Urgent - Squeaking Glow Plugs
 

So, removing the glow plugs and hear them squeaking. Does that mean I need to ream them? Been just over a year.

What does wet glow plugs mean?

Please answer simply and not derail this. Thank you all! :D

Could just be metal squeaking on metal. If you have a reamer, go ahead and ream it, but if not, you can probably leave it alone... squeaking sounds more like metal-to-metal than metal-to-carbon.

Hmmm.

I think it's standard procedure to ream them each time you pull them.

not sure what squeaking would indicate, but reaming is always good practice.

as for the wet plugs, it means the motor was not firing on that cylinder just before you pulled the plug. and that the plug is bad, so it did not vaporize the fuel...

just replaced mine yesterday and there was a squeaking sound on a couple, a couple were wet when i pulled them, just means that cylinder was about to fire and the injector has likely leaked down from sitting, i made my own reamer using a old GP and a drill, i reamed the ones that were easy to get to and there was NO carbon so i didn't bother on 4 and 5, i had actually checked 5 with a bore scope a couple weeks back and didn't see anything.

number 1 was hard to get lined up and get the threads started that's why i made the reamer, the reamer was hard to get going and i got a bit of metal but really no carbon, my guess was the prechamber wasn't lined up very well and making contact with the GP or maybe a burned and distorted prechamber like i have seen in pictures on line? the new GP did go in pretty easy after that.

thought they always squeeked. replaced a set on a 300D and a 240D, both times squeeked

Same on both OM603's I've changed glow plugs on.

Wow! Thank you all for the replies! :D

I started right after a long hot drive of 15 miles, so why was a couple cylinders not firing? Or, are you saying that cylinder was about to fire? That makes more sense.

After I posted this, I found my reamer! Did a test on a squeaky one, and we were right: the reamer barely goes in! :eek: Is that normal?

Well, this is my first time, and putting up a good fight! Didn't help getting called away.

Now with you alls help, I am set to go once I eat enough to get my blood sugar up. :P

Turns out position is key! Get it in the hole right and one can shove it deep and clean it out. Once I shoved it in it felt as if a chunk broke free and went deeper inside. The other two only had light amount of carbon. Since it is way late and was causing misery, figured stop at three, since number five was the only supposedly bad plug. Plus, to do the front two one has to remove the fuel lines. Can't wait to hear if it makes any difference.

Also got the oil pad glued to the new pan, but needs to cure and also haven't ordered Mobil T.D.T.. :P

If it is the threads that are squeaking a shot of penetrating Oil ought to stop the squeaking.

If it is the Tip that is squeaking then the Glow Plug holes should be reamed or otherwise cleaned out.

If you installed Autolite Glow Plugs (I did that) in as little as 6 months I remove them and found 2 of them were squeaking but it was because on those 2 the tips of the Glow Plugs had swollen and took considerable force and a Vice Grips to yank them out.

If you put some Never-seez type compound on the Glow Plug Threads (also good on the Injector Threads) when you install them they will not squeak the next time they are removed.

Thank you so very much for the reply! :D

There was only light carbon on two out of three, and the one not positive. Most likely the wetness was the penetrant and the squeaking was the metal on metal.

Good to know to stay away from Autolight! I used and will only use Beru! ;)

I was concerned about too much thickness causing a grounding issue. I used A.T.F. and plan on removing them next Fall in preparation for winter.

So, still clacky, but less. I also adjusted the arc and injection pump throttle linkages, and now have a scalded kitten! :eek: Idle between these two means now about 900R.P.M., so will turn in the pump rod a tad. The only reason I adjusted as didn't feel right compared before taking apart the linkage to gain access to the glow plugs. Guess soggy is the best way to describe the feeling.

Answer
 

Yes, this is normal.

It is the reason why MB calls for using a reamer every time the glow plugs are removed / installed.

Breaking up the accumulated carbon is important.

Carbon frequently forms a semi rigid sock around the electrode, this acts as an insulator potentially causing premature (overheat) failure of the glow plug.

At the very least; this semi rigid Carbon sock insulation makes cold starting more difficult.

On my personal vehicles, I actively look for justification to remove, test and ream, at least once per year. :)

.

Always ream the GP hole before installing a new GP.

Yes, the squeaking is caused by the carbon.