Loud Tapping, Rough Idle, Had to Tow - Page 2 - PeachParts Mercedes-Benz Forum

leathermang · #16 05-13-2015, 07:51 AM

Rod Bearing Babbitt itself is not magnetic. I suppose that the part of the " insert ' that supports the Babbitt could be magnetic.... but I think there is too much mass shown to be that...
So I think you are looking at the vacuum pump ... lots in the archives about it imploding and putting major amounts of junk into the pan...
Can also be the chain mechanism for the oil pump drive...
At this point Diesel911 's suggestion is top of the list...

BillGrissom · #17 05-13-2015, 01:38 PM

The oil level can get too high if the "lift pump" (below hand plunger) has a leaking seal thus letting diesel into the crankcase. That would dilute your oil and could cause wear & perhaps eventual failure of bearings and oil pump wear.

In most cars it is possible to replace the crank bearings with engine in car. You push the upper half around to get it out. Clean the gap w/ ethanol before sliding the new upper shell in. I tore apart my 1985 engine when it failed (pistons, not bearings) and don't recall the main bearings differing from my Chryslers (one of which I replaced main bearings from below). Rod bearings can always(?) be replaced from below, and usually fail before main bearings.

The problem on your engine is removing the upper oil pan to expose the crank. Search if anyone has managed to remove w/ engine in car (looks challenging). It doesn't use a gasket, rather a special "anerobic sealant" which is a type of superglue.

kalikar85 · #18 05-13-2015, 05:18 PM

new developments:
here are pics of the Vacuum Pump

it appears fine to me?
im thinking its a chain/ oil pump part maybe as leathermang is suggesting?

looking into checking or replacing rod bearings with the engine on. not finding much info on this so far.

Quote:

Originally Posted by BillGrissom

....The problem on your engine is removing the upper oil pan to expose the crank. ...

doesnt the crank case expose the crank? Im actually unclear, after removing the crank case during valve adjustment and removing the oil pan as to where the rod bearings are. Aside from Valve Adjustment procedure, Ive never had any other experience with working inside the engine.

mannys9130 · #19 05-13-2015, 05:50 PM

If the shards are magnetic that will usually rule out bearing material. It has to be Iron.

That vacuum pump doesn't look like it grenaded. How does the timing device look behind the pump? The wavy drive piece should be smooth and intact.

If you can remove the upper oil pan with the engine in the car, you can inspect and replace the main and rod bearings. However, I don't think it's a bearing since the shards are magnetic.

Did the knock sound like it was coming from a particular spot, like up high in the head or down low by the crank?

kalikar85 · #20 05-13-2015, 06:23 PM

pics of valve area.

The timing device looked ok behind the vacuum pump.

The tap sounded like it was coming from starboard side. Im assuming from the crank case. Pulling over it sounded like something banging around down into the oil pan.

I started it up again (before the tow) and it was apparently fine: no tap and no rough idle. Second time it was tapping again and shaking.

im debating at this point wether to close it up, try starting it, and listen where exactly its coming from.

Any good links on removing the upper oil pan? seems like I have nothing to lose at this point by pulling it off.

mannys9130 · #21 05-13-2015, 07:36 PM

Does it sound like this?: http://m.youtube.com/watch?v=SogAyxDFDgo

The cause ends up being this: http://m.youtube.com/watch?v=IHm8OB9bcO8

If you don't mind a little mess, you can run it with the valve cover off to observe the valve train.

I have a feeling it's rod knock though.

kalikar85 · #22 05-13-2015, 10:09 PM

Quote:

Originally Posted by mannys9130

Does it sound like this?: http://m.youtube.com/watch?v=SogAyxDFDgo

The cause ends up being this: http://m.youtube.com/watch?v=IHm8OB9bcO8

I have a feeling it's rod knock though.

yeah thats what it sounds like.

pretty resolved that its a rod bearing/ rod knock.

my question now is this:

are there any resources or links on pulling the upper oil pan and/or replacing rod bearings on a 617 with the block in the car?

e.g. is it possible to get the upper pan off? if so, can you access the rods and rod bearings from there? how many rods are there? how do you turn the crank to get to the different rods/ bearings? do they just pop out/in with a screwdriver?

Partscarver · #23 05-14-2015, 12:48 AM

Quote:

Originally Posted by mannys9130

Yes, if the bearing is so far gone that it's shedding shavings of itself and creating a loud knock, the engine is no longer usable.

too much iron in the oil pan, crank is a boat anchor. lucky the block did not self ventilate.

search for a new motor..

charmalu · #24 05-14-2015, 02:09 AM

I agree with what you found in the pan, time to take up fishing, you have a great Boat Anchor. LOl.

Look for another engine, keep this one and tear it down to see what went wrong.

Found this link if you want to remove the upper pan w/o removing the engine from the vehicle.

Removal and installation of complete oil pan

I have removed the pan with the engine on a Stand, can`t imagine doing it
laying under the vehicle, at least on one of these MB`s.

Charlie

leathermang · #25 05-14-2015, 06:03 AM

Quote:

Originally Posted by BillGrissom

....==
In most cars it is possible to replace the crank bearings with engine in car. You push the upper half around to get it out. Clean the gap w/ ethanol before sliding the new upper shell in. I tore apart my 1985 engine when it failed (pistons, not bearings) and don't recall the main bearings differing from my Chryslers (one of which I replaced main bearings from below). Rod bearings can always(?) be replaced from below, and usually fail before main bearings.

The problem on your engine is removing the upper oil pan to expose the crank. Search if anyone has managed to remove w/ engine in car (looks challenging). It doesn't use a gasket, rather a special "anerobic sealant" which is a type of superglue.

I vote no on both of these concepts...... Just no way to properly measure or check for damage caused by what has happened.... Twenty One to ONE compression ratio puts tremendous pressure on those rod bearings... how could that much torn up insert get to the oil pan with scaring the rod journal ?????? or perhaps the rod itself... ?????? and if you put a new rod in .... pretty much impossible due to not being able to pull the piston out the bottom... then it would not be the same weight as the others.... and doing this stuff upside down.... one needs to actually read the FSM to get an appreciation for the tightness of the parts put together in these engines...
Look for replacement engine... or take this one out and do the rebuild correctly on an engine stand with the FSM at your elbow all the time...

Shortsguy1 · #26 05-14-2015, 09:04 AM

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.

leathermang · #27 05-14-2015, 10:03 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 · #28 05-14-2015, 11:58 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?

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.

barry12345 · #29 05-14-2015, 12:11 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.

leathermang · #30 05-14-2015, 12:14 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......