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  #1  
Old 01-14-2004, 11:01 PM
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Penetrating oil on GPs - safe?

Hi,

To my knowledge the Glow Plugs on my car have never been replaced. The car starts fine to about 10F without a block heater, so Id have to assume they are working well, but reading all the posts in the archive about stuck glow plugs and troubles if the head breaks off, etc., I worry a bit, and think that I will replace all 5 (PEH isnt here, so its OK )

I will be doing diesel purge for the first time ever in a week or two, so I figure after then is an optimal time to do it.

But, to ensure an easy job, I want to start using penetrating oil on the outside.

My question is, is that safe? Will the residues from the penetrating oil cause more harm than good in the long run? Or is it unsafe to have that stuff slowly burning off as I use the car?

Its either spray them every few days and keep using the car (the oil will burn off when I run it, but at least itll work in when it sits), or if thats too risky, Ill just do it the last day to two.

Any comments?

JMH
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #2  
Old 01-14-2004, 11:47 PM
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In the latest GPlug talks some have stated they use various screw loose type products on their GP's. Did not hear anything about problems caused by this. Did not hear it helped a whole heck of a lot either. Maybe it needs to be shot everynight for a week or so before attempting to pull them?

Talk I hear is that the best stuff is "PB Blaster"
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The Glow Plug Wait: This waiting period is a moment of silence to pay honor to Rudolph Diesel. The longer you own your diesel the more honor you will give him". by SD Blue

My normal daily life; either SNAFUed- Situation Normal... All Fouled Up, or FUBARed- Fouled Up Beyond All Repair

62 UNIMOG Camper w/617 Turbo, 85 300SD daily driver- both powered by blended UCO fuels
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  #3  
Old 01-15-2004, 08:48 AM
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No, you could have a heck of a time on the cast iron head too. # 5 GP on my 300D sheared off and it was a bear to get the rest of it out. Had to remove the oil filter housing and drill most of it out, then pull the injector and vacuum out debris. Just a little stressful! I'd give them all a shot of Liquid Wrench or similar every day. I used a copper based anti-sieze on the new ones, too. Nothing like drilling into a perfectly good engine to make one cautious!

Fred
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  #4  
Old 01-15-2004, 09:06 AM
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Yeah... scary. Thtis is why I figure its smart to replace them... I dont want to deal with this sort of thing, and I figure every time that they get hot, every time I drive 100mi, etc., they get a little weaker.
I figure new ones can at least last me another 100k before I have to think about it again, since these have lasted 216k

JMH
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #5  
Old 01-15-2004, 09:20 AM
I told you so!
 
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Yes, it's a good idea to let the threads soak in penetrant for a while, but not so long that it dries out. I believe penetrant is formulated with a mild acid. Once it does its job it should be cleaned.

Ditto on PB Blaster (also Kroil).

Definitely put a light coating of antisieze on the threads before installation.
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  #6  
Old 01-15-2004, 09:48 AM
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I have always made a habit of penetrating oil on the glow plug threads at least the night before I am going to remove them ever since I broke one off in a VW diesel. I prefer Kroil, that's what I am using these days and definitely either nickel or copper antisieze on the threads prior to installation.

Tom
'82 SD
'86SDL
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  #7  
Old 01-15-2004, 10:05 AM
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JHZR2,

I would not tempt fate and fix something that is not broken. If your present set of plugs work, and are not stuck, how have you improved the situation by replacing them with new ones? And if you go to replace them and one or more are stuck, and you damage them in the process, they won't work and you will have to replace them. When you are done, you will have at least temporarily "unstuck" glow plugs, but they will be no more functional then the ones you have in there now.

You apparently have an unusually robust set of glow plugs, or a set that is nearly perfectly matched to the glow plug relay, or are just lucky. I guess giving them a spritz of WD-40 or PB Blaster or Liquid Wrench every now and then to ward off the demons might not be bad, but I would definitely not replace them as preventative maintenance. There is documentation of problems getting them out, having poor quality plugs from any manufacturer as replacements, and generally difficulty reassembling, requiring reaming tools and the like. And, on your engine what makes you think a new plug is less likely to stick than an old one that may not be sticking yet?

I have changed glow plugs on our 240Ds and the 220D a number of times each, and never had a problem. Some were a little distorted when they came out, but I have never had one stick. The biggest problem is getting good access so you don't apply any bending moments as you try to remove the old plugs.

Good luck, Jim
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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
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  #8  
Old 01-15-2004, 10:22 AM
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OK, good point...

Yeah, replacing them for the heck of it isnt all that great of an idea, but I figured that even though no starting ease would be gained from the replacement, at least Id know for sure that I had some plugs in there that were clean (not carbon encrusted so that their heating isnt all that great) and had anti-sieze on the threads.

Its like 50/50, some have no problem ever, others have them break. My thinking is that replacement with high quality bosch plugs will at least leave me with a baseline of how old they are, and I will have the piece of mind that they are OK and not siezed. Right now I have no record of any ever being repalced, the car starts fine to about 10F on one or two glows after sitting overnight, with no problem but an occasional nailing for 5-10 seconds at very cold startup, which goes away with a slight depression of the pedal and never returns.

Sounds like all is well, right? Id say so. But what if one of those glow plugs is on its way out, and the fatigue of glowing and being there while driving another 3 or 4000 miles, or even 30 or 40000 for that matter will be enough to cause it to break or be more stubborn.

I know PEH has some original plugs after 300K in his 78 and 79 cars, so its not a bad idea to leave them alone. And, your letting me know that you have not had any troubles makes me feel more secure.

I suppose my thinking is that replacing $40 worth of glowplugs while I can might save me $400 worth of work later when they are older and more likely to break.

But Im not as worried now...

JMH
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #9  
Old 01-15-2004, 11:11 AM
R Leo's Avatar
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Trans-X for rust...

"Rust Buster," a citric acid-based penetrating liquid also works well on reluctant fasteners. I'm a huge fan of Kroil but IMHO, Rust Buster is what I'd use first on a fractious GP.

I worked in the appliance repair industry for about 15 years and have used this stuff hundreds of times on rusted, ancient appliances to successfully remove seized fastners.

It's sold in a 'zoom' spout dispenser bottle and, in the past, I've bought it at appliance parts distributors like Johnstone Supply.

To get some, go here (www.johnstonesupply.com) and keyword search on "Rust Buster." I think you can even find a 'location near you' through their website.

For the DIYer, I'd be willing to bet that a strong mix of MBZ citric acid cooling system flush and water, applied to the outside of the GP area would accomplish the same thing as rust buster.
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  #10  
Old 01-15-2004, 03:52 PM
jcd jcd is offline
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Jim Smith is right again

I replaced my GP's last year, the original ones, as ill conceived preventative maintenance. In fact, I got hollered at by PE Haiges for doing so.

I had two go bad in the last year,,, all Bosch.

If it ain't broke don't fix it,,,,, but if you can't help yourself, take your time and use plenty of the penetrating oil recommendations.

Final note, my 300D is a 1977 and the original plugs worked just fine. I wish they were still in my car.
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  #11  
Old 01-15-2004, 09:44 PM
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I just changed the glow plugs in my 300SD. I used Kroil Oil and PB Plaster liberally with no problems. Doing the job without removing any of the injector lines is a bit tricky. None of my glow plugs were bad but I'm glad I changed them. At least three were very hard to get out and carboned up pretty good. I used the "screw them out of the carbon" technique which worked well. I didn't have the special reamer but I wish I did. I'll just have to wait til next time to ream out the carbon.
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  #12  
Old 01-15-2004, 10:33 PM
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That was kind of my thinking in wanting to change them... At least Ill know they arent siezed/carboned up.

I might just leave them all, but unscrew them all, blow the carbon out, and coat them with anti-sieze. But its too cold to do it in the next number of days.

Can you enlighten me as to what you do in the 'screw it out of the carbon' technique?

Thanks,

JMH
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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