Strange engine noise - Page 3 - PeachParts Mercedes-Benz Forum

yuke · #31 04-03-2020, 03:12 PM

Well took vacuum pump off and everything that I see looks good in there pictures posted so I'm gonna put it back on and pull valve cover back off again can I do a compression check with valve cover off thru GP holes or will it make to much a mess of oil? Before I took VP off I listened again heard some of the noise at the pump but again when I put the probe tip on middle of intake pipe noise sounded its loudest at that point louder then if I put it on the valve cover in middle sure hope I can get to the bottom of this as I love this car.

junqueyardjim · #32 04-03-2020, 05:37 PM

Hope you can find it Yuke, does seem to be noisier in the front on the pass. side. I would like to have you describe the trash you found in the air cleaner. What was it, organic or inorganic. It is not beyond reason to think that a rodent was building a winter home in that round house? Could be, they have a sense where to find the right place, "for them". But if the trash did not break through the air cleaner to get eaten by the engine, then you have no cause for alarm.

yuke · #33 04-03-2020, 09:25 PM

Can I temporarily run the engine with the VP off to see if that is causing noise or not? If I plug the open vacuum line coud I idle it and shut it off? And could I idle it with valve cove off that maybe would help isolate where noise is coming from?

barry12345 · #34 04-03-2020, 09:46 PM

Check that the manual engine shutoff works before running with no vacuum pump. I do not know how much oil these engines flow up top with no valve cover.

I do agree that both tests sound appropriate. . You could do the vacuum pump one first. Others may disagree on the valve cover off one.

Yet this is not like the old Mercedes gas engines that you would never want to run with the valve cover pan off.

With the cover off I might get someone to crank the engine over first watching the valves train very carefully.

I would also use the sounding device at that time on each cam follower.

ROLLGUY · #35 04-03-2020, 10:08 PM

Quote:

Originally Posted by yuke

Can I temporarily run the engine with the VP off to see if that is causing noise or not? If I plug the open vacuum line coud I idle it and shut it off? And could I idle it with valve cove off that maybe would help isolate where noise is coming from?

The only problem with running the engine with the VP and or the valve cover of, is the oil that will go EVERYWHERE! You could remove the cam (roller coaster as it is called) from the timing device and then put the VP on with a couple bolts. That would keep the majority of oil from being thrown out the hole. With the valve cover off, there will be so much oil slinging all over the place that you won't be able to see if anything is amiss. I still think you have something in the combustion chamber making the noise. Pulling the injectors and glow plugs should give you some good information.

yuke · #36 04-04-2020, 06:32 AM

Thanks for replies I will put VP back on and just keep looking and thinking as what is causing this noise it is not as loud as on a previous engine when I blew # 4 prechamber into the engine that noise I could hear inside the cabin and the engine died after 1,000 miles. This noise seems to diminish when engine revs up and there does not seem to be any loss of power yet. When I do put a stethoscope on the middle of the intake manifold noise seems right there more so then if I just move it a tad higher on the valve cover leading me to believe there is something in that combustion chamber. I'm really starting to believe faulty injectors bring a lot of these engines down maybe I just expect too much out of them like I was used to the old tractor engines on the farm they just seemed to run and run and run.

ROLLGUY · #37 04-04-2020, 10:48 AM

Quote:

Originally Posted by yuke

Thanks for replies I will put VP back on and just keep looking and thinking as what is causing this noise it is not as loud as on a previous engine when I blew # 4 prechamber into the engine that noise I could hear inside the cabin and the engine died after 1,000 miles. This noise seems to diminish when engine revs up and there does not seem to be any loss of power yet. When I do put a stethoscope on the middle of the intake manifold noise seems right there more so then if I just move it a tad higher on the valve cover leading me to believe there is something in that combustion chamber. I'm really starting to believe faulty injectors bring a lot of these engines down maybe I just expect too much out of them like I was used to the old tractor engines on the farm they just seemed to run and run and run.

If you think it might be a faulty injector, put the suspected bad one in another location, and listen with your stethoscope. If the noise travels with the injector, you found the problem. Either way, have a real good look down the injector hole......Rich

yuke · #38 04-04-2020, 10:14 PM

Quote:

Originally Posted by ROLLGUY

If you think it might be a faulty injector, put the suspected bad one in another location, and listen with your stethoscope. If the noise travels with the injector, you found the problem. Either way, have a real good look down the injector hole......Rich

Good suggestion Rollguy I cleaned the vacuum pump up real good and really lubed the bearing put it back on started to take a compression check on a cold engine got a reading 350 on #3 cylinder was happy with that will do the rest tomorrow I really think the noise is coming out of either 3 or 4 cylinder hope 4 checks out all right tomorrow. I will be so happy if it turns out to be a faulty injector and not a blown prechamber. I sure will take a look tomorrow keeping my fingers crossed as I have 385,000 on this car and would like to hit at least 500.

yuke · #39 04-05-2020, 10:42 PM

Ok checked compression today and it had 2 cyl. at 400, 2 at 360, and 1 at 380 which I was happy with. Then I pulled the injectors a couple were pretty wet down in there do'nt know if that means anything or not but I was very happy that none of the prechambers were blown down into the pistons like happened on my last engine. I did order some liquid moly purge should come in a few days. I think you put a new filter on after you do it not before am I correct on that? I think I will send my injectors to greezer to set and balance them as after I did the last set is when I blew the prechamber out was getting really good fuel milage till the prechamber blew. So as far as I can see noise is either being caused by faulty injector or worn cam lobes or followers like Kala from mercedes source.com suggested. Thoughts or other suggestions welcomed.

yuke · #40 04-06-2020, 11:35 AM

Quote:

Originally Posted by yuke

Ok checked compression today and it had 2 cyl. at 400, 2 at 360, and 1 at 380 which I was happy with. Then I pulled the injectors a couple were pretty wet down in there do'nt know if that means anything or not but I was very happy that none of the prechambers were blown down into the pistons like happened on my last engine. I did order some liquid moly purge should come in a few days. I think you put a new filter on after you do it not before am I correct on that? I think I will send my injectors to greezer to set and balance them as after I did the last set is when I blew the prechamber out was getting really good fuel milage till the prechamber blew. So as far as I can see noise is either being caused by faulty injector or worn cam lobes or followers like Kala from mercedes source.com suggested. Thoughts or other suggestions welcomed.

I tried to add pictures and the upload keeps failing and I do not know why as I am not that computer savy.

MB140300SD · #41 04-06-2020, 08:58 PM

I am leaning heavily toward a rod knock. Can you shoot another video with you revving it up and down and/or changing the engine speed? A compression test will not tell you anything about what is making the noise unless 1 cylinder was completely dead. If that was the case the engine would be rocking back and forth.

ROLLGUY · #42 04-06-2020, 09:34 PM

Quote:

Originally Posted by MB140300SD

I am leaning heavily toward a rod knock. Can you shoot another video with you revving it up and down and/or changing the engine speed? A compression test will not tell you anything about what is making the noise unless 1 cylinder was completely dead. If that was the case the engine would be rocking back and forth.

I am leaning that way as well. Pull the dipstick and smell the oil. Usually if it has a bad bearing causing a rod knock, the oil will smell burnt.

yuke · #43 04-07-2020, 11:59 AM

Where I am at is have the injectors pulled wll check them for spray pattern and pop pressure am communicating with greazzer on replacements. Spoke with a mechanic yesterday and he said sounded to him like a double tap that could be a broken valve spring or maybe a worn wrist pin sticky cyl. on walls cause I run wvo in this engine. I will check injectors just put back in did not take out heat shields yet just to restart it and I will try to take another vidio and alter engine speed while filming. Keep you posted I work slow.

yuke · #44 04-17-2020, 08:47 AM

Spoke with another diesel mechanic and he told me the noise sounded to him like I spun a bearing on the crankshaft meaning total rebuild $5,000-$7,000 not going to do. On a vidio a guy said you can find any bad bearing from the top by putting the piston on a downward stroke and then taking a screwdriver and pushing down on the piston for play at first I thought good idea then realized I have to pull my prechambers to do that and I know how hard they come out on my last engine that blew one I never did get it pulled must have fused down in there and can only be pounded out from inside pulling the head so backed off of that idea. The mechanic also told me if it was valve train noise when you adjusted the valves noise should have went away and I agree correct me if I am wrong. Well I had a thought that if the valve train is making this noise due to worn cam lobes what if I put some engine assembly lube almost like grease on all the lobes and followers then see it that alters the noise telling me its up top not down below or would that gunk up the return holes too bad and my oil would not return? I did get 2 qts. of Marvel Mystery oil shot some about 3 oz. on all the valve stems and then I am going to drain oil look for shavings and give engine a mystery oil treatment cross my fingers restart and run awhile to see if noise changes. If it dont I have 2 options either run it till it stops or pull it put another engine in and then start looking into bottom end trouble.

Usaguy · #45 04-17-2020, 09:58 AM

Quote:

Originally Posted by yuke

run it till it stops

That's what I would do in your situation.

It will either go like this forever or a problem will become more obvious (sometimes by failing completly but wth

)