Need Help with Electrical problem.

olthumpa · Dec 29, 2013

Never thought I would be asking for help with an electrical problem because I am “usually” pretty good at chasing them down. Just to keep it interesting, it is an intermittent problem. Sometimes when I use the glow plugs the connection where the fusible link is connected to gets hot enough to smoke and start to melt the connection. The wire does not get hot and the link does not burn.

I have torn the dash complete apart and used a VO meter and visual inspection both with the ignition on and off. I can not find any shorts, melted or bare wires or lack of continuity where there should be or continuity where there should not be. I have also used an IR gun to look for hot spots, you guessed it, I found none. IR gun shows glow plugs and indicator heating up, (sometimes with smoke from the connection other times none). Continuity on all three plugs check positive. I have not pulled the glow plugs out yet. To do that I have to remove the fuel lines to the injectors and remove the intake manifold to take them out. I replaced the glow plugs about two year’s age.

I come up with three things it might be: bad switch, bad glow plug indicator, maybe bad glow plug.
I was going to NAPA yesterday so I took the battery and had then check and load test and it is OK. (don’t see how a bad/weak battery could cause this but checked it any ways)

Silly me, I thought after the clutch and rear diff problems that this would be easy.

Any help greatly appreciated.

85Hokie · Dec 29, 2013

olthumpa said:
Never thought I would be asking for help with an electrical problem because I am “usually” pretty good at chasing them down. Just to keep it interesting, it is an intermittent problem. Sometimes when I use the glow plugs the connection where the fusible link is connected to gets hot enough to smoke and start to melt the connection. The wire does not get hot and the link does not burn.

I have torn the dash complete apart and used a VO meter and visual inspection both with the ignition on and off. I can not find any shorts, melted or bare wires or lack of continuity where there should be or continuity where there should not be. I have also used an IR gun to look for hot spots, you guessed it, I found none. IR gun shows glow plugs and indicator heating up, (sometimes with smoke from the connection other times none). Continuity on all three plugs check positive. I have not pulled the glow plugs out yet. To do that I have to remove the fuel lines to the injectors and remove the intake manifold to take them out. I replaced the glow plugs about two year’s age.

I come up with three things it might be: bad switch, bad glow plug indicator, maybe bad glow plug.
I was going to NAPA yesterday so I took the battery and had then check and load test and it is OK. (don’t see how a bad/weak battery could cause this but checked it any ways)

Silly me, I thought after the clutch and rear diff problems that this would be easy.

Any help greatly appreciated.

thumpa,

I know this might be a crazy thought, but could the fusible link be going bad? Is there a fuse in it or is it the type that burns and you must replace it?

OT - I have a stereo in my car and an amp.....not sure that you know, but a little blue wire off the back of the stereo "tells" the amp to cut on....well my amp would just stop working, no power, then it would work, then off...etc...
checked and rechecked the blue wire and each time I messed with it, I could get it to work for a while....long story short - I had to pull the amp out one day, so to do that I pulled the 20A fuse that runs to the battery.....it fell apart in my hand.....the fuse in the holder was basically broken! I cleaned the fuse holder and placed a new fuse in and poof, never another problem.
Could the fusible link be such that too many amps are flowing across a small or corroded wire that is hard to spot inside the FL?? A VOM would show it being good but when a load is placed on it ........can you replace it just for S & G's???

mendonsy · Dec 29, 2013

It is fairly common for glow plugs to lose resistance as they fail and eventually become a short circuit. You might try measuring the resistance to ground of each of them to see if they read the same. New ones are typically in the 0.5 to 1 ohm range depending on the type.

lsmurphy · Dec 29, 2013

I'm with Hokie on this one.

I'd replace the fusible link with a new wire and a breaker.

I'd also replace the indicator......it is a resistor......correct? I think they are cheap also.

I'd consider replacing the wire to the plugs also.....is yours a solid and not stranded wire? they can get brittle.

olthumpa · Dec 29, 2013

85hokey
"I know this might be a crazy thought" I am open to crazy thoughts as I have exhausted all of the sane ones I could think of.
It's the type that burns and you must replace it. I have to replace the plastic connector as it is half melted and brittle. (see attached photo - 4 in line)
I did not think of a bad link, it is flexible and does test ok but I will replace it.
It is thinner than the two wires that it connects.
Would a bad link cause the out put side, the end of the link furthest from the starter to heat up hotter than the end closer to the starter?

mendonsy
On a 20k ohm setting on the meter I am getting a reading of 12.40 ohm on all three plugs.
Would bad glow plugs cause the connection to melt? My guess is yes.
What is your recommendation as far as them being good or bad?
I never tested tested glow plugs for ohm's before, I just replaced them when it started to take longer for them to heat up.

Thanks for your help.

skrap1 · Dec 29, 2013

What resistance should the glow plugs read? I've got a L175, each plug reads 1.9 ohms with a digital meter. The indicator starts to glow after about 8 to 10 seconds (at 40 degrees F). All I've ever read is that the plugs should read less than 5 ohms.

olthumpa · Dec 29, 2013

lsmurphy said:
I'm with Hokie on this one.

I'd replace the fusible link with a new wire and a breaker.

Plan on replacing the wire. Any rcommendations on a breaker.

I'd also replace the indicator......it is a resistor......correct? I think they are cheap also.

The indicator is a resister and I think it is $13 +-.

I'd consider replacing the wire to the plugs also.....is yours a solid and not stranded wire? they can get brittle.

The wire is stranded but not brittle. I will replace it.

I had planned on rewiring the whole tractor this past summer, all wiring, fuse block alternator etc but time and money have conspired against me as well as a new clutch, rear diff and other parts. Now shooting for this coming summer.

Thanks for the help.

olthumpa · Dec 29, 2013

Glow plugs were replaced 04/2011 with Kubota plugs.

chim · Dec 29, 2013

Bad connection at the link would be my first guess. The end that gets hotter is where it is. Your glow plugs and everything else are most likely OK.

Lots of fires start because of a bad connection. The problem is a poor connection produces heat even when the wires are carrying less than their rated current. Since there is no excessive current, the fuse or circuit breaker sits there thinking everything is just peachy. Imporperly tightened screws on a receptacle have caused many fires.

Heat, measured in watts = current in amps x current in amps x the resistance in ohms. A loose screw/wirenut/etc provides the "ohms" and becomes but a small heater when current passes through it.

I can't tell from the photo if you can re-make good solid connections. It looks kinda toasted. You may need to replace the link.

85Hokie · Dec 29, 2013

thumpa,

Another electrical story.....
in college - started my 71 ford torino - all the gauges are pegged.....hot on the thermo, full tank gas.....just started the car, and KNEW I had only 1/2 tank unless someone peed in the tank!
anyway.....
lights didnt work, radio didnt work......

got it home, took it to a buddy at Advance Auto.......tested the charging system, said my alternator was charging almost 17 volts......said I needed a new battery, bought one.....that hurt....then the same sht again......ford said I needed a new VR, bought it too, didnt help one @#!$@#! bit!!!!

One night I am going on a date, car still acting funny, pop the hood and start grabbing wires......radio came on strong!!! THE @#$@#$#@ grounding strap was about the size of a small paper clip!, it had worn away rubbing something wlse!!!! I went inside and placed a coat hanger wire from point to point....

learned my lesson ! ALWAYS CHECK GROUND first........doesnt apply to your situation, but it leart me a lot !!!! ( 30 years ago !)

North Idaho Wolfman · Dec 30, 2013

olthumpa,
If your problem only occurs when in pre heat mode it really could be any thing from the Wire, fuse, switch, indicator, or glow plug.
This would be my plan of attack, Start by removing the positive battery cable off the battery, attach an Ohm meter to the positive cable and to ground, read OHM's (should be infinite) turn key to preheat should go to a value (?) if it's real low like in the Ones, then you have something that's shorting (Bad glow plug or indicator probably) if it's too high like thousands, then you have a partial open / high resistance spot (bad switch, wire, connection,... literally any part) then you have to start breaking it down to find the bad part or parts, If you find one bad part still check for others!

85Hokie,
Don't think that a ground problem can't be relevant in this situation because it can.
Bad ground connections can cause other things to go wacko too.

olthumpa · Dec 30, 2013

Wolfman

The problem only occurs when pre heating and not every time.
I tested the wires individually. As everything is apart I will have to plug things back in to do the ohms testing as you suggest, why didn't I think of that.

With a ghost problem, I learned long ago to check everything out before you call it good.

I am cleaning ALL connections before reassembly.

If a job is worth doing, it is worth doing right!

Thanks for your always useful help.

chim · Dec 30, 2013

I'm fairly certain that there is a connection that is loose, dirty or corroded right there on the link. I don;t know how the connection is made, but some of those male/female Stakons lose their "spring" and don't mate tightly.

mendonsy · Dec 31, 2013

The 1.9 ohms resistance value sounds reasonable for a glow plug. That would draw about 6.5 amps per plug and produce about 75 watts.
There are other glow plugs that draw even more current. A new Mercedes Benz glow plug is 0.71 ohms and draws 16 amps.

bmisch01 · Dec 31, 2013

your connection must be good, glow plugs pull high amps, any loose or weak connection will overheat, over time open connectors let the terminals get corroded, before replacing glow plugs, I would make solid connecions , remove the connector & connect wires solid, might save lots of time & money, also check all ground & make sure they are clean & tight, a bad ground will have you chasing your tail for hours.hope this helps

cb750k8 · Dec 31, 2013

Hi
I support most responses on this one but would go with Chim's. Keep in mind that current flows from Battery + all the way round a system to Battery -. If there is heating where it should not be then there ( the connector) may be the problem.

Check if the fusible link is a fusible link ?. Previous owners have replaced these, when they blow, with copper wire !!. Could be your fusible link should be heating up and blowing and not the connector.

Cheers.

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