For an om617- what would the upper limit be? I have a few plugs that are testing at 4.5 to 6 ohms (engine warm, if that matters) and want to know if I should replace them.

Thanks.

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I could not own any MB without the help from you...fellow forum members.


83 300td 207,XXX

1.5--2 ohms is what I've seen stated before. Yours seem high to me. Best way to check is to pull them out and put 12 volts to them.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Do NOT touch the glow plugs!!!!

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
Cluster Needles Paint
New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more

As the get hotter the element reistance of the glow plug increases. If you are getting say 1 ohm readings on some plugs and at the same time basically 4.5 ohms or so on others.

It is a pretty sure thing you have to examine things more carefully. Since there may be variables present. Pulling them and doing a direct voltage test application for observation may be best.

If a plug and its feed wire from the timer box is showing 4.5 ohms something is not normal.

.

you have to be precise
first do you meter correction readings
(probe wires head to head)

I practice to change any above 1 ohm - measured cold GP only.


from your post I would say that you have those 6 ohm to change

.

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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered