Tech Specs Injectors- Torque and Bar Pressures - PeachParts Mercedes-Benz Forum

DieselConvert · #1 05-03-2005, 05:27 AM

Hey all.

Before I forget, this is for an 83 300D

Cleaing injectors for a friend and I realized something midway through - I don't have the torque specs for the injectors. I need both the torque for the injectors themselves (screwing top half into bottom) and also the torque specs for putting them back into head. The other thing that would be of great help is the opening pressure for these injectors. The bodies ( kca30s35) say 115 bar on them, but that seems rather low. I keep reading on here that it is in the 135 range...what gives? I tested a couple and they were from 120-140. I know - they should be matched. The nozzles are dn0sd240's if that info is relevant.

Thanks in advance for any help.
-Tony O

TwitchKitty · #2 05-03-2005, 06:30 AM

Quote:

Originally Posted by Beagle

The most common faults with the DN pintle nozzles are blocked, partially blocked or intermittently blocking jets and that should be the first thing you check when you have an injector problem. The centre hole in the SD 240/ pintle is 0,20mm dia, the average dia of a human hair is 0.10dia, a VERY small hole and all the fuel going into your engine must pass through it. The only way to check and clear these holes is with the special cleaning needles available from Bosch. Two are available:
0,18mm dia for SD 240/ (KDEP 2900/5) and 0,15mm dia for SD 240 (KDEP 2900/3).
They are expensive and you need sharp eyes, a VERY steady hand and a feather touch. We use a microscope but a 5x magnifying will suffice. Break the needle in the hole and you can throw away the nozzle! The cross hole is cleared with the same needle.

If the Jet becomes blocked the needle will over-lift giving a poor quality cone shaped spray (see sketch). A good injector will have a narrow parallel +/- 5mm dia jet that is well atomized.

Hope that helps

Have a nice day.

Had my injectors tested. Need input.

I don't use a torque wrench on the bodies or on the installation. The factory shop manual has an extensive write-up on cleaning injectors (07.1.4-135). You should be able to access the FSM at skinnerbox.com, find a link in the FAQ sticky at the top of the forum.

Body 70-80NM
Pressures for Non-turbo are 115-123 min 100 for used injector. For the turbo they are higher, I don't have that book in the house. Off of the top of my head I want to say it is 130 or 135.

TwitchKitty · #3 05-03-2005, 06:34 AM

Hi, welcome to the forum.

You are on the right track. Clean nozzles should be first on the list for diesel performance. For most people it is a last resort, big mistake.

New German Nozzles - Bulk Order

Search for injector information in threads with the name TomJ, he is one of the resident experts on the subject.

DieselAddict · #4 05-03-2005, 12:48 PM

I don't use a torque wrench either, but the recommended torque on installing injectors is about 50-60 lb-ft, basically pretty much all the torque you can generate with one hand with a 1-ft ratchet. Be sure to use new heat shields! The torque on the injector halves is about the same.

For a OM617 Turbo the pop pressure should be around 135 bar. If yours say 115 bar, those are not the original injector bodies and the injectors have likely been rebuilt. The nozzles you want are 240/ and you want to bring the pop pressures within 5 bar of each other.

TomJ · #5 05-03-2005, 01:18 PM

Quote:

Originally Posted by DieselAddict

I don't use a torque wrench either, but the recommended torque on installing injectors is about 50-60 lb-ft, basically pretty much all the torque you can generate with one hand with a 1-ft ratchet. Be sure to use new heat shields! The torque on the injector halves is about the same.

For a OM617 Turbo the pop pressure should be around 135 bar. If yours say 115 bar, those are not the original injector bodies and the injectors have likely been rebuilt. The nozzles you want are 240/ and you want to bring the pop pressures within 5 bar of each other.

The above is right on the money.

One that I might add is, I've had body halves leak even at the 60ftlb torque if I don't lap the parts before the ultrasonic cleaning. If you find your bodies leaking, you can go up to 100ftlbs with no ill effect, but take them apart and make sure the parts are SPOTLESS CLEAN and re-torque and try. 60ftlbs into the head (as DA stated above.)

DieselConvert · #6 05-03-2005, 01:39 PM

Wow. Thanks for all the quick replies. I have heard good things about this forum from the "run you car on vegoil" crowd over at infopop forums, and you guys have not disappointed!

Tom J - what do you mean by lapping? Also since I have your attention - I've come across quite a bit of info from you and others on injectors on this forum - what is the best solution (currently just using a water/simple green solution) to use for cleaning the injectors ultrasonically? and what do you do with the injectors to make sure ALL the water is gone from the tiny holes? I fear putting them on the pop tester and damaging the pintle holes because of some stubborn micro droplets of water.

In the past I have used carb dip (not in the ultrasonic) to clean them, but I swear, that stuff is responsible for the injector leak in my Peugeot 505TD and I'd rather avoid it if possible.

btw, some day I hope to get a mercedes or three, and have been keeping my eyes open for a 190D turbo 5spd.

thansk again for your help.
-Tony O

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