Loud Tapping, Rough Idle, Had to Tow - Page 3 - PeachParts Mercedes-Benz Forum

leathermang · #1 05-14-2015, 11:03 AM

Quote:

Originally Posted by Shortsguy1

Assuming it is a bearing, is there a typical reason this occurs? Is there anything one should do to specifically avoid this problem? Or is regular maintenance the only preventative?.....

The use of approved DIESEL OIL for the temperature ..... the regular changing of the oil and proper filters..

If you had a way..... the use of a preoiler like commercial engines use is very nice...makes sure your bearings have lubrication from rpm ONE and up.... as much of the wear on an engine happens in the time between start up and getting to working temperature.

I personally change to straight 40 wt oil after 100,000 miles on all my cars.. gas or diesel.... I am in a hot climate to I use a straight number.... those additives which make for multi viscosity ratings take away from the lubrication ability of the oil..... as evidenced by the fact that the worst running conditions.... a small gas air cooled engine... were always specified as needing STRAIGHT 30 wt oil.....

barry12345 · #2 05-14-2015, 01:11 PM

Quote:

Originally Posted by leathermang

The use of approved DIESEL OIL for the temperature ..... the regular changing of the oil and proper filters..

If you had a way..... the use of a preoiler like commercial engines use is very nice...makes sure your bearings have lubrication from rpm ONE and up.... as much of the wear on an engine happens in the time between start up and getting to working temperature.

I personally change to straight 40 wt oil after 100,000 miles on all my cars.. gas or diesel.... I am in a hot climate to I use a straight number.... those additives which make for multi viscosity ratings take away from the lubrication ability of the oil..... as evidenced by the fact that the worst running conditions.... a small gas air cooled engine... were always specified as needing STRAIGHT 30 wt oil.....

Fundementaly in a summer use car or where the temperatures will allow it. The use of straight 40 diesel oil is going to provide more wear protection. There are several common sense observations that actually prove it. I do not think having 100k miles aquired is a requirement to do it either.

I always thought that these engines should last longer than owners report. One problem is many may have already as so many odometers are not accurate.

Even as far north as the cooler east coast of Canada most old timers believe that anything less than 15-40 should not see regular service in older style diesel engines.Not changing the oil often enough is a really bad ideal on these high soot level generating engines. When the soot clumps it is abrasive in nature.

barry12345 · #3 05-14-2015, 12:58 PM

Quote:

Originally Posted by Shortsguy1

Assuming it is a bearing, is there a typical reason this occurs? Is there anything one should do to specifically avoid this problem? Or is regular maintenance the only preventative?

I definitely feel bad for the op. Good luck with a resolution.

If it is the number one rod bearing. There is a chance the engine was run with low fuel pressure in the base of the injection pump for a long time.

Either still low or was. In my opinion it increases the loading on the first cylinders rod bearing. Enough to cause additional bearing wear on it compared to the others..

Not as big an issue as it is on the 616 engines.. Not changing fuel filters until they have been run somewhat restrictive for a long time is my thought on the usual causitive. Or a weak return spring in the relief valve as well or with the filters in combination.

The weaker lift pumps pressure output on the 616 engine compared to the 617 turbo engines may also be an additional contributor as well. It is hard to prove this other than the original thinking it was because. Being at the end of the lubrication chain of the rod bearings was the issue.

That it is more prevelant on the 616 engines to me eliminated the then original belief it was a lubrication issue.. I could still be wrong but suspect not.

This is reinforced by the wife not correcting my thoughts on this issue.

My additional belief that re kitting the lift pump and installing a pressure regulating spring from a 617 turbos pump in a 616 lift pump might be a good upgrade. If nothing else it will do no harm.

It took a lot of thought for me to arrive at this suspected conclusion with my small brain.Over time I have not observed anything new to lessen this belief. To the contrary everything I have noticed since tends to support my belief.

Hopefully by adjusting the fuel pressure to `19 pounds instead of the factory recommended 12- 14 pounds. May just with a little good luck shift the injection profile enough to equalise the wear by reduction of the loading on the first cylinder even a little more than normal.

Now this portion is just a totally unproven suposition. The problem with the fuel pressure is the effect it has is bad enough to actually be audiable. That was one of the principal reasons amoungst many that originally led me to my suspicion.

I do not want to come across as a parrot on this issue. Yet at the same time I think it is a very important part of a maintenance program on these engines that is not taken seriously enough.

For a 616 owner to ignore it especially Is a roll of the dice you should not take. You want to know what your fuel supply pressure is in the base of the injection pump. Seems to be somewhat less critical on the 5 cylinder 617s but still an issue with them at least my mind.

I really hope that some other theory will prove mine wrong. I do not always have to be right. Until then if you like it or not keep your fuel pressure in the base of the injection pump up where it belongs. The price of not doing so can be too high in comparison to the prevention. If I am right. Also your engine will run quieter on the highway.

I have two 240s. One was or seemed noisier on the highway. It had low fuel pressure. It seemed to quiet down at least a little after I got the low fuel pressure corrected.

I am aware of the issue of we wishfully want to believe something is now quieter. Several 617 owners have also reported the same effect.
They too may be delusional as well though.

leathermang · #4 05-14-2015, 01:14 PM

Barry has proposed this theory many times before...
there are no physics rules which agree with the idea that less fuel to the first cylinder would cause more pressure... none..
.... will elaborate if I get a chance.. but wanted to save this space next to his post..
Well, Barry posted fast enough that this is not next to his post...
but I appreciate the vote of confidence on the oil choice......

barry12345 · #5 05-14-2015, 03:47 PM

Not a dog with a bone syndrome. I am wide open to others thoughts. My thought is rather than differant amounts of fuel fill and that is probably occuring. The principal suspicion is the sequential timing is changed as any element with getting less fuel.The injector will open later than by design.

The lift pump is a constant pressure type but at the same time only recharges once per injection pump revolution. Filling the later elements in a a really low fuel pressure initial setup may mean they are almost scavaging from the decreasing low pressure profile.

Since the relief valve is no longer functional. There is nothing to provide a constant fuel pressure through the remaining fills until the lift pump recycles again.fuel most likely is not able to flow through the filters quick enough to make up the deficiency even if the constant pressure is still available at the lift pump.

As I have said I feel this is a long term deficiency problem that wears the first cylinders rod bearing faster. Why I know something is going on is the engine sounds different with different fuel pressures to the base of the injection pump. The power balance of the engine sounds better with good pressure as well. . Anything you can actually hear has got to be signifigant.

Plus in corrected situations there seems a little more power available in the seat of your pants. With that relief valve closed because of not enough pressure to keep it open. The pulses that are generated inside the base of the injection pump are fierce. How and if they contribute to the issue is another unknown to me.

Now back to your oil viscosity issue.I am no rocket scientist. Say you have a car on 10-30. The car is burning a quart of base oil every 300 miles. You change to a straight 30 weight. Your consumption on average will drop to 5-600 per quart usually..

The only change that seems reasonable to me is the viscosity in effect must remain better. The multi grades state they protect to the same. Still it almost cannot be on a true overall viscosity basis.

The 10-30 has a polymer type component that changes with temperature. The molecule size of it might be much larger in any temperature state than oil. Or only at higher temperatures.

We all realise that a 240d on 15-40 will usually consume more oil than normal on the highway. I attribute this to the higher rpms on average it must run at in comparison to the 617 for a usable speed. I do wonder if the same engine was on straight 40 if the consumption pattern would be less or more on the highway. I suspect it might be less. Just not certain of that either.

Another thought along this line.If you are burning multi grade oil. Is the polymer being burnt up at the same rate? If not by continually adding oil you would have an increase overall of the polymer component. That may be good or bad. I just do not know.

The producers of the multigrade oils have not been particularily open about the whole picture. My wifes car for example takes a 0-20 synthetic oil. To keep the warrranty valid they want only certain oils used. This has led my to wondering why the synthetic oil must be special. Plus what is in it that is different than the normal run of synthetics.

The best yardstick I have been using to determine the probable life left in my engines is the oil consumption rate for a long time now.There is a serious problem with wear. Once it reaches a point it almost exponentially increases.

leathermang · #6 05-14-2015, 04:16 PM

Quote:

Originally Posted by barry12345

Not a dog with a bone syndrome. ....

The evidence is looking otherwise...

first.... the setting of the fuel is done with the drip method ON THAT NUMBER one cylinder.... so if anything IT WILL BE CORRECT and the others 'overfueling' according to your visualization.

second.... even if that first one was getting less fuel no physics rule suggests that would cause more pressure on that piston... in fact it suggests less .

third.... the pop pressures are within a range ...none are perfect... and do effect the timing.. but there is NO evidence that what you suggest about number one.... and refer to ' first' ..... would cause it to be out of sync with the piston movement....

barry12345 · #7 05-14-2015, 04:08 PM

Not a dog with a bone syndrome. I am wide open to others thoughts. My thought is rather than differant amounts of element fuel fill and that is probably occuring. The principal suspicion is the sequential timing is changed as with any element getting less fuel than another.The injector will open later than another one. The effect being a timing reduction more likely than a fuel amount. Any element overloads in a good fuel pressure situation.

The lift pump is a constant pressure type but at the same time only recharges once per injection pump revolution. Filling the later elements in a a really low fuel pressure initial setup may mean they are almost scavaging from the decreasing low pressure profile available down the line of sequential loading.

Since the relief valve is no longer functional. There is nothing to provide a constant fuel pressure through the remaining fills until the lift pump recycles again.Fuel most likely is not able to flow through the filters quick enough to make up the deficiency even if the constant pressure is still available at the lift pump. Any filter acts as a restrictor to some extent.

As I have said I feel this is a long term deficiency problem that wears the first cylinders rod bearing faster. Why I know something is going on is the engine sounds different with different fuel pressures to the base of the injection pump. The power balance of the engine just sounds better with good pressure as well. . Anything you can actually hear has got to be signifigant.

Plus in corrected situations there seems a little more power available in the seat of your pants. With that relief valve closed because of not enough pressure to keep it open. The pulses that are generated inside the base of the injection pump are fierce. How and if they contribute to the issue is another unknown to me.

Now back to your oil viscosity issue.I am no rocket scientist. Say you have a car on 10-30. The car is burning a quart of base oil every 300 miles. You change to a straight 30 weight. Your consumption on average will drop to 5-600 per quart usually..

The only change that seems reasonable to me is the overall viscosity in effect must remain better. The multi grades state they protect to the same. Still it almost cannot be on a true overall viscosity basis.

The 10-30 has a polymer type component that changes with temperature. The molecule size of it might be much larger in any temperature state than oil. Or only at higher temperatures.

We all realise that a 240d on 15-40 will usually consume more oil than normal on the highway. I attribute this to the higher rpms on average it must run at in comparison to the 617 for a usable speed. I do wonder if the same engine was on straight 40 if the consumption pattern would be less or more on the highway. I suspect it might be less. Just not certain of that either.

Another thought along this line.If you are burning multi grade oil. Is the polymer being burnt up at the same rate? If not by continually adding oil you would have an increase overall of the polymer component. That may be good or bad. I just do not know.

The producers of the multigrade oils have not been particularily open about the whole picture. My wifes car for example takes a 0-20 synthetic oil. To keep the warrranty valid they want only certain oils used. This has led my to wondering why the synthetic oil must be special. Plus what is in it that is different than the normal run of synthetics.

The best yardstick I have been using to determine the probable life left in my engines is the oil consumption rate for a long time now.There is a serious problem with wear. Once it reaches a point it almost exponentially increases.

As for air cooled engines. I do not care if the manufacturere specifies 10-30. They are more prone to metal to metal contact. I only cut grass in warmer weather. So all our lawn tractors get straight 30 or 40 weight detergent oil.

We never have worn engine problems. The overall lawn tractors eventually all fall apart around engines that are still running as new. Although if the tractor had an internal 100 percent aluminium oil pump except the shaft. I might not do this.

My brother in law has said he has run into a few problems with modern oil pumps. The owners had been using a heavier oil than specified is what he thinks the issues may be.

leathermang · #8 05-14-2015, 02:54 PM

When I first pull the dipstick out on my 240 it shows NO OIL ON IT...
my heart almost stopped the first time I saw that...
but if you put it back in you should get the true reading... it showed just right..'
and many have recommended that these cars be run with the engine oil showing half way between High and Low on the dipstick...... over that can cause oil burning for some reason... does with mine..
AND something to check.... the COLOR of your dipstick has to be correct for YOUR engine.... we have had people find it was the wrong color... and thus length...

BillGrissom · #9 05-14-2015, 04:00 PM

I would at least take off the lower oil pan, since fairly easy. One often must do that to replace a leaky gasket anyway. That might give enough view to tell what is wrong. As I recall, all you can see thru that hole is the oil pump, lower timing chain, and #1 cylinder, but perhaps a mirror would let you see all the rods. You can rotate the engine with the crank bolt, with exactly the right socket to fit the narrow gap to the fan shroud. The bolt on the p.s. pump is tempting. People say not to rotate the engine using it, but I have.

I agree that if the metal shards are from a bearing, then the crank is probably marred, but doesn't hurt to inspect if you can.

leathermang · #10 05-14-2015, 04:06 PM

Quote:

Originally Posted by BillGrissom

.... The bolt on the p.s. pump is tempting. People say not to rotate the engine using it, but I have.....

NOT PEOPLE...

The Mercedes Benz Factory Shop Manual specifically forbids using that nut to turn the engine.

That is a tapered shaft and pulley inside and you can ruin the shaft over torquing it... which by definition turning the engine will do. But it is YOUR car and you are free to mess it up as you please by not following what the factory says is correct procedure... they make these rules just to harass owners.. not because they know that much about the cars....

leathermang · #11 05-14-2015, 04:19 PM

Two point Seventy Five ..... GALLONS .....?????
is that correct for what you drained out ??????
How much is your car supposed to hold ?

kalikar85 · #12 05-14-2015, 04:28 PM

Quote:

Originally Posted by leathermang

Two point Seventy Five ..... GALLONS .....?????
is that correct for what you drained out ??????
How much is your car supposed to hold ?

sorry, it was about 2.5 gal. total that came out, yes. (plus what I pulled the night before chasing the leak pre-problem)
it filled up a 2.5 gal Topsider Oil Extractor Can when drained to check the pan.

So it was about 2-3 qt over-filled still. is this a serious factor?

leathermang · #13 05-14-2015, 04:31 PM

OK...
here is a potential reason for the failure..
Overfilling is WAY BAD because it can put the oil level so high that it is whipped by the crankshaft .. or the air around the crankshaft... so it oxidizes it......
that VERY QUICKLY takes away its lubrication properties..

Maxbumpo · #14 05-14-2015, 04:41 PM

So it sounds like you added a gallon when you thought it was low, two months ago, and it immediately began to drip oil from between engine and transmission, which may mean the oil level was overfilled by 1 gallon (4 qts) or more, and was lapping at the rear main crank seal, which is not designed to have fluid pressure against it and promptly began leaking.

leathermang's comment on the crankshaft whipping the oil is right on, all that splashing would add air bubbles into the oil, which could then get sucked up by the oil pump and from there reduce the lubricating and cooling ability of the oil, so then bearings may have suffered.

What is really curious to me is that you say it ran with no noise and smooth idle for a minute right before the tow. Maybe when you let it sit, the air came out of the oil, and there was enough oil pressure / lubrication to temporarily prevent the knocking?

leathermang · #15 05-14-2015, 05:12 PM

Quote:

Originally Posted by Maxbumpo

=....leathermang's comment on the crankshaft whipping the oil is right on, all that splashing would add air bubbles into the oil, which could then get sucked up by the oil pump and from there reduce the lubricating and cooling ability of the oil, so then bearings may have suffered.....

OH... I did not visualize it past the oxidation... that is a very likely scenario....once you have significant actual bubbles in the oil then the oil pump immediately has pressure problems just the way a brake system with air in it does... the air compresses.... so your whole ability to push oil under sufficient pressure to those bearings is compromised FAST....
Good Catch....