New injectors, now twice the smoke.

[MarioG]

From another thread:

I went to the rebuild shop and found out that the shop uses reconditioned parts for the injector overhaul. I got the bright idea of going over to Detroit Diesel in Miami and picked up reliabuilt N90P "premiums" at twice the price at $98.50 a pop. Before installing them, I took them over to get tested and the injectors were all even and well within specs. we installed them today and fired it up. eventhough the engine fired up on the first try and ran smooth, it smoked twice as much compaired the old injectors.

Back to the drawing board.

valves gapped to .15
injector calibraded to 1.460

what am I missing?

[JLR]

Get rid of the Reliabuilt injectors and get Interstate.

[Brian Degulis]

Mario read the spare injectors thread I just did the same thing 24 Reliabuilts in then mosquito control so 24 Reliabuilts out and 24 Interstate in and no problems. I FEEL YOUR PAIN!!! You can get the Interstates at Diesel Pro in Miami or PC Industries in Ohio around $50 each.

Brian

[MikeP]

This tells me that whatever is used to "test" the injectors is essentially useless. I still don't understand this issue - if these injectors are so bad, how are they still being sold? If an automotive product was so bad, it would be gone immediately!

Ooops - well that's not true, the Quadrajet is still around. But you CAN make a Qjet into a good, reliable unit.

But I have a question related to this (I don't have the service manual handy - it's 2500 miles away on the boat), is it possible that the injectors could be improperly installed which could cause this high failure rate? I mean if something tests ok and then, in place it doesn't work properly, what are the odds that it failed between the test and the installation? I'd say just about zero.

Or is the testing machinery at fault?

The fact that injectors are "rebuilt" should be meaningless. A rebuilt engine can ALWAYS be a better engine than a new one. I don't see any reason that a rebuilt one can't be as good as a new one. SOMEBODY/SOMETHING has to check and assemble them in either case.

One thing that occurs to me based on other types of applications is the torque when installing the injectors. So, based on the tiny internal clearances the installation torque is likely fairly critical. I realize that the injector is steel, not pot metal or Al but overtorquing might deform the body sufficiently to cause a problem, especially with the tiny clearances internally. Is that a possibility? Note that the torque reading the wrench is seeing (calibrated recently?) and the actual installation torque may be quite different based on the condition of the individual threads, the lubricant used (if any), etc. Another issue - maybe the fuel pipes to the injectors are getting contaminated with foreign material?

At the same time, I have to admit that when I was in the Army (Tank Battalion Maintanance officer at one point) diesel injectors on DDs were changed in the field (literally in a field!) with no apparent problems. Were the injectors better then or did we not really care if there was some smoke? I don't really recall - we just cared about getting non-running vehicles running.

I know it seems I may be beating this horse to death but I just CANNOT get my head around the fact that so many of these injectors are bad from the suppliers. ["puzzled" icon would be here if I knew how to generate one]

[REBrueckner]

Taking Brian's input at face value, Reliabilts just don't measure up: he got clean burn from Interstates and smoke from Reliabilts. That tells me the Reliabilt testing is probably useless ...unless he incorrectly installed Reliabilts and properly installed Interstates....not very likely.

Difficult to believe since this is not new and unique testing...but we have all seen crazier things I'll bet...

[krush]

Quadra-jets give you problems? I've never dealt with a better carb than the Q's. Holley's won't hold a tune for shit.

[MikeP]

"Quadra-jets give you problems? I've never dealt with a better carb than the Q's. Holley's won't hold a tune for shit."

Good one K, Pretty funny...

I had to hunt up one of my previous minor rants re Qjets that I posted on this subject a while back:

"Unfortunately, carbureted GM engines (Crusaders) came with Quadrajet carbs and the phrase "well adjusted carburetor" and "Quadrajet" have, to my knowledge, never appeared in the same sentence. And if they did, it was a typo.

As you can tell, I am not a Qjet fan but I assure you that a carb can be essentially trouble free and work perfectly if properly set up. My first reaction when faced with a Q jet is to immediately fill a trash can with it but have to admit that even a Qjet can be forced (admittedly with much kicking and screaming) into working quite well. But one of my minor fantasies is to see all the QJets ever made sitting together in one landfill! (Then we could melt them down to make pot-metal replica Chevy Vegas.)"

[krush]

I would choose a Quad jet over any other carb, especially for a boat. Powervalves are junk.

[TedZ]

To get back on the topic i'm assuming the injector tool was used to set the heights, and it was the right one???

Ted

[MarioG]

yes. injector height set to 1.460 assuming 1.460 is the proper height for N90's