CDI Injector seal issues - PeachParts Mercedes-Benz Forum

Wodnek · #1 05-07-2016, 12:54 AM

Rewind 6 months ago, i had a serious case of Black death on #4 injector. I couldn't get the injector out, so i took it in. Then 2 months ago, i had the same injector seal blow again, this time with it spraying diesel out every time it cycled. So last week, the same one went again. I pulled the injector out today, and noticed a crack at the bottom of the injector. I am not sure if this is the source, or if too much has been reamed of the head seat, making the washer too thin to seal properly. With what injectors cost, i don't just want to throw parts at it.
Today i reamed the seat and reinstalled the injector. It leaks already, although not visibly, or enough to hear, but if you fill around the injector with water, it bubbles.
I should have taken a picture, but i didn't. On the very bottom, there is a "cap" that you can unscrew. the crack is on this part, it is just a sheet metal part, not the body of the injector, so it doesn't appear to be a part that would spray diesel, but I do admit, i don't posses much knowledge about injectors.

Diesel911 · #2 05-07-2016, 12:12 PM

Might be best if you had a picture.

If they engine is a direct injection (no prechamber) every time you ream the Injector gets closer to the Piston.

On my year and model you can replace the Injector Nut with another one without disturbing the pressure settings if you are careful and properly torque it.

Wodnek · #3 05-07-2016, 06:28 PM

Has anyone had any luck using 2 seals to increase the thickness when one just doesn't seem to be thick enough? I also read about using the Honda 2.2 seals, but they are challenging to find in the US.

Skid Row Joe · #4 05-07-2016, 09:56 PM

Woodnek, sorry for your problems, but this is a learning experience for we CDI owners. Just wondering if a new head may be in order?

Diesel911 · #5 05-08-2016, 12:48 AM

"I pulled the injector out today, and noticed a crack at the bottom of the injector."

If it was me I would fix the above first.

The tip of the Injctor has a specific range of measuerment it can be protruding into the combustion chamber and it is also no good if the tip is pulled up too far upwards.

The normal way that injector protrusion would be checked is with the Cylinder head off and measureing the the distance the tip sticks out.
By they way it is the same for a lot of other diesel engines.

It would have been ideal if some way had been figured to measuer how much was reamed out.

On other diesel engines if there is a leak where the Injector seats you can see a black streek a cross the leaking area. However, that assums the Injector itself is not the cause of the leak.

Wodnek · #6 05-08-2016, 12:53 PM

Quote:

Originally Posted by Diesel911

"I pulled the injector out today, and noticed a crack at the bottom of the injector."

If it was me I would fix the above first.

The tip of the Injctor has a specific range of measuerment it can be protruding into the combustion chamber and it is also no good if the tip is pulled up too far upwards.

The normal way that injector protrusion would be checked is with the Cylinder head off and measureing the the distance the tip sticks out.
By they way it is the same for a lot of other diesel engines.

It would have been ideal if some way had been figured to measuer how much was reamed out.

On other diesel engines if there is a leak where the Injector seats you can see a black streek a cross the leaking area. However, that assums the Injector itself is not the cause of the leak.

OK, i made a mis diagnosis of the issue. Combustion gasses are not being expelled, raw diesel is, so the crack MUST be the issue.
Can one just order a new camp for the end of the injector? or am i stuck buying a rebuild? If I do buy a rebuilt injector, could I program it with an isoft MB II? Or is this going to be a job for my indy? it is easy to pull my injectors, the front 4 are at least free. The rear two are looking like they will be an issue if I ever have to pull them. They got pretty carboned up from the #4 that was leaking.
All wasn't wasted though, i did fix the two injector seals that were leaking.

hangit · #7 05-08-2016, 01:34 PM

Have you posted in this forum? W211 E-Class - Mercedes-Benz Forum

More info regarding newer era cars.

John

Diesel911 · #8 05-09-2016, 01:51 AM

Quote:

Originally Posted by Wodnek

OK, i made a mis diagnosis of the issue. Combustion gasses are not being expelled, raw diesel is, so the crack MUST be the issue.
Can one just order a new camp for the end of the injector? or am i stuck buying a rebuild? If I do buy a rebuilt injector, could I program it with an isoft MB II? Or is this going to be a job for my indy? it is easy to pull my injectors, the front 4 are at least free. The rear two are looking like they will be an issue if I ever have to pull them. They got pretty carboned up from the #4 that was leaking.
All wasn't wasted though, i did fix the two injector seals that were leaking.

I don't know. I have not even seen a picture of the Injector.

Wodnek · #9 05-09-2016, 08:16 AM

Here is a stock picture, and i circled the part.

Diesel911 · #10 05-09-2016, 03:05 PM

Quote:

Originally Posted by Wodnek

Here is a stock picture, and i circled the part.

It is possible to change that. The only issues is going to be keeping dirt out of the innards when you remove that (the Injector Nut).

Direct Injection Injectors used to have pins inside of them that keep the Injector Nozzle and the other parts lined up inside.

You could take it to a fuel injection shop and have them change the Injector Nozzle Nut and that is the likely source for a new Injector Nozzle Nut anyway.
Also a shop would likely have a the gland nut socket to fit the Injector Nozzle Nut so it can be torqued properly and the shop would also be responsible for keeping the dirt out of the innards.