Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-18-2012, 11:48 AM
Registered User
 
Join Date: Feb 2011
Location: Baltimore, Maryland
Posts: 314
Glow Plugs Bad......how to tell ?

On one of my MB's (1982 240D) the PO removed the glow plug relay and put a manual solenoid with a toggle switch in its place.
With a relay, according to reports the glow plug resistance controls the amount of time that the plug stays on and controlled by the relay.
Using a manual solenoid, how do you tell when the glow plugs need to be replaced ?

Greg

Last edited by steeleygreg; 01-19-2012 at 12:03 PM. Reason: added year model data
Reply With Quote
  #2  
Old 01-18-2012, 01:17 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,353
Glow plug resistance has no relationship to the length of time they are energized with the OE relay. OE relay has a timer. If you're talking pencil plugs you can get a rough guess of the status of a glow plug by measuring its resistance. It should be 1 ohm or less. This is not a definitive test however. With loop plugs you test for continuity through the loop.
__________________
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
Reply With Quote
  #3  
Old 01-18-2012, 01:22 PM
Registered User
 
Join Date: Sep 2004
Posts: 8,487
Quote:
Originally Posted by steeleygreg View Post
With a relay, according to reports the glow plug resistance controls the amount of time that the plug stay's on and controled by the relay.
What reports?
Reply With Quote
  #4  
Old 01-18-2012, 01:35 PM
Registered User
 
Join Date: Feb 2011
Location: Baltimore, Maryland
Posts: 314
Tangofox007, I probably used bad wording. What was meant is this is what I heard from other owners.

Greg
Reply With Quote
  #5  
Old 01-18-2012, 01:37 PM
Registered User
 
Join Date: Feb 2011
Location: Baltimore, Maryland
Posts: 314
Kerry, yes these are pencil plugs. 82 240D.
Reply With Quote
  #6  
Old 01-18-2012, 06:33 PM
layback40's Avatar
Not Banned
 
Join Date: Nov 2009
Location: Victoria Australia - down under!!
Posts: 4,023
Resistance will tell you if they are definitely bad. It will not tell you that they are good. The ONLY way to determine that they are good is to remove & bench test. It will also allow you to de-coke/ream the holes.
__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
Reply With Quote
  #7  
Old 01-18-2012, 07:06 PM
Registered User
 
Join Date: Jan 2012
Posts: 450
Yes, you need to remove and apply 12V to really tell if they are working.

Does MB use a self-regulating glow plug (i.e. can't burn out from energizing them too long)?

Sincerely,

PE
Reply With Quote
  #8  
Old 01-18-2012, 07:25 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,353
Quote:
Originally Posted by PackerEdgerton View Post
Yes, you need to remove and apply 12V to really tell if they are working.

Does MB use a self-regulating glow plug (i.e. can't burn out from energizing them too long)?

Sincerely,

PE
No
__________________
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
Reply With Quote
  #9  
Old 01-18-2012, 07:38 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 23,333
This one Ohmed out OK but when bench tested was bad.

It gets hottest in the middle when the tip is supposed to be te hottest part.
(This is a Monark Glow Plug.)
Attached Thumbnails
Glow Plugs Bad......how to tell ?-glow-plug-test-ngd.jpg  
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #10  
Old 01-18-2012, 08:33 PM
Biodiesel300TD's Avatar
|3iodiesel300T|)
 
Join Date: Dec 2004
Location: Albany, OR
Posts: 4,845
Quote:
Originally Posted by Diesel911 View Post
This one Ohmed out OK but when bench tested was bad.

It gets hottest in the middle when the tip is supposed to be te hottest part.
(This is a Monark Glow Plug.)
I've always had problems check the resistance and telling they were bad. This is probably why.

I always pull mine and bench test them. Watch your fingers they get hot.
__________________
Andrew
'04 Jetta TDI Wagon
'82 300TD ~ Winnie ~ Sold
'77 300D ~ Sold
Reply With Quote
  #11  
Old 01-19-2012, 01:05 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,105
I moved the new question to it's own thread!
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #12  
Old 03-08-2012, 09:54 AM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 23,333
Hunter speaking of Glow Plugs dieing due to Carbon insulation
Injectors and Glow Plugs for Dummies - PeachParts Mercedes ShopForum
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #13  
Old 02-04-2013, 04:45 PM
turbobenz's Avatar
Registered User
 
Join Date: Nov 2007
Location: Cameron Park CA
Posts: 1,863
The easiets way is to pull the glow plug harness plug at the relay and apply +12 with an alligator clip directly to each pin of the harness (numbered 1-5). No spark, definitely a bad plug (no current).
__________________
1981 300SD 512k OM603


Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 05:34 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page