617.951 odd engine noise... help?? - PeachParts Mercedes-Benz Forum

79300sdtd · #1 07-21-2007, 11:12 AM

i posted this in the OT but only got one response so i am going to try it in it's own thread.

my engine that was just installed seems a but loud to me. here are some videos with sound to see if there is any help.

http://www.youtube.com/watch?v=a5vTce0JnrU

http://www.youtube.com/watch?v=Pog9AnL17Ho

thanks in advance

Brian Carlton · #2 07-21-2007, 11:22 AM

Doesn't sound like an injector knock, but, just to be sure...........crack each injector line fitting...........one at a time...........while the engine is running.

See what happens when you find the cylinder with the problem. It might completely disappear...........or partially disappear.

Report back.

79300sdtd · #3 07-21-2007, 11:50 AM

Quote:

Originally Posted by Brian Carlton

Doesn't sound like an injector knock, but, just to be sure...........crack each injector line fitting...........one at a time...........while the engine is running.

See what happens when you find the cylinder with the problem. It might completely disappear...........or partially disappear.

Report back.

just did that after i posted. the number 3 cyl i think is the culprit. i cracked it the idle smoothed out and the noise went away.

Brian Carlton · #4 07-21-2007, 12:06 PM

Quote:

Originally Posted by 79300sdtd

just did that after i posted. the number 3 cyl i think is the culprit. i cracked it the idle smoothed out and the noise went away.

Ok, now just for an experiment, switch injector #2 with #3. See what you get.

Also, with #3 removed, take a strong light and peer down into the PC and see if the shaft and distribution ball is intact. Remove the heat shield at the bottom............naturally.

79300sdtd · #5 07-21-2007, 12:08 PM

cracked the lines. #3 cyl pretty much eliminates the noise. oddly enough, these are the injectors from the old engine. swapped cyl for cyl, the #3 on that one is kinda dry and rusty in side the hole, where the others were nice and wet.

i didn't know if the newer injectors were good. One of them did not have the little diffuser thingy in the top so i swapped them all. i didn't know if they were different pop pressures or not.

could i just swap one of thoes out?

Brian Carlton · #6 07-21-2007, 12:11 PM

Since you have provided no background regarding "old engine" or "new engine", and I'm not clairvoyant, I cannot advise you as to what to swap.

However, it was my intention to change the #3 injector and see if the sound changes.

parnelltk · #7 07-21-2007, 02:42 PM

Quote:

Originally Posted by Brian Carlton

Doesn't sound like an injector knock, but, just to be sure...........crack each injector line fitting...........one at a time...........while the engine is running.

See what happens when you find the cylinder with the problem. It might completely disappear...........or partially disappear.

Report back.

When you say "crack each injector", do you mean to loosen the connection fitting? Something else? Does this cause a fuel leak?

Cervan · #8 07-21-2007, 03:40 PM

Quote:

Originally Posted by parnelltk

When you say "crack each injector", do you mean to loosen the connection fitting? Something else? Does this cause a fuel leak?

yes lossening the injector line on that cylinder to stop getting fuel pressure to the injector. meaning not enough pressure to pop the injector. no fuel in the combustion chamber.

79300sdtd · #9 07-21-2007, 03:42 PM

i figured that but i thought it would have been easier just to replace the injector.... then i thought again and i would not have known if it was the injector.

you crack the hardline on top of the injector, yes some fuel comes out and sometimes it squirts.

Orovalleydude · #10 08-30-2007, 02:47 AM

Gents,

I hope I am not piggybacking here, but my odd engine noise only happens when I start it up in the morning or afternoon for the first time. It is a fairly loud clacking that goes away after the engine warms up. I am the new owner of the car. The previous owner used B100 almost exclusively, and regularly added ATF to the gas, and also used Castrol 20W50. Here in Tucson, BioDiesel is hard to find, so I have been using #2 Diesel. The oil is changed regularly and religiously; I am adding Stanadyne "lubricity formula" to the gas, 4 oz at each fill-up.

I had the valves adjusted at a local European car repair shop that has experienced MB techs. The noise stopped for 48 hours and then returned.

If I pop the hood and grab the throttle linkage and take the engine up to 2k rpm, the noise is also there. However, when I am driving around the city, 40 mph in fourth gear runs around 2000 rpm, but with no noise.

Last week, 100 miles ago, following a suggestion from the previous owner, I added some Diesel Purge to the gas. Noise is still present.

I'll keep in touch here, looking for insights and clues. Great forum, Thanks!!

- Stu

79300sdtd · #11 08-30-2007, 09:42 AM

Quote:

Originally Posted by Orovalleydude

Gents,

I hope I am not piggybacking here, but my odd engine noise only happens when I start it up in the morning or afternoon for the first time. It is a fairly loud clacking that goes away after the engine warms up. I am the new owner of the car.
- Stu

not piggybacking at all. i am still at a loss with my noise.

Watch your oil pressure, does the sound stop when the car is warmed up or when the oil pressure rises.

another possibility... watch your exhaust for a bit. if you are seeing blackish smoke (possibly white on start up) after you see oil pressure you might have a cyl that is not firing till it is warmed up. this could be due to a bad glowplug or a cyl that has low compression.

Orovalleydude · #12 10-10-2007, 01:24 PM

An update on my pilgrimage to fix the noise in my 1981 300 SD:

I did four tanks of gas adding the Stanadyne, the sound persisted, but only in the morning before it warmed up, or as it got cooler here in Tucson, after it had been sitting for a while.

After many long talks with my brother about oil and gas. We decided to try a tank full of diesel with MMO added. I had also finally seen how much black smoke comes out the butt of the car when I romp on it in second gear. My brother suspected that was dirty injectors that the MMO would help.

Well....after 200 miles on that tank of gas, the noise is worse. I have been checking the oil religiously, after the engine is warm, and I am not burning any oil.

So...my plan is to back to the Stanadyne, and see how the next oil changes deals with this. My plan is to use up the half-case of Castrol 20W-50, and then decide about some Rotella after that.

I am wondering about the previous owner's long term use of ATF added to each tank of Bio-diesel, but there is lots of bad ju-ju traffic about adding ATF to diesel fuel; so I am not certain about that...It looks like adding ATF to newer diesels is bad, but adding to older ones is okay. Any ideas on that?

This a bit of a pain, as I want to keep this little baby; but it is fun.

Stu

kerry · #13 10-10-2007, 01:44 PM

Quote:

Originally Posted by Orovalleydude

An update on my pilgrimage to fix the noise in my 1981 300 SD:

I did four tanks of gas adding the Stanadyne, the sound persisted, but only in the morning before it warmed up, or as it got cooler here in Tucson, after it had been sitting for a while.

After many long talks with my brother about oil and gas. We decided to try a tank full of diesel with MMO added. I had also finally seen how much black smoke comes out the butt of the car when I romp on it in second gear. My brother suspected that was dirty injectors that the MMO would help.

Well....after 200 miles on that tank of gas, the noise is worse. I have been checking the oil religiously, after the engine is warm, and I am not burning any oil.

So...my plan is to back to the Stanadyne, and see how the next oil changes deals with this. My plan is to use up the half-case of Castrol 20W-50, and then decide about some Rotella after that.

I am wondering about the previous owner's long term use of ATF added to each tank of Bio-diesel, but there is lots of bad ju-ju traffic about adding ATF to diesel fuel; so I am not certain about that...It looks like adding ATF to newer diesels is bad, but adding to older ones is okay. Any ideas on that?

This a bit of a pain, as I want to keep this little baby; but it is fun.

Stu

Do a diesel purge. Run the engine directly on purge, don't just put it in the tank. The procedure is outlined in a number of posts on this site and I believe DieselGiant's site also explains the procedure. It sounds like nailing.

rrgrassi · #14 10-10-2007, 01:29 PM

That 20w-50, is it a diesel rated oil? The Rotella 15w-40 is.

Orovalleydude · #15 10-10-2007, 10:28 PM

Quote:

Originally Posted by rrgrassi

That 20w-50, is it a diesel rated oil? The Rotella 15w-40 is.

That has been the topic of many loooonng discussions with my brother. For the past ten years, the previous owner has been serviced by an LA area Mercedes-Benz repair shop. For that period of time, they used Castrol 20W-50 non-diesel, but API rated SM, SL, SJ, SH, [which I understand is the highest API rating for that type of oil] and used bio-diesel whenever he could. I spoke to the repair shop owner, and he told me the Castrol would be okay for that older engine.

My brother talk about this constantly..

I'll let you all know how the next step goes, thanks for the forum..

Stu