How to test glow plugs

[bcwayne]

I added another kitty to the fleet today... D2 5U183xx... placed into service in April 1957 working in the orchards in the San Joaquin Valley of California.
Its my first factory equipped direct electric start with glow plugs...

I have two questions: how does one test each glow plug to insure that its operating as designed ??? ( the amp gauge does show a healthy discharge when activating the pre-heat switch )

How long should I have to heat the glow plugs before starting the engine when the ambient temp is 40 to 50 degrees F ???
Thanks, Wayne

[KCB]

bcwayne;

Nice tractor. It also has the rear #41 Hydraulic unit.

Each glow plug should pull about 7 amps (28 amps for all four). You can disconnect the wiring at the top of the glow plugs, then plug only one in at a time and check the current draw. Do this individually for 1,2,3, and 4, if each test shows 7 amps then each is working. Another crude test is to disconnect all wiring at the top of the glow plugs, hold the heat switch on, then touch the wire to each glow plug - if you see a spark it is most likely working. The starting instruction decal shows the following:

Above 60 F ... No heat switch needed
60 to 45 F ... Heat on 45 sec
45 to 32 F ... Heat on 1 min
32 to 20 F ... Heat on 2 min, plus use 1 either capsule
20 to 10 F ... Heat on 3 min, plus use 2 either capsules

My experience in 40 - 50 F weather is to use 1 minute, I usually time it with a clock. At the time it seems like a long time, but it is of little value to go much less than 1 minute. Once the engine has run a while, if you do a shut off and a second start within 4 hours, you probably won't need to use the heat switch.

[bcwayne]

KCB, Thanks for the information... I wouldn't have thought it necessary to pre-heat for a minute or more.... I'm used to the modern day diesel in my pick-up truck that takes only a few seconds to pre-heat. I need to get some new batteries and when it stops raining I'll give her a try. Wayne

[Dunefanatic]

Nice Ride Wayne! Very straight tractor. I have to ask what the two little fittting looking thingies located under the battery disconnect switch on the firewall are? I have never seen a Cat 41 pump on the rear of a D2 so that picture was very illustrative.

Kent is correct that I have found on my direct start after it had the new glow plugs and injectors installed, when starting I get a guaranteed quick start when I pre-heat the glow plugs for a minute and leave the glow-plug switch on while hitting the starter switch.

Greg

[side-seat]

The thingies look like the place you put an ether cartridge in and press down to puncture them.

[ronm]

Have to tell my glow plug story-back in the 70's I was at the JD store, & the ol' grouchy-ass parts man came back into the shop w/a glow plug out of a 2010. Asked how to check it, so I gave him a couple jumper wires & showed him how to hook it to a battery...about 30 seconds later a string of profanity issued from the area of the charger bench, & the plug flew across the shop...I asked, what happened, Bill? He said "That SOB got red hot right where I was hangin' onto it!!!" I said, "Well why do you think they call 'em glow plugs?" He swore I did it on purpose, but I never had any idea he'd hang on to the hot end... Gave everybody in the shop a good giggle, anyway...

[jmvmopar]

Just unhook the wire to the glow plug. Connect a test light to battery + (assuming a - ground system of course) and touch the test light to the terminal of the glow plug. If the test light lights up the glow plug is good.

[bcwayne]

Installed new batteries... pre-heated for one minute... and she fired right off. Life is Good.

[Soapy]

KCB, Thanks for the information... I wouldn't have thought it necessary to pre-heat for a minute or more.... I'm used to the modern day diesel in my pick-up truck that takes only a few seconds to pre-heat. I need to get some new batteries and when it stops raining I'll give her a try. Wayne

Wayne, the plugs in your modern diesel pickups are 6-volt, that is why they heat so fast.

[83Jim]

Since the machine starts the issue is pretty much moot but, my understanding is that most Cat glow plugs of that era draw 5 amps each. If the machine has a working amp meter it should indicate 5,10,15 or 20 amps discharge depending on the number of plugs working.