If knocking is from timing chain.... - PeachParts Mercedes-Benz Forum

jozsef61 · #1 10-16-2004, 12:16 AM

because the chain tensioner is no good, would the knocking go away when he engine rpm is raised??
thanks in advance

psfred · #2 10-16-2004, 01:09 PM

Sometimes. Usually worst at idle and mid-range speeds, depending on when the chain resonates.

Easy to find it -- it will be located at the very front of the engine and won't go away as you loosen the injector lines one at a time. If it goes away when you loosen an injector line cap nut, it's a bad injector (or cylinder problem).

Other things can knock, too, though -- rods, main bearings, bad alternators, loose AC compressors or brackets, etc.

Rods and mains will have a distinct clank to them, definitely metal to metal noise. Injector knock is often referred to as "nailing" because it mimics the sound of a 16 oz framing hammer driving a large nail into a heavy oak timber -- definitely a snap and not like a metal to metal impact.

injector knock will be definitely in the head -- rod knock lower down, (ditto for wrist pin noises, sometimes called piston slap, although that's different and I've never heard it in a Benz), and mains will be definitely at crank level.

Alternator stator/rotor noises are similar to injector knock, and the belt will wear very quickly (I know, the one on the 220D did this).

Last, missing rubber bushes on a York AC mount, or a loose or missing mount bolt, will make a sound VERY similar to a rod knock, and you will have to look closesly to see the mount move!

Peter

jozsef61 · #3 10-16-2004, 02:38 PM

im really lost now, i had the inector pump rebuilt, injectors rebuilt, head rebuilt. Put it all together, it runs, but at idle it has a heavy knock then when u smooth out very nicely when u raise the rpm. The knock is there throughout all engine running temperatures. Changed all fuel filters and lines while doing the job. As far as I remember, on the old engine it never had such a severe knock. Is tere something i missed with timing? I lined up the marks on crank and cam then turned to 15 degrees atdc and installed IP. Whats up with the timing device? ANother thing i checked is the compression on the cylinders, they are all fine, around 400psi. Alternator and A/c look good. Only thing i didnt check was the cam bearing clearance, is there a spec for this?
Im really in the hole with this one, any help would be apreciated

psfred · #4 10-16-2004, 03:14 PM

What engine?

Your injection timing is way too advanced! You need to set it properly, but I cannot tell you how without knowing what engine you have.

Running it with the injection timing too fast will burn the prechambers and cause other problems.

Peter

jozsef61 · #5 10-16-2004, 03:27 PM

it is a 1987 300 turbo diesel. 603 engine
the service manual tells u to put that holding tool in the IP to hold it in place. Then put the engine at 15 degrees atdc and install pump. Now i realize that timing is 24 degrees btdc, 15 is only a reference point.

psfred · #6 10-16-2004, 04:22 PM

Ok, several things!

One, 15 ATDC is correct if you used the pump locking tool, as that is the point at which it locks the pump. This is NOT the same as start of injection timing, that is still 24 BTDC if you measure with a drip tube.

Your knock is most likely leaking pressure valve holders seals (no smoke, but rought running and knock below 1500 rpm right?)

Retorque pressure valve holders -- loosen after removing lock rings and injection lines (you need a splined socket), then tighten to 30 Nm, loosen, tighten to 30 Nm, loosen, then tighten to 35 Nm. If you don't follow this sequence you can damage the pump from over tightening, or the seals will leak. Quite common on the 603 for some reason.

Timing this engine can be set dynamically with the proper tool.

I would check the pressure valve seals -- crack the injector lines at the injectors one at a time and see if the knock dissapears on one or more cylinders. If it does, retorque the appropriate pressure valve holder.

On my 603, one of them was loose enough to unscrew by hand when I got the car....

I think the tensioner is a simple oil pressure type, not a ratcheting one on the 603.

Peter

jozsef61 · #7 10-16-2004, 04:41 PM

i have some more questions after taking a look at everything once again.
Yes i have the locking tool, and that is what i used. One thing though, when settign timing marks, what sequence do u use? crank and cam aligned first then the IP timing device? because the way i did it, which i think is wrong...was cam last. And when i did the cam last, i had to pull the chain back over spring tension (which i think was from the timing device). Is the timing device supposed to be fully unloaded when installing everyting?

jozsef61 · #8 10-16-2004, 04:45 PM

so basically, im confused about which side i take the slack out of when setting the timing marks between cam and crank. The timing chain tensioner side or timing device side?

psfred · #9 10-16-2004, 04:52 PM

If you rotate the engine in the normal direction only, all the slack will be pulled out of the correct (left) side. It is taken up on the right side by the tensioner.

I will have to look up the installation procedure for the IP on th 603 -- I believe you must pre-tension the timer, it's not like the one on the 61x engines.

Proper procedure is to install chain and set cam to crank timing correctly, then install IP with engine pointer on 15 ATDC. It's a good idea to verify the pointer when the head is off, but I'd leave well enough alone now!

I'll post again after I dig this up on the CD.

Peter

psfred · #10 10-16-2004, 05:42 PM

here's the scoop:

Remove pump after (or before) locking it with the tool at 15 ATDC on #1 (it will only lock at that position.

Verify crank/cam timing, and set to 15 ATDC by rotating ONLY in normal (clockwise from the front) direction using ONLY the crank bolt (27mm). This will get the engine at correct postition.

Make sure the pump is locked correctly -- that is, the locking bolt catches on the "button" in the pump, it's not just holding the pump by friction. I believe you can see the "button" through the lock hole with a flashlight.

Install pump and loosely tighten the hold down bolts so that you can rotate it slightly with the adjuster on the flange.

remove lock tool, rotate engine round normal direction twice and stop at 15 ATDC. Adjust IP so that tool will lock onto locking "button" using the adjuster if ncessary to get it exactly right.

Tighten pump bolts, then install vac pump, etc.

I suspect what you did was turn the crankshaft to adjust the cam timing, and this pulled the IP forward a bit.

Peter

jozsef61 · #11 10-16-2004, 05:47 PM

thanks so much, im gonna start pulling things apart now. i'll let u know if timing was the case.

jozsef61 · #12 10-16-2004, 08:25 PM

and everything is dead on. So is the pump. I guess that wasn't my problem. While i have things apart is there anything else i should check out?
Another thing is the cars been sitting for 3 months now, and i heard diesel goes bad. Could that really be making the loud nailing/knocking.

jozsef61 · #13 10-16-2004, 08:36 PM

another thing i want to note is that after doing the injector test (opening lines) the idle would not stop fluctuating up and down. Since then its been doing it. Also the smoke coming out the back is whitish-blue. Any thoughts?

psfred · #14 10-17-2004, 12:46 AM

You probably have air in the IP and in the fuel lines.

What condition are the fuel hoses in around the fuel pre-heater thermostat and the clear pre-filter? If they are cracked and smell of fuel, likely you are getting air pulled thorugh them, and getting air into the IP, causing the knock and smoke from bad combustion.

Diesel fuel lasts for years, I'd not worry about the quality of it.

White/bluish smoke is unburned fuel -- are you SURE the IP timing is correct? Late timing will usually cause terrible white smoke cold, turning black hot (so will low compression, but I don't think that is the problem).

Leaking pressure valve seals will cause terrible knock, but no smoke...

Peter