Ticking and low oil pressure at start - PeachParts Mercedes-Benz Forum

JHZR2 · #1 10-01-2021, 11:54 PM

I adjusted valves and changed oil after today.

I’m noticing a tapping sound besides the diesel clatter. I think it’s easier to hear with hood closed:

https://youtu.be/367uf1nvC-U

Then open:

https://youtu.be/I8NreJc4jPQ

Where it seems more faint. It is pretty fast ticking noise.

After changing oil, I was also surprised that I didn’t see a pegged pressure gauge with the new oil that was ambient temperature. I’m used to seeing a pegged needle at cold start, but instead saw this with fresh rotella 5w-40:

This engine barely cranks before it fires, and idles so smooth when cold, it’s unbelievable. Just great. Hot sustained idle gets a bit of idle shake, with good mounts and shocks.

Any thoughts on that ticking? Cause for concern? I did have the injectors rebuilt and balanced

Sugar Bear · #2 10-02-2021, 12:00 AM

Oil pressure not pegged at idle is not concerning.

Have you been using the 5W-40? The first and only time I used it in a 617 the engine sounded so different I promptly changed it back to 15W-40.

Good luck!!!

rrgrassi · #3 10-02-2021, 02:52 AM

Also, when was the last time the valves were adjusted?

barry12345 · #4 10-02-2021, 06:49 AM

Old timers figure 15-40 is thinnest oil for these older diesels. Both your problems are probably a result of that thinner oil. You pretty well have the proof of it.

JHZR2 · #5 10-02-2021, 09:12 AM

Quote:

Originally Posted by rrgrassi

Also, when was the last time the valves were adjusted?

Yesterday. A few were tight, and one intake valve was loose.

JHZR2 · #6 10-02-2021, 09:14 AM

Quote:

Originally Posted by Sugar Bear

Oil pressure not pegged at idle is not concerning.

Have you been using the 5W-40? The first and only time I used it in a 617 the engine sounded so different I promptly changed it back to 15W-40.

Good luck!!!

I have run 5w-40 in other 617 engines since around 2002. I’ve run 5w-40 in my low mileage 616 engine since 2007 or so.

The 617 I have now starts and runs beautifully. But this is the first time I’ve noted a not-pegged needle on a cold start. That’s what I picked up upon.

JHZR2 · #7 10-02-2021, 09:16 AM

Quote:

Originally Posted by barry12345

Old timers figure 15-40 is thinnest oil for these older diesels. Both your problems are probably a result of that thinner oil. You pretty well have the proof of it.

5w-40 is still pretty viscous when cold.

I’m not convinced the ticking noise is a valve, as it’s faster than my perception of the diesel clatter. How it would be oil related is beyond me.

Diesel911 · #8 10-02-2021, 10:26 AM

If it was me I would start listening with a Mechanics Stethoscope or a piece of broom stick (which I prefer) on various parts of the engine especially around the Vacuum Pump to locate where the tapping ins coming from.

JHZR2 · #9 10-02-2021, 11:18 AM

Quote:

Originally Posted by Diesel911

If it was me I would start listening with a Mechanics Stethoscope or a piece of broom stick (which I prefer) on various parts of the engine especially around the Vacuum Pump to locate where the tapping ins coming from.

Agree.

I don’t really know enough about the differences between valve noise, injector noise, nailing, and vacuum pump noise. And, I suspect that a belt could do it too… if there was a spot on a pulley.

Broomstick is better than a stethoscope?

Where on the VP is the best spot to listen, if it is coming from there, it means what, that a bearing is loose in the race?

Diesel911 · #10 10-02-2021, 02:23 PM

Quote:

Originally Posted by JHZR2

Agree.

I don’t really know enough about the differences between valve noise, injector noise, nailing, and vacuum pump noise. And, I suspect that a belt could do it too… if there was a spot on a pulley.

Broomstick is better than a stethoscope?

Where on the VP is the best spot to listen, if it is coming from there, it means what, that a bearing is loose in the race?

It is a personal thing. I find the mechanics stethoscope to be too loud and more importantly too short which has me bending over and getting my face too close to moving parts. The probes on the ones I have are metal and I don't like the idea of metal making contact with moving nor electrical parts.

A 3-4 foot wooden broom stick keeps your face a long way away from moving and hot parts. It also does not conduct electricity. When the fan clips it I have so far never seen any damage done to the fan.

Some people do the same with screw drivers especially a long one. Ear on the end. But, of course it can conduct electricity.

The articulating parts are inside of the middle of the Vacuum Pump. You are going to be limited to places you can get at on the vacuum pump. Someplace

The attached picture is deceptive because the Power Steering Pump is gong and there is no Power Steering belt blocking the V Pump.

You should be able to get at some where within the lazy circled area. There may be a small area on the other side you can also get at but I cannot remember specifically.

JHZR2 · #11 10-02-2021, 10:45 PM

Strangely enough, relative to the low oil pressure at cold start, it pegged as normal today.

I had run the engine to fully circulate and verify level, before the car sat a while and then I observed the above outcome.

I drove the car maybe 75-ish miles yesterday after all that.

This was the first time I ran an OE MB filter (I assume it’s a Mann), not some other off brand. I wonder if the OE filter is somehow different t such that it takes longer to fill, has a different level of restriction , or something else. I’d assume it’s just a Mann filter with a different t stamping on the top cover. Regardless, it was fine today fwiw.

83w126 · #12 10-03-2021, 01:46 AM

I used to run 5w-40 in my om617 with 400k+ miles on it and it had no issues with it.

250 Coupe · #13 10-04-2021, 04:52 PM

On the broomstick or screwdriver trick, I find it works best if I use the end of the tool to close the ear by placing it just forward of the ear and sliding it back. This blocks the sound path via air while still allowing bone conduction which is what you want.

Michael

JHZR2 · #14 10-23-2021, 10:47 AM

Quote:

Originally Posted by 250 Coupe

On the broomstick or screwdriver trick, I find it works best if I use the end of the tool to close the ear by placing it just forward of the ear and sliding it back. This blocks the sound path via air while still allowing bone conduction which is what you want.

Michael

I’ve been doing this, using the broomstick versus a typical stethoscope.

I’d say it’s definitely not the vacuum pump. The ticking sound seems to be coming from the rear of the engine, manifold side. Injector 5 return hose is seeping, but putting the stick on the injector doesn’t seem to transmit different noise from the others. Putting the stick on the injector line may sound slightly different, but I can’t tell 100%. What I can notice is being down at the rear on the opposite side by the ATF filler I hear it most pronounced.

I also seem to notice diesel exhaust pretty pronounced from up there.

250 Coupe · #15 10-23-2021, 11:19 AM

A leaking exhaust manifold can make a ticking sound.

Switch from a solid stick to a piece of tubing to find it. Most any flexible tube will work although small stuff like vacuum hose can be a pain. 3/8” fuel hose or 5/8”-3/4” heater hose works very well.

Michael