New injectors leaking - PeachParts Mercedes-Benz Forum

rgnprof · #1 05-16-2008, 10:12 PM

I just replaced my nozzles with Monarks and had a local shop rebuild them for me - pop tested, balanced, etc. Got them installed tonight and one is definitely leaking at the injector - not the return lines, but where the injector itself screws together. I don't know if they didn't torque that tight enough or what... Do you think I will hurt anything by pulling the injector and checking and retorquing it - if necessary? And, can I reuse the heat shield, or is it ruined once I loosen up and remove the injector?

ryan

TMAllison · #2 05-17-2008, 12:06 AM

You are supposed ot use a new washer each time the inj comes out. Many dont do that with no ill effect.

You could try tightening it a bit more in a vice.

Or, you could disassemble it and "lap" (sand/polish) the two halves to create a better seal. Just dont touch the nozzle with bare hands if you do that.

#3 05-17-2008, 12:10 AM

Quote:

Originally Posted by TMAllison

You are supposed ot use a new washer each time the inj comes out. Many dont do that with no ill effect.

That is only because they can't see the injector tip overheating.

Injector washers should only be used once.

rgnprof · #4 05-17-2008, 12:37 AM

Do you think I can tighten it while it's still in the car? If I could get a large box wrench on the bottom part and hold it while torquing the top half??

ryan

Diesel911 · #5 05-17-2008, 02:44 AM

If a shop did the work you should take it back to them and let them fix it. If you mess with it you will void any warranty.
Some possible causes of leaks between the injector nut and upper body are a hairline crack in the nut, improper torque, poorly lapped surfaces in the interior parts of the injector and something got caught between the lapped surfaces when the assembled the injector.
If there is something caught between the surfaces tightening it more will only make it worse. If the surfaces were not lapped well tightening it may not help either.

nhdoc · #6 05-17-2008, 06:46 AM

Quote:

Originally Posted by Diesel911

If a shop did the work you should take it back to them and let them fix it. If you mess with it you will void any warranty.
Some possible causes of leaks between the injector nut and upper body are a hairline crack in the nut, improper torque, poorly lapped surfaces in the interior parts of the injector and something got caught between the lapped surfaces when the assembled the injector.
If there is something caught between the surfaces tightening it more will only make it worse. If the surfaces were not lapped well tightening it may not help either.

This reply is 100% correct, follow his advice.

C Sean Watts · #7 05-17-2008, 09:02 AM

Quote:

Originally Posted by Diesel911

If a shop did the work you should take it back to them and let them fix it. If you mess with it you will void any warranty.
Some possible causes of leaks between the injector nut and upper body are a hairline crack in the nut, improper torque, poorly lapped surfaces in the interior parts of the injector and something got caught between the lapped surfaces when the assembled the injector.
If there is something caught between the surfaces tightening it more will only make it worse. If the surfaces were not lapped well tightening it may not help either.

The mating surfaces must be clean almost on par with a NASA clean room. When I service injectors, I will spend more time on this than most of the rest of the process. Also, don't reuse heat shield washers since they are 'crush to fit.'

Diesel911 · #8 05-17-2008, 01:34 PM

Quote:

Originally Posted by C Sean Watts

The mating surfaces must be clean almost on par with a NASA clean room. When I service injectors, I will spend more time on this than most of the rest of the process. Also, don't reuse heat shield washers since they are 'crush to fit.'

In addition, what I was taught where I used to work was that just before you assemble the parts dip them in diesel fuel; hold it up and let it drip off and assemble the part right now. This works well.
Of course this is the last cleaning step.
Dip a part in diesel fuel or light oil and let it set on a counter in what you think is a clean shop for 30 min and take a look and you will be surprised
at all the crap sticking to it.

rgnprof · #9 05-19-2008, 10:13 PM

Took them back to the shop today and had them check them out. Reinstalled them and so far so good...No leaks and car seems to run well...maybe a little sluggish at upon initial acceleration but runs great at highway speeds. I'll drive it around for a few days..

Thanks the replies...

ryan