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  #46  
Old 12-03-2011, 10:09 PM
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Quote:
Originally Posted by t walgamuth View Post
I thought our starters had bearings instead of bushings.
A bushing is a type of bearing AFAIK. The ones I replaced are sintered bronze I believe. It is definitely not ball bearings. A bushing type bearing is also called a sleeve bearing.

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  #47  
Old 12-03-2011, 10:55 PM
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Originally Posted by vstech View Post
that is a great picture. imagine the plug is in a chamber of carbon from lack of reaming, and only the tip is inside the prechamber... fuel is going to spray on the tip, and turn into a warmed mist... not instantly vaporize and ignite...

so, Kerry, did you only ohm the plugs, or did you actually pull them, and found only one not working?

I agree. If the Plug gets hottest in the middle of the Element and there is any Carbon the heat is more likely to try to heat up the Cylinder Head instead of the Air in the Precombuation Chamber.

Ignore the arrows in the pic, they were for something else.
Attached Thumbnails
One bad glow plug--no start-w-glow-plugzb.jpg  
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  #48  
Old 12-03-2011, 11:30 PM
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Originally Posted by layback40 View Post
Most of the resistance test supporters go quiet when they are reminded that the test only shows when a GP is definitely bad. It does not show that it is definitely good. The only way to show a GP is definitely good is to remove it & test it. On that point any intelligent person would concede.
Since reading for content is not one of your strong points, allow me to educate you on the content of this thread.

Although you may believe that a glow plug that doesn't glow white hot is no good, it has been conclusively shown by those on this thread that the plugs with reduced tip temperature are utilized to start these engines on a daily basis. The reason that I state "conclusively shown" is the fact that only one member has stated that he felt the engine start on four when all glow plugs checked out acceptably well with the resistance check.

The remainder of the members don't have any issues starting these engines with less than perfect glow plugs.

Of course, you wouldn't so ignorant to make the conclusion that all these members are operating glow plugs that all glow white hot?

No, I'm sure you wouldn't do that...........because that would be just stupid.
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  #49  
Old 12-04-2011, 01:04 AM
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Originally Posted by Brian Carlton View Post
Since reading for content is not one of your strong points, allow me to educate you on the content of this thread.
Personal attack !!
You have no knowledge of my reading skills a part from having seen a copy of my engineering degree.
Best keep you comments on the topic.

Can you please provide a link to some credible information from a GP manufacturer that supports the theory that on can rely on resistance testing to determine if a GP is serviceable.

Quote:
Originally Posted by Brian Carlton View Post
Although you may believe that a glow plug that doesn't glow white hot is no good,
I have not stated this & so it is a factually incorrect statement.
There is an earlier post with a pic of a GP that has no glow on the end yet the resistance was as expected from a good GP.

Quote:
Originally Posted by Brian Carlton View Post
it has been conclusively shown by those on this thread that the plugs with reduced tip temperature are utilized to start these engines on a daily basis. The reason that I state "conclusively shown" is the fact that only one member has stated that he felt the engine start on four when all glow plugs checked out acceptably well with the resistance check.
This is a factually incorrect statement. Please provide a link to a credible reference that gives the range of acceptable resistances to achieve an acceptable glow.

Quote:
Originally Posted by Brian Carlton View Post
The remainder of the members don't have any issues starting these engines with less than perfect glow plugs.
If that was the case there would not be so many threads on here about GP's.


Quote:
Originally Posted by Brian Carlton View Post
Of course, you wouldn't so ignorant to make the conclusion that all these members are operating glow plugs that all glow white hot?

No, I'm sure you wouldn't do that...........because that would be just stupid.
I cannot speak for the other members you mention. I am not that arrogant.
As mentioned before & an example pictured, a GP can have a resistance that is about typical yet not have a satisfactory glow pattern.
If you have not experienced this, best put it down to lack of enough practical experience.
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1980 300D now parts car 800k miles
1984 300D 500k miles
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  #50  
Old 12-04-2011, 09:44 AM
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Quote:
Originally Posted by layback40 View Post
Personal attack !!
Go and cry to John as you usually do..........

Quote:
Originally Posted by layback40 View Post
You have no knowledge of my reading skills a part from having seen a copy of my engineering degree.
I have perfect evidence of the lack of reading skills on your part, as you have ignored the entire discussion above regarding those that have easily been able to start with old glow plugs.




Quote:
Originally Posted by layback40 View Post
I have not stated this & so it is a factually incorrect statement.
Of course you have stated it repeatedly. Your position is that a glow plug is not considered "good" until you take it out and verify that it is white hot.


Quote:
Originally Posted by layback40 View Post
This is a factually incorrect statement. Please provide a link to a credible reference that gives the range of acceptable resistances to achieve an acceptable glow.
Now, you're just being ignorant. All of the folks on this thread, with one exception, have stated that they do not have starting difficulties with older glow plugs that meet the resistance criterion. You've got three options:

1) Assume that all of them don't know WTF they are talking about.

2) Assume that these older glow plugs must all have white hot tips.

3) Admit you are dead wrong and glow plugs that are not performing like new are starting these engines on a daily basis.


Quote:
Originally Posted by layback40 View Post

I cannot speak for the other members you mention. I am not that arrogant.
As mentioned before & an example pictured, a GP can have a resistance that is about typical yet not have a satisfactory glow pattern.
If you have not experienced this, best put it down to lack of enough practical experience.
It might not have a "satisfactory glow pattern" in your opinion. However, as far as the engine is concerned, unless this glow pattern results in a tip temperature below X (not yet quantified), the engine will not have a problem creating sufficient heat for ignition.

The practical experience is gleaned from the other members on the thread. Only one has experienced a start on four with proper resistance readings. All of the remaining members start just fine on all five. As mentioned, some of these plugs are quite old and surely don't meet the expected tip temperatures of a new plug.

I'll grant you the fact that some plugs will not meet the tip temperature required for a start but will meet the resistance check. However, these will be in the small minority of the population. The far more likely scenario is that the glow plug deteriorates over time and the tip temperature drops, but the engine has no problem with that plug. Eventually, the plug fails outright and is open on a resistance check.

In conclusion, your blanket statement that the only way to check glow plugs for proper function is to pull them and check tip temperature is factually incorrect for most of the members on the forum. Only for those that need 100% performance for starting in extreme cold would your advice be accurate.
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  #51  
Old 12-04-2011, 09:46 AM
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I don't want to get between you two because you seem to be enjoying your prickly exchange.

It may be true that folks start their diesels every day with weak glow plugs. This of course would be more likely to be true if they happen to live somewhere warmish.

It is when the temp gets down around zero F that any weakness will put you out of business.

I am no expert on this but isn't the tip of the glow plug what the injector aims at when trying to start?

Arguing about whether to change them all at once or one at a time is a little like arguing about whether is is better to clean your whole house once a month or one room per week.
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  #52  
Old 12-04-2011, 09:53 AM
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Quote:
Originally Posted by t walgamuth View Post
It is when the temp gets down around zero F that any weakness will put you out of business.


Arguing about whether to change them all at once or one at a time is a little like arguing about whether is is better to clean your whole house once a month or one room per week.
It might put you out of business if you have low compression. It doesn't put the SD out of business............it starts in 1 second at 0F. I can guarantee you that several of those plugs have been in there for years and the tip temperature surely has deteriorated somewhat.

No, that is not an accurate comparison. If it is expected that all glow plugs have a similar finite life, the loss of one will clearly indicate the loss of the remaining four in the very near future. However, if the manufacturing of said plugs has wide variability in methods, the life of the plug cannot accurately be predicted and changing them all when the first goes out would be a waste of money.

I'm of the opinion that the latter is the true situation. I've got 10 years with the SD to back it up.
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  #53  
Old 12-04-2011, 12:41 PM
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So, do you have any evidence that a glow plug tapers off in its temp as it gets older?

This is a question that might be answered by a side by side test with a temp gun and glow plugs tested back to back outside the car.

For all we know the glows might get hotter with age as the outer skin wears thinner.
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #54  
Old 12-04-2011, 12:45 PM
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I have visually compared old but glowing plugs to new plugs outside the vehicle. The new plug got hotter much more quickly and glowed much brighter. I assume the brightness indicated it was hotter but I did not use a thermometer. The speed of the glow is probably relevant because the sooner the plug reaches peak temperature, the faster the combustion chamber will get hot.

By the way, the engine started right away this morning also.
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  #55  
Old 12-04-2011, 01:05 PM
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Quote:
Originally Posted by t walgamuth View Post
So, do you have any evidence that a glow plug tapers off in its temp as it gets older?

This is a question that might be answered by a side by side test with a temp gun and glow plugs tested back to back outside the car.

For all we know the glows might get hotter with age as the outer skin wears thinner.
I do not.

I'm making an educated guess based upon the typical results that most people see with old glow plugs when they connect 12V to them outside the vehicle.

From the comments on the forum, it is immediately obvious when an old plug is compared to a brand new plug. The old plug does not generate as hot a tip temperature as compared to new.
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  #56  
Old 12-04-2011, 01:05 PM
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Quote:
Originally Posted by kerry View Post
I have visually compared old but glowing plugs to new plugs outside the vehicle. The new plug got hotter much more quickly and glowed much brighter. I assume the brightness indicated it was hotter but I did not use a thermometer. The speed of the glow is probably relevant because the sooner the plug reaches peak temperature, the faster the combustion chamber will get hot.

By the way, the engine started right away this morning also.
Were you comparing identical plugs by part number? The new fast glow Bosch Duraterm plugs glow much faster than the old plugs.
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  #57  
Old 12-04-2011, 01:06 PM
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Did you throw away the weak plug or put it back in like Brian would have done?
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #58  
Old 12-04-2011, 01:10 PM
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I didn't think Brian was saying he would put it back in. I thought he was saying he wouldn't take it out to begin with

No, I'm not sure I was comparing the exact same plugs.
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  #59  
Old 12-04-2011, 01:20 PM
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Checking a glow plug with an ammeter would be the easiest way and most definitive. If it draws the rated current, you can bet your life that it is getting hot to it's rated temperature. Only the most anal will want to take the plug out to watch it glow to be sure it's glowing. .


inappropriate language
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Last edited by vstech; 12-04-2011 at 06:46 PM.
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  #60  
Old 12-04-2011, 02:08 PM
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Originally Posted by funola View Post
Checking a glow plug with an ammeter would be the easiest way and most definitive. If it draws the rated current, you can bet your life that it is getting hot to it's rated temperature.
.............and you, my man, are ideally suited to make five measurements of current draw and report back with your results..............

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