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Old 12-18-2010, 03:14 PM  
Aqua Puttana
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Default Re: Aqua Puttana's Cheap Tricks - Nothin' Fancy Here

Some additional information about glow plugs

20131202 Edit: It was mentioned that the glow plug testing procedure isn't easy to find.

Originally Posted by Aqua Puttana View Post
We have such short memories here. A simple test from Herr Doktor himself for T1N glow plugs which uses a simple jumper wire with 20 amp in-line fuse. (Not to be used on the 4.5 volt [or there abouts] NCV3 glow plugs though.)

Originally Posted by abittenbinder View Post
That is not the easiest or most accurate test for open glow plugs.

See my old original post for making a simple fused glow plug test wire.

Connect to each glow plug pin socket in the engine harness connector at the glow module, one at a time. Simply brush the clip you would normally clamp to the battery + post, across the + post, for each glow plug pin test.

Pins are numbered on back side of plug with an accurate glow plug location.

A strong, harsh spark (if you're quick) or a blown fuse (if you're slow) indicates a failed shorted plug.

A gentle brush of sparks ,and no blow 20A fuse in 10 second, indicates a operating glow plug.

NO sparking indicates a open circuit glow plug.

Easy to see in strong daylight.

Doktor A
As always the original post/thread can be accessed by clicking the blue arrow within the quote box.


Back to my original information post....

The diagram of the glow plug shows where the seal is made down near the combustion chamber. It also shows the "control winding". I believe it is that control winding that makes checking glow plugs with an ohmmeter ineffective so you need to use Doktor A's 20 amp in-line fuse lead test.

I also think that the distance between the threads and the seal ridge is one of the reasons it is best to remove the glow plugs with the engine hot. I say this because the expansion of the aluminum head is most likely greater than the expansion of the steel glow plug body. When the engine is hot that relieves some of the tension between the threads and the seal. This is as opposed to a spark plug where the sealing shoulder and metal seal is right at the threads of the steel spark plug body so contraction of the aluminum with a cold engine is then your friend. I have no data to back this observation up.





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Last edited by Aqua Puttana; 12-02-2013 at 08:06 PM.
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