My worried mind.....

[Vtnewbie]

Just replaced the glow plugs in my Branson 4720 tractor. That cured the hard starting problem I was having. Started right up strong at 12 degrees with a dead cold engine. Thanks again Ken of Valenti's Tractor Valenti's Vintage Vehicles L.L.C dba Valenti's Tractor

Now for the worry. Two of the plugs had slight black smudge deposits, but the number 1 and 2 cylinder plugs had white rings around them where they were inside the head. If all the plugs were the same I wouldn't be as concerned, but 2 plugs with black deposits versus 2 plugs with white deposits have me worried. I attached a picture of 1 of each of the old glow plugs I replaced to show the difference.

Do any of my fellow TBNers have an opinion what caused this, and if so, is there anything I can do to fix it before it becomes a larger problem?

[Vtnewbie]

Lots of views but no replies? Did I leave out something?

[Thomas]

Interesting...
How long do let the glow plugs warm before staring turning engine?
Are you useing good winter blend diesel?
Are you running enough RPM's

[retiredmgn]

Opinions don't cost much so here's mine.
Contamination. Cracked head or faulty head gasket.
Coolant is creeping in. The fact that the threads are of a different color within their
length is telling.
But, talk is cheap.

[Ken]

I would think the glow plug could be looked at the same way of looking at a spark plug.
White area the heat burned the fuel away. Black no heat so became fouled
Maybe recheck the area where the 2 became black. They just mignt be getting lesser voltage. or had loose connection.
ken

[pedalstomper78]

It could be any one of a number of things. If you're really worried about it, do some tests.
It's the same in the automotive world as with tractors.....people don't test.
Go to AutoZone and rent a cooling system pressure tester. You get your money back when you take it back. Put it on the radiator cap, pump it up, see if it holds for 20 minutes. If not, there's a problem that needs looked into farther.
Suggestion 2, get a compression tester. Need one that's diesel specific, but Harbor Freight has one that works OK for most applications. Run a compression test.

If those two tests come back normal you can rest at ease. If those show some signs of being "off", well then it's time for farther investigation.

The forums are a great place to find information....but also a great place to find speculation. Only you can determine the real problems with your tractor. We're here to help you find the correct way to do it.

[Vtnewbie]

Thanks to all for the responses! Think I'll be getting those testers.

[Vtnewbie]

Thanks to all for the responses! Think I'll be getting those testers.

[puckgrinder85]

Normal!

The plug sealing area is the tapered area just above the small electrode, anything above that is NOT sealed to the elements and water and such can leak through the threads and pool up down there and corrode. Dont worry about a thing, if they came out thats your biggest concern as usually they break off because of too much corrosion in that area.

[Vtnewbie]

Thanks for the info. I took the tractor in to a diesel engine specialist and they confirmed that the white deposit on the glow plugs was normal for precisely the reason you gave.