Is a 603 engine supposed to knock? - Page 4 - PeachParts Mercedes-Benz Forum

whunter · #46 08-25-2004, 08:30 PM

Quote:

Originally Posted by Dervman

Fuel Filters were just replaced prior to my drive home.
I'll try a can or two of Diesel Purge and see if that helps.
I admit to being new to Diesels, but my mechanic (a local M-B Specialist) is very familiar with them and he certainly thinks the cold idle 'rap' noise is excessive.

You could always get a 4x4 and try to beat the RAP out of it. LOL ROTFL

I have a customer whose car looks like that is how he fixes it.

I removed the RAP from my car by locking all stations on JAZZ. LOL ROTFL

Your SIG line may tempt some young diesel mechanic to pop up and marry your daughter.

Have a great day

Mr. FancyPants · #47 08-25-2004, 09:30 PM

Since I've had my new head gasket installed, and put everything back together and started it up for the first time, Monday, I've been debating whether or not to clean the injectors!

I decided today to pull the injectors, take them apart clean and reinstall. Now they all nail more loudly at idol than before, #4 in particular and doesn't begin to fade away before 950 rpm.

I noticed the first time I removed and cleaned all my injectors, about 6,000 mi ago, that nailing was loud for the first week or two but subsided to the piont that they were only barely audible.

I hope they returns to more quiet as before. I understand that new injectors have a break-in period and wonder now if they too are loud at first before settling down?

whunter · #48 08-25-2004, 09:53 PM

Sorry sarafin
But I have to ask these questions.
Did you mix parts between injectors?
Did you pop test them after rebuild?
Did you check the spray pattern after rebuild?

Back in 1974 one of my friends did that to his fin tail diesel.

I spent three weeks convincing him to take them to a rebuild shop for testing.

He admitted that he mixed up parts and cleaned the injector spray hole with a drill press.

They convinced him to NEVER touch injectors again.

Mr. FancyPants · #49 08-25-2004, 10:35 PM

No I didn't mix parts. There was very little to clean and I rinsed everything spotless with ether and only lubed the needle pin with W-D 40 before reassembly. Each injector went back to the same cylinder.

Was thinking tonight that I ought to have a pop-tester!

If they don't sound down as before, I may consider new injectors and have'em balanced. The engine does run pretty smooth though!

DieselAddict · #50 08-26-2004, 03:40 AM

I too am wondering if injectors have a break-in period. I got the 6 Bosch rebuilds today and I tested them right away. Only one was good.

What the hell? All the others were squirting pretty bad and I tested them twice. Fortunately I was able to correct 2 out of my 3 bad, old injectors by disassembling and cleaning them again. The 3rd one didn't want to spray good even after 2 rebuilds so I will replace it with the one good Bosch rebuild and return the rest. Hopefully tomorrow (Thursday) I will have the injectors installed and the car ready to drive. I'll let you know the results.

whunter · #51 08-26-2004, 08:30 AM

injectors don't have a break-in period.

They are built correctly or not, right from the factory.

Rebuilt injectors are the same.

What we face is trash production from third world countries.

I will have mine rebuilt and balanced by a local shop.

Mr. FancyPants · #52 08-26-2004, 03:12 PM

I just posted a new topic on "new Bosch injectors 603" with questions I think are answered for me right here!

Now I ask, can new german injectors, or rebuilds be found anywhere, Europe maybe, I have connections over there and could ask to send?

What the hell wares out? Is it the nozzle needle pins, what? What actually makes the rapping noise we hear and what is it that causes the spray pattern to become ineffective, or inefficiant?

What is the best alternative given new nozzles are worse than what we want to replace?

Steve..............

whunter · #53 08-26-2004, 03:44 PM

Quote:

Originally Posted by sarafin

What is the best alternative given new nozzles are worse than what we want to replace?
Steve..............

have them rebuilt and balanced by a local diesel shop.

Ask at the big truck garages or fleet garages about who is the best near you.

gsxr · #54 08-26-2004, 03:55 PM

Well, you can get rebuilts from your MB dealer for $58 plus a $15 core charge, or get brand new ones from the dealer for $165 ($132 wholesale), no core needed....

DieselAddict · #55 08-26-2004, 04:40 PM

You may go to the dealer and pay more but you'll get exactly the same product unless you're talking about new injectors but they probably have Indian nozzles too. What wears out is the surface of the pintle and the inside of the nozzle. When the surface gets rough you'll get channeling of the fuel which will lead to squirting and knocking idle. Almost any nozzle will spray fine under high pressure, but a lot of them squirt under low pressure. That would explain why my engine sounded fine at higher rpms but like crap at idle. As far as alternatives go, the only alternative I see is to hold on to your old injectors and if you need a nozzle go look in the junkyard. Having a pop tester certainly helps whether you do your own rebuilding or having somebody do it. Can't trust anyone these days.

Mr. FancyPants · #56 08-27-2004, 12:27 AM

Sounds like there's no easy answer except to buy a pop-tester and additional shims.

It would have been nice to buy German nozzles! Wonder now what junk yard injectors might cost and who may have them. I doubt there are many available as the 86-87 603's are not plentiful.

Was this model Bosch injector exclusive to MB 603's, or were they also used in other engines as well?

Hell, if you had a computerized milling machine, and used the quality metal alloy, probably heat tempered, and produced superior quality injector parts, there maybe potential for profit. The India company probably bought the foreign patent rights from Bosch! Hmmmm.

Now I'll be looking for a pop-tester! I have seen here some people found some on Ebay, and a few others built there own. I'm going to do some looking and see what else is out there!

whunter · #57 08-27-2004, 05:48 PM

Quote:

Originally Posted by sarafin

Wonder now what junk yard injectors might cost and who may have them. I doubt there are many available as the 86-87 603's are not plentiful.

Read this thread and PM them, bet you would have a used set quick.

http://www.peachparts.com/shopforum/showthread.php?t=102218

DieselAddict · #58 08-29-2004, 02:00 AM

Yesterday I was finally able to reinstall my injectors. I ran into some trouble so that's why it took a little longer. That one good Bosch rebuild didn't fit my car because it had an incorrect lower half of the housing! So I had to swap to a different housing but I was never able to get the injector to spray properly again. It really seems like the pintle is a very sensitive part and once you turn it it may take a lot of work to get it to spray properly again. After several tries I just gave up and instead I put the effort into my old injector which I was able to fix the pattern on after rotating the pintle like 10 times. BTW, these rebuilds had French made nozzles. I did spray some carb spray into the prechambers, but I think that had a minimal effect if any. I also installed the heat shields with the bigger openings which according to two separate mechanics I talked to help eliminate knocking. So I changed a few variables at a time, but I'm pleased to report that my idle is now more civilized. Not as clean as some of the other sound files I've heard, but I didn't hear any isolated knock anymore. Maybe tomorrow I'll post another sound file.

kevinaw · #59 08-29-2004, 10:35 AM

Our 87 300D had some of the noise issues described above. After reading many of the forum threads I decided to replace all 6 injectors with new. I purchased the injectors new from Phil and based on the advice from gsxr and others before installing them I took them to a professional truck injection shop to have them pop tested. I took the new ones and a couple of my old injectors just for grins. The tech guy invited me back to watch the test. The pop test was done in a sealed lighted box with ventilation. The test was a combination of measured pressure, volume and the pro’s observations on the spray pattern and maybe a few other spec issues that as a novice I failed to recognize. All 8 injectors passed but the two old ones spray pattern performed inconsistently. He pop tested all of them twice and I was very impressed with the overall procedure. Personally, I would find it hard to duplicate the technical aspects of the pro test at home. I would advice using a pro vs. a at home pop test. Using a pro shop eliminates an important variable. I was careful to install the new injectors to spec. The Benz quieted down and I haven’t had any issues with it since!

DieselAddict · #60 08-31-2004, 02:05 AM

You probably found a good injection shop but I haven't. There are two here, but one charges over $20 to pop test each injector and the other told me that even pop pressure differences as high as 14 bar don't matter to the car which we all know is BS. I'm surprised all your Bosch rebuilds passed. Did you happen to see if any of them were squirting under low pressure as the guy was trying to read the pop pressure? Or could you give him a call and ask him if it's ok that a nozzle squirts near the pop pressure? I still don't think it's ok, but with so many nozzles doing it I'm not so sure anymore.

Unfortunately my car's knock came back again on the second day.

I noticed it's more audible from inside the car than when I stand right over the engine, but it's still there. Take a listen...