# Cat 247B Glow Plugs - Need help



## Snakeman (Dec 12, 2005)

My Cat 247B started to not start when I pushed the glow plug button in. Cranks, and white smoke comes out the exhaust.
OK, looks like the glow plugs are not working.

I traced it, and found the glow plug relay was bad. I replaced it, and got one good start before it blew the relay again.
The way Cat has them wired, all of the plugs are on a common rail, with the wire from the relay on one end.

I pulled all the glow plugs out (4), and they all look physically good.
So I put a ohm meter on each one, and they had continuity from the wire attachment point to the body.
To me, I think they are shorted. They are $38.00 each, and another $24.00 for the relay. I don't want to throw money I don't have at it, guessing.

So, how does one check the plugs to make sure they are bad?

Thanks in advance, Snakeman


----------



## Snakeman (Dec 12, 2005)

Since I got no reply, I Googled testing glow plugs this morning, and found a surefire way to test them, using a battery charger. 
The web sight is in the UK, and they have alot of diesels over there, so I thought, what the hell, and tried it, and one was bad. Shorted

http://www.honestjohn.co.uk/forum/post/index.htm?t=60725

I also found a method of using a test light to check them, and that way showed the bad one to be good. Same with a ohms meter, showed it to be good.

Thought I'd share this for others to use.


----------

