How To Clean Diesel Glow Plugs

Cole Sabigh1956 · Wednesday, 17 November 2021

Update. What the hell I'm baffled.

So here's my troubleshooting results thus far...

Battery voltage into GP Relay 12.54V
Strip fuse 12.54V both sides.
Glow plugs front to back of engine, number 1 at front...
1 = 0.3 Ohms
2 = 0.2 Ohms
3 = 0.3 Ohms
4 = 0.3 Ohms

Inside the sockets for the glow harness connector.
1 = Nothing. No reading at all, as if I hadn't even connected the probe to it.
2 = 0.8 Ohms
3 = 0.8 Ohms
4 = 0.8 Ohms

With the ignition on and testing the each prong in the relay...
1 = 12.47V
2 = 12.47V
3 = 12.47V
4 = 12.47V

And I kept the probe on the tip of Number 1 prong till the relay kicked off and it immediately went to 0V.

I then tested the plugs that I pulled last year. They were Bosch made in France.
Three tested 0.3 Ohms, the fourth was 153 Ohms, so I marked that as bad.

Assuming that my problem was number one cylinder plug I removed it from the chamber and found it to be covered in carbon. I pulled number 4 as well and found it to have almost no carbon and completely clean tip.

I assumed that as the only discrepancy was the reading in the socket to # 1 plug that if I had both #1 and #4 outside the engine when I ran the cycle I should see # 4 light up and # 1 not. So I reattached the two plugs to their respective wires, held them in place with clamps in the engine bay so I could watch them and turned on the ignition.

The cycle lasted about 25 seconds and neither plug glowed.

I Used one of the old Bosch plugs that tested good in place of # 4 it repeated the process and still no glow.

So what is going on here? Am I looking at a new harness and or all new plugs?

- Peter.

__________________
2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S