Took what I think to be the problem injector to the shop that rebuilt them. The guy looked at it and sort of clucked his tongue a few times. He said that he's certain that it wasn't seated right against the heat shield, and that the injector tip shows sign of exposure to detonation. He took it into the back and came back and said the injector is fine, but I should (again) clean the area where the heat shield rests inside the collar and reinstall with new heat shields (even though the old ones had been in use for about 10 days).

So, I went to the stealership, bought five new heat shields for $20, reinstalled everything and.... surprise, it still nails! I am confident that it is coming from this single injector, which the "experts" say is just fine.

At this point I'd had about enough of taking the injectors in and out and all that that entails, so I called a local indy that some on this board have recommended. I am ready to just drop it off and say "fix it".

The indy asked me when I'd last adjusted the valves, and I said 6,000 miles ago. He asked if I did it hot or cold, I said "cold" (I thought that was the universally accepted way of doing it, at least around here) and he told me that it is better to adjust them hot, and that I should do that and then call him back if it isn't better.

Thoughts on this??

IIRC, FSM advises adjusting valves on a cold engine.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

There is a sticker under the hood of the 240, says
Valve Lash at water temp below 30c, intake 0.10mm, exhaust 0.30mm.
water temp above 45c, intake 0.15mm, exhaust 0.35mm.

The FSM has it listed

valve clearance---with engine cold(approx. 20c)--with engine warm (60 +- 15c)
Intake------------ 0.10---(1)------------------------0.15---(1)

Exhaust-----------0.35------------------------------0.40

(1) note: 0.05mm higher during lasting outside temperatures below -20c


Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Swapping the injector with another in the engine will let the noise travel with it if the injector is bad. Or replacing the injector with a spare one as a test.

The injector test on a stand is at a very slow rate compared to the dynamics of an engine running. This is why a given injector may do well testing under almost a static condition but have problems when used dynamically in my opinion.

Yesterday I saw that the "problem injector" was leaking between the top and bottom halves, so I pulled it and took it in to the Bosch shop that serviced my injectors a couple of weeks ago. They had it for a few hours, and then called to tell me (again) that the injector was suffering due to an "improper installation" (by me). Specifically, the injector had not seated properly against the heat shield and was therefore being exposed to detonation. They cleaned it up and tested it again at no charge, and it all tested fine.

I took it home, made sure for the tenth time that the surface on which the heat shield rests was perfectly clean, dropped a new heat shield (purchased at the dealership) in there and re-installed the injector. I fired up the car and right away there was a pronounced nailing sound coming from this injector (it's injector #1), which seemed to be even louder than before. I cracked the hard line to that injector and the noise went away completely. The nailing grew quieter as the engine warmed up, but never went away.

In the next couple of days I'll swap this injector with #5 to confirm that it is the injector itself. So far the injector is no longer leaking, so that's something.

JDH, I feel your pain. I had an 85 that did this same thing before and after new nozzles. I narrowed it down to a single injector which, when moved, carried the sound to the new cylinder. I tightened and retightened, tested and retested, cleaned and recleaned to no avail. The shop that I worked with definitely got tired of seeing me. I finally gave up and accepted the noise.

Later I sold the car and bought the 84 TD that I drive now which has a nailing noise just like my last one even after installing new nozzles. I'm apprehensive to invest much time into this because of my past experience, but I'll watch this post closely as I would really like to have a purring 617.

I know what you mean about getting good at pulling stuff off and putting it back on. Those injector lines sure are easier the second time around once you have the method down. Wish I had some good advice, but mostly I just wanted to say that I'm pulling for you, and that you're not the only one to cuss these things.

__________________
84 300td (Yes, a wagon)
"The Golden Dragon"
195k, 2nd owner
Lives in Redmond, WA

I'm about to do my first valve adjustment, in interior Alaska, so we're going to have "lasting" temperatures below -20C (about 4 months worth!). I don't have the FSM but could someone interpret that last line for me... does "higher" mean a higher clearance (0.15 instead of 0.10) or physically higher (0.05 instead of 0.10)?

Thanks.

When you adjusted the valves the second time hot. You found them tighter simply because the engine was hotter. This heat alone causes the valve stems to expand and this closes the gap somewhat as it is designed to do.

The new nozzle and seat have to kind of match wear in and this can take some milage on occasion. Evidence of detonation they are seeing could be consistent with the injector opening at a lower than test pressure when it a dynamic operating mode perhaps.

There are lots of used injectors around in decent condition to substitute it if the noise does not clear up. Although you have not reported the results yet of swapping injector locations and seeing if the noise does or does not travel with the injector.

If not my suspicion is the injection pump element timing for that cylinder may be off a little with wear and age. There are ways you can deal with that for one element at home. Takes a little time and effort to verify and fix but costs nothing. The new detonation evidence they saw on that injector does indicate something is going on.