loop to pencil glow plugs upgrade, 1978 300D - PeachParts Mercedes-Benz Forum

Diesel911 · #1 11-22-2013, 11:23 AM

Quote:

Originally Posted by Left Coast

My Google turns up a handful of bad reviews for Monark glow plugs; nearly as many reviewers state that they haven't had any problems with them, and not too many of the comments are more recent than 3 years ago. My own experience puts me in the latter group. I bought four Monarks last year for my '83, and they still work fine.

I think that if you have an opinion, then it's OK to state your opinion-but if you have no firsthand experience to convey, then you do nobody any favors by overstating your opinion.

Perhaps it's because I have a low-mileage engine and it doesn't get very cold here, but the upgrade on my '79 really didn't make much difference. I do get faster starts with the pencil plugs, but I never had starting problems to begin with. I went with the 80035's because they were only a couple of bucks more than straight replacements. If the loop plugs are in good shape, and you have clean pre-chambers, then they will certainly get the car going. They just take a minute longer.

I think sharing information is what the Forums are about; even if it is saying this is what others have said.
I the case of cooljjay He gave His opinion and said see for yourself.

In installed Monark Glow Plugs in My Car and one died about 1.5 Years later. That is in Southern California weather, Glow Plug Holes Reamed and low mileage driving on Injectors rebuilt 2 years before.

It was a sneaky one. It ohmed out OK but as you see in the pic it gets hottest in the middle of the Element.
Also after I took that pic and it cooled off I Ohmed it again and it failed and when I tested it on the Battery again it died!

Left Coast · #2 11-22-2013, 01:20 PM

Quote:

Originally Posted by Diesel911

I think sharing information is what the Forums are about; even if it is saying this is what others have said.
I the case of cooljjay He gave His opinion and said see for yourself.

I agree, and seeing for myself caused me to conclude that his argument was very weak. He has his right to his opinion, and I have my right to assert my opinion that his opinion is based on very little research and no first hand experience. Since there is very little hard data to help us decide about many of the things that are discussed here, a variety of opinion and anecdote is about as good as we can get. I did see for myself, and I shared my results. I'll reiterate them: Google turns up few reviews on Monark plugs. Not all of them, and not even an overwhelming majority, are negative. Few of them are more recent than 2010, and that fact is worth considering in a rapidly changing world. Judging from the sample size and age of the reports, I found nothing that would influence my own decisions.

I recently read somewhere (and regretfully, I can't provide the link), that Monark did experience manufacturing problems in the 2008-2009 time frame, and they have since corrected their quality issues. I don't know if that is true.

While opinion is perhaps the best information available, much of the opinion shared here and elsewhere is regurgitation, and much of that is not quality information. Everyone should understand that and dig deeper.

Your own account of your experience doesn't indicate when it happened either. I'm not implying that your experience is worthless to me, but it carries nowhere near the weight of controlled test results. Unfortunately, there seem to be no controlled test result. BTW, I had the same experience once with a Bosch plug. Based on that, I wouldn't condemn all Bosch plugs. Would you?

Shortsguy1 · #3 11-22-2013, 02:07 PM

Quote:

Originally Posted by Left Coast

BTW, I had the same experience once with a Bosch plug. Based on that, I wouldn't condemn all Bosch plugs. Would you?

I have had several failures of Bosch loop GPs in my 220D and no longer use them. I found a bunch of Beru NOS GPs and they have been better than Bosch for me. My car runs hot and and some internal part of the Bosch loop plugs was failing. The same has not happened with Beru. Again, this is only for Bosch loop GPs, which were made in India.

I have recently installed Bosch pencil GPs in my w124 (made in France, by the way), and they seem to work great.

Diesel911 · #4 11-22-2013, 09:00 PM

Quote:

Originally Posted by Left Coast

I agree, and seeing for myself caused me to conclude that his argument was very weak. He has his right to his opinion, and I have my right to assert my opinion that his opinion is based on very little research and no first hand experience. Since there is very little hard data to help us decide about many of the things that are discussed here, a variety of opinion and anecdote is about as good as we can get. I did see for myself, and I shared my results. I'll reiterate them: Google turns up few reviews on Monark plugs. Not all of them, and not even an overwhelming majority, are negative. Few of them are more recent than 2010, and that fact is worth considering in a rapidly changing world. Judging from the sample size and age of the reports, I found nothing that would influence my own decisions.

I recently read somewhere (and regretfully, I can't provide the link), that Monark did experience manufacturing problems in the 2008-2009 time frame, and they have since corrected their quality issues. I don't know if that is true.

While opinion is perhaps the best information available, much of the opinion shared here and elsewhere is regurgitation, and much of that is not quality information. Everyone should understand that and dig deeper.

Your own account of your experience doesn't indicate when it happened either. I'm not implying that your experience is worthless to me, but it carries nowhere near the weight of controlled test results. Unfortunately, there seem to be no controlled test result. BTW, I had the same experience once with a Bosch plug. Based on that, I wouldn't condemn all Bosch plugs. Would you?

I said what I did mainly to show that a Monark Glow Plug can fail even in Southern California weather.
If one Person cannot use information someone puts out another Person might.
There was no controlled test because I do not have any sort of Laboratory with expensive test instruments.
Story:
I had symptoms of a failed Glow Plug = nailing on what sounded like one Cylinder (notice that this is a subjective as I have not read a really good description of what is Nailing and what is not).
I checked them with an Ohm Meter and they were all the same; none obviously different.

So, I pulled the Glow Plugs and tested them on a Battery and found that one got hottest in the Middle while that other got hot at the Tip.

After the thought to be defective Glow Plug Cooled off enough to be handled I retested it with the Ohm Meter and it failed. Also when I put it on a Battery again it did not get hot at all.

And since then Glow Plug wise I have happily ever after for at least 3 Years now.

What did I learn. Considering price, availability and longevity for My Engine Bosch Glow Plugs Rule the Roost.

Left Coast · #5 11-23-2013, 01:08 AM

Diesel 911, You don't need to defend your opinion! I certainly don't feel that your process was flawed, and I wouldn't expect you to have done extensive controlled experimentation just to be able to post your opinion. You conveyed personal experience, as I did, and left it at that. Even though you indicate a bit of a bias, you do have some justification for that bias, and you haven't suggested that using a brand you don't prefer is a mistake. That's pretty well balanced.

The previous owner of my '79 240D managed to squeeze 18 years out of the original glow plugs before he needed to replace them. His second set was still in use when I took possession 10 years later. Were they superior quality? Maybe, but based on that information, it is still not reasonable to conclude that glow plugs should last for 10 or more years. Perhaps the facts that the car had had been driven less than 20K in its first fifteen years, and that the PO always used the block heater, year round, before he started the car every day, greatly extended their life. His experience does not give anyone reason to think that a set of glow plugs should last anywhere near that long. With a good data set, that single experience would be an outlier, and it would be (statistically) meaningless.

Point is, that there is no statistical evidence or results obtained from controlled experimentation to guide us in making this particular choice. I'll leave it at that.

Stugist · #6 11-23-2013, 02:04 AM

I actually have firsthand experience with Monark plugs. Hell, the same one's in that "kit" you purchased. I did purchase this kit myself a few months ago. I will give it this; they worked beautifully and made the car so much nicer to start when cold.

HOWEVER, please note the word "worked".

2 failed almost instantly on the 1 month mark. I did a full diagnosis of the GP system and the only plausible cause was a premature failure. I still have the plugs sitting around; they're brittle. Not very good....I'm really lucky they didn't snap on me. I immediately bought some Bosch large-bore plugs from Pelican and they've worked flawlessly for the past few months. And in the much colder weather to boot! I can't imagine those Monarks in weather like this...

TL;DR, These "opinions" against Monarks that people rant about have much credibility to them. The fact is they make a shoddy plug.