Thursday, July 25, 2013

Spark Plugs - How to change and check for signs of other problems

Spark Plugs are a simple and easy easy way to keep you car performing well and you fuel economy high. They typical last 15-30k miles and with most cars costing around $10-20 in parts its a cheap maintenance tactic to keep your car running great.

How to tell if is time to replace, well there's a few thing to look for when your looking at a spark plug. Color, shape of electrode, and fluids on  plug and and contact point. If you don't want to pull the plugs every oil change (which I recommend) you can also get a feeling on when to change your plugs by keeping track of you mpg and your overall cars performance. Weak acceleration, rough idle and poor mpg are all sign of failing plugs.

First thing to look for and the easiest to see is if there are any fluids on the plug. Fluid above the thread mean a possible valve cover leak, below or on the thread signifies a leaking head gasket or possible piston ring failure.

Next is the color. The plug should be a light tan color. Dark or black mean to much fuel, white means not enough. These signify possible fuel issues such as bad distributor cap, rotor or even a fuel filter or pump.

The electrode is the the next thing to check. It should be a larger flat stem, as the plug gets older it will become a finer and finer point until its almost invisible.

Notice the worn electrode, but there is no fluid
on the plug and the color is near perfect
This is the same plug brand new. Here you can
see how much larger the electrode is

Lastly is the contact point. To check this you will need a spark plug gap tool (available at any auto part store for a few cents). Every car has a specific gap for optimal spark firing. if the gap is to small it will make contact to often if to far (which will happen over time as the electrode wears down) it won't make proper spark causing bad MPG and performance

Here's how to access and replace them when and if needed. You'll need a park plug socket (5/8 fits most cars) and about an hour of time. Thats it.

Do one plug at a time checking each for signs as above. This will prevent the spark plug wires from becoming mixed up. They have a specific order they go in and if not put back on in the correct order your car will NOT run.

Simply remove the plug wire insert the spark plug socket and remove the plug. Then replace with new pug if needed making sure to use threat protectant and not over tightening. The reason for the thread protectant is most heads now are aluminum and spark plugs are steel. The two metals will react causing the treads to to wear out. When tightening they only need to be hand tight or else you can strip out the head causing serious damage.

Thermostats - What they do, when they go bad and how to replace them

Thermostats control the water flow from block to radiator. They work by a temperature controlled spring which when heated to a preset temp open a valve letting water flow through the passage back in to the radiator for cooling. Why is it needed? well in certain climates like here in Florida we really don't, but in northern climates where it get cold or freezing it prevents engine damage. In older cars thermostats were often removed to increase cooling but in newer cars this is not a great idea. Though it can be done, most newer cars require the engine to be at a certain temperature to  go into a normal driving mode. Until that temp is met the car will maintain a higher fuel percentage  also known as "cold start" mode to prevent any internal damage being done.

Unfortunately factories have not adopted a fail-safe model thermostat into cars yet, all though most cars now have fail-safe replacements available at your local auto part stores. How do you know if your thermostat has gone bad? Well there is an easy way to tell. With the car at normal operating temperature or starting to over heat if diagnosing a problem. Carefully feel the top radiator hose for approximate heat. Then feel the lower hose they should be at the same temperature. If the lower line is colder then most likely your thermostat is not function properly and should be replaced.

The steps to replacing are pretty simply and can be done with little effort on most vehicles. You'll need a drain pan, couple hand tools and some more antifreeze to replace any that leaks out during the change.

First locate the drain plug on the bottom of the radiator and empty the fluid in the pan. You don't have to do this but will save you a ton of mess and allow you to reuse all your fluids.

Next locate your thermostat housing. Each model car has one, but they are NOT located in the same areas. Once located there are normally 2-3 bolts holding the housing to the engine.

Remove the bolts and the out housing shell to reveal the thermostat. depending on the vehicle there maybe a gasket between the housing cases or simply one on the thermostat itself, below are pics of both.

Gasket on thermostat
Gasket on housing

Next simply remove and replace the thermostat with the new one making sure to place exactly how the old one was in. Its important to get the same direction and placement as there is a small weep hole that needs to be in a certain area to ensure proper functioning of the part. And, if placed in the wrong direction the thermostat will not open at all. Then simply reverse the steps to access it to finish the install.

When filling the fluids back in, leave the radiator cap off and start the car after returning all fluids. This will allow any and all trapped air to escape preventing any air from trapping the thermostat valve shut.