Hard knocking after installing new Monarks

[cirrusman]

So I just purchased a set of new monarks. Took the injectors out and took them to this diesel place where they put them in. Just installed then a couple minutes ago and now I'm hearing this "pfft-pfft-pfft" out of one of the injectors and a loud knock... I torqued the injectors @ 50 pounds and all lines are tight and there are no leaks anywhere. What could've gone wrong here...?

[scottmcphee]

You took out the old and put in new injector seals down the holes, right?

[Zacharias]

When this happened to me it was one of the hard line connections. Even with care it's not that hard to misalign the ends and then the nut won't tighten properly.

[cirrusman]

Thanks guys; yeah, I got new heat shields with the new nozzles that went down the holes just perfectly.
I was worried about the lines as they did not aling perfectly at first, but they are tight and secure, no diesel leaks anywhere; the sound seems to come more from injector #4 (from front to back). The injectors were cleaned professionally and look like new, no leaks there either. I do not know, however, at what specs were the injectors adjusted. For all I know they could have used the very same shims to adjust the pressure. Would using the same shims cause the sound and the knocking?

[funola]

Sounds like you don't have a good seal. Mabe washer put in wrong? Maybe dirt not cleaned off? You need to take the injector out, clean mating surfaces and install with a new washer.

[cirrusman]

Well, the washer was new and put in in the right position, the injector was thoroughly cleaned. I think they even polished it, it looks like new. The hole where the injector goes did have some oil, but I wiped it off as much as I possibly could in such a limited space... So no matter what the pressure is, the injector should mot make any noise? how can you tell that the pressure is off?

[Biodiesel300TD]

New injectors can be a bit noisy. It takes them a 100 miles or so to settle into their normal working. My 240 was extra noisy after I put in the injectors, but soon what quite and smooth as a baby's bum.
But I'd call the shop and verify what they set the pop pressure and they set the pop pressure.

[cirrusman]

Oh, really? Didn't know that... thanks! I will check with the shop that pressure.

[JiveTurkey]

Just to clarify. Did they install new nozzles on the old body? Or are these entirely new injectors? My brand new injectors (supplied by member Sean Watts, hell of a good guy) took about 150 miles to break in and stop knocking. I too was horrified when I fired mine up. It sounded like someone dropped a bunch of diamond hard ball bearings into the crankcase. Drop some lubricity additive into your diesel tank (Lucas comes to mind) and see if that helps.

[cirrusman]

Originally Posted by JiveTurkey

Just to clarify. Did they install new nozzles on the old body? Or are these entirely new injectors? My brand new injectors (supplied by member Sean Watts, hell of a good guy) took about 150 miles to break in and stop knocking. I too was horrified when I fired mine up. It sounded like someone dropped a bunch of diamond hard ball bearings into the crankcase. Drop some lubricity additive into your diesel tank (Lucas comes to mind) and see if that helps.

They just put in new nozzles in my old injectors, but they cleaned them up and they actually look like new. Really nice job. It seems to have settled now and I can't believe how quiet the engine is now! Wow! Difference of night and day. It sounds like when I run the engine on diesel purge; one can hardly hear the clac-clac-clac anymore. Or my injectors were just really lousy and I had gotten used to that sound, I don't know. Now my injector #5 is leaking from the body so I'll have to return that one so they can fix it, but otherwise I'm really happy with the change.

[Biodiesel300TD]

My 240 was a whole new car when I put the new injectors in. The idle is so much smoother now. It won't spill your coffee while sitting at the light

[warmblood58]

Originally Posted by Biodiesel300TD

New injectors can be a bit noisy. It takes them a 100 miles or so to settle into their normal working. My 240 was extra noisy after I put in the injectors, but soon what quite and smooth as a baby's bum.
But I'd call the shop and verify what they set the pop pressure and they set the pop pressure.

Gus at pacific Fuel Injection did my injectors and set mine 10psi over spec as I remember, he said this is always done for high mileage motors -

[Biodiesel300TD]

I think you mean 10bar over. Certainly not going to hurt anything, a lot of the VO'ers bump their injectors up 10-15bar. Helps atomize fuel. It will slight retard injection timing though.