if too much water boils out of long lasting anti freeze, the long lasting anti freeze solidifies inside the engine and radiator.  This prevents the flow of coolant through the engine and radiator causing the engine to overheat.  

The solid mass can be removed, but it is an expensive repair.  Years ago I met with a GM engineer and asked him about this problem. He said GM was aware of the problem, and to prevent this from happening, he said long lasting anti freeze should be changed every two years or every 24,000 miles which ever comes first. 

Monday, April 9, 2012

Transmission Oil

Transmission Oil
Transmission oil does two very important things.             
1.       Inside the torque converter it moves the power from your engine to your transmission.
2.       It lubricates your transmission.

Your transmission is the second most expensive part of your vehicle to replace.  The engine is the most expensive part to replace.  Oddly enough, I rarely replace engines, but I replace 6 to 8 transmissions each year.

It is in my professional opinion that you take good care of your transmission, and all you need to do is change the transmission oil.

Years ago there were two types of transmission oils.  Now it seems like there is a new one each month.   If your car was stuck on the side of the road, it would be okay to use the wrong to get you to the next exit.  As soon as possible, though, you need to have a mechanic flush out the old fluid and replace it with correct transmission oil.

The wrong transmission oil, in the short term, may cause your transmission to poorly change gears.  Years ago I did a pre-purchase inspection of a Honda.  The transmission had a slight hesitation changing gears.  Slight, but definitely noticeable.  I called my transmission rebuilder who had me check a few items on the transmission.  He told me he suspected the transmission had the wrong oil and suggested I remove the old oil refill the transmission with the correct transmission oil.  Sure enough, once I changed the oil, the transmission properly changed gears.  Luckily for the owner, I was told, the wrong oil would not cause abnormal wear and tear of the transmission.

In 1986, when I opened my repair shop, we changed the transmission oil by removing the transmission pan.  When the pan came down, about 3 to 4 quarts of oil came down with it.  Often making a big mess of my shirt and my shop floor.  Once the pan was removed I had access to the transmission oil filter which I changed before reassembling the pan and adding transmission oil.

Thanks to some mechanical genius, who saved many shirts and shop floors, we no longer change transmission oil this way.  I now connect my equipment to a transmission line which runs between the transmission and the radiator.  (Transmission oil is pumped to the radiator to cool it.  The anti freeze in the radiator and your oil never mix.  The transmission fluid has its own set of cooling coils inside the radiator.)  Once my equipment is connected to the transmission line, I start your car and the transmission oil is pumped into my equipment rather than the radiator. My equipment pumps an identical amount of oil back into the transmission. 

A transmission can hold up to 16 quarts of oil.  My newer equipment replaces 99% of the oil in your transmission.  The old way only replaced 3 to 4 of the oil in your transmission.

Some transmissions have an external transmission oil filter. These filters screw and unscrews just like an oil filter. 

Most manufacturers recommend changing the transmission oil every 36,000 miles or 3 years whichever comes first.  A few, very few, like VW recommend that you NEVER change the transmission oil.  Your owner’s manual is the best source for information about your car.