300SDL Injector Heat Shields Required? - PeachParts Mercedes-Benz Forum

CBGraves · #1 10-24-2006, 11:32 AM

I've got a leak where the hardline goes into the top of the injector. Fuel is bubbling out around the hardline on top of the the nut that holds the hardline on the top of the injector. I've pressure tested the line and it does not seem to leak or have any crack in it. My next step was to remove the injector to see what parts I need to order to replace the injector. From my research here it appears that I need the injector and a replacement heat shield. However, upon removing the injector, I've found that there are no heat shields on any of my injectors. The injectors are screwed into the pre-chamber directly. I can see the slotted pre-chamber ring. Sooo, do I need heat shields are not? While we are on the subject, would a failed injector force fuel back and around the taper on the hardline so that it bubbles out where described above?

sixto · #2 10-24-2006, 11:52 AM

I would continue to suspect a bad fuel line. Maybe the ball end of the line wasn't seated properly in the injector cup.

You should replace the injector seal, the nickel size ring that goes between the firing tip of the injector and the prechamber. Drop a magnet or a pick into the injector hole to see if you can dislodge a camouflaged seal. If not, give the engine a quick crank with the stop lever down to see if the old seal blows out.

Kinda hard to describe how to check visually if there's a seal in place. The seal has a smaller hole than the prechamber but the difference is like 5mm for the seal and 7mm for the prechamber.

Sixto
93 300SD

vstech · #3 10-24-2006, 11:57 AM

on my 79 TD na 617, the seals were at the bottom of the injector seat. one of them was so carboned up, that it would not come out without major cleaning, and scraping... the bottom of my injector seats was convex, and the shields/seals, were flat with a small 1/4" approx hole drilled in it. the PC hole looks cast as opposed to drilled.
John

CBGraves · #4 10-24-2006, 12:05 PM

So can I get the seal from Fastlane? What about heat shields. I thought these went at the top of the prechamber on top of the slotted ring and would be visible without taking the injector out. Do they actually drop into the prechamber?

sixto · #5 10-24-2006, 12:57 PM

Injector seals are commonly available.

I only know of plastic shields for splined lockrings. I've never seen one for a slotted lockring. Shields for splined lockrings are no longer available. EPC says it's okay to go without. You'll have to ask Phil (Buy Parts link at the top of the page) if anything's available for your car.

The shields I'm familiar with engage the splines in the lockring. In fact the splines clock them. They slip onto the lockring then the injectors go on.

Sixto
93 300SD

vstech · #6 10-24-2006, 01:59 PM

http://www.dieselgiant.com/mercedesinjectornozzlereplace.htm
this will show you what the heat shields look like, and where they go. basically, they go in the PC before you screw in the injectors...skip all the injector take apart stuff, and look at the reassembly pictures at the end.
John