Injector body leaking - PeachParts Mercedes-Benz Forum

argus445 · #1 02-13-2008, 09:38 PM

i just installed 5 new injector nozzles and the body's are leaking where the top and bottoms thread together i followed diesel giants suggestion of soaking them in brake cleaner for 30 min but seems it's leaking agian any ideas suggestions on what is leaking or what area to check? is the threads suppose to be leak proof or is the thing that sits inside the body of the injector to blame? any ideas simular ideas? i'm bout to just put some hylomar on the threads or something. torque was 80 n/m top/bottom and 80 into the head i think that's about 50-60ft/lb not sure?

#2 02-13-2008, 10:40 PM

You need to take them apart, clean the threads, clean the mating surfaces and torque them to 100ftlbs.

C Sean Watts · #3 02-13-2008, 11:23 PM

clean the top and bottom surfaces on the spacer disk? It's in the FSM under the injector service section. Use a super fine emery cloth on a foot square, or so, piece of plate glass, put some light machine/lube oil on it and rub the disk in small circles to dress it. Do not try to sand it - just very light pressure until it's clean and smooth.

toomany MBZ · #4 02-14-2008, 05:48 PM

I had the same thing happen, you DO need to gorilla tighten 'em down, when I did that, no more leaks. My threads were not an issue, I did not emery cloth it either.

argus445 · #5 02-14-2008, 06:31 PM

ended up taking the crap back off 2x before taking them to work and putting them in a huge ultrasonic cleaner they use to clean springs and such off with. There's a ton of little fine carbon crap that goes everywhere i guess or the torque is way too low i thought 60# is low i think vw's spec was like 87-90ft/lb not sure anyhow kudos..

toomany MBZ · #6 02-14-2008, 07:39 PM

I did not use a torque wrench on the two halves, and torqued down the complete injector to 55 ft. lbs.

Diesel911 · #7 02-15-2008, 01:33 AM

My 2 cents worth.
When you only replace the spray nozzle and do no other work on the injector you are hoping for the best. When a shop rebuilds the injectors the inside precision surfaces of the injector are lapped on a lapping plate (with 500 or 600 grit compound) to make them flat again. Glass seems to work OK as a substitute for a lapping plate if you do not have one. Regular Valve Grinding Compound is too coarse. You should see a good even gray surface over the lapped area. Clean compressed air is very valuable in blowing out the injector parts to get all the fine stuff out. Dipping the parts in diesel fuel before assembly helps get rid of any lint or fine dust that settled on the parts. If a good job was done lapping the surfaces the proper torque will seal the injector. Also inspect the injector nuts before assembly for hairline cracks or errosion between the spray nozzle and the nut.

toomany MBZ · #8 02-15-2008, 01:48 AM

I replaced just the nozzles, sprayed down with brake cleaner, reinstalled, pulled again to correct leak, fine. That car died a different death too shortly after that for me to get any viable data.
Pics are from my nifty new manual.