Help Diagnose Glow Plugs- IH B-275

So I have resurrected my granddads 1960 B-275 that has been sitting for about 7 or 8 years. One of the things that I can NEVER remember working on the tractor was the glow plug system. My granddad always used a shot of ether to start it.

I am interested in getting the glow plugs working so I started digging into it today. I took the dash panel off to see how the wiring was and make sure somebody didn"t rig something up over the years. Low and behold wiring is all there so I checked some voltages with my multimeter. I have 12.65 volts on the turn switch. When I put the multimeter on one battery cable and touch it against the first glow plug wire I get 0.00 volts when the switch is not turned (seems correct so far to me) and when I turn the switch sometimes I will get a reading of 12.65 volts and other times I will get a reading of 6.5 volts. The 2 voltage variances can be different literally seconds apart from the other.

I believe the indicator on the dash is a resistor (correct?) and the reading at the first wire on the glow plug should be 6 volts??

Where do you guys suggest I start? Does it seem like I need a new resistor or all new glow plugs? I am probably going to buy all new glow plugs anyway since they are cheap but I don"t know if I need a resistor. The resistor gets really hot, which I assume it"s supposed to anyways when functioning correctly. What is the resistor indicator supposed to do anyways when working? I didn"t even know if mine was getting any power at all until I took the dash off and noticed it was hot. Otherwise, if it is supposed to light up or something mine does not do that.

Another question, when the system is working correctly how do you go about using the glow plugs? I am not familiar with them especially on an old tractor? How do you know how long to hold the switch down for?

Thanks

Ryan

Hi Ryan, Re glow plugs, if it was my tractor I would replace the glow plugs with new style like jdemaris did in the following post.

See:
http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=farmall&th=955091

Re the current glow plugs:
You are correct the indicator on the dash is a resistor and gets hot and glows in the dark, Don't hold the switch on to long or you will burn out the indicator. The 6V you measured at the first glow plug is about normal. If the reading is 12V then one or more glow plugs are burned out. The glow plugs are wired in series. Take note of how the copper wires goes between each glow plug, the outer and inner pattern. The last glow plug is grounded to the engine block by the water pump. I would clean the contacts on the copper wires and the bolt on the engine block. DO NOT put 12V directly on a glow plug or it will burn out.

Re using the glow plugs, a lot depends on the condition of the engine compression and the temperature of the engine block. I live in Canada about 150 miles north of Watertown NY and in summer when temperatures in the morning where in the 60 to 70F, holding the glow plug switch for about 30 seconds or when the dust just started to burn off the dash indicator was enough to start the tractor and once tractor was warmed up it could be shut off and glow plugs were not required again for a start.

In winter it was a different story, had to hold glow plug switch until dash indicator glowed red and sometimes if tractor was shut off for an hour or more and engine cooled off, the glow plugs were required for a start.

DO NOT USE glow plugs and ether together.

Hope this helps
JimB

Those original glow plugs operate at one volt each and are all wired in series. I.e. four plugs and the indicator in the dash with the same resistance. All five items wired in series. If any one of them is bad - nothing will work.

Do yourself a favor and convert to Bosch 12 volt plugs wired in parallel. Makes a huge difference in starting with a B-275. Especially if it's an old one with the air-governed in-line CAV injection pump.

A few photos . . .