603 motor - why louder than 617?
 

I've noticed that the 603 seems to be louder at idle than my 617. At first I was pretty worried about the timing chain and what-not but after checking for stretch (less than 1.5°) I got to thinking more.

Could my tensioner be going bad? I'd assume it was replaced with the chain a while back due to milage. Oil pressure is ~2bar, hot idle.

Are the hyd lifters just that loud over the 617?

Do the injectors deliver fuel at a different pressure?

603s are much quieter than 617s. You probably have an issue with your lifters.

Both use the Bosch MFI pumps and the pressures are similar.

A warmed up 603 doesnt really have much clatter and is pretty quiet, a 617 is much louder and has a more distinctive diesel clatter. Which I happen to like :) You tried to run cetane booster or something ?

A properly tuned 603 should be quiter at idle then a 617. Your injectors probably need to be checked.

I vote for the hydraulic lifters. I've watched some 603's and they are pretty darned quiet (With a stock exhaust). You might try an oil/engine cleaner before your next oil change to get some of the varnish and sludge out of them. You might even think of switching to synthetic oil, I've been told it does wonders for noisy lifters.

I've tried some Cetane and changed the oil twice as I have no clue how long the syrup was in there.

Just as long as nothing is going to explode I will not worry. I plan to have this extra set of 603 injectors balanced by the board member, which I was going to do anyway.

Also, I've never heard another 603 at idle so I can't really compare. :o

Perhaps if I eliminated this blasted oil leak on my SDL I would. It's from that oil level sending unit! :mad:

On the subject of engine noise. Does anyone know of a place to get a recording (P3 is fine) of a healthy well tuned 617 at idle?

I could record mine..... :D Its quite healthy. And also a very quiet idler.....our 83 is more truck-like.....can't record that one though, its a tad disassembled.... :rolleyes:

Are you running synthetic oil? If I recall, someone in the past mentioned that theirs quietened down significantly once they changed over. It seems those hydraulic lifters like synthetic better.

my 603
 

had several injectors that wanted to work loose. they rattle like hell when loose. a bit of the red locktite and voila. quiet.

tom w

I took a recording of my car tonight, professional Microphone clipped on the hood halfways up with it open in the standard arc position, the recording is about 2mins, it includes starting up the engine, it was "warm" it had been off for almost an hour in 16 degrees, t-stat on dash said around 50C when I started it, so it was still plenty warmed up.

The recording has a couple "blips" in it, you can tell where they are, this is because my laptop has a hard time recording in raw .wav because the files are so big so quickly. (Its an old laptop, be nice to it)

One is mid-rev somewhere in there....the other blip is toward the end of the recording when its reving back down it sounds like it backfired or something, when it certainly did not, my engine is smooooth. :D :D

Here is the recording! Enjoy! (Its in MP3 now, so waaay smaller.)

The Recording

Right click it and do a "save as" then enjoy!

Sounds like my 617 yet I can hear my turbo sing with ease. :)

If the lifters are the problem, will snake oils like seafoam help? A buddy swears that putting the 0-20 weight oil and running the engine under various rpms in neutral for 30 minutes quieted his lifters.

Could we possibly get a recording of a well tuned 603 by any chance?

(I wish my 603 sounded as good as your 617 :o )

Thanks guys!