Timing Chain Tensioner: question by Pete Accini | ’67 GTV
Hi, my car had its engine rebuilt by the previous owner about 4000 miles ago but it sounds a bit rattly to me! I'm pretty sure that the noise is from the top timing chain. When I bought the car I had a garage give the engine a quick once-over and they suggested that the chain tensioner is not properly working or at least the adjuster isn't. Does this sound likely and if so what kind of a job is it to replace the adjuster. | | Answer : First of all, you need to understand that the chain tensioner in your engine is a manual, not automatic, tensioner. In general, it is a fairly simple operation to replace the chain tensioner of your vehicle. However, it is a fairly rare occurrence for the tensioner of a 105 Alfa engine to fail. Chances are that it just needs adjusting. If proper adjusting of the chain doesn’t quiet things down, it’s probably not the upper chain that is making the noise. | O2 Sensors and Emissions : question by Roy Moreno | ’85 Spider Graduate
My car failed WI emissions after passing 2 years ago. Performance has not changed with car over the past 2 years. CO at idle was elevated, other values passed at idle and 2500rpm. In addition to new spark plugs, new air filter, new oil and cleaning up contacts of distributor, I am contemplating changing the 02 sensor. I have heard that the 3-wire type is better than the 1-wire type? Is this true for the 1985 model? There is a modification that reuses part of the 1-wire to adapt the 3-wire. Would this be advisable? Drawbacks/durability issues? | | Answer : The only advantages to the three wire O2 sensor that I am aware of is that it warms up faster, thus providing better drivability during the warm up cycle and it provides a more consistent and accurate signal to the processor at idle. The three-wire sensor has a power and ground circuit for the heater and the third wire sends back the sensor reading to the processor. There are also four wire sensors. These have separate power and ground circuits for the heater and for the sensor. In a one or three wire sensor, the sensor circuit is grounded only by the exhaust system itself. Whenever you are taking an emissions test, it is very important to get the converter hot enough to function at its best efficiency and not allow it to cool down before the test. I recommend getting the engine up to full operating temperature on the highway, driving the car spiritedly, and, very important, do not turn vehicle off as it will cause the cat to cool down and become less efficient. A new O2 sensor may cure your emission woes, however it appears as though your Alfa has the classic symptoms of an inefficient catalytic converter. Your car is the age when we see the performance of many converters fall off significantly. Editor's Note: Catalytic converter technology has come a long way since 1985. In addition to improving emissions, a new converter may offer increased flow leading to a boost in perfomance. | Page 1 | Page 2 |
