Hi,

I have a few questions regarding glow plugs. First, what are te possible indicators of a bad glow plug/plugs besides the car not starting? Mine starts fine, but sometimes the preglow light doesnt go on until the other left side lights such as battery, etc go out. Someone said this may be a sign of a bad glow plug, ut Im not sure if maybe its just a bad connection. Id liek to know the possible lighting behaviors of the preglow light, if it blinking, turning on in different ways/not at all may indicate a problem or something.

As for actually testing the plugs, Id liek to know the procedure. What should I connect to what in order to test the plugs. Will Ineed to remove wires, etc? I have no idea how to do it, so Id appreciate helping a newbie out. Also, I dont have an ohmeter. Currently the only thing similar that I own is a battery tester... Any reccomendations on a good cheap ohmeter that would be good for this type of thing would be appreciated. I would guesss radio shack carries this type of thing?

Any help would be most appreciated. Thanks very much,

JMH

Well, first of all you can test the glow plugs with a ohm meter. To do so diconnect the wires from each plug, then connect your meter from the terminal of each plug to ground. If it is infinite, that plug is open and therefore bad. I don't know how many ohms a good plug will read, but they should all be about the same. On my 300d I can remove an injector and see the plug turn bright orange, when the glow plug light is on, and I know it stays on for a while after the light goes out. I don't know why your light is doing what it's doing. It sounds to me like a wiring problem, but I don't know if bad plugs would cause it to act like it is.

The test that will give you the clearest indication of glow plug health is a test of how much current it is drawing. The newer type that connect in parallel (i.e. they all get 12-volts) should draw something like 12-15 amps. I had one that drew about 2 amps when hot. The difference is obvious. However, when cold, it was difficult to tell any difference between the good and bad by just reading ohms - since the resistance is so small anyway.

Thus you need a multimeter that can handle measuring this level of current.

I recommend the Tenma compact digital multimeter sold at MCM Electronics for $19.95

Go to www.mcmelectronics.com and enter as a "Guest". Enter "72-5095" in the product search and that should locate this meter for you.

This meter has the special 20-amp current measuring range that you need, and is reasonable in cost. It's what I use.

Ken300D

Hi,

OK, this is really dumb, Im sure, but where is the best place to connect to ground? Can I use the car body? Can I hold the one connection in my hand since Im grounded? Newer cars have grounding wires all over the place, but these dont, so advice would be great. Thanks

JMH

You can use the body of the glow plug to ground to and the tip (where the lead connects) to check continuity.A meter isn't necessary,you can use a powered test light,but if your needing to buy one get a meter like the one mentioned above (20 amp ).Good luck

__________________
Democracy dies in darkness, you have to kick at the darkness till it bleeds daylight

one easy test us hillbillies use to test glow plugs is to hookyour test light to the positive side of the battery. unhook the wires from the glow plugs and ground the test light probe to the glow plug terminal. if the test light lights then you still have resistance and tje plug is working. if the light doesnt light then the plug is burned out. its not rocket science but it still works in arkansas.
hillbilly