How does a glow plug reamer work, and can it cause damage?
 

I'm about to order a glow plug reamer from zdmak.com for my 1982 300D.

How does it work, and shoul you only use it if you suspect carbon buildup (i.e., can it be used as a preventative measure, or does it possible to cause some damage to the threads or anything else when you use it).

Thanks,

Pete.

No, the reamer does not fit the threads. It is simply a reamer that is shaped to fit into the hole in which the glow plug fits. It is smaller than threads just as the body of the glow plug is smaller than the threads.

I have never bought one before. The few times that I've ever needed one, I was able to get the crud out with an ice cream stick. It is much more time consuming but it worked for me.

That said, the times I've done it, I was dealing with goo rather than crust. If you have crust, then the only way to safely remove it is probably with the reamer.

It won't hurt anything, but if you don't have so much goo or crud that it is pressuring against the glow plug, it is not necessary. Also you will probably need to remove the injector tubes to get access to use it.

Good luck,

Thanks, Larry.

However, I'm still visually and intellectually challenged on this one (not an infrequent occurence in general :) ).

What is actually going on when the reamer is doing its job? How is it cleaning the carbon deposits?

Thanks,

Pete.

One of our members, stayalert, rents this reamer for $6.

Seems like a waste of money to buy one.

Check out the sticky regarding the tool rental program at the top of the page.

The reamer simply scrapes the carbon crud out of the glow plug hole. You stick it in, turn it around, and pull it out.

Thanks.

Can a Q-tip be used for more "gooey" like substances?

In the event that a head is surfaced... necessitating the installation of thicker shims under the precombustion chambers... to keep them from contacting the pistons...
The Reamer is used to cut the hole to align with the glowplugs... ( in addition to the cleaning function already mentioned ).....

Any reamer or drill put into a situation like this should have heavy grease on the threads to try to capture as much of the cuttings as possible...
It should be done in stages renewing the grease and wiping off the old grease and crud.... and renewing the grease for next step....

Sounds like Italian tuneup time, then some PB Blaster/Kroil/Rust Buster-that helps blow out the excess carbon.

reaming the GP holes
 

Ok, a guy that says he knows a lot about MB's adviced me to do this.

Remove the glow plugs and insert a drill slightly smaller than the original threads of the GP to ream out the carbon deposits (lightly without damaging threads). Then with the glow plugs removed crank over the engine and watch the carbon fly out of the GP holes.

Crazy, smart, cheap?

--Hugh

Not crazy.

Quite smart.

Very cheap (as in low cost).

Well, think about this.....
you have crud loosened in that area... you are hoping that the movement of the air caused by the piston travel will blow it out...
but what if that piston is at the top of the stroke and about to head DOWN ?

This stuff has been discussed in the archives... you do not want any stuff to get stuck below the pintle in the precombustion chamber or in the tiny little holes in there.... it will really mess up the fuel dispersion and efficiency of that cylinder...

Using a vacuum seems like a better deal... and using the rental plan in the sticky above is really a better idea than taking a chance on breaking off the tip of a drill when you catch an edge... a drill and reamer work in very different fashions... AND you have the advantage that the correct reamer will be held straight by the threads on its base....

Thanks, leathermang. Sounds like good advice.