Barking up the wrong injector tree?

[cityhix]

Say a fella had a '79 300d that seems to run pretty well. Starts up decent (glow plugs probably need replacement) but gets fairly poor fuel mileage (I know, valve adjustment is probably in order). The current injectors have probably been in service for 110k since the car got a factory new motor. Now what if the same guy was on a very tight budget but had access to two sets of injectors, five each from a '79 and '80 300d of which he knew nothing of the condition? Would it make any sense to take all five injectors, have them tested and make a good set out of the ten? Or would this fella spend as much having them tested as he would pulling the existing injectors and having them rebuilt. Or, should he buy five used injectors and new nozzles and attempt to rebuild himself and then have them tested? Obviously, this fella (you guessed it, me) doesn't have the know how or access to a pop tester to test them himself.

[rs899]

If yours have 110K miles and the other are unknown, I would be betting that the unknown ones have more than 110K miles on them. I would opt for the new nozzles, if you can find a cooperative shop that doesn't mind having its profit reduced. Best thing is to make your own pop tester..

[Stevo]

Buy nozzles, forget pop test, chances are they will be fine.

[rs899]

you can try new nozzles w/o pop test, but my experience is that there's always one that doesn't pop right without sone fiddling, or is just plain bad.

[Diesel911]

You never said what the milage you are getting is or what type of driving you are doing or what type of fuel you are using. Is the car smoking at all.

If you do not have the $ right now concentrate on those thing that will not cost you anything like adjusting the valves and checking the timing on the fuel injection pump. Poor tire inflation uses up more fuel; things like that. I had a gas car and that started to use more fuel and found that the brake calipers were sticking enough to reduce the fuel milage but not enough do damage the brake pads.
I bought some new made in Germany spray nozzles from C Sean Watts at a resonable price. But you should always consider completely rebuilding the injectors with pop testing; if done correctly the 1st time and your fuel system is kept clean you are good for anothe 1K. That is the best economey in the long run.
To answer your other question; all of the injectors you are talking about have the same opeing pressure setting stamped on the side they can be interchanged. Non-turbos 115bar; 135bar for turbocharged. Years aprox.77-85.

[cityhix]

[quote=Diesel911;1776998]You never said what the milage you are getting is or what type of driving you are doing or what type of fuel you are using. Is the car smoking at all.

With mostly around-town driving and the occasional 10 minute jaunt on the freeway at 65-70 I am averaging almost exactly 18 mpg. White smoke in the morning at startup (mostly from one weak glow plug I think). New air filter. Burning B99. Definitely leaking some fuel from primer pump and secondary fuel filter (not gallons though). New tires, properly inflated. I did change the brake pads recently and have not checked for brake drag front or back (calipers moved freely when I changed the pads).

I have no idea when the valves were last adjusted (thus no knowledge of the condition of the timing chain).

I haven't even begun to do the research here on what is involved in setting the IP timing.

Thanks for the input on this guys.

[mobetta]

hard saying on what it would cost ya to take in the set of them to test and get 5 good ones out of. I dropped off 5 out of the junkyard to a local mom and pop place- they tested them (all good) and wouldn't even take my money. I did get some heat shields from them. $4/5.

first time customer, too. needless to say, I'll be back.

[toomany MBZ]

Cost me $12 each to test.