W126 Prechamber fuel leaks - PeachParts Mercedes-Benz Forum

7033grip · #1 08-19-2014, 10:34 AM

I am looking for the extractor tool and the torque tool to reseat my injector collars on my 1991 350SDL. All six are leaking after the last injector change. ************** used to sell these tools but they are no longer in stock. Anyone have an old set they can sell?

vstech · #2 08-19-2014, 11:31 AM

are you getting exhaust blowing out the injector holes? if you are seeing bubbles, it could simply be from heat, and you have fuel seeping around the bodies of the injectors. or your return lines may be leaking...

7033grip · #3 08-19-2014, 11:35 AM

Excellent ideas, but it is definitely fuel coming up around all six collars. My mechanic said to try and find the extractor and torque-down tools and order new collars. I will call Peach Parts today and see if they have the tools.

krwsenior · #4 08-19-2014, 02:05 PM

I just did the injectors in my 91 350SDL, and I was convinced that the housing seals were leaking because of the bubbles in the fuel that pooled around the prechambers. But it turned out to be the return lines were seeping. What a relief to fix it so easily.

New Monarch nozzles balanced at 2000 psi made it very smooth.

winmutt · #5 08-19-2014, 02:20 PM

I rent the collar tool for the price of a 6 pack + dp + shipping both ways. Collars are reuseable but never hurts to have one.

vstech · #6 08-19-2014, 03:29 PM

Improper removal of the injectors can ruin the prechamber seal seal... but FUEL leaking from them is extremely unlikely. ..
If the leak is liquid the problem is above the head. Either the injectors themselves or the return lines.

vstech · #7 08-19-2014, 03:33 PM

Quote:

Originally Posted by 7033grip

Excellent ideas, but it is definitely fuel coming up around all six collars. My mechanic said to try and find the extractor and torque-down tools and order new collars. I will call Peach Parts today and see if they have the tools.

This mechanic wouldn't happen to have rebuilt the injectors. ..

Diesel911 · #8 08-20-2014, 01:23 AM

Quote:

Originally Posted by 7033grip

Excellent ideas, but it is definitely fuel coming up around all six collars. My mechanic said to try and find the extractor and torque-down tools and order new collars. I will call Peach Parts today and see if they have the tools.

One by one spray Brake Cleaner between the Prechamber Retaining Collar and mop up what comes out with Rags or Paper Towels until it is ad dry as you can get it.
The idea is to keep diluting the Fuel with the Brake Cleaner untill the Fuel Level of the Fuel trapped in the space under the Collar and between the Injector and Prechmber is too low to bubble out.
Make sure the Injector is also dry so you can be sure no Fuel is leaking from the Injecto or the Return Hoses.

If you really want to be sure concerning the Prechamber leak after doing the degreasing- you need to reduce the preceeding Fromula.
Bubble Mix- One Gallon of Water mixed with 1 Cup of Dawn Dish Soap.

Put that mix in a generic pump typ Spray Bottle and spry it on a cold Engine. Start the Engine.
If you have an Prechamber leak it is going to blow some Bubbles.

Diesel911 · #9 08-20-2014, 01:27 AM

When sufficient Fuel or even Oil gets in that space between the Injector and the Prechamber it appears to bubble due to the shock wave created by the Injection of the Fuel and I gues due to the Ignition of the Fuel.

There is several Memebers who have actually had a prechamber leak due to the Cylinder Head being warped in the perchamber area. You might want to look up their symptoms.

In the pic the red areas represent where Oil or Fuel can build up between the Injector and the Prechamber if it leaked down from above at one time; like when bleeding the Fuel Injection hard Lines at the Injectors.

funola · #10 08-20-2014, 10:05 AM

If you use some logical thinking, you will see that it is unlikely the pre chambers are leaking.

Atomized fuel from the injectors would not escape as a liquid and collect at the pre chamber threads. Injectors are pointing downwards, how can it defy gravity and flow upwards as a liquid? Wouldn't the leaking high pressure combustion gas blow it nice and clean? What is the chance that all 6 pre chambers are leaking. It is more likely leaking from above the pre chamber rings, dripping down.

PaulH · #11 08-20-2014, 09:42 PM

I've have had a diesel fuel leak around the #2 injector for over ten years. The return hose and the injector are dry. I stuffed small strips of alum. foil around the base of the injector and for years that stopped almost all the leak. Now, it's getting worse again. Head never overheated (orig. owner).

7033grip · #12 08-21-2014, 07:43 AM

You guys are the best and I appreciate all the advice and ideas. Yes, the mechanic put new Bozios on the injectors before the leaks started. There was an immediate performance upgrade until then. Originally, only #1 and #3 were leaking but it's slowly getting worse.

funola · #13 08-21-2014, 11:17 AM

Quote:

Originally Posted by 7033grip

You guys are the best and I appreciate all the advice and ideas. Yes, the mechanic put new Bozios on the injectors before the leaks started. There was an immediate performance upgrade until then. Originally, only #1 and #3 were leaking but it's slowly getting worse.

Did the mechanic have the proper equipment to put the new nozzles in, i.e. a pop tester? Did he use new heat shields and clean the pre chamber before installing them? Did he remove and replace all 6 pre chambers? It seems strange that only #1 and #3 pre chambers was leaking and now all 6 are leaking.

Diesel911 · #14 08-22-2014, 09:15 PM

Quote:

Originally Posted by 7033grip

You guys are the best and I appreciate all the advice and ideas. Yes, the mechanic put new Bozios on the injectors before the leaks started. There was an immediate performance upgrade until then. Originally, only #1 and #3 were leaking but it's slowly getting worse.

As one of the other Members said if the parts inside the Injector are not lapped properly and extremely clean when they ae assembled you can get a seeping Fuel Leak between the upper and lower Half of the Injector.

In fact way back when I worked in a Shop even when you think you have lapped the Injector Properly maybe 1 Injector out of 100 will leak between the upper and lower Body. Of course at a Shop you are in a hurry to get the job done so even with the correct equipment things don't turn out as planned.

Also you normally cannot detect that sort of leak on the Pop Tester unless it is extremely bad. On the Pop Tester the Injector is wet (because when you assembled the Injector you dipped all the Parts in Diesel Fuel) making it hard to see any tiny leak and the Pop Tester is just not the same as the Injector being on the Engine Torqued into the Head and subjected to changing heat and vibration.

The other thing that happens occasionally is that the lower half of the Injector develops a Hairline Crack. But, it would be odd for that to happen to more than one Injector unless someone did not torque them correctly when the Injector was assembled.