New sound from my turbo diesel - Page 2 - PeachParts Mercedes-Benz Forum

Graham · #16 10-31-2013, 09:37 AM

Thanks for all the input so far!

If I can find a valve cover gasket in town, I will probably adjust valves first (while engine is cold), just because they need to be done anyway and that will let me check around intake/exhaust. Otherwise I will do some more probing and listening around individual injectors as well as loosen belts to try and locate source of chirping.

The sound clip is about right. I find if I keep volume down, the higher pitch noise is easier to hear.

Zacharias · #17 10-31-2013, 10:01 AM

This morning I remembered something. Before you remove any belts, check to see if one is a bit loose.

I had something similar to this two years ago, around this time of year. It was a loose belt that got wet then when the overnight temperatures dropped, as they have in the last week, it made an odd sound until the car was warm. Not a normal belt squeal, more like a bearing or mechanical noise, and not unlike your noise. Worried me greatly the first day it occurred.

Just throwing that extra $0.02 into the mix.

Graham · #18 10-31-2013, 11:55 AM

Quote:

Originally Posted by Zacharias

This morning I remembered something. Before you remove any belts, check to see if one is a bit loose.

I had something similar to this two years ago, around this time of year. It was a loose belt that got wet then when the overnight temperatures dropped, as they have in the last week, it made an odd sound until the car was warm. Not a normal belt squeal, more like a bearing or mechanical noise, and not unlike your noise. Worried me greatly the first day it occurred.

Just throwing that extra $0.02 into the mix.

I was thinking same thing. With the crappy weather we have today, all I have done is ordered the valve cover gasket

Dan Stokes · #19 10-31-2013, 03:15 PM

If you suspect the belt there's a quick and dirty check. With the engine running spray the belts with anything slippery - I've used WD 40, soapy water, etc. If the sound goes away you've got it. If you're real careful you can even isolate which belt is the issue. I start from the one closest to the engine and work out as the fan can blow the slippery stuff back.

I had an old Comet that I couldn't get the belts quiet on, even with new belts. I'd do this every couple of weeks to shut the darn thing up! Now that I'm older and wiser I'd sand the pulleys but I was a kid at the time.

Dan

Graham · #20 10-31-2013, 03:32 PM

Noise still there but here is an update:

Checked for different sound from injectors. All sound same.
Checked fuel for water, but found none.
Changed primary fuel filter.
Filled new filter with ATF and ran it through.
Added some diesel treatment to tank (mixed with fuel first)

All of above, because I recall seeing a tanker truck presumably filling tanks at gas station when I filled up. But it doesn't seem to be the problem.

Checked belts for tension. No problem, but I am not discounting the belts as the problem.
One of alternator belts has a mark around outside as though it has been touching something. Perhaps alternator bolt head but it seems to have clearance.
Tried to find location of noise with listening tube. There is higher frequency noise from water pump hub, but it is a steadier sound than the chirping we hear. Probably just the normal pump noise?

Anyway coffee break over. Back to work!

Graham · #21 10-31-2013, 05:54 PM

OK, I "think" I have found the problem. Or at least I have found out how to make the noise go away (briefly).

I went back to the belts. I sprayed window cleaner (no water handy) onto the alternator belts. The noise went away immediately! But it comes back in a minute or so and even sounds worse for a short while!

You can hear the change in this clip at about 10sec in. (Ignore the cord hanging in the front - it must be part of my jacket!)
https://dl.dropboxusercontent.com/u/54783344/MVI_2021.AVI

I loosened off the three 17mm alternator bolts/nuts with a view to tightening belts. But without diagram it was not obvious which way to turn the adjuster nut! Besides, it seemed to me that nut turned a little too easily. I may just be bending the bracket. It doesn't look right!

I found a pic of what bracket should look like. Maybe I can just bend mine back into shape? I presume it gets like mine because alternator doesn't swivel freely?

Dan Stokes · #22 10-31-2013, 08:13 PM

I TOLD you that was a good trick! Now that you've found it it's just a matter of applying the fix that works.

Dan

Graham · #23 10-31-2013, 09:59 PM

First thing tomorrow will be to try and screw the adjuster rod all the way out so I can remove the nut and see if I can straighten the bracket.

Any advice on that welcomed!

I should buy new belts while I am about it, but they won't be here until next week, so will try and get it buttoned up tomorrow.

Stretch · #24 11-01-2013, 02:15 AM

Word of warning about jackets with dangly bits next to rotating parts...

...oh come on you know how it could end up!

vstech · #25 11-01-2013, 10:00 AM

Quote:

Originally Posted by Graham

I found a pic of what bracket should look like. Maybe I can just bend mine back into shape? I presume it gets like mine because alternator doesn't swivel freely?

nah... it's bent because PO or CO tried to use the adjuster to tighten the belt without all the alt bolts loose. I see it a lot. then there are the brackets that have been cut off, because they BROKE THE BOLT attempting to tighten the belts without loosening ALL THREE ALT BOLTS!

Graham · #26 11-01-2013, 10:58 AM

Quote:

Originally Posted by Stretch

Word of warning about jackets with dangly bits next to rotating parts...

...oh come on you know how it could end up!

Funny, I didn't notice it until I played the video clip!

Graham · #27 11-01-2013, 11:01 AM

Quote:

Originally Posted by vstech

nah... it's bent because PO or CO tried to use the adjuster to tighten the belt without all the alt bolts loose. I see it a lot.

I am sure that is true, but right now with all three bolts and nuts loose, the adjuster turns freely, but I think it is just bending the bracket. I will try and get some WD-40 down in around the bolts or maybe a crowbar!

my123ca · #28 11-01-2013, 12:13 PM

Quote:

Originally Posted by Graham

One of alternator belts has a mark around outside as though it has been touching something. Perhaps alternator bolt head but it seems to have clearance.
Tried to find location of noise with listening tube. There is higher frequency noise from water pump hub, but it is a steadier sound than the chirping we hear. Probably just the normal pump noise?

Anyway coffee break over. Back to work!

Is it the inner belt? I have an unusual wear on one side of the inner belt. I suspect the water pump pulley is not in spec anymore. It looks like the grroves have expanded causing wear on the inner belt. The outer belt is fine.

Graham · #29 11-01-2013, 01:19 PM

Quote:

Originally Posted by my123ca

Is it the inner belt? I have an unusual wear on one side of the inner belt. I suspect the water pump pulley is not in spec anymore. It looks like the grroves have expanded causing wear on the inner belt. The outer belt is fine.

I haven't removed the belts so can't be sure. They both look about same tension, just the wear mark on outside of inner belt where it probably at some time has been contacting the head of a bolt under alternator.

JB3 · #30 11-01-2013, 01:22 PM

Quote:

Originally Posted by Graham

I am sure that is true, but right now with all three bolts and nuts loose, the adjuster turns freely, but I think it is just bending the bracket. I will try and get some WD-40 down in around the bolts or maybe a crowbar!

almost every alternator ive removed has been seized to the inner mounting bracket ears and had to be knocked or wedged free with a crow bar so that it would actually swing.

I think most of these brackets are bent for this reason honestly, they are just too weakly constructed with that folded ear to break the corrosion bond and bend in first.