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M.B Spares & Service
14 Lyell st Fyshwick ACT 2609
Ph (02) 6239 1099 Fax (02) 6280 4596
Supporting Australia's Mercedes-Benz
Owners on the Web since 1996.
Newsletter Number 32
Hello and welcome to another newsletter.
This week news of a new toll free phone number, more Fuel injection information and some great photos from the USA.
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Fuel injection explained
As promised in the last newsletter this time we will discuss the cold start system.
First we need to refresh our memories on the requirements for combustion to be achieved in an internal combustion engine. Combustion is basically an explosion and for this to occur you need fuel, spark and squeeze. I am sure you understand fuel and spark but what's squeeze? Squeeze is the air that has been sucked into the cylinder and has been compressed (squeezed) by the cylinder. But more about this in a later newsletter.
With a cold engine you can have fuel, spark and squeeze but it won't start. When an engine is cold it needs a richer air/fuel ratio to start. To achieve this extra fuel needs to be injected when the starter is engaged. The amount of extra fuel required diminishes as the engine gets warmer, to a point where no extra fuel is required.
The system works like this. There is a temperature sensor in the cylinder head called a thermo time switch. It is an open/shut switch that is controlled by the temperature of the coolant in the engine. When you try to start the engine a signal is sent to the thermo time switch. It will then send the same signal to the cold start injector if (and only if) it is appropriate. The amount of fuel that the cold start injector injects is also controlled by this switch. This is done by controlling the amount of time that the cold start injector is open. The warmer the engine the shorter the time it will be open. This is the reason it is called a thermo TIME switch.
The thermo time switch for the M110 engine in the late W116 280SE and W123 280E has the following specifications. It works only below 15deg C coolant temperature. The actuating time increases with decreasing coolant temperature to a maximum time of 12 seconds at -20deg C. The switching time increases by 1.5seconds per 5deg C.
The cold start injector is a solinoid injector like the ones discussed a few newsletters ago. It has fuel supplied to it at all times the engine is either running or someone is trying to start it. It should only inject fuel when the thermo time switch tells it to.
Next newsletter we will get back to some real basics. We will discuss the OTTO cycle.
New Phone Number.
We have a new phone number! With our ever increasing number of interstate customers we thought it was time to do something for them so we now have a toll free number. The new number is:
Calls to this number are charged at the same rate as a local call from anywhere in Australia.
Site of the week.
Last newsletter we spoke about the Mercedes-Benz Club of North America. Here are some pictures from one of there premier events. Check out the many special cars, that we would only dream about seeing here in Australia. One of my favourites is the 230 Ambulance. It was built by Miessen, a specialist German body builder.
Most of the pictures were taken by Bob Gunthorp and the site was put up by Bill Wachsmuth both are super keen MB fans who hang out on the Veterans Mailing List with me.
Cars for Sale.
Not much action on the car front since the last newsletter. We had a beautifull 300E 2.6 come and go. It was a great one owner car with only 136000kms. We have just brought a 1990 300E 24 sedan, it is a great car with an interior that looks 6 months old not 11 years! The 180E has been reduced to$16990.00. Have a look here at our Cars for Sale page.
180E sedan 1992 model.
One local owner with full service history. Unmarked grey cloth trim. All the usual Mercedes features including: Air conditioning, Power steering Multi point central locking, etc. $16990.00AUDMore details
300E 24 sedan 1990 model.
One owner car with only 107000kms. The rare 24 valve version of the 300E was the top of the line W124 sedan in the early 90's. Has the lot, sunroof, cruise control, Air conditioning, Power steering Multi point central locking, leather interior, ABS brakes, external temp gauge, 10 stack CD player, remote alarm, tow bar, etc, etc. The car is currently fitted with genuine 16" alloy wheels. The original 15" alloy wheels are available. $29990.00AUDMore details
So that's it for another newsletter. Hope you liked what you saw. If you have any ideas or want to contribute any articles, pictures or other material please e-mail me here.
Also don't forget that you can check out the old newsletters here
Thanks, John Green.