Air bubbles from injectors... - PeachParts Mercedes-Benz Forum

Bill()C · #1 07-30-2008, 11:57 AM

87 300 SDL...

I just noticed this and, of course, can't help but thinking this is not the way the injectors are meant to operate.

I have air bubbles leaking from where the injectors screw into the block. Is there supposed to be a gasket between the injectors and the block? I don't see how. Perhaps just use some thread sealant? Maybe just plain old thread lock or teflon pipe sealant?

I have tightened some of the injectors down and the problem is resolved, but others don't seam to respond to tightening.

Thanks,
Bill

vstech · #2 07-30-2008, 12:06 PM

yes, it's called a heat shield.
about 2.00 each. get 12, cause you will need an extra set when you have your injectors pop tested.
make sure you clean out the carbon that will be in there so the injector's threads don't get all banged up when you reinstall.

Hatterasguy · #3 07-30-2008, 01:09 PM

Yeah it happens anytime you touch them.

Yank the injectors, and re torque them with new heat sheilds. They may leak a bit at first but should seal up in a few hundred miles.

winmutt · #4 07-30-2008, 01:23 PM

Are the air bubles coming from the injector edge or from the ring under it? You could also be leaking at the prechamber. Not uncommon to have the prechamber seals burn out.

whunter · #5 07-30-2008, 02:57 PM

Quote:

Originally Posted by Bill()C

87 300 SDL...

I just noticed this and, of course, can't help but thinking this is not the way the injectors are meant to operate.

I have air bubbles leaking from where the injectors screw into the block. Is there supposed to be a gasket between the injectors and the block? I don't see how. Perhaps just use some thread sealant? Maybe just plain old thread lock or Teflon pipe sealant?

I have tightened some of the injectors down and the problem is resolved, but others don't seam to respond to tightening.

Thanks,
Bill

Here is the heat shield you need.

6010170060 Injector Heat Shield

I suggest extras, they are easy to loose, and one shot = tighten to specification.

Instant trash when you loosen the injector.

Have a great day

Bill()C · #6 07-31-2008, 10:31 AM

OK...I've taken a better look and I understand what/where the heat shield is.

I don't think that's causing my leak but I want to relate what I see.

The only good diagram I have is from Performance Benz, but even that doesn't truly match what I see. It appears the injectors screw into an "injector guide". The injector guide holds the heat shield in place.

I have two new injectors to play with and they have a rubber sleeve, but I don't know where that goes.

So my bubble leak is inbetween the injector and the "injector guide". I think I have to take the injector guide out to get to the heat shield. All of which I'd like to do to clean the crud out that I see. Is there a special tool to get this injector guide out????

Thanks!!!

Bill

Hatterasguy · #7 07-31-2008, 11:52 AM

Their is no rubber gasket in their.

The injector screws into the prechamber, thats what you are seeing.

The torque on the injectors is important to; I forget what it is off the top of my head I want to say 80nm.

Bill()C · #8 07-31-2008, 11:56 AM

Ok... just got back from the dealer. The injectors screw into a collar which holds the heat shield in place which screws into the pre-chamber. I can't replace the heat shield without getting the collar out.

I CAN'T GET THE COLLAR OUT! YIKES!!!

The dealer admits there's a special tool to do this but says he'd probably just take a screw driver and try and whack it with a hammer. I thought of that too, but you can't get the angle on it without taking off the intake manifold.

Making a special tool seem awfully enticing. The collar does have a wide slot all the way across it for some sort of tool, but I don't know where to find that. My searches so far have been fruitless.

Thanks,
Bill

Hatterasguy · #9 07-31-2008, 12:07 PM

You only need to remove that collar if you want to remove the pre chambers. Since you said the leak is between the injector's and pre chambers you don't need to do that. The heat sheild is under the injector, yank an injector and you will see it.

You also need to get a FSM because this is all covered with pictures.

Hatterasguy · #10 07-31-2008, 12:09 PM

Thats under the injectors, thats the heat sheild.

Bill()C · #11 07-31-2008, 12:14 PM

OK... taking your word. The sucker must just be stuck on there then. Can't get the friggin thing out without bending it up. So when the dealer said the collar was on top I didn't argue, maybe I led the dealer to that conclusion.

Although all this has me wondering if I SHOULD pull the prechamber to clean it out. There must be some good carbon build up on it.

I appreciate your patience and all your advice. I'm going to order the heat shields now since it looks like I won't have to order anything else.

I actually bought an FSM off eBay, but it was a pirated copy and the installation instructions are impossible!!!

What's your thought on pulling and cleaning the prechamber?

Bill

vstech · #12 07-31-2008, 02:20 PM

with the injector out, spray a LOT of PB blaster all over everything, and let it soak for a few hours.
then get a thin screwdriver or a dental pic and chip all the carbon that has been leaking past the shield off of it and the prechamber.
it will be smooth in there once the carbon is out. the shield will come right out once the carbon is cleaned out.
then before you put the injector back in, spin the motor over good to be SURE there is no liquid PB blaster left in the cylinder.

winmutt · #13 07-31-2008, 02:57 PM

I always get my heat shields out by turning over the motor, just make sure you are not in the exit path as they will fly with a good amount of speed.

whunter · #14 07-31-2008, 03:37 PM

Quote:

Originally Posted by Bill()C

OK... taking your word. The sucker must just be stuck on there then. Can't get the friggin thing out without bending it up. So when the dealer said the collar was on top I didn't argue, maybe I led the dealer to that conclusion.

Although all this has me wondering if I SHOULD pull the prechamber to clean it out. There must be some good carbon build up on it.

I appreciate your patience and all your advice. I'm going to order the heat shields now since it looks like I won't have to order anything else.

I actually bought an FSM off eBay, but it was a pirated copy and the installation instructions are impossible!!!

What's your thought on pulling and cleaning the prechamber?

Bill

Never pull the pre chamber without extreme need.

Easy FSM to use = http://www.alldatadiy.com

Special Tool:
A three inch long 1/4 lag bolt works great for pulling heatshields.

Have a great day.

winmutt · #15 07-31-2008, 03:49 PM

Why not on the PC? They are regular inspection items.