603 Engine Precombustion Chamber Leak - PeachParts Mercedes-Benz Forum

tinbum · #1 12-05-2005, 12:05 PM

I have a vehicle (Hagglunds BV206) fitted with the mercedes 603-950 engine. One of the rubber hoses on one of the injectors had perished so i replaced it and in so doing some diesel spilt into the recess round two of the injectors. When i started the engine up i noticed small bubbles appearing in the diesel. This doesnt apear to be from the injector seal itself but from the locking ring for the precombustion chamber. Questions:- is this normal, how is the pre-combustion chamber sealed and is the tool available to remove/ tighten the locking ring? Thanks, Nick

WANT '71 280SEL · #2 12-05-2005, 12:10 PM

I'll bet that it just looks life a leak. It's probably the vibration of the engine. It's like it's foaming, etc. Diesel can be funny stuff sometimes. If it leaked I would think you'd have a compression loss.

Thanks
David

tinbum · #3 12-05-2005, 12:29 PM

No certainly is a leak. Have just filled the other injector recesses with diesel and all but one do it to varying degrees.

dieseldiehard · #4 12-05-2005, 01:35 PM

Quote:

Originally Posted by tinbum

No certainly is a leak. Have just filled the other injector recesses with diesel and all but one do it to varying degrees.

It is common to see a tiny bubble leaking on these engines. It is likely coming from where the injector seats against the head.
I wouldn't worry about a tiny bubble but if it's streaming pretty good you are losing compression so tightening the collars is not a bad idea. The surface should be clean where they mate, so don't loosen the collar then blow compressed air down around there. If you had a serious leak it would be necessary to remove the injector and PC chamber and clean the surfaces and reinistall, but that is seldom needed unless you've got a major leak.

The best tool for this purpose is made by Hazet.
In the US we have Samstag Sales as distributor of german tools: http://www.samstagsales.com/
An alternative for similar tools is: http://www.zdmak.com/
I believe you are located elsewhere so finding a tool distributor that sells MB tools is your next challenge. A search on the Internet might be fruitful otherwise ask an Indy where they buy their tools.

Unfortunately the Shopforum tool rental program doesn't include one of these, maybe it should. If I owned one I would gladly have contributed it to the program. The last 603 head I sent to be rebuilt had the rings badly damaged by some mechanic who used something that must have resembled a chisel to attempt removing (or tightening?) the split collars. The machine shop had to weld nuts onto the collars to remove them (at an additional expense on my part!).

Hatterasguy · #5 12-05-2005, 01:41 PM

Mine used to do that after I put the new injectors in. I guess torquing the injectors disturbed the pre chambers and they leaked a bit. After a few thousand miles they re seated themselves and they no longer leak. If it really bothers you replace the pre chamber, they are not very expensive.

dieseldiehard · #6 12-05-2005, 01:54 PM

Quote:

Originally Posted by Hatterasguy

Mine used to do that after I put the new injectors in. I guess torquing the injectors disturbed the pre chambers and they leaked a bit. After a few thousand miles they re seated themselves and they no longer leak. If it really bothers you replace the pre chamber, they are not very expensive.

Sounds like good advise.
say, OT but have you ever searched Google for "french military victories" ?

Hatterasguy · #7 12-05-2005, 02:07 PM

What victory? After Napoleon the French havn't won anything.

Lets not turn this to OD though, back to the topic.

MarineCraft · #8 02-24-2012, 01:29 AM

Quote:

Originally Posted by dieseldiehard

Sounds like good advise.
say, OT but have you ever searched Google for "french military victories" ?

Hi
Perhaps you can advise me on my current 603970, 1991. I first noticed diesel around the bases of all six injectors. The return hoses looked nasty to me and seeping so i replaced them all, 20.00 from MB plus shpg. The leak on #1 inj. is quite pronounced. Squirting soap/H2O about 4 inches in the air. # 4 wasn't as bad but was the nextest in line culprit, but ALL 6 had micro bubbles around the bases of the heat shields.
So we go to the mechanic. We pull each inj. out one at a time and thoroughly clean the carbon out after removing the the threaded rings, replaced the heat shield washer that seats the injector onto the pre-chamber. This cures all but #1 and #4 which haven't changed much. The car still runs fine but is much louder now and still have O would estimate a 5 to 10 percent leakage on #1 and <<1 percent on 4. Can you help? Will you?

Oldbeaver · #9 06-14-2013, 10:56 AM

Hello Tinmbum:

Have you already fixed the blowing of the precombustion chamber?

I am having the same problem with a OM603 turbo engine in a 1993 car.
If you have fixed it, please share yr experience. I will share mine when I fix mine.

Best,

Oldbeaver

Diesel911 · #10 06-14-2013, 02:48 PM

Pic of Prechamber Cutter.

If I faced this problem I would first try a re-torque of the Prechamber Retaining Rings. Since the Injectors would be removed that would allow you to see if the hole the Injectors go into has Carbon build up indicating; indicating there was a leak past the Injector Heat Shields.
Also if you see carbon deposits going across the whole end of the Injector Nozzle indicates a compression leak there.

I have never done this or read of some one doing this:

If the Prechambers really were leaking I would be inclined to buy some thin Copper Sheet. They used to sell this in Craft Shops. They also have Aluminum Sheet.

I would purchase a new Prechamber Seal and lay that on top of the Copper Sheet and use an Exacto type Knife and cut out a thin Crush Washer.
Clean out the prechamber sealing areas on the Head and the Prechamber and stick the Copper Washer at the Bottom of the Hole and install the Prechamber and torque the Retaining Ring and see if that cures the leak.

You only need to try this on one to see if it will work.

In theory it should work if the Prechamber seal area in the Head is not too warped and the thinness of the Copper should not raise the Prechamber up much.

While I guess the Aluminum Sheet could be used but the Copper is more difficult to burn through because it conducts heat fast and does not easily oxidize. It also tends to be softer and more likely to seal.

The Copper Sheet I am speaking of is something that you would lay over an embossed Plastic item with something like those Praying Hands and you lay that Copper over them and you start rubbing with a piece of wood and the Sheet is so thing that you easily impress the Praying Hands image into the Copper. The same with the Aluminum Sheet.

Zulfiqar · #11 06-14-2013, 03:00 PM

Quote:

Originally Posted by Diesel911

Pic of Prechamber Cutter.

If I faced this problem I would first try a re-torque of the Prechamber Retaining Rings. Since the Injectors would be removed that would allow you to see if the hole the Injectors go into has Carbon build up indicating; indicating there was a leak past the Injector Heat Shields.
Also if you see carbon deposits going across the whole end of the Injector Nozzle indicates a compression leak there.

I have never done this or read of some one doing this:

If the Prechambers really were leaking I would be inclined to buy some thin Copper Sheet. They used to sell this in Craft Shops. They also have Aluminum Sheet.

I would purchase a new Prechamber Seal and lay that on top of the Copper Sheet and use an Exacto type Knife and cut out a thin Crush Washer.
Clean out the prechamber sealing areas on the Head and the Prechamber and stick the Copper Washer at the Bottom of the Hole and install the Prechamber and torque the Retaining Ring and see if that cures the leak.

You only need to try this on one to see if it will work.

In theory it should work if the Prechamber seal area in the Head is not too warped and the thinness of the Copper should not raise the Prechamber up much.

While I guess the Aluminum Sheet could be used but the Copper is more difficult to burn through because it conducts heat fast and does not easily oxidize. It also tends to be softer and more likely to seal.

The Copper Sheet I am speaking of is something that you would lay over an embossed Plastic item with something like those Praying Hands and you lay that Copper over them and you start rubbing with a piece of wood and the Sheet is so thing that you easily impress the Praying Hands image into the Copper. The same with the Aluminum Sheet.

I have actually seen this repair on an old Bedford diesel engine.