Get the truck back and dump two quarts of 2-stroke into the tank and see if the noise goes away or lessons. Those balance rates are acceptable.
LBZ: Engine Knocking
- Thread starter dsauka
- Start date
Balance rates only go so far. You'd be better off doing a fuel return rate test and see if you have an injector that is leaking badly causing your knocking issue. You may also want to do a compression test to rule out any mechanical compression issues. I would also get something to read your own codes and check balance rates (like an Edge Insight CS or CTS).
So I talked to the shop and they appolagized for saying it's +-1 when it's 4.0 but they said they did other tests and analyzed my exhaust gases also while shutting down the injectors and from what I understand now is that some of the balance rates were good but the pilot injection was not performing right on 6 injectors. They also confirmed the knock went away when they shut down the one injector with the bad cylinder. So I didn't quite understand everything he said but in lamans terms it was other tests other than the balance rates that the injectors failed. He also said he would send my injectors to another shop with this 60,000 dollar piece of equipement that could tell run test to confirm they are no good. I'm looking fwd to seening the paperwork on that.
He also said that BC (Western Canada) has the driest fuel around (ultra low sulphur diesel) and that these injectors go bad all the time. He has lead me to believe the root cause of the failure is due to dry fuel.
He also said that BC (Western Canada) has the driest fuel around (ultra low sulphur diesel) and that these injectors go bad all the time. He has lead me to believe the root cause of the failure is due to dry fuel.
That is what they should have done in the first place, start shutting down injectors one at a time until the knock went away and then replace that injector......problem solved. You can't analyze exhaust gasses on a diesel like you can on a gas motor so I call BS on that. Also every Province is running ULSD fuel so I have no idea what they are talking about with that respect. Yes, on the earlier trucks you need to run some additive (like Diesel Kleen) to keep everything lubed and clean but I don't buy their arguement one bit that Dmax injectors are failing all the time because of it. I'd tell them replace the one that was knocking and that's it. After that, you can run a return rate test and check balance rates at home and change out any others that fail at your leisure. I'll bet just doing a good DIY injector cleaning would probably get rid of any remaining issues with the rest of them.
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Yup they are some what miss leading in there approach to diagnose. It's straight forward balance check ,shut down cylinders one by one and as mentioned a return rate check. Everything else is pretty much BS.
You run lines to the fuel return port on top of each injector, disconnect the engine bale connectors, crank the engine for 15 secs and measure the fuel in separate 100ml graduated cylinders. Any injector returning more than 5 ml of fuel in that time is out of spec and should be replaced.
Here's what it looks like at home:
http://www.dmaxcentral.com/forum/showthread.php?t=3206
Well I based my decision to allow them to replace them all due to the fact that the balance rates were all out according to their -+1.0 spec. They have addmitted that the guy that told me that was wrong and the reason they need replacing is because they fail some other test....which I'm still confused on.
The work is all done now but I haven't gone to pick it up or agreed to pay yet. I think the fact that they misslead me in the first place is grounds enough for them to put my old injectors back in free of charge. I may agree to the replacement of the one injector making the knocking noise but that is it.
How easy is it for a professional shop to swap out injectors? I think initially he said 3 hours per bank so a total of 6 hours. Does it really take that long?
The work is all done now but I haven't gone to pick it up or agreed to pay yet. I think the fact that they misslead me in the first place is grounds enough for them to put my old injectors back in free of charge. I may agree to the replacement of the one injector making the knocking noise but that is it.
How easy is it for a professional shop to swap out injectors? I think initially he said 3 hours per bank so a total of 6 hours. Does it really take that long?
Well I dropped by the place today and talked to the "boss". He told me he will do anything to make me happy. He doesn't want to make any decisions until the injectors come back from testing. He told me he sent them to a shop to do a MAK test. He says this is the definitive test to tell if the injectors are good or not.
Anyone heard of this "mak" test? Sounds like some sort of bench testing for the injectors....or is he just feeding me another line.
Anyone heard of this "mak" test? Sounds like some sort of bench testing for the injectors....or is he just feeding me another line.
MAK sounds like the brand of test bench they are using, not the name of a test itself.
http://www.maktest.com.tr/test_equipments.php?kod=common_rail_injector
Make sure they give you a FULL printout for every injector including pilot injection, main injection, leak and return fuel testing.
Should cost around $20-30 per injector to test them and as much as $50-75 each if they will be ultrasonic cleaning them as well.
Ok thanks. But even if they give me a full printout of all that info how can I tell if it failed any of those tests? Are those tests a pass/fail kind of result or are we looking at being in a range of specs. If so what would those specs be?
The machine's software should have the specs for your injectors loaded and should give you the value and also a pass/fail on the printout next to each test it does. The spray pattern test is usually visual so that is a bit more subjective. Post up some scans of what they give you and we can comment on it if you'd like.
Ok, thanks. They are supposed to send me some info tomorrow so I will post if fer sure.
Well just talked to the shop. He said he talked to the place where he sent the injectors. He said he didn't want to get into the details of the tests (hmmmm) but only asked if they would "run" an engine he said the test shop said yes (very hesitant). So long story short, he's putting all 7 injectors back in my truck and I"m only paying for the replacement of one injector.
My gut feeling is the 7 injectors are perfectly fine. My truck ran great before the knocking noise so why would all injectors fail at once. One failing I can handle.
I think I will be getting an edge cts to monitor the situtation from now on. And if any more go I'll just replace them myself as needed.
My gut feeling is the 7 injectors are perfectly fine. My truck ran great before the knocking noise so why would all injectors fail at once. One failing I can handle.
I think I will be getting an edge cts to monitor the situtation from now on. And if any more go I'll just replace them myself as needed.
I'd say you called his bluff and saved a ton of money my friend. :thumb:
Next buy yourself an Edge Insight CS or CTS and don't bother going back to that shop again.