1976 240d glow plug reamer
 

so it's time to change the glow plugs on my 1976 240d. i tested them and two seem to be bad. my question is about reaming. the reamers for the 616 engines seem to be pretty expensive so i thought i would check on mcmaster-carr's web site. i can get a 1.5mm hand reamer with four flutes for about $15. i was thinking maybe i could hog the center out of an old glow plug and weld in the $15 reamer. does anybody know how long one of the $95 reamers is? what about the dimension from the bottom of the threads to the tip of the reamer?
john

That will be perfect if that size will work.
You can figure out the length from the length of the part of the glow plug that sticks out into the pre-combustion chamber. It just needs to go past the inner part of the GP hole and not far enough to touch the Injector.
More important is that it is not supposed to ream out any of the metal in the ID of the Glow Plug hole itself.

Theoretically very possible, and I've been considering it myself. The trouble is figuring out the proper diameter and depth of the proper reamer. What we really need are specs for the 617589005300 reamer.

Are the loop plugs in need of a reamer to the same degree the pencil plugs are? Wont the loop itself do some reaming as the old plug is removed?

If the 76 has already been converted to pencil plugs then the question is moot.

Well, they're not as susceptible to damage from being crowded with carbon, from what I can tell, but they do still need reaming. The loops actually are a pain to get out if there is a lot of carbon in there. They also tend to bend and twist on the way out when there is a bunch of carbon in the way. Two of mine took at least twenty minutes each to remove thanks to the carbon having closed in around them.

Of course, even when converted to pencil plugs, you still need to ream the chambers out with the larger reamer, since it's the only one that will thread in to place as intended. I wouldn't been keen on leaving huge amounts of carbon in there, anyway.

If you don't have a reamer, how about a small brass spoon scraper (like ones made for cleaning out ear wax)? Put a stop on the handle so it only can go in as far as the glow plug tip. It could conceivably clean more carbon out of the hole than a reamer.

When I decided to make the 2 types of Pencile Glow Plug type reamers that I make I bought 1 each of the Factory Made ones. However the Loop type one cost too much and the demand is low.
Most people seem to want to switch to the up-date Pencil Glow Plug kit due to the better performance of the kit.

I also think since the Loop style GP hole is big you could easily us something like a 20 Gauge Shot Gun Cleaning Brush; which come in Bronz or Stainless Steel (careful not to buy the Nylon one that is not stiff enough.)
However, it would be handier to also have a short section of the Shot Gun Cleaning Rod to mount the brush on.
It may even be that dipping the Brush in Gun Cleaning Solovent might help clean the Carbon out too.
But I have no example of an Engine with the Loop style plugs to try this out on so someone who owns one will have to do so.
If you want to try it measure or take the Glow Plug with you; I believe even Wal Mart sells the cleaning brushes.

Updated pencil plugs or not, the old loop plug glow plug chambers still need to be cleaned out, and that means a reamer is required. One could probably get away with just screwing the updated pencil plugs in where the loop plugs had been, but there could still be a ton of of carbon in there.

As for using a bore brush... Yeah, that would probably work great. I'd just be worried about loosing a bristle in there. A reamer would be much safer and more efficient.

Do you actually have the larger reamer? If so, would you be willing to share the dimensions?

Where can you buy the "real" glow plug reamer for the larger threaded holes on the old model 61x engines? Diesel911, do you make your own for sale? I've only seen the one for the newer models (1979 and up I think) and it's too small. It seems like a good investment to have the proper tool if you plan on keeping the car for many many years like I do. I guess one could try to weld a drill bit onto an old glow plug thread, I would think that would work better than using a brush.

I know of only two sources; Your friendly neighbourhood Mercedes-Benz dealership, where you can get the real deal for $$$, is one option. The other option is eBay, where you can pick them up for much less, but it's still a lot to spend for a seldom used tool. El Paso tools frequently have one listed on eBay. Here's one for the 18mm old-style plugs.

http://cgi.ebay.com/ebaymotors/Mercedes-Glow-Plug-Reamer-Diesel-615-616-617-Tool_W0QQcmdZViewItemQQitemZ120191670821QQptZMotorsQ5fAutomotiveQ5fTools

I'm don't want to go there if I don't have to, since my motor may not be worth fixing, but I'm close to dropping the nearly $100 on the eBay special out of desperation.

I have no reamer at all for the Loop style Glow Plugs.

Ah. Well, then you certainly wouldn't know how big they are!

I think it is time for me to go shopping.

If someone does make one, it would make a good addition to the tool rental program here. I'd use it. I swapped my loop-style plugs for the pencil tips before winter and didn't have a way to ream the holes. I stuck my pinky in there and didn't feel much and the old plugs came out easy. So I just stuck the new plugs in. They seem to be working fine so far. But next time, I'd like to ream the hole just for peace of mind.

Not a bad idea. Small, quick to use, and not needed very often seems to make it the ideal rental tool, as it would be cheap to ship about. I might be happy to just buy one and rent it out, since I won't need it often. The deposit would be a little steep, though. On the other hand, no one has ever tried to rent my spring compressors, which seem to be a much more needed item. I'll still think about it, though.

Unfortunately shipping a Reamer 1 way USPS 1st Class cost about $1.5-$2.00 and that is without a Delivery Conformation Number at 75 cents and I have no idea what the insurance on them cost. Also there is the rental fee.

There is also the 25-50 cent cost for the Padded Envelope.
If you use PayPal to handle the fund transfer some more money is gone.
So someone has to pay shipping both ways + insurance or at least delivery conformation. When all the costs are added up 1/5-1/4 of the cost of a new Glow Plug Reamer is used up.

The other problem is who is responsible if it gets lost in the mail.
If you can it is better to barrow from some one local.

However, it makes sense to rent a small tool that is expensive and seldom needed like the Timing Chain Crimping Tool and ect.