I bought a new set of Monark nozzles for my injectors for my 84 300 td (turbo diesel wagon). I had the injectors rebuilt, pop tested and balanced at a local diesel fuel shop...but I really screwed up! I mistakenly told the fuel shop to adjust the pop pressures to 130 to 135 bar! I got this info. about the pop pressures from the web thinking it was correct (I may have mis-read something), and I didn't verify what the stock pop pressures for new nozzles should be. The injectors have 135 bar stamped on them. I now realize that I should have had them set at 135 to 140 (spec is actually 135 to 143 for new nozzles, with no more than 5 bar difference between any two). Boy, am I pissed that I screwed this up. The shop did a real nice job, and charged $30 per injector to do it.... $150 for the job, (plus the cost of nozzles).

My question is this...should I install them like they are now (130-135 bar), and maybe have them re-balanced in a year or so? Or should I go back to the shop and have them re-balanced at 135 to 140...I'm sure they would charge at least another $100 or more!

Thanks,

Mark

(note: my car is now running with a second set of injectors from my previous 300td...so I don't have to put the newly rebuilt injectors back into the car right away).

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

If you are going to run biofuels I would.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

you're still within manufacturers spec.


which is 135 plus or minus 5 bar.

that means if all are between 130 and 135.. you are all set.


your timing will only be ever so slightly advanced by this unspeakable misfortune.

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I am only using plain old diesel fuel from the pumps....so I am inclined to not spend more money to have the injectors reset to the correct pressures...I will probably just install them as is...they will probably be absolutely terrific. But starting their new life at a lower than spec. pop pressure means that it will probably just take a shorter amount of time (2 years??? who knows) when the pop pressures start to go down to less than optimum pressures (120 bar is the lower limit) due to wear and tear. The injectors and nozzles will still be good (assuming good engine maintenance, etc.), so in a couple of years it would make sense to have the injectors pop tested and readjusted back to spec., or back to 135 (since at that time they will not be new).

I do have a question though....assuming that I install the rebuilt injectors with 130-135 pop pressures, are there any adverse performance characteristics that I should expect due to less than optimum pop pressures (assuming all else is OK such as compression, good injection pump, etc.)?

Thanks again,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

If it were me I would install them and carefully monitor a few things. I do not expect you will have trouble. As always I am expressing an opinion only.

Here is what I would monitor:

• Any mpg change
• Any engine operating temp change
• Any nailing
• Any performance change (acceleration, hesitation, etc.)
• Any new vibration - but this will be due to imbalance, not the absolute pressure

You might even find an improvement. Please get back to post your findings in three months. Good luck to you.

In fact the engines are much more sensitive to balance (5 bar between) than to the pop pressure.
I predict your report will be great and it will be due to the Monarks rather than to the pop pressure.

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Dionysius

I say run them like they are for 8K miles, and then take them in to be pop-tested and re-calibrated - just on principle - My shop charges me about 50-60 bucks for that. I think you will be pleased that you did once you find out where they are after that mileage.

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327K on 1986 W201, 602.911, 722.414 2.5 190D ("The Red Baron")
139K on 1993 W124, 104.942, 722.433 2.8 300E ("Queen")

http://farm5.static.flickr.com/4081/...0bb92d3c_m.jpg http://i370.photobucket.com/albums/o...g?t=1325284354

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.
- Albert Einstein

take a walk down memory lane...

I say run them. The Pop Pressure is important but the having the new Nozzels instead of worn ones is much more important.

Thats why some people most often get away with swapping their worn Nozzles with new one and not checking the Pop Pressure at all.

I also would doubt if they would cause any nailing; but if they did just time the Fuel Injection Pump.

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84 300D, 82 Volvo 244Gl Diesel

x2 you will have no issues at all.

Most people in this forum driving around with 200k miles on their injectors have pop-pressures that deviate 20 psi or more from the spec, because they've never been rebuilt or shimmed back up to spec.

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'98 E300 turbodiesel

I installed the newly rebuilt injectors (with pop pressures of 130 to 135 bar), and the car runs very smooth...it hasn't idled that smoothly in a very long time. I also replaced glow plugs...they were only two years old, still functioning, but in my experience, the glow plugs typically do not heat up as hot after 2 to 3 years (although that will also be related to carbon buildup). I did ream out the glow plug holes..yes there was carbon buildup, glow plugs hard to pull out.

I also removed pre chambers to inspect...they were all in good condition (no cracks, etc.). I brushed everything off and vacuumed, and reinstalled with new pre-chamber seals.

I also checked compression, and the results were unfortunate:

1. 320 psi
2. 238
3. 240
4. 318
5. 320

Cylinders 2 and 3 are 80 psi lower than the others

A couple of weeks ago, I adjusted valve clearances, so open valves are probably not the cause of the low compression....valves may be burnt (?) or lower end (rings) may be bad.

This week, I will do the valves again just to see if a few of them have tightened a little resulting in lower compression...on these old cars, I think when you adjust valves properly, they may "bang themselves into their less-than-optimum seats" and required re adjusting so that the clearance is properly open...if the clearance gap has closed, then compression will be lost.

So, all in all, the car still runs terrific, 25 to 30 mpg highway, and is very reliable.....not bad for a car with 322,000 miles and never any work on the head, valves, or lower end. The low compression may result in harding starts in cold weather, but the new glow plugs and especially rebuilt injectors will likely compensate for that.

Regards,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

20 psi or more? Lot's more!!! Like 200-300 psi more.

A deviation of only 20 psi would be beyond incredible for a newly adjusted set of injectors. After 200k miles, it would qualify for the Guinness Book.